Food Processing and Engineering

name 3 factors that affect the stability of an emulsion according to Stoke's Law.

Particle radius, particle density, fluid viscosity, fluid density, standard gravity

What is ultrafiltration?

Particles retained 0.001 - 0.02 µm, Pressure 10-100 psig, Proteins rejected (macromolecules)

What is microfiltration?

Particles retained 0.02 - 10 mm, Pressure 1-50 psig, Bacteria, fat globules (suspended particles) rejected, Applications: dairy (milk - removal of bacterial and spores, fractionation of proteins), egg (remove bacteria) juice (clarification) Beer (recover yeast)

What is active and passive modified atmosphere packaging?

Passive MAP: Uses the natural respiration of the product and the specific permeability of the film to allow the atmosphere to change over time. Active MAP: The intended atmosphere is actively flushed into the package (or oxygen scavengers are added) at the start to achieve the desired environment immediately.

What are the key difference between Pasteurization and heat sterilization?

Pasteurization: Mild heat treatment, Few week shelf life, Microbial and enzyme reduced, Insignificant nutrient and sensory loss, For liquid and canned foods Heat Sterilization: rigorous treatment, 6 or more month self-life, microbes and enzymes destroyed, substantial nutrient and sensory loss, mainly for canned foods

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

List three factors that contribute to the buffering capacity of milk.

Phosphate, citrate and lactate salts, whey proteins, carbonic acid from the dissolved CO2

Name three compounds capable of poisoning the catalyst during commercial hydrogenation.

Phospholipids, water, sulfur compounds, soaps, partial glycerol esters, carbon dioxide, and mineral acids.

Name 8 of the 12 methods to preserve foods.

Pickling, salting, smoking, canning, bottling, pasteurization, refrigeration, sterilization, dehydration, lyophilization, chemical additives, radiation

What are the 4 parameters for the processing of fluids flowing through a pipe?

Pipe diameter, viscosity, velocity, and density of fluids

What are some examples of indirect-contact freezing system?

Plate Freezers: The most common type, where products (often packaged fish or meat) are placed between metal plates (vertical or horizontal) that are cooled internally by a refrigerant. Contact Belt/Contact Plate Freezers: Product is placed on a cold metal conveyor belt that moves through a freezer, allowing for continuous, efficient, and uniform freezing. Submerger (Immersion) Freezer: Packaged foods are passed through a bath of refrigerated brine, glycol, or calcium chloride solution, creating intense indirect contact for rapid freezing. Scraped Surface Heat Exchanger: Used for liquids or pastes, this involves a rotating blade within a cylinder that scrapes the frozen product off the inner surface.

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

Name any three enzymes that are inactivated during blanching.

PME, PPO, lipoxygenase, polygalacturonase,chlorophyllase

What are the different types of membrane materials available?

Polymers most common, inorganic more stable. Synthetic membranes : PVC. Polymeric membranes: widely used for UF, wide tolerance to pH temp and chlorine. Ceramic membranes: made from mineral materials such as glass aluminum oxide, and zirconium oxide, expensive and can be brittle, mainly for MF. Glass membranes. Metallic membranes: ability to withstand extreme chemical and thermal stress. Zeolite membranes: a solid with lots of tiny holes. Can have different selectivity, long term stability at high temp resistance to harsh environments and high pressure drops. Inertness to microbial degradation and easy cleanability and catalytic activation

Give 3 visible signs of chilling injury.

Poor ripening, pitting, collapse of structural integrity, development of off-flavors and rotting

What are 4 applications that use spray drying?

Powdered cheese, cream powders, egg powers, milk products

What are the parts of a continuous retort?

Pre-heat, steam chamber, air cooling, (hydrostatic cooling), cooling bath, can feed and can discharge

What are the units for the following: pressure, force, and energy?

Pressure: pascal, force: newton, energy: joule

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

Describe the pasteurization process.

Product heated to desired temperature, product held at desired temperature for defined time (typically for 5D-6D reduction targetting specific pathogens), product cooling, and product handling/distribution under refrigeration