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Food processing and engineering

Multiple choice cards
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Cards total
Name 5 examples of unit operations.
evaporator, storage tanks, filler, shipping, peeler/dicer, washing, mill, pasteurizer, grinding, extraction, drying
What is the Weissenberg effect?
the tendency of some viscoelastic fluids to climb up a rod that is rotating in them. (fluid flows in a right angle to the direction of shear stress)
What added ingredient keeps confectioners sugar from clumping?
corn starch
The sterilization value, also known as F sub zero describes what?
the integrated impact of time and temperature on the microbial population, expressed as time at the reference temperature, calculated by using the lethal rate times heating time
What does power dissipation measure and what are the units?
conversion of microwave energy to heat, and W/cm^2
Name 3 types of conventional heating.
conduction, convection, and radiation
What is the difference between traditional thermal processing and aseptic processing?
traditional: food is packaged then sterilized, ex canning. aseptic: food is sterilized and packaged in a sterile container and is only practical for liquid or fluid products
The main component of an Infrared Heating Equipment is the radiator, name 3 types of radiators and length of wave.
gas heated (long waves), electrically heated radiators (tubular/flat metallic heaters (long waves), ceramic heaters (long waves), quartz tube heaters (medium/short waves), and halogen tube heater (ultra short waves))
What is SCP?
single cell protein
What is an ideal surface which absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence, and emits the maximum possible thermal radiation at a given temperature?
Which of the following is not found on pyschrometric chart: Enthalpy, abs humidity, wet bulb temp, thermal conductivity
thermal conductivity
Name three types of freezers.
air blast freezer, contact or plate freezer, spray or imersion freezer
What are some of the advantages and disadvantages of radio frequency heating?
advatanges: longer wavelength, deeper penetration depth, shorter treatment time, less equipment space requirement, volumetric heating; being a continuous process disadvantages: non-uniform heating,
How many main effects are there in a three way ANOVA?
Potassium sorbate can be applied to sausage casings before or after stuffing to retard what?
mold growth
What is the SI unit for pressure?
What are 4 applications that use spray drying?
powdered cheese, cream powders, egg powers, milk products
With respect to food processing, what is SS 316?
SS 316 is a food grade austenitic stainless steels
What is a theoretical plate in simple distillation?
A theoretical plate is an area in the column where the recondensing liquid and the rising vapor come into equilibrium with one another
What type of heating arises from the direct conversion of electrical energy in the form of microwaves to heat within the volume of the food itself?
microwave heating
What is the log of 1?
What process is done prior to freezing or dehydration to inactivate enzymes?
blanching, chemical inactivation
What general type of foods must go through either retort or pressure cooking under anaerobic conditions?
low acid, high pH foods
In Planck Distribution, At a given wavelength, what happens to the emissive power as the temperature increases?
emissive power also increases
In enzymology, what is turnover number?
moles of substate converted to product by an enzyme molecule (activation site) in a given time period
Describe the meaning of 150-grade pectin.
A 150 grade pectin is one that will form a satisfactory gel at a ratio of 1 kg (or unit) pectin to 150 kg (or unit) sugar.
Which food processes is acetaldehyde found in?
Foods that involve yeast fermentation, it is a metabolic byproduct from the yeast.
What are the 3 main components of a microwave heating system?
magnetron, waveguide, and cavity
What is the mechanism of action for the microbial destruction by High Hydrostatic Pressure and Pulsed Electric Fields?
PEF: electroporation (the formation of pores in cell membranes by the action of high voltage electric fields). PEF inactivation via electroporation is believed to be associated with the migration and accumulation of charge across the cell membrane under the action of applied electric field; HHP: Rupture or damage to cell membrane
How does fat have "shortening power"?
It interlaces between protein and starch structures and makes them tear apart easily and 'short' rather than allowing them to stretch long. This is a tenderizing effect for meat and baked goods.
What is the definition of calorie?
The quantity of heat needed to raise the temperature of 1 kg of water by 1°C.
Give 2 examples of emulsifiers.
SPAN, TWEEN, Lecithin, egg white
What is a commercial undercounter refrigerator known as?
A lowboy or a bar refrigerator
Falling film is a type of which equipment in food processing?
Name 5 types of heat exchangers used for food processing.
shell and tube heat exchanger, spiral heat exchanger, plate heat exchanger, jacketed pans, scraped surface heat exchangers, corrugated tube heat exchanger, finned tube heat exchangers, double pipe heat exchanger
What is a technique used to inject pickle simultaneously and automatically through a series of hollow needles, the shafts of which have numerous, evenly spaced holes along their lengths?
multiple injection pumping (stitch)
The sun can be approximated as a blackbody at what temperature?
What is the boiling point of water in Fahrenheit, Celsius and Kelvin?
212 F, 100 C, 373 K
What is the difference between direct and indirect heating systems?
direct: having steam condense into a product (directly contacts product). indirect: the use of equipment to exchange heat between the surface that is heated and the product
What is the main advantage of an agitating retort over a still retort?
increase in heat transfer, decrease time for geometric center to reach desired temperature
What are the 4 purposes of evaporation industry?
reduce the volume of a product Preconcentrate a liquid Increase solid content in food Reduce the microbial load
Why do foods freeze faster than they thaw?
Water layer insulates, thermal conductivity and thermal diffusivity of ice>water
Name of the food derived from dried maize that has undergone nixtamalization)
Cornmeal that has been soaked in an alkaline solution, e.g., limewater (a process known as nixtamalization), it is called masa harina (or masa flour),
What property of a liquid provides resistance to flow?
Why are fruits or vegetables often heated prior to maceration for juice production?
to speed up the process or to infuse flavors prior to maceration, to increase extract yield and to inactivate the enzymes
Name 3 types of non-thermal pasteurization.
high pressure processing, pulsed electric field, ultraviolet, radio frequency, ultrafiltration
What process is used to set color and inactivate enzymes?
Name 3 pieces of equipment that thermocouples are frequently used in
ovens, furnaces, flue gas, and other areas that have temperatures above 250 C
What are the 3 effects of high temperature on whey protein?
denaturation, coagulation, cooked flavor
Why are fats neutralized during processing and manufacture and how is it done?
oil breakdowns to Free fatty acid & other simple compounds, lead to off flavor & off odors, Soap is formed from the fatty acids by addition of alkali to remove these undesirables.
What is one advantage and one disadvantage to direct heating?
advantage: rapid heating minimizes organoleptic changes, less fouling/burn-on. disadvantage: requires culinary steam (expensive), increases volume of product (adds water from steam), bad for products containing oil (oxidizes quickly)
Give two ways starch is modified for use in foods.
Cross linking, derivatives e.g. phosphate esters, acid/enzyme thinning, precooking
What is a humectant?
Humectants control water activity in foods, thus enhancing stability and viscosity, maintaining texture and reducing microbial activity. Humectants chemically bind water and reduce water activity.
What term is a measure of ability to store electrical energy?
dielectric constant
What are the units for absolute humidity?
grams of water vapor per cubic meter volume of air
What is the main purpose of food processing?
to extend shelf life of a product by reducing or eliminating microbial activity and ensure food product safety
Describe the difference between shear and normal stress.
Shear is parallel to the surface, normal is perpendicular
Name two refrigerants that are not CFCs.
NH3 and SO2
Thermal destruction of microorganisms obeys zero order, first order, or second order kinetics?
first order
Why does water heat rapidly in a microwave oven?
Water is a dipole molecule. As the microwave field oscillates, the dipole of water will try to oscillate to follow the field
List all the different types of thermocouples.
J, K, E, T, N, B, R, S
What is sodium silicoaluminate used for?
An anticaking agent
Why do bubbles form in boiling and not evaporation?
because the vapor pressure can overcome the atmospheric pressure
The hydrolysis of a specific bond in kappa casein (phe 105 - Met 106) results in what?
destabilization of the casein micelles (cheese curd formation)
Define the Biot number.
dimensionless quantity used for heat transfer calculations. The ratio of the heat transfer resistance inside of and at the surface of the body.
