Food Processing and Engineering

What are the effects of drying on rehydration?

A comprehensive quality parameter (good rehydration, good drying process) a good indication as to whether the various processing conditions were correctly applied. Biomatrix changes during drying: loss of the elasticity of cell walls, a reduced swelling ability of starch gel, loss of the osmotic properties of cell walls, destruction of membranes and structural proteins. Rehydration is a measure for the severity of the destruction caused by drying

What are the stages of drying?

A-B: initial settling down period to heat up the product and water. B-C: constant rate period; free water vaporization at surface, surface temp=wbTemp, external controlled-the resistance to heat and mass transfer is located solely in air stream, constant rate. C-D: falling rate period; no free water at the product surface, internal moisture has to migrate to surface, if diffusion the drying rate is controlled by the rate of diffusion inside the product, drying rate decreases. D-E: second falling rate period; bound water removal

What are the common metric units for the following: acceleration, power, mass, force

Acceleration= meters/seconds squared; power= watt; mass= kg; force= Newton

Give 3 methods for the production of corn syrup from starch.

Acid hydrolysis, acid-enzyme hydrolysis, enzyme-enzyme hydrolysis

What are the advantages and disadvantages of continuous retorts?

Advantages - gradual temperature and pressure change, less strain on cans. Disadvantage - high capital investment, breakdown will stop process line

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

Advantages of using membranes: - Low temperature - Lower costs - Lower floor requirements.

What are the advantages and disadvantages of spiral membrane modules?

Advantages: Compact, Minimum energy consumption, Low capital/opening cost Disadvantages: Not suitable for very viscous fluid, Dead space, Difficult to clean, Faulty membranes - change whole module

What are the advantages and disadvantages of tubular membrane modules?

Advantages: Feed stream with particulate matter can be put through membrane, Easy to clean Disadvantages: High energy consumption, High hold up volume

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 are the advantages and disadvantages of hollow fiber membrane modules?

Advantages: Low hold up volume, Back flushing possible, Low energy consumption Disadvantages: Susceptible to end-face fouling, Not suitable for viscous fluids, Single fiber damage - replace entire module

What are the advantages & disadvantages of flat sheet/plate and frame membrane modules?

Advantages: Low hold up volume, Permeate from individual membrane element, Membrane replacement easy Disadvantages: Difficult to clean, Susceptible to plugging

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

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

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 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

Name 3 enzymes required to produce high fructose corn syrup.

Alpha-amylase, glucoamylase, glucose isomerase

Name 3 natural colorants and the food from which they come from.

Annato extract: Annato seeds, Beet powder: Dehydrated beets, Paprika: ground dried mild capsicum pod, Grape color extract: Concord grapes, Turmeric: ground rhizome of Curcuma longa L.

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.

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

Name 3 applications for radio frequency in food processing.

Baking, drying, defrosting, pasteurization/sterilization, kill pests still in walnut shells