Food Processing and Engineering

What are the methods for exhausting containers?

Hot fill foods, cold fill then hear container with partially sealed lid, apply vacuum to remove air, flush cans with steam

High-pressure processing (HPP): Explain how HPP inactivates microorganisms. Name two foods commonly processed using HPP. Describe one advantage and one limitation of HPP.

How HPP inactivates microorganisms: Applies pressures of 300–600 MPa, Disrupts cell membranes, protein structure, and enzyme activity without high heat. Two foods commonly processed with HPP: Guacamole, Deli meats, Fruit juices, Ready-to-eat meals One advantage and one limitation: Advantage: Retains fresh flavor, color, and nutrients; Limitation: High equipment cost and limited effectiveness against bacterial spores

Describe the principle behind High Pressure Processing (HPP) and its effect on microorganisms.

HPP applies pressures typically between 300–600 MPa uniformly to foods, disrupting cell membranes, protein structures, and enzyme systems in microorganisms without significant heating. It inactivates vegetative cells while largely preserving fresh-like sensory and nutritional qualities.

Explain high-pressure processing (HPP).

HPP uses pressures of 300–600 MPa to inactivate microorganisms by disrupting cell membranes and proteins without significant heating. Limitations include cost and limited effectiveness against bacterial spores.

Describe the difference between HTST pasteurization and UHT processing.

HTST (High-Temperature Short Time): ~72°C for 15 sec, extends shelf life for days to weeks under refrigeration. UHT (Ultra-High Temperature): ~135°C for 1–2 sec, produces commercially sterile product with months of shelf life unopened.

What are the advantages of spray drying?

Huge capacity(15000lb/hr), cost of maintenance low, purity of product maintained since particles do not contact with surface of equipment until dried, simple operation and cleaning condition contributes to low labor cost, low bulk density of product can be obtained, particle size is very small 10-500 um

What are some of the external conditions that affect drying?

Humidity, relative humidity, are velocity, dry bulb temperature, wet bulb temperature, dew point temperature, specific volume, enthalpy, geometry of the food

What are the effects of drying on color?

Hunter lab and CIE Lab are most widely used color systems (lightness - L, red/green - a, yellow/blue - b) humans perceive color in terms of lightness, hue, and chroma by the integration of complex color systems. Mechanisms: drying changes the surface characteristics of a food and hence alters its reflectivity, enzymatic browning - dark pigment, photo-oxidation of pigment caused by light in combination with oxygen - meat, chemical changes to carotenoid and chlorophyll pigments caused by heat and oxidation

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 are the different types of freeze concentration units?

Ice Crystallization (Direct contact freezers, Indirect-contact freezers) and Separation Devices (Mechanical press, Centrifugal, Wash column)

What are some of the ways parameters can be changed to alter the drying?

If the air temp is increased you increate the Rc (constant rate). Increase the air relative humidity, increase density of moist air and decrease change in temp and decrease Rc. Increase the air velocity the increase heat transfer coefficient and increase Rc. If increase thickness, decrease constant rate.

What are some factors that may affect aseptic processing?

If the product has particulates, size of particles, viscosity, product thermal sensitivity

What are the different types of osmotic dehydration?

Impregnation soaking process, osmotic dewatering, dewatering impregnation soaking, solvent drying

List three positive effects of properly used thermal processing on the nutritive value of foods.

Improves digestibility, inactivates degradative enzymes, inactivates antimetabolites

What is the difference between Reverse Osmosis (R.O) and Ultrafiltration (U.F)?

In both processes, the driving force for transport across the membrane is the pressure applied to the liquid feed. However, R.O is utilized to separate water from low-molecular weight solutes (i.e., salts, monosaccharides, volatile compounds), while allowing water and some salts with the smallest size to pass through. High pressure is needed to achieve this (4000-8000 kPa). UF limits only the largest (i.e., proteins, colloids) and smaller solutes are transported through, therefore lower pressure is needed.

How does the Short-Tube Evaporator function?

In Short-Tube Vertical (STV) evaporators (the "standard" evaporator), the liquid is inside the tubes and the steam is in the shell. Sometimes, steam is fed through the inside of internal tubes, while evaporating product flows around the outside. Density changes cause warmer fluid to rise and cold to sink. Used sometimes in sugar processing.

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)

list 2 approved application of gamma irradiation in foods.

Inhibit sprouting in tubers and bulbs,reduce microbial population in spices,destruction of salmonella in poultry,destruction of spoilage microorganisms

What are the basic components of evaporators?

Introduction: All evaporators have the same basic components: Principal components include: Steam chest or other ways of introducing steam into the product. Liquid feed: preheated to evaporator temperature before being distributed uniformly to the heat transfer surface area. When boiling has occurred, an efficient separator is required to isolate vapors from liquid concentration.

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