What is a dielectric material and give an example?
dielectric materials are an electrical insulator that can be polarized by an applied electric field. examples include: porcelain/ceramic, mica, glass, plastics, various metal oxides
Explain thixotropic and pseudoplastic.
Thixotropy is the property of certain fluids and gels of becoming thinner when a constant force is applied. A pseudoplastic fluid is a fluid that increases viscosity as force is applied. The main difference is that viscosity of thixotropic fluids decreases upon applying a force whereas the viscosity of pseudoplastic fluids increases upon applying a force.
Given type of heat exchange, say whether there is aroma retention or not: steam injection/infusion, plate heat exchanger, tubular heat exchanger, scraped surface heat exchanger
all yes (retain aroma) except steam injection/infusion
What are the X and Y axis on a lineWeaver Burk plot?
X=1/[S] (substrate concentration) and Y=1/v (velocity (reaction speed)
Name the microorganism responsible for tequila fermentation.
zymomonas mobilis
A force of 60 kg m/s^2 is applied to a body with a mass of 2 kg. What is the acceleration?
30 m/s^2 (F = mass x acceleration)
List the following olive oil grades from most pure to least pure. US virgin olive oil not fit for human consumption without further processing, US extra virgin, US virgin, US olive oil, US refined olive oil
US extra virgin, US virgin, US virgin not fit for human consumption without further processing, US olive oil, US refined olive oil
Define absolute zero and provide the kelvin, Celsius, and Fahrenheit temperatures for this point?
temperature at which particle motion stops (is minimal), 0 kelvin, -273.15 Celsius, -459.67 Fahrenheit.
What are 3 reasons for piling blocks of curd during the cheddaring process?
Acid development, texture development, uniform heating
The amount of heat required to raise the temperature of 1 g of water 1 degree Celsius is called what?
How does the high sugar content in food affect the drying process?
It takes longer, as sugar attracts water.
List three advantages of intermediate moisture foods.
refrigeration is not required, spoilage is slower, relatively cheap and energy efficient
The theoretical expression describing the force which must be applied before a substance will flow freely is called ...
yield stress
Turbulent flow is characterized by NRE = _______________
> 3500
Name 3 advantages of microwave heating.
reduced process time, higher food quality, better appearance/flavor/taste, convenient, easy clean-up, decreased cost of electricity, increased retention of vitamins and minerals
What type of enzymes are commonly added to fruit prior to juice production?
pectic enzymes (specifically polygalacturonase, pectinesterase, and cellulases, and other enzymes)
Describe the winterization process for an oil.
Colling the oil Filtering the solids formed This filtering ensures that the long chained saturated fats do not crystallize at low temp
Name the only fruit or vegetable that is never sold frozen, canned, processed, cooked or in any other from except fresh.
What type of sensors have resistance characteric fall off with increasing temperature?
negative temperature coefficient
What are 5 factors that will influence dehydration?
temperature, dryness, air volume, particle size, type of food or load
Describe the process of forming an hermetic seal.
the can end and body are interlocked during two rolling actions, first action curls the edge of the can end up and under the flange of the can body, and the second action roll flattens and tightens the seam
Name a dielectric material that is composed of weakly bonded molecules that reorient so their symmetry axis aligns to the field.
glass is dielectric
What are some of the advantages of resistance temperature detectors (also known as RTD)?
most accurate sensors for industrial applications and have the best long-term stability, can cover a wide range of temperatures, and can hook up to a computer
What is a process where an electric current is passed through the food with the main purpose of heating it?
ohmic heating
What is the boiling point of water in Fahrenheit, Celsius and kelvin?
212 deg F, 100degC, 373degK
What is the denominator of a t-test?
standard error of the mean
What are the advantages of a plate heat exchanger?
low initial cost, high heat transfer efficiency, small hold up volume in heat exchanger, easy to inspect and disassemble unit, flexibility of the system (can be readily expanded/contracted to perform multiple duties)
What salts can be used to promote coagulation when making tofu?
Calcium sulfate or magnesium chloride
What is the Aw limit or requirement for filing a process when heat-processing foods in hermetically sealed containers?
What is "converted rice" and how is it manufactured?
Whole grain rice is parboiled or steeped in hot water prior to removal of the hulls, bran, and germ in milling. The rice loses fewer nutrients as the B vitamins and minerals from the hulls, bran, and germ are leached into the endosperm. The converted rice is then dried, milled, and polished
Shear stress is linearly proportional to shear strain in which type of fluids?
Newtonian fluid
What is the microorganism used to make miso and sake?
Aspergillus orzae
What is carboxy-methyl cellulose often used for in foods?
What is ohmic heating?
it is where an electrical current is passed through a suitable conducting product causing it to heat
In Microwave processing, what is penetration depth?
The penetration depth is used to denote the depth at which the power density has decreased to 37 % of its initial value at the surface.
A food preservation method that utilizes liquid nitrogen to rapidly freeze foods is called what?
Cryogenic Freezing
A higher attenuation factor does what to the distribution?
makes the distribution less uniform
When making extra virgin olive oil what is the maximum number of hours required from harvest to processing?
What is the process by which the passage of an electric current through a conductor produces heat
Joule Heating
What is the protein source in TVP (textured vegetable protein)?
What is a mathematical technique for determining the best use of available resources when these resources can be used in other products?
least cost formulation
What is an intermediate moisture food?
contains 10-50% water with an Aw of 0.60 - 0.90
What are two types of processes that involve the removal of thermal energy and at what temperatures are these two processes?
refrigeration (40 F or 4.4 C) and freezing 0 F or -17.8 C)
The point at which the air is saturated or the relative humidity is 100% is called what?
The dew point
What is a material property that determines the distribution of energy within the material?
attenuation factor
Name the equation that relates electrochemical cell potential to redox states.
Nernst equation
What is the relationship between dielectric constant and frequency?
as frequency increases, dielectric constant decreases
What are two approaches used to make intermediate-moisture foods?
Partial Drying, Osmotic Drying, Dry Infusion, Blending (formulation)
Define thermal death time.
the time it takes to kill a specific bacteria at a specific temperature
Name any three enzymes that are inactivated during blanching.
PME, PPO, lipoxygenase, polygalacturonase,chlorophyllase
What is another name for industrial evaporation?
Name a chart used in unsteady state heat transfer.
gurney-lurie chart, heisler chart
What three parameters determine hold tube length?
residence time, system flow rate, hold tube internal diameter
What are some of the advantages of a tubular heat exchanger?
few gaskets, low maintenance costs, compact units, no moving parts
Why is flash cooling important?
it produces a consistent product density
What is the cutoff Reynold's number for laminar flow?
What is a common unit of brightness or luminous intensity?
How does a bimetallic thermometer work?
there is a bimetallic strip that converts a temperature change into a mechanical displacement. There is a mechanical displacement because the strip is formed from two different metals that expand at different rates when heated
What type of heat exchanger is preferable for high viscosity sauces/foods in an aseptic process system?
Which Serbian-American inventor born in present-day Croatia, also an electrical engineer, mechanical engineer, and a futurist is attributed with the invention of alternating current and also has a unit of magnetism named after him?
Nikola Tesla
Define "microencapsulation".
Microencapsulation is the science of trapping components (core or active) into a secondary material (encapsulant, wall material, carrier, or cover), producing small solid particles (1–500 ?m in size). These particles are able to release their contents at a specified rate or under specific conditions.
What is the number of equivalent minutes at 121 C delivered to a container of product calculated using a z value of 10 C known as?
F or sterilization process equivalent time
What is active and passive modified atmosphere packaging?
