Food Processing and Engineering

What are the disadvantages of drum drying?

Some products may not form good film on surface, products with high sugar content may not be easily scrapped off, relatively low throughput compared to spray drying, high cost of changing drum surface b/c of machining that required, possible scorching of the product to impart cooked flavor and off-color due to direct contact with high temp surface

What four ingredients are necessary for making soy sauce?

Soybeans, wheat, salt, water.

Name three methods of microencapsulation technology.

Spray drying, spray cooling, emulsification, extrusion, simple coacervation, complex coacervation, internal/ external gelation, fluidized bed coating, etc.

Compare spray drying and freeze drying in terms of process and product quality.

Spray drying: Rapid water removal by hot air; economical but may lose volatiles or cause oxidation. Freeze drying: Sublimation under vacuum; retains nutrients, structure, and flavor but costly and time-consuming.

Rank the following pulse waveforms used in pulsed electric field processing in order of increasing electrical efficiency: oscillatory, square wave, exponentially decaying

Square wave, exponentially decaying, oscillatory

Give 4 reasons why compounds are micro-encapsulated.

Stability against oxidation, bioavailability, stability, resistant to pH, protect reactive substances from the environment, controlled/delayed release of compounds

Name 3 methods of fruit and vegetable peeling.

Steam peeling, knife peeling, abrasion peeling, caustic peeling and flame peeling

Name four commercial types of thermal processing.

Steam Retorting, Pasteurization (HTST, UHT), Aseptic, Hot Fill, Frying, Flaming, Baking, Dry Oven...

Name the 4 layers of a tin can.

Steel, tin, iron alloy, tin, enamel

What are the steps in freeze concentration?

Step 1: It all starts from the ice crystal point of view by removing heat from the solution, Typically done by using a scraped surface heat exchanger ( inside scraped by a rotating shaft while outside cooled by refrigerant). Tiny ice crystals are formed at this cold surface. Step 2: Once crystals formed in SSHE, enter a mixed vessel (recrystallizer). Most of the small crystals will melt allowing larger ones to grow. Why? Bc melting required the addition of heat and changing from solid to liquid. Known as ripening and forms the heart of separate nucleation and growth process. Step 3: Since we want a continuous flow of small crystals to the recrystallizer, we must extract liquid from a filter in the recrystallizer and circulate that over the SSHE (scraped surface heat exchanger). Step 4: Once sufficient crystals in recrystallizer can start separation from concentrated liquid, This is done with wash column, where crystals sep from liquid, washed to remove and remaining concentrate, melted and discharged as pure water, Concentrate returned to recrystallizer. Step 5: Fresh feed replaced the water that is removed from the system. The feed is mixed with the recirculation stream feeding the SSHE. Since the feed is replacing the water that is removed from the system the concentration of the soluble solids in the system will increase. Step 6: Next add a way to remove the concentrated product, discharged from the liquid recirculation line after filtration. Since the concentrate contains all of the soluble solids originally in the feed the system will now remain constant

Name three types of retorts.

Still, agitating, continuous , discontinuous, still with overpressure

Bonus: Give the engineering term which describes the following: the ratio of the characteristic time of a particle (or droplet) to a characteristic time of the flow or of an obstacle; the ratio of yield stress to the viscous stress; the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity

Stoke's Number, Bingham Number, Prandtl Number

What are kiln dryers?

Tall, deep bed of product 20cm, large capacity, used for apple slices, hops, grains, batch drier, simple to operate, cheap to build, high labor cost, slow, poor control drying

What are the different variables that are monitored in a retort?

Temp material, temp steam, temp cooling water, process time, hearing and cooling rates

What factors influence dehydration?

Temp, dryness, air vol, particle size, type of food, load

Name 3 factors that contribute to the preservative actions of smoking foods.

Temperature (heat kills cells), drying and salt lower water activity, and smoke contains chemicals that are antimicrobial and antioxidants

What are 5 factors that will influence dehydration?

Temperature, dryness, air volume, particle size, type of food or load

Name 5 microwave applications in food processing.

Tempering, heating/reheating, cooking/pre-cooking of meat/poultry, drying/dehydration, baking/cooking, blanching, pasteurization/sterilization

What are the potential issues with spray drying?

Tg, if rubbery sugar very sticky and build up on wall, so need to make sure it becomes glassy before hits wall. Powder explosion: can happen when enough particles get into the air and if spark explosion will occur

Describe the process of forming an hermetic seal.

The can end and body are interlocked during two rolling actions, first action curls the edge of the can end up and under the flange of the can body, and the second action roll flattens and tightens the seam