Food Processing and Engineering

What is the mechanism of moisture migration?

Diffusion ( moisture content difference), Capillary & Bulk flow (pressure difference), Heat is applied to the food and start with wet food and dry air and end with dry food and wet air

Two general categories of freezing methods used in commercial food processing are. Give examples.

Direct (air blast, immersion); Indirect (plate, scraped surface).

Name two direct and two indirect methods of thermal processing.

Direct: steam injection, steam infusion, baking, frying, microwave cooking, retorting; Indirect: plate heat exchange, scraped surface heat exchange, tube type heat exchange.

What are the disadvantages of using Reverse Osmosis (RO) and Ultrafiltration (UF)?

Disadvantages of using membranes: -Membranes can get clogged. -Concentration gets to only between 40 to 50% compared to 80% in evaporation.

What are the different types of centrifuges?

Disk bowl, decanter, tubular, basket

Name four types of commercial thermal processing.

Dry oven, steam retorting, HTST, UHT, aseptic, hot fill, frying, flaming, baking, broiling

Name 4 applications for Infrared in food processing.

Drying, heating, frying, roasting, baking, thawing, surface pasteurization

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

Name 5 chelating agents used in the food industry.

EDTA, citric acid, malic acid, tartaric acid, oxalic acid, succinic acid, adenosine triphosphate, pyrophosphate, porphyrins, and proteins.

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

Name 5 examples of unit operations.

Evaporator, storage tanks, filler, shipping, peeler/dicer, washing, mill, pasteurizer, grinding, extraction, drying

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

Give four pulse waveforms used in Pulsed Electric Field.

Exponentially decaying, square wave, bipolar, oscillatory, instant charge reversal pulse

Explain the principle of extrusion cooking and name two key variables that influence product expansion.

Extrusion combines heat, pressure, and shear to gelatinize starch and denature proteins. Expansion is influenced by moisture content and die temperature/pressure.

What are the steps of membrane separation?

Feed enter, permeate penetrates the membrane, retentate is what doesn't pass through) reject, concentrate, residue)

What are the components of a spray drying unit?

Feed tank, high pressure pump, air heater, nozzle atomizer, drying chamber, inlet duct, primary product collector, secondary product collection, main cyclone, exhaust fan

What are the three sections of an extrusion screw?

Feed, compression, and metering.

What are the different membrane module selections?

Flat sheets - can wrap into different shapes, Plate and frame module - feed fed through spacer(between membranes) and permeate moves through membrane, Spiral module - product flows through center and then permeate moves outward through membranes, Tubular >10mm tubular, Capillary 0.5-10mm, <0.5mm hollow fiber

What are the five classes of unit operations?

Fluid flow (fluids transportation, filtration, solids fluidization) heat transfer (canning, freezing, blanching) Mass Transfer (extraction, dehydration, frying) thermodynamic processes (gas liquification, refrigeration) Mechanical processes (solids transportation, crushing and pulverization, screening and sieving)

Name four types of freezing processes used in the food industry.

Fluidized Bed (or Individually Quick Frozen-IQF); Plate; Immersion; Blast Freezing (Convective Freezing); Cold-Room freezing (stagnant air freezing); Swept-surface heat exchanger (as with ice-cream)