Active - respiration of product will produce the intended or necessary store environment, that is, the storage atmosphere changes over time; passive: intended atmosphere is applied and stays the same through the storage period
Name two types of heat exchangers used to process particulate foods?
Scraped surface and tubular
What are some of the disadvantages of thermal processing?
nutrient loss, reduce desirable qualities such as texture, flavor, color, lower antioxidant and phenolic content
What is the dielectric constant?
a quantity measuring the ability of a substance to store electrical energy in an electrical field
SI unit for Power & dimensions
W (J/s)
The door of a microwave is often glass with a metal mesh imbedded, why is that so?
while microwaves can go through glass, they cannot go through metal, and so the mesh has holes small enough that microwaves cannot pass through but allows for the person to view the food inside
What is the simple term for conversion of raw materials or ingredients into a consumer food product?
Food Processing & Engineering
What is a unit operation?
a basic step in operation
In a closed vessel, what happens to the density of gas when the temperature changes?
The density of gas stays the same
What is the name of the process that is used for high-acid foods? The food is held at 170-190 deg for 25-30 minutes.
hot, fill, hold
Lyophilization refers to the process of what?
Freeze Drying
Dielectric heating is also called what, and why?
volumetric heating, and because heat is generated throughout the food volume
Name 2 non-thermal food processing technologies?
UV light, ultrasound, high pressure, pulsed light, pulsed electric field, irradiation
What is the latent heat of fusion?
constant temperature as a liquid turns to a gas
How does ultraviolet light affect fat oxidation?
What are some of the disadvantages of frozen foods?
thermal abuse during transportation/storage (warming or freezing product), ice crystal formation (affects food quality), freeze burn/ice crystal formation breaks down cells
A physical change in an amorphous material promoted by the addition of heat and the uptake of low molecular weight substances called plasticizers is called what?
glass transition
What is a Kilojoule?
The SI unit of energy.
In indirect heating, what is heat regeneration?
using sterilized product to heat sterilized product and thereby cooling the sterilized product
Name two methods for irradiation of foods.
Cobalt 60, x-rays, or E-beam
What are levels of exposure in kGy for radurization, radicidation, and radappertization?
radurization: 0.75-2.5 kGy; Racidiation 2.5-10 kGy; Radappertization: greater than 30-40 kGy
How is banana oil made?
Synthetically using isoamyl acetate
Thermistors are NTC sensors. What does NTC stand for?
negative temperature coefficient
The science of the deformation and flow of matter is known as
At what frequency are radio waves typically at?
less than 300 MHz
What are some two reasons for roasting cocoa beans for chocolate making?
Flavor development, separate outer husk from inner bean (makes cracking and winnowing much easier), virtually sterilizes cocoa been (prevent growth of bacteria/fungi/molds), even color and texture
What are the 4 parameters for the processing of fluids flowing through a pipe?
Pipe diameter, viscosity, velocity, and density of fluids
How much heat is needed to raise 1 gram of water by 1 degree Celsius?
1 Kelvin
What is the process of sterilizing the product and package separately called?
aseptic or ultra high temperature (UHT) processing
Generally, what is the net rate of heat transfer of food?
rate of absorption- rate of emission
What is the temperature and time range for commercial sterilization?
116-121 C (240-250 F) for 50-90 min
In cocoa processing, what does NARS stand for?
Nibs alkalizing roasting and sterilizing
What law describes the theoretical spectral distribution for the emissive power of a black body?
Planck law
A strawberry processor makes a "4+1" product. What do that "4" and "1" stand for?
4 parts strawberries, 1 part refined sugar
Complete the term: First in
first out, aka FIFO
What are the four main products of the corn wet-milling proces?
protein, starch, oil, fiber
What are the 2 types of direct heating?
steam injection and steam infusion
What are some advantages of aseptic processing?
convenience (many foods can undergo aseptic processing), safety (protect against spoilage and foodborne illness), flavor and freshness (captures the natural flavors and has a fresh clean taste), natural (no need for preservatives)
What are some factors that may affect aseptic processing?
if the product has particulates, size of particles, viscosity, product thermal sensitivity
What preserving process loses the most vitamins and minerals?
There are many types of ISM bands available for dielectric heating, what does ISM stand for?
Industrial Scientific Medical
What are three types of food containers commonly used in retorting?
metal containers (cans), glass containers, retort pouches
What disease is currently devastating the Florida Citrus Industry?
Citrus Greening or HLB
Until a few decades ago, Freon-12 was commonly used in what food processing operation?
Give three reasons for drying foods.
The main objective of drying food is to prolong its shelf-life beyond that of the fresh material, while at the same time minimizing undesirable changes in appearance, texture, flavor, and nutritional value during the drying process. In addition to the preservation of the product, drying can bring about savings in storage and transport of foods owing to the reduction in weight and bulk that occurs during most methods of drying.
Which gas often removed from packaging in thermal processes?
Sharp freezing can be described as ___________?
still air freezing
Named after the Italian physician & physicist Luigi Galvani, name the instrument used to measure electric current.
Galvanometer (Ammeter also acceptable)
2 piece cans for low acid foods are made in what? a. impact exit b. draw + iron c. draw redraw(?) d. welding
c. draw-redraw
Explain IR radiation.
it is transmitted as a wave and gets converted into heat when it impinges on the food surface
In dairy processing, what do the initials CIP stand for?
Clean in place
What are 5 methods of freezing?
plate/contact, still air/cold room/sharp, blast air, IQF/Fluidized bed, immersion/spray, cryogenic, sharp, rotary, spiral, band
In cheese making, the "cheddar" process involves: A) adding lactic acid to milk B) adding rennet C) turning and piling the curds D) chopping the curds and adding salt
C) turning and piling the curds
What does HTST stand for?
High temperature short time
In cheese making, what terms describe the solid mass and the liquid phases?
solid; curd; liquid:whey
beta-d-galactosidase is added to dairy products for what three reasons?
Hydrolyzes lactose to galactose and glucose- latter combination is sweeter than lactose; prevents sandiness defect in ice cream; makes products consumable for lactose intolerant individuals
What equipment is preferred to sterilize canned soups?
Rotary retort
What are some of the disadvantages of using a thermistor?
limited temperature range, low accuracy at higher temperatures, non-linearity at higher temperatures (resistance over temperature decreases exponentially)
What is the relationship between temperature and penetration depth?
as temperature increases, penetration depth decreases
Rate the following materials from lowest thermal conductivity value to highest: water, aluminum, stainless steel, glass, air, copper
air, water, glass, stainless steel, aluminum, copper
What does IQF stand for?
Individually quick frozen
Ratio of viscous/elastic portion in rheology:
tan delta or damping factor
What is the purpose of the heat penetration test in thermal processing?
to determine the temperature of slowest heating zone in a food container, and use the time/temperature data to calculate a thermal process that will render the product commercially sterile
What is another name for the Carnauba wax?
Brazil wax, palm wax, "queen of waxes"
What is the name of the viscous liquid in which legumes have been cooked?
It's called aquafaba
In material/energy balance for continuous processes, what must also be considered?
Two main functions of emulsifying salts in processed cheese making?
Flavor, emulsification
What is accomplished by passing steaks or boneless sub-primals through a bank of needles or through a steak macerator?
Mechanical Tenderization
What is reverse osmosis?
Reverse osmosis is a process that removes foreign contaminants, solid substances, large molecules and minerals from water by using pressure to push it through specialized membranes. It is a water purification system used to improve water for drinking, cooking and other important uses.
What effect is described by a visco elastic fluid climbing an impeller shaft during mixing or agitation?
The Weissenberg Effect
Rank the following pulse waveforms used in pulsed electric field processing in order of increasing electrical efficiency: oscillatory, square wave, exponentially decaying
exponentially decaying, square wave, bipolar, oscillatory
Give 3 visible signs of chilling injury.
poor ripening, pitting, collapse of structural integrity, development of off-flavors and rotting
What food characteristics influence microwave heating?
dielectric properties, thermal properties (specific heat), size and shape of food, food orientation in microwave, physical state of water (ice and water), moisture content, salt content, oil content
What would be acceleration of a 2 kg mass when 60 N force is applied?
