Food Processing and Engineering

With respect to quality, what do the following acronyms stand for? TQM, JIT, GMP, CIM, HACCP, AQL, SPC, PONC

TQM-Total Quality Management; JIT-Just In Time; GMP-Good Manufacturing Practices; CIM-Computer Integrated Management; HACCP-Hazard Analysis and Critical Control Points; AQL-Acceptable Quality Level; SPC-Statistical Process Control; PONC-Price Of Non-Conformance

What are the driving forces of membrane processes?

Transmembrane pressure, concentration gradient, chemical potential, osmotic pressure, electric field, magnetic field, partial pressure, pH gradient

What are some characteristics of microwaves?

Travels at speed of light, non-ionizing form of radiations, can be focused into beams, can transit through hollow tubes, may be absorbed or reflected by the material depending on its dielectric properties, may also transmit through materials without any absorption (includes glas, ceramics, some thermoplastic plastics)

What are some critical factors in designing a thermal process?

Type of food, target microorganism, location of cold spot, shelf life requirement

What are the factors that determine what pasteurizer is selected?

Type of food, type of packaging, and storage method

What factors of heat penetration effect sterilization time?

Type of product, size of container, agitation of container, temperature of retort, type of container

What are the factors that affect in-container sterilization time?

Type of product, size of containers, agitation of container, retort temp, type of container, heat resistance of microbes and enzymes, pH of foods

Which kind of thermal couple is used in thermal processing, which is in high pressure, and which is in extrusion?

Type T, K, J

What are the different types of food materials?

Types of food materials: liquid solutions and gels,(milk, juice, gelatin), capillary-porous ridged cells, (wet sand, wheat, corn), capillary porous colloidal materials (plant tissue, meat). Hygroscopic foods are those in which the partial pressure of water vapor varies with the moisture content

What is UHT used for? What are some examples?

Used for liquid foods: milk, juices, cream, wine, baby food, tomato products, salad dressing

What is roll feeding for drum drying?

Used in single and twin drum, effective for viscous and glutinous materials, multirolls used to increase film thinkness, gap adjusted bwn rolls and drum, sometimes used combination with other methods

What is dipping feeding for drum drying?

Used in single and twin dryers, dryer is partially submerged in a tray and product in tray adheres to the surface as the drum rotates, good for certain suspensions of solids and used usually with a recirculation of material to prevent the setting of the solid in a tray

Give three characteristics of spray drying.

Used to create powders, very rapid process, atomizers make food into mist

Discuss the changes in kinetics and how they relate to drying.

Used to quantify changes. Zero order: overall quality of frozen foods, nonenzymatic browning, chlorophyll loss. First order: ascorbic acid degradation, thiosulphinate loss, oxidative color loss, microbial destruction, enzyme inactivation, texture loss in heating processing

What is centrifugal separation?

Utilizes fundamental physical laws and centrifugal force. Centrifugal force is produced through rotation around an axis. The force generated through the rotation acts in an outward direction. Depending on the speed of the rotating body, it increases or drops on the circular path. Mechanical separation technology makes use of this property when light, heavy or substances of different density have to be separated from each other.

What is the natural circulation tubular method, how does it work, what is it used for?

Utilizes the density difference between the liquid and the generated vapor to circulate the liquid past the heating surface. It is a continuous process and the residence time is 10-20 minutes. It is used for cane sugar solutions

Name 3 non-thermal food processing technologies.

UV light, ultrasound, high pressure, pulsed light, pulsed electric field, irradiation

State the Poiseuille's law for a Newtonian fluid.

V = pi.R^4.deltaP/(8.nu.L)

Give the michaelis-menten equation and give two assumptions underlying its derivation.

V0 = Vmax ([S]/([S] + KM)); This equation includes the assumption that during the early stages of the reaction so little product is formed that the reverse reaction (product combining with enzyme and re-forming substrate) can be ignored (hence the unidirectional arrow under k3). Another assumption is that the concentration of substrate is much greater than that of total enzyme ([S] >> [Et]), so it can essentially be treated as a constant.

How does Mechanical Vapor Recompression save energy during evaporation?

Vapors from a single stage are compressed to higher pressure in a mechanical compressor and then reused as steam in the steam chest. Only a small portion of fresh steam is needed. Present advantages: - Reduced cooling-water requirement - Energy recovery schemes are still feasible - Low temperature between steam and product is used - Short residence time at high temperature - Results in high quality.