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FSC229
UNIT OPERATIONS IN FOOD PROCESSING
EXAM II
October 20, 2000
Part I. (30 - 3 pts each) Please indicate whether the following statements are true or false. If
the statement is false explain why the statement is false or provide the correct statement.
1. Irradiation of foods refers to the exposure of foods to ionizing energy source. Today
irradiation of wheat (and wheat flour), white potatoes, spices, pork and some fruits and
vegetables are already approved by FDA. These food products are irradiated to eliminate insect
infestation, prevent sprouting, eliminate microbial contamination, inactivate trichina and delay
maturation, respectively.
2. Kilo-Gray is the international unit for the measurement of radiation dose.
3. In hot-water blanchers, typically, you have larger losses of water soluble components such as
vitamins and minerals. Steam blanchers, although, are more expensive they provide for better
nutrient retention compared to hot-water blanchers.
4. Heat treatment is one of the most widely used methods of food processing and preservation.
Heat treatment typically improves the eating quality of a food as well as preserve foods by
inhibiting enzymes and microorganisms. However, heating of foods also results in some
nutrient losses.
5. Cellulose, cellophane, plastics, paper, metals are all materials used in the manufacture of
ultrafiltration and reverse osmosis membranes. All of these materials have wide pH range for
use, can withstand high temperatures and pressures.
6. The four microorganisms that make-up the list of emerging pathogens include Escherichia coli
0157:H7, Salmonella typhimurium, Listeria monocytogenes and Campylobacter jejuni.
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7. The antimicrobial effects of ionizing radiation is due to the effect of ionizing radiation on the
cleavage of the DNA of a microorganism which results in the loss of cell’s ability to reproduce.
The DNA of an organism is considered the ‘radiation sensitive’ portion of the cell.
8. Fermentation is the controlled action of selected microorganisms. Apple cider, cheese,
milk, sourdough bread, olives, ice-cream, wine, vinegar, yogurt, blue cheese, pickles, honey,
buttermilk, ribeye steak, soy sauce, chili powder are all fermented dairy foods that are
manufactured using fermentation processes.
9. HACCP stands for Hazard Analysis and Critical Control Points. This is a preventive rather
than corrective method of practicing food safety. It involves identifying the production hazards,
determining control points, establishing critical limits for each control point, setting procedures
for monitoring, establishing corrective actions, establishing record keeping and verification at
established time intervals.
10. GRAS stands for Generally Regarded As Sacred. These are religious foods that have to be
‘blessed’ by a religious leader such as a priest, a rabbi or an imam in a religious ceremony so that
they can be labeled GRAS.
Part II. (30 pts 3 pts each) Please discuss the following in relations to unit operations in food
processing.
1. Blanching:
2. Flow diversion valve:
3. Plate heat exchanges:
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4. Papain:
5. Radura:
6. Gamma radiation:
7. Ceramic membrane:
8. Rejection coefficient:
9. Chymosin:
10. Lipoxygenase:
Part III.
1. (5 pts) What is the difference between ale and lager?
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2. (5 pts) Please discuss the four (4) phases in the life-cycle of a microorganism.
3. (5 pts) Give one (1) advantage and one (1) disadvantage of membrane concentration.
4. (5 pts) Please discuss two (2) common membrane module designs.
5. (5 pts) What is the difference between homo- and heterofermentative bacteria?
5. (15 pts) If you were asked to give a talk to a group of consumers very concerned about the
safety of their foods, how would you start your talk and what would you say? (I am looking for a
well written essay on the subject based on what you know as a food scientist and how you
interpret the scientific information and the law).
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