Accl: 30 m/s2
What are 4 advantages of radiant heat?
non-contact heating, fast response, reduced heating time, uniform heating, reduced quality losses, versatile, simple, compact equipment, and significant energy saving
Turbulent flow is characterized by NRE = _______________
pvD (p = density, v = flow velocity, D = orifice diameter)
What relies on abrasion of meat against stainless steel rotating paddles to accomplish diffusion and binding of curing ingredients with meat?
In what year was there a patent registered for use of a commercial refrigeration process for fish?
In a multiple effect evaporator what term is used to calculate efficiency?
SE (steam economy)
The unit used to measure an absorbed dozes of ionizing radiation is the “RAD”. What does “RAD” stand for?
radiation absorbing dose
What are the advantages of non thermal processing over thermal processing?
prevention of thermal off flavors, better flavor, better nutrient retention
What is freeze drying?
Process of removing water from a product by sublimation and desorption.
What are the 5 classes of unit operations?
fluid flow, heat transfer, mass transfer, thermodynamic processes, mechanical processes
Why does water have a high specific heat?
Stabilizing effect of hydrogen bonding
In unsteady state heat transfer, what is the dimensionless number used to evaluate the importance of internal and external resistance to heat transfer?
the biot number
How many pecks are in a bushel? 2, 4, 8, 16
b. 4
Name 3 applications for radio frequency in food processing.
baking, drying, defrosting, pasteurization/sterilization, kill pests still in walnut shells
What is the difference between dried food and dehydrated food?
dehydrated food as no more than 2.5% water on a dry basis and dried food can be more than 2.5%
What is the purpose of thermal processing?
ensure food safety and extend the shelf life of food (by killing bacteria)
What temperature type of sensor is based on the effect of a junction between two different metals that produce a voltage that increases with temperature?
In the SI system what are the units applied to the following 5 dimensions or measurements? length, mass, time, electric current, thermodynamic temp
meter, kilogram, second, ampere, Kelvin
Name 2 chemical agents used to accelerate bleaching of wheat flour.
chlorine dioxide (widely used), and benzoyl peroxide
What is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity (RH) of 100%?
What is the most common technique used to make dried pet food?
Why are chelating agents used in dairy products?
de-aggregate casein complexes
State Hook's law.
F = -kx (k = spring constant, x = spring elongation, F = force)
(Bonus) For fluids, flowing through a pipe. Name the four parameters included in the calculation of Reynolds number.
viscosity, pipe diameter, velocity, density (Re: Dv(rho)/(nu))
Name the piece of milk processing equipment used to remove some bacteria and sediment originating from the cow's udder.
Which unit of electricity measures the number of electrons moving through a wire?
How are processed cheeses made?
processed cheese are made either with the trimmings that are left over from the manufacture of other cheeses, or from dried milk powder
During typical food heating, what is the starting size of gap that microwaves cannot pass through?
0.122 m to 0.328 m
What is the surface temperature of a block of dry ice?
-109.3 degrees Fahrenheit (-78.5 degrees C)
Give 3 advantages of food dehydration over sun drying.
more controlled conditions, shorter drying time, better sanitary conditions, no climate losses due to weather, some products (such as milk) cannot be sun dried
What is specific gravity?
ratio of density of a substance to the density of water at a given temperature
What instrument is used for dough-mixer to measure torque?
Name 4 enzymes required to produce high fructose corn syrup.
alpha-amylase, glucoamylase, glucose isomerase, xylose isomerase
In which dairy product is acetaldehyde a problem or defect
What are the 8 key elements in an aseptic processing system?
the product, flow control (pumps), deaerator (optional), product heating, hold tube, product cooling, surge tank, filler for packaging
What is the term for the use of heat to eliminate a desired number of microorganisms from a food product?
thermal processing
What is the thermal conductivity of ice?
2.22 - 2.35 W/m K (4 times more than water)
What is the purpose of having a back pressure device for the hold tube?
to prevent flashing or boiling
What off flavor of milk develops as a result of the release of hydrogen sulfide?
Cooked flavor
What is the boiling point definition?
the temperature at which the vapor pressure becomes equal to the atmospheric pressure (760 nm)
What are some of the disadvantages of a tubular heat exchanger?
excessive pressure drops, inability to open and inspect surfaces, only 70-75% regeneration which is lower than plate heat exchangers, fouling tendencies because of low shear, restriction of products by viscosity and particle size
What are some ways to heat process food?
retort, aseptic, pasteurize, blanch, hot fill
What happens during the secondary phase of freeze drying?
removable of non-freezable water via evaporation, lowers the water activity
Name 4 factors that influence dehydration.
temperature, dryness, air volume, particle size, type of food, and load
In sterilization and pasteurization, what is the purpose of the hold tube?
make sure the product has the correct residence time (aka the time necessary to sterilize/pasteurize at a certain temperature)
Solids are __ to thermal radiation.
What are some advantages of a scraped surface heat exchanger?
process any pumpable product, adding surface area, low pressure drops, can process at high temps without burn-on
Give 3 methods for the production of corn syrup from starch.
acid hydrolysis, acid-enzyme hydrolysis, enzyme-enzyme hydrolysis
What are the ingredients needed to make sweet pickles?
cucumbers, salt, vinegar, and sugar
Which MAP gas has bacteriostatic/bactericidal properties?
carbon dioxide
Which is the name of the process where a foods temperature goes from 32deg F to 25degF in 30 minutes?
Quick freezing
What is the most advantageous type of IR and why?
far-IR, most food components absorb radiative energy in this region
What is microencapsulation?
a process in which tiny particles or droplets are surrounded by a coating to give small capsules.
What is the spectrum range for thermal radiation?
0.1 um to 1000 um (1 mm)
At what frequency are microwaves typically at?
300 MHz to 300 GHz
What is the distance from the surface of the food material at which the incident microwave power is reduced to 1/e of its value at the surface of the product?
penetration depth
A retort temperature of 250 F is achieved with how many pounds of pressure?
What are some disadvantages of a scraped surface heat exchanger?
high cost per units area, high operating costs, large floor space requirement vs other heat exchangers, disintegration of fragile particles
Which Serbian-American inventor born in present-day Croatia, also an electrical engineer, mechanical engineer, and a futurist is attributed with the invention of alternating current and also has a unit of magnetism named after him?
Nikola Tesla
What is the inverse of attenuation factor?
penetration depth
True or false? Milk homogenization slows creaming by changing oil droplets radius
Give three product or product category applications for lecithin as an additive?
The primary applications for lecithin are in baked products, dairy blends, baby foods, nutritional drinks, margarines, chocolates, chewing gums, and confectionaries
What is the term for determining the microwave absorptivity of a material and absorbed microwave energy determines the amount of energy converted to heat?
dielectric loss factor
What is the range of BCU used in baking applications?
The BCU range will be from 0.00 (darkest) – 5.25 (lightest) BCU.
Name 6 food products that use freeze concentration.
coffee, citrus, juices, beer, wine, vinegar, dairy products, meat/fish extracts
Name 4 enzymes required to produce high fructose corn syrup.
alpha-amylase, glucoamylase, glucose isomerase, xylose isomerase
What is the term for determining the magnitude of reflection, refraction, and transmission of microwave radiation?
Fresnel equations
Soft wheat is preferable for flours used in making cake because
development of weak gluten (soft crumb etc.)
Given an example of a product that requires asceptic processing.
Liquid eggs, milk, milk products, long term products that need to be sterile
What salt is traditionally used to coagulate tofu?
Calcium sulfate
Name three methods of microencapsulation technology.
