This set of Food Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Fermented Dairy Products”.
1. Torulaspora delbrueckii is a species of ______
a) Yeast
b) Bacteria
c) Protozoa
d) Algae
View Answer
Explanation: Torulaspora delbrueckii is used in dairy fermentation, winemaking etc. It is used as a starting culture in winemaking to decrease volatile acidity in Sauterne wines etc.
2. Which of the following is made with lactic acid bacteria?
a) Cider
b) Sauerkraut
c) Wine
d) Bread
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Explanation: Sauerkraut is a dish made with fermented cabbage. This fermentation is carried out with the help of lactic acid bacteria. Bread, cider and wine are fermented with the help of yeasts. The presence of yeast in lactic acid bacteria fermented products or the presence of lactic acid bacteria in yeast fermented products is an indication of contamination.
3. Two broad types of fermentation are left fermentation and right fermentation.
a) True
b) False
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Explanation: The two broad types of fermentation are top fermentation and bottom fermentation. Top fermentation is when the yeast strain ferments the substrate near the upper parts of vats as in the case of ale; whereas, bottom fermentation is the exact opposite. This can be seen in the case of production of lager beer.
4. Zygosaccharomyces rouxii is used in the fermentation of plant products due to its ability to grow at ___________
a) High water activities
b) Low temperatures
c) High temperatures
d) Low water activities
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Explanation: Zygosaccharomyces rouxii can grow at low water activities even when high concentrations of salt or sugar are present. Hence, it is used in the fermentation of plant products where addition of salt is very necessary.
5. Oenococcus oeni was previously known as ____________ oeni.
a) Serratia
b) Erwinia
c) Leuconostoc
d) Escherichia
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Explanation: Oenococcus oeni was known as Leuconostoc oeni until 1995. It is used in starter cultures for natural malo-lactic fermentation. This type of fermentation is used to produce wines with reduced acidity due to the formation of malic acid which occupies around 50% of the total acid content.
6. _________ starters convert lactose to lactic acid.
a) Lactose
b) Lactic
c) Casein
d) Fermentation
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Explanation: Lactic starters are bacteria that convert lactose to lactic acid. Heterolactic organisms are added if there is a requirement for aroma or flavor such as diacetyl.
7. The buttery aroma and taste of cultured sour cream is due to _______
a) Diacetyl
b) Carbonates
c) Acetic acid
d) Carbohydrates
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Explanation: Diacetyl and acetoin are by-products of dairy fermentation. They’re aromatic compounds and are used for aroma and flavor.
8. There are 2 principal types of bacterial spoilages that can take place in butter.
a) True
b) False
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Explanation: The first type of bacterial spoilage is putridity. This is caused due to the growth of bacteria on the surface of the butter. The second type is rancidity. This is caused due to the hydrolysis of butterfat which results in the liberation of free fatty acids.
9. What is the main volatile flavor component in yogurt?
a) Fats
b) Glutamic Acid
c) Acetyl
d) Acetaldehyde
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Explanation: The cocci bacteria present in the yogurt starter are responsible for the majority of the initial acid production. The production takes place at a higher rate when 2 species of bacteria (rods and cocci) are mixed together. This also yields more acetaldehyde.
10. A starter is also called as _________
a) Inoculum
b) Rennin
c) Ager
d) Slime
View Answer
Explanation: A starter or inoculum is a small quantity of substance from a pure culture. This is introduced in the substrate to start a chain of certain reactions of growth without any contamination. It can be used to start a new culture.
Sanfoundry Global Education & Learning Series – Food Microbiology.
To practice all areas of Food Microbiology, here is complete set of Multiple Choice Questions and Answers.
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