Food Processing and Engineering

List all the different types of thermocouples.

J, K, E, T, N, B, R, S

Name four products in which pectin is used.

Jams, jellies, fruit juices, tomato sauces

Define lag constant for heating/ Give the formula for lag constant for heating.

jh = (Tr - Tpi) / (Tr - T0); jh: lag constant, Tr: Retort (Heating medium) temperature, Tpi: Theoretical "intercept" temperature, T0: Actual initial temperature of the food

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 different types of quality changes that can occur from drying?

Kinetics, Effects of food texture (shrinkage, case hardening, crust formation, stress development and cracking, rehydration, flavor, color, nutrition, microflora)

what are 3 common units for expressing pressure from either the metric or English system?

kPa, Pa, torr, atm, psi, mmHg

What are the three types of fluid flow through a pipe and the Reynold's number that defines them?

Laminar (Re < 2100), transitional (2100 < Re < 4000), turbulent (Re > 4000)

What is a hydrostatic cooler and how does it work?

Large continuous sterilizers used for productin of high volume products where ther eis no requirement to regularly change the container size or processing conditions

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

In the SI system (Systeme International d'Unites) what are the units applied to the following seven dimensions or measurements? Length, Mass, Time, Electric current, Thermodynamic temperature, Amount of substance, Luminous intensity.

Length-Meter; Mass-Kilogram; Time-Second; Electric current-Ampere; Thermodynamic temperature-Kelvin; Amount of substance-mole; Luminous intensity-candela

What are the advantages of osmotic dehydration?

Less energy cost (30-40%lowe, no phase change), less heat impaired changed in the food components , retention of natural quality, desirable nutrients added during preservation process (fortification)

Name two processing considerations for a tubular centrifuge.

Limitations for solids <25kg, has relatively high speed and length to radius ratio, useful clarifying lightly loaded suspensions

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 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

State the Arrhenius equation and its variables.

ln K= ln A - (Ea/RT) or K=A.e^(-Ea/RT); Where k is the rate constant, A is the pre-exponential factor, Ea is activation energy, R is the gas constant, and T is absolute temperature (Kelvin)

How does a continuous retort work?

Load the cans, then heat container with steam, allow to cook food for specified time, then cool by filling retort with water, then emptying the retort

What are the disadvantages of osmotic dehydration?

Longer drying times, leaching of natural acids, floating of food pieces and necessity for agitation, disposal of used osmotic medium high of BOD, lack of knowledge of microbial development in medium and products, reduction in acidity levels of fruits, substantial modification of original product composition (flavor)

Why do we need vacuum in canned foods?

Loss of gases from tissues, container stability, exclusion of oxygen from headspace, and prevention of buckling during the retort process

What are the effects of drying on stress development and cracking?

Loss of valuable product, loss of consumer satisfaction, seed reduced germination(a biopolymer during drying shrinks at the surface causing tensile stress at the surface and compressive stress on the material surface exceeds the material breaking strength,, the material cracks

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