Spray drying, spray cooling, emulsification, extrusion, simple coacervation, complex coacervation, internal/ external gelation, fluidized bed coating, etc.
Why add K(ALSO4)2 to a pickle mix?
To keep the pickles firm (the AL3+acts as a cross linker between pectin polymers)
What is the equation for conduction and define each term?
Q=KA[?T/L] Q=the heat rate K = thermal conductivity L= thickness of the wall A = surface area of the wall ?T = the difference in temperature between the 2 sides
What is reverse osmosis filtration?
only water can pass through the membrane, filters out un-disassociated acids and monovalent species, pressure is 200-300psig
What is the relationship between wavelength and frequency?
wavelength= speed of light / frequency or speed of light = frequency * wavelength
Give 3 types of natural and 3 synthetic surfactants in foods.
natural - saponins, lecithin, lipoproteins, gums; synthetic - mono and diglycerides, sorbitan monostearate (SPANs) and polysorbates (TWEENs)
How does ionic polarization contribute to heating?
ions in solution move in response to applied electric field component of the microwave, and the collisions with other molecules convert kinetic energy into heat
Why are fruits or vegetables often heated prior to maceration for juice production?
to inactivate native enzymes, reduce microbial load and affect an increase in juice yield
What law of filtration rate to change in presse drop across a filter bed?
Dary's law
In thermoprocessing, what is the difference between "sterility" and "commercial sterility"?
commercial sterility means the probability that spores or cells survive is low but not absolute. Sterilization means the destruction of all viable microorganisms that may be present, and they cannot grow because of pH, temperature of storage, etc.
The viscosity of egg white decreases with shearing force. In rheology this is called:
pseudoplastic or shear thinning
What term refers to the percentage change in length of a material due to pulling stress before breakage?
elongation or strain
Resistance temperature detectors, also known as RTD are PTC sensors. What does PTC stand for?
positive temperature coefficient
In thermoprocessing, what is the difference between "sterility" and "commercial sterility"?
Sterility: free from microorganism Commercial Sterility: Free from pathogenic microorganisms and reduced levels of spoilage microorganisms that does not affect quality of a product
Name three types of retorts.
Still, agitating, continuous , discontinuous, still with overpressure
What type of pump is preferable and why in an aseptic processing system and?
PD pump (positive displacement pump), it is less sensitive to pressure drop than centrifugal pumps
How long is the average lactation cycle of a cow?
The cycle is split into four phases, the early, mid and late lactation (each of about 120 days, or d) and the dry period (which should last as long as 65 d). In an ideal world, cows calve every 12 months
What is the term used to describe the ratio of the viscous portion to the elastic portion?
Tan delta or loss factor
What is 1 way to measure sorption isotherms?
gravimetric, manometric
What is the difference between plate heat exchanger and tubular heat exchanger in regards to the heating/cooling medium flow?
plate heat exchangers have concurrent flow while the tubular heat exchanger have countercurrent flow
What two factors largely determine the degree of thermal processing required?
pH of foods and rate of heat penetration into canned products
Why is glucose oxidase sometimes added to egg whites before dehydration?
removes glucose and reduces browning
Type of food spoilage organisms depend on food composition and intrinsic and extrinsic factors. Give 3 each of intrinsic and extrinsic factors
intrinsic: physical structure, Moisture content, pH. Extrinsic: temperature, relative humidity, gas atmosphere, light
Name the basic components of a mechanical refrigeration system.
Compressor, condenser, evaporator, expansion valve
What is the typical shelf life of pasteurized milk held under refrigeration?
12-16 days
Explain how gamma rays destroy microorganisms.
Gamma rays induce free radical formation, which can interact with DNA and other cellular constituents, which would destroy the organism.
Give me four reasons why compounds are micro encapsulated?
Increase bioavailability, delayed release, stability, to protect (to protect reactive substances from the environment To convert liquid active components into a dry solid system to separate incompatible components for functional reasons to mask undesired properties of the active components to protect the immediate environment of the Microcapsule in capsules from the active components, and then the controlled release or delayed release)
What does FIFO stand for and why it is used?
First in First out, to ensure product turnover
What would you do to change a temperature reading from Farenheit to degree Rankine?
add 459.67
Acrolein is a potentially toxic product that can occur in food processing applications. Give the source and the type of degradation can yield this chemical.
Thermal decomposition of fats
What should be the size of milk fat globules after homogenization?
less than or equal to 2 microns
What factors affect heat penetration in canned foods?
container size/shape, product consistency (homogenous or not), type of retort (still vs agitating)
A plot of 1/Vmax plotted against 1/ substrate concentration is called what?
lineweaver burk plot
Give two examples of an emulsifier.
Lecithins, Mono and diglycerides, Monoglyceride derivatives, fatty acid derivatives. Examples include: Soy lecithin, Tween, Potassium stearate
What is the name of the holes in swiss cheese and what are they caused by?
Eyes; the carbon dioxide produced by the microbe Propionibacterium freudenreichii subsp. shermanii
Prior to dehydration, many fruits are exposed to sulfur gas in order to prevent microbial growth and browning.
Give 3 ways to produce ethylene gas.
There are three main ways to produce ethylene: 1) gas from a cylinder, 2) catalytic generator, and 3) ethephon
Prevention of damage in food during freezing is promoted by slow cooling to minimize ice nucleation. True or False?
True or False: Canned foods are sterile.
False, they are commercially sterile
What is the amount of antibiotics allowed in milk?
Additional component in mass and energy balance equation in food processing
- Time sucrose +heat + acid --> Hydrolysis/inversion
Another name for decimal reduction time is?
What are the 3 regions of IR radiation?
near-IR, mid-IR, and far-IR
What vegetable oils are approved for use in butter manufacture?
What is the 1st law of thermodynamics?
Energy can neither be created nor destroyed. It can only be converted from one form to another. The total amount of energy of an isolated system is constant.
What is the world's oldest and most common form of food preservation?
Why does a hold tube have an upward slope?
to eliminate air pockets and ensure self draining
A US gallon is equivalent to how many UK gallons (out to 1 significant figure)?
What is the difference between accuracy and precision?
Accuracy refers to how close a measurement is to the true or accepted value. Precision refers to how close measurements of the same item are to each other.
What does a correlation coefficient define?
a statistical measure of the strength of a linear relationship between two variables
The thermal conductivity of ice is approximately how many times greater than that water?
four times
What are the two roles of salt in bread making?
changes taste, effects rheological properties by making dough stronger
What is thermal conductivity?
a measure of a material's ability to transfer thermal energy
Nonthermal process which is called as purple blow torch, inactivates 99% of norovirus on fruit surface?
Cold plasma
Give four pulse waveforms used in Pulsed Electric Field.
Exponentially decaying, square wave, bipolar, oscillatory, instant charge reversal pulse
What is aseptic processing?
food and container are sterilized separately and then filled in a sterile environment
With respect to distillation, what is a vaporize/condensation stage called?
A theoretical plate
What's the equation for Planck-Einstein relation with respect to radiation?
E = h * (nu)
This substance is formed from gliadins, glutenins and glycolipids when water is mixed with wheat flour.
What are 4 advantages of impingement heating?
efficient heat transfer, uniform heating, better moisture retention in food, heat transfer is independent from the conveyor belt, easier nozzle configuration, adjustable velocity and temperature
Give 4 reasons why compounds are micro-encapsulated.
Stability against oxidation, bioavailability, stability, resistant to pH, protect reactive substances from the environment, controlled/delayed release of compounds
What does URP stand for?
unique radiolytic product
What are some advantages of using the formula (ball) method to calculate lethality?
allows use of semi-log curves for detailed analysis of time/temp data, can calculated processes of a rang of IT and RT utilizing heating factors, conservative process model
What is zymology?
the science of fermentation
What are the parameters that are controlled during post harvest preservation of fruits and vegetables?
temperature and humidity
Name three drying methods used.
spray drying, freeze drying, bed, drum, convection, sunlight, dehydration
Name two unripened cheeses?
Cottage, cream, ricotta, farmers Neufchatel, mozzarella, queso blanco, quark, camorra, bakers
Gel formation in frozen egg can be prevented by
2-10% NaCl 8-10% sucrose
What are the advantages of traditional thermal processing over non-thermal processing?
Thermal processing can destroy spores
Name 2 types of dielectric heating.
radio frequency and microwave heating
What pH distinguishes the difference between low acid and high acid foods?
pH 4.6
What are the three most commonly used additives?
sugar, salt, corn syrup
The study of dielectric properties concerns ____ and ____ of electric and magnetic energy in materials
storage and dissipation
What is the interior temperature of a block of dry ice?
Name 5 types of nonthermal pasteurization.
high-pressure processing, pulsed electric field, ultraviolet, radio frequency, ultrafiltration
What does it mean for data to be accurate?
that data is close to the true value of measurement
Describe how a material is heated using radio frequency heating.
the radio frequency generator creates an alternating high frequency electric field between two electrodes (or capacitor), the material being heated is conveyed between the electrodes causing power water molecules in the material to continuously reorient to face opposite electrodes. the friction from the molecular movement causes the material to rapidly heat volumetrically
When viscosity of a fluid increases, what happens to the reynolds number?
What is the condition caused by dehydration and oxidation from the frozen surface of a food product?
freezer burn
Named after the Italian physician & physicist Luigi Galvani, name the instrument used to measure electric current.
Galvanometer (Ammeter also acceptable)
At which frequency, 915 or 2450 MHz will the penetration depth be larger?
915 MHz
How do refrigeration and freezing affect staling? a. both slow staling b. fridge slows staling, freezing aids staling c. fridge aids staling and freezing slows staling d. both aid staling
c. fridge aids staling, freezing slows staling
Define viscosity.
The state of being thick, sticky and semifluid due to internal friction. measure of its resistance to gradual deformation by shear stress or tensile stress
What does the “c” stand for in the equation E=mc^2?
the speed of light
Name 3 methods of fruit and vegetable peeling.
steam peeling, knife peeling, abrasion peeling, caustic peeling and flame peeling
Briefly describe the still retort process
cans are loaded into the vessel, steam is injected into the vessel, fan circulates steam for uniformity, vent valve (cold air goes out), temperature and pressure increase to desired temp then vent valve closes, temperature is maintained for desired time (processing time), then precooling begins where the pressure is maintained while slowly cooling the cans, circulating pump with cold water moves into the vessel and gradually decreases the temperature, the drain opens to drain water, and once the cans are cooled and the pressure decreases, the cans can be removed
What commercial product can be described as dilute acetic acid?
What are some of the benefits of using a conveyor system in an air impingement oven?
help cook food well/evenly, control temperature and time, control cooking, cook large amounts of food in a continuous process, shorter process times, improved product quality, can use for both heating and freezing foods
Why is the recommended storage temperature for potatoes greater than 25 degrees C?
Lower temperatures result in more reducing sugar formation creating the potential for browning (called Cold-Induced Sweetening)
What is the term for electromagnetic radiation generated by the thermal motion of charged particles in matter?
thermal radiation
Okara is a by-product of what processing?
What is Coulomb's law?
The electrical force between two charges of magnitude Q1 and Q2 separated by a distance r in vacuum is; f = k(Q1*Q2)/r^2) where k= 1/(4*pi*epsilon naught)
What are the main stages of canning?
heating phase (removal of air, come-up time, holding time at processing temperature), cooling phase
What are isotonic solutions?
solutions that have the same osmotic pressure at the same temperature
What type of temperature sensor is made from certain metal oxides whose resistance decreases with increasing temperature?
Why is quality of food better in retort pouches than in conventional cans?
thinner profile means the less time to reach sterilizing treatment at center of pouch, saves money and time
What is the simplest and cheapest method for food drying?
Sun drying
Name 2 approved bleaching agents used in flour production.
Cl2, NOCl, N2O4, benzyl peroxide, ClO2, NO2, lipogenase
Steady state mass balance equation
Mass in - mass out = mass acumulation
What are some ways to reduce non-uniform heating during microwave heating?
rotating food with motorized platter, pre-heating and holding time after the microwave heating, adjusting power settings in microwave ovens
What is the unit of ionizing radiation dose in the International System of Units (SI)?
What is a sorption isotherm?
relationship between equilibrium moisture and water activity
Why can microwaves go through glass but not metal?
glass is dielectric
Which equation describes the relationship between temperature and water activity?
Clausius Clapeyron Equation
The ratio of the sine of the angle of incidence of a ray of light on the surface separating two media to the sine of its angle of refraction is called:
refractive index
What are some disadvantages of using the formula (ball) method to calculate lethality?
only can use at a constant retort process temperature, the cooling portion modeling is empirical and may over/under estimate lethality
What are the 5 classes of unit operations?
fluid flow (fluid transportation, filtration, solids fluidization) Heat transfer (canning, freezing, blanching) Mass transfer (extraction, dehydration, frying) Thermodynamic processes (gas liquefaction, refrigeration) Mechanical processes (solids transportation, crushing, pulverization, screening, and sieving)
Do resistance thermometers or thermocouples have a higher upper limit temperature?
Food radiation is capable of destroying all the following in foods except, A. microrganisms, B. bacteria, C. viruses, D. insects, E. prion
What is the cooking loss percentage of a roast that had a raw weight of 20 lbs and a cooked weight of 15 lbs?
The temperature at which the water vapor in the air under a constant barometric pressure will condense into liquid water is called?
the dew point
Which of the following are emulsifying salts for use in the processing cheese? A - sodium tartrate, B - sodium chloride, C - Potassium chloride, D - all of the above
a. sodium tartrate
What is flash cooling?
the process of removing heat, moisture, and entrained air from the product prior to filling
What is the main disadvantage of commercial sterilization of a food?
significant changes in nutritive and sensory characteristics
What are 2 internal conditions that affect drying?
properties of the food, thermoconductivity, density, porosity, sorption isotherms
What is the % sugar w/v of a solution with specific gravity of 1.06 and 15 brix?
15.9% (15*1.06)
Another name for thermal resistance constant is
Give the michaelis-menten equation and give two assumptions underlying its derivation.
V0 = Vmax ([S]/([S] + KM)); This equation includes the assumption that during the early stages of the reaction so little product is formed that the reverse reaction (product combining with enzyme and re-forming substrate) can be ignored (hence the unidirectional arrow under k3). Another assumption is that the concentration of substrate is much greater than that of total enzyme ([S] >> [Et]), so it can essentially be treated as a constant.
How many radians are there in 360 degrees?
2 pi
what are the 2 main components of food that absorb far-IR energy?
water and organic compounds (such as proteins and starches)
Enzymes are used extensively by the food industry as processing aids for ingredient production. The enzymes alpha amylase, glucoamylase, and glucose isomerase are used in sequence to produce what food ingredient?
High fructose corn syrup
Term for temp at which Vapor Press = press of surrounding?
Boiling pt
In temperature sensing, what does the abbreviation RTD stand for?
resistance temperature detector
What are some characteristics of microwaves?
travels at speed of light, non-ionizing form of radiations, can be focused into beams, can transit through hollow tubes, may be absorbed or reflected by the material depending on its dielectric properties, may also transmit through materials without any absorption (includes glas, ceramics, some thermoplastic plastics)
If you had 10 ml of Kool-Aid with 10% sucrose, how much water should you add to make the drink 0.1% sucrose?
990 ml water
Naturally occurring and synthetic agents that are used in food processing for production and stabilization of dispersions are called what?
surface active agents (surfactants)
What is the relationship between dielectric loss factor and penetration depth?
as dielectric loss factor increase, penetration depth decreases
What is the name of rotating screw technology?
At what temp does a solution of 20% amylose and 80% water boil?
100 C
What is the slowest freezing method?
Sharp freezing
Name 5 types of air convection dryers (heated air dryers)
Kiln, cabinet, tunnel, Solar, conveyor, fluidized bed, air lift, rotary, spray drier, Freeze Dryers, Vacuum Dryers
What are the units for the convective heat transfer coefficient?
W/m2C or W/m2K
Polyvinylpolypyrrolidone, gelatin, egg albumin and Icing glass are commonly added to beverages direct processing, why?
To clarify because they form complexes with tannins and polyphenols which then precipitate out.
Name four types of sucrose used in industry.
bottler's, canners, liquid, granulate (sanding, baker's special, cordial, fine, gelatin, unigran), powdered/ confectionary sugar, brown sugar (dark and light)
Give the equation for determining loss tangent, also called dissipation factor.
dielectric loss factor divided by dielectric constant
Name 4 applications for Infrared in food processing.
drying, heating, frying, roasting, baking, thawing, surface pasteurization
Starting with 1 atm, how are the following units related; atmosphere, inches of mercury, pascal, psi?
1 atm = 30in Hg = 101,325 Pa = 14.696 psi
Describe one way nanoparticles are used in food processing.
nanocapsules to improve the availability of neutraceuticals and/or flavors. Nanotubes and particles as gelation and viscosifying agents Particles that bind and remove chemicals and pathogens
For a refrigeration cycle, what term is used to describe efficiency?
COP, the coefficient of performance
What are some of the benefits of a thermistor?
they are preferable in simple applications due to their low cost and simple electronic circuitry, also they can be produced in very small designs with a fast response and low thermal mass
Define the saponification number.
milligrams of KOH to saponify 1 gram of fat
What is the single most important phase of a sterile canning operation?
What are the units for the following: pressure, force, and energy?
pressure: pascal, force: newton, energy: joule
The temperature at which water condenses is called what?
Dew point
What is the fish most commonly used for making Surimi?
Alaskan Pollock
Name 3 types of heat treatment during food processing and what is their purpose
blanching (inactivates enzymes), pasteurization (kill pathogenic bacteria), and sterilization (kill all bacteria and other organisms)
In IR heating, what happens to the wavelength as temperature increases?
wavelength gets shorter
What are the 3 simple components of a radio frequency heating system?
radio frequency generator, electrodes, and product
The food drug and cosmetic act contains guidelines requiring what foods to require lot coding?
Low acid canned foods, acidified foods, bottled drinking water, infant formula, bottled water
What are some of the disadvantages of a liquid-in-glass thermometer?
large sensing element, not possible for continuous or automatic readout, long time constant
Give an example of a climacteric fruit and a non climacteric fruit.
Refrigeration system, vacuum system, control system, product chamber, condenser
What is a psychrometric chart?
A psychrometric chart is a graphical representation of the psychrometric processes of air. Psychrometric processes include physical and thermodynamic properties such as dry bulb temperature, wet bulb temperature, humidity, enthalpy, and air density.
An exoenzyme that catalyzes hydrolysis of maltose units from the non-reducing end of starch is what?
What does a BCU of 0.00 indicate?
The BCU (baking contrast units) range from 0.00 (darkest) – 5.25 (lightest) BCU.
What common purpose is sodium metasilicate, Sodium hexametaphosphate, and sodium pyrophosphate is served in the food industry.
alkaline cleaners.
What are some of the advantages and disadvantages of microwave heating?
Advantages: Higher heating rates; no direct contact between the heating source and the heated material; selective heating may be achieved; greater control of the heating or drying process; reduced equipment size and waste Disadvantages: Radiation; the texture of food, color, and taste will change
What is the name given to a mixture of flour and water that are used for manufacture of extruded pasta products ?
Alimentary pastes (do not accept batters)
What are 4 ways to lower water activity?
dehydration (remove water), concentration (increase solids content), add salt, add sugar (both salt and sugar compete for water)
What are some of the factors that affect the dielectric properties of foods?
frequencies, food composition, moisture content, product temperature, physical state of water in the food, fat content, and product density
What is the difference between commercial sterilization and pasteurization?
sterilization: processed at temps higher than 100 C, mainly for canning (retorting), destroys all microbes that may cause spoilage (may contain heat resistant bacteria spores such as endospores or thermophiles or flat sour bacteria), shelf life of 2+ years at room temperature, pasteurization: processed at temps lover than 100 C, typically high temperature for short time (HTST), destroys pathogenic microbes, reduces spoilage microbes, inactivates enzymes
What microbe is used to make vinegar?
Name three artificial sweeteners that are approved for use in the U.S.
Aspartame, Saccharin, Acesulfame K + others
In terms of dehydration please describe how osmosis works.
as water on the surface evaporates, the water moves from the interior to the surface due to the new concentration gradient.
Which food is made by fermenting soaked and cooked soybeans with a mold, usually rhizopus?
Certified food colorants can be divided into 2 types. What are they?
Dyes (water soluble) and lakes (water and oil soluble)
What are the three categories of freezing equipment used in the food industry?
1-The air blast freezers / cold storage freezers 2-The cartoon freezers / box freezers 3-The spiral belt freezers 4-The fluidized bed freezer / IQF freezer (or tunnel freezers) 5-The immersion freezers / brine freezers 6-The plate freezers / block freezers 7-The contact belt freezers 8-The impingement freezers / flat product freezers 9-The cryogenic freezers
What is the 12D process?
the time/temperature process that will reduce the microbe spore population (typically C. bot) by 12 log cycles
What are the minimum times and temperatures for LTLT and HTST pasteurization of milk?
LTLT – 145 degF (62.8 degC), 30 minutes HTST – 161 deg F (71.7 deg C) 15 seconds
What is the typical width of the pulse used in pulsed electric field processing?
1-10 microseconds
What are the four main requirements in an aseptic system?
aseptic processing and equipment, aseptic packaging and sealing hermetically in an aseptic environment, monitoring, and proper handling of finished products
What are the 3 USDA quality grades of rabbits?
US Grade A, US Grade B, and US Grade C
What is hydrogen swell?
when a canned high-acid food product attacks the metal lining of the can and releases hydrogen gas.
What are the 3 main types of indirect heating?
PHE, THE, SSHE (plate heat exchanger, tubular heat exchanger, and scraped surface heat exchanger)
Why is mozzarella cheese "stringy" compared to other cheeses?
Kneading and stretching the curds help to elongate this protein chain, which causes the stringiness of mozzarella.
What are the three types of junctions in a thermocouple?
Exposed, ungrounded, grounded.
The mash obtained in the fermentation of soy to produce soy sauce is called
In canning, what is come-up time?
the time it takes to reach the thermal processing temperature
How does frequency affect dielectric properties of foods?
it changes the dielectric constant, higher frequency lower dielectric constant
Cloud stability in products like tomato and orange juice is favored by which of the following? A) Inactivation of polygalacturonase B) Inactivation of PME C) Addition of PME
B) Inactivation of PME
What is the amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius?
1 Calorie
Name 3 design considerations in an air impingement oven.
air velocity, jet configuration, nozzle to target surface spacing, location of exhaust ports, induced or imposed cross flow, surface motion, angle of impingement, nozzle design, temperature differences between the jet and the impingement surface
Give 2 ways to block production or reception of ethylene post harvest.
There are several anti-ethylene chemicals. Silver thiosulfate (STS) is used on flowers. Aminoethoxyvinylglycine (AVG, trade name ReTain) blocks ethylene synthesis. It is applied preharvest. The fruit (plant) will not produce much ethylene, so there is not an ethylene response. The ethylene blocker 1-methylcyclopropene (1-MCP, trade name EthylBloc) blocks ethylene by binding to its receptor. It is applied postharvest. The fruit (plant) may still produce some ethylene, but there is no response to the ethylene.
What are the HTST conditions?
72.8 C, 15 sec
What are the three types of emulsions?
semi permanent, permanent, and temporary
Shear modulus is represented by which letter?
What are some disadvantages of a plate heat exchanger?
limited to low viscosity products, re-gasketing costs can be high, fouling tendencies may exist for some products
How does heating of a dielectric material via dipole rotation occur?
frictional heat between dipoles (e.g., dipoles in water) while rotating to orient themselves to the rapidly oscullating electric field
Given a closed vessel of an ideal gas at room temperature, what happens to the density of the gas when the temperature of the vessel is raised to 100 C?
the density remains the same.
Please put the following steps in order as they would be used for processing? Grinding, cleaning, Cocoa separation, shell removal, conching, roasting, addition of other material, tempering
Cleaning, roasting, shell removal, grinding nibs, cocoa separation, addition of other material, Conching, tempering
Name 5 microwave applications in food processing.
tempering, heating/reheating, cooking/pre-cooking of meat/poultry, drying/dehydration, baking/cooking, blanching, pasteurization/sterilization
Name 2 types of retorts.
still (not agitating, vertical, horizontal, hydrostatic), agitating
What is the purpose of a deaerator in an aseptic processing system?
to remove air and prevent lipid oxidation as the product temperature is increased during the process
What is commercial sterilization?
destroys both vegetative cells and spores of pathogenic and spoilage microorganisms that would be capable of growing in the product under normal storage conditions
In separations such as distillation, what is the name of the plot used by engineers to describe the physical state at each step?
McCabe-Thiele plot
Which unit of electricity measures the number of electrons moving through a wire?
What might the Doppler effect be used to measure in food settings?
Flow velocity or food intake
What is "latent heat of vaporization"?
The amount of energy required to convert a unit mass of liquid to gas at its boiling point.
Describe the winterization process for oils.
the oil is cooled and then solids are filtered so that the long-chained saturated fats do not crystalize at low temperatures
Name 4 varieties of cheese that ripened principally by blue mold in the interior.
blue cheese, gorgonzola, stilton, wensleydale
What is fuzzy logic in simple terms?
Fuzzy logic is an approach to computing based on "degrees of truth" rather than the usual "true or false" (1 or 0) Boolean logic on which the modern computer is based.
Why do you add aluminum sulfate to pickles?
It can improve the crispness of the pickle (it's a firming agent)
Name two emulsifying salts used to make processed cheese.
disodium phosphate, sodium citrate, sodium tartrate, sodium pyrophosphate, trisodium phosphate, sodium potassium tartrate
Does a smaller or larger electrode gap result in faster heating of the product?
smaller electrode gap
List three factors that contribute to the buffering capacity of milk.
phosphate, citrate and lactate salts, whey proteins, carbonic acid from the dissolved CO2
What are some critical factors in designing a thermal process?
type of food, target microorganism, location of cold spot, shelf life requirement
State Stoke's law.
F = 6(pi)r(eta)v; Drag force = 6(pi)sphere radius.fluid viscosity.velocity of the sphere
What are descriptions of routine tasks in a food processing operation?
Standard operating procedures
What is the SI unit for power and what are the respective dimensions?
Watts, joules per second
What is regression analysis?
statistical method to analyze a relationship between 2 or more variables such that 1 of them can be predicted by using the information of the others.
At what temperature are bacterial spores destroyed?
250 F
To be called peanut butter the product must contain 90% peanuts. Name 3 items used as the other 10% of peanut butter.
salt, sugar(sweetener) hardened vegetable oil, or emulsifier
Describe the pasteurization process.
product heated to desired temperature, product held at desired temperature for defined time (typically for 12D reduction), product cooling, and product handling/distribution under refrigeration
Name a fermented milk that contains alcohol.
Kefir or koumiss
Often phage or viruses are used for DNA cloning, what is the process called?
Why is having excess flour particulates in a milling plant hazardous?
Fire hazard
What value is the time required to have 1 log reduction in microorganisms or spores in a sample at a specific temperature?
What is hysteresis?
Hysteresis represent the history dependence of physical systems. If you push on something, it will yield: when you release, does it spring back completely? If it doesn't, it is exhibiting hysteresis, in some broad sense.
Why do you have to blanch fruits and vegetables before canning?
soften texture, remove oxygen (exhausting, prevents explosion during sterilization process), inactivate enzymes, cleans surface (removes dirt and organisms), brightens color, helps reduce loss of vitamins
Name 5 ways that processors can reduce the microbial population or growth of microoragnisms in a food product.
heat treatment, refrigeration (or decreasing temperature), decrease water activity, removing contaminated portions (or trimming), using chemicals (accept both addivitves and sanitizers, such as chlorine), encouraging the growth of fermentation microorganisms, minimizing contamination, cleaning and sanitization of equipment and facilities, etc.
What are the 3 types of still retorts?
vertical, horizontal, and hydrostatic
What two metal wires compose a T-type thermocouple?
copper and constantan
What are some advantages of a liquid-in-glass thermometer?
easy portability, independence of auxiliary equipment, low cost, compatible with most environments, moderate ruggedness, wide range of temperatures
What is absolute humidity?
mass of water/mass of dry air
Why was Alum added to a pickle mix?
It was added for crispiness but no longer recommended
What are two non thermal methods that are currently under investigation
pulsed electric field, and high hydrostatic pressure
What are some disadvantages of aseptic processing?
over processing, not easy to ensure the sterility of all equipment used in the process, products that contain particulates processed at high temperatures lose shape and form during the heating and cooling steps
The extraction technique used by the meat industry to remove fats from most by-products that have no better market potential is called what?
What term is used when there is a percent change in length of material before pulling?
Strain or elongation
What is the benefit of HTST pasteurization?
less change in nutrient composition and sensory attributes, less change in overall food quality, continuous throughput, lower utility costs, longer shelf life
What causes wrinkled casings of beef sticks?
There could be several reasons for these results. The temperature may have risen too high. The sausage may not have been showered with cold water immediately after it was finished smoking. The sausage casings may not have been stuffed to their full capacity.
What two types of heating are dielectric heating?
microwave and radio frequency
Give three reasons for adding starch to food.
coating and glazing agent, thickening agent, colloidal stabilizer, moisture retention, gel forming, binding
What is the equation used to convert deg C to deg F?
F= 9/5C+32
Explain what is meant by aseptic processing.
The food and container are sterilized separately and are filled in a sterile environment
What are some advantages of indirect heating?
easier to control food temperatures, process viscous products without causing food to burn, conserves energy by heat regeneration
What is a PERT chart and how are they used by food companies?
PERT - Program Evaluation Review Technique Used as an organization tool for food product development
How many significant figures are in the number 0.000401?
What is the graph of water activity vs. water content called?
moisture sorption isotherm (MSI)
What are the disadvantages of removing water from foods during processing?
different physical appearance (excluding freeze drying), energy consuming (more expensive), and if it is heat drying there is a decrease in food quality
Enzymatic browning is caused by the oxidation of what type of compounds? Name the enzyme.
polyphenols; Polyphenoloxidase/phenolase
What is the effect of drying on Vitamin C?
vitamin C reduction/loss
What is the frequency range for infrared radiation?
430 THz down to 300 GHz
The quantity of heat required to change the state of a substance without changing the temperature or pressure is called what?
latent heat
What is a food additive?
substances added to food to preserve flavor or enhance its taste, appearance, or other qualities
What are 4 limitations of IR heating?
IR radiation has limited penetration power, penetrative radiation energy does not make significant contribution to internal heating (need to combine IR with other heating methods for best result), maily efficient for solid products only, risks of infrared energy hazard to eyes and skin
Name 8 of the 12 methods to preserve foods.
pickling, salting, smoking, canning, bottling, pasteurization, refrigeration, sterilization, dehydration, lyophilization, chemical additives, radiation
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