Food Microbiology MCQ: Introduction and Explanation

Ans: c. Penicillium roqueforti

Explanation: It is necessary to inoculate the curd with the microbe Penicillium roqueforti, which causes the necessary modifications, in order to make blue cheese or Roquefort cheese. Lactic acid bacteria and fungi are primarily responsible for the fermentation and maturing of blue cheeses. Penicillium roqueforti is highly adapted to the low oxygen levels and temperatures experienced during the production of blue cheese.

Ans: b.Yeast

Explanation: Vitamin content is high in several microorganisms, particularly yeasts. Hydrocarbons mixed with mineral salts make up the yeast cells' growth medium. Nutritional yeast is high in protein, B vitamins, and trace minerals. Many B vitamins are found in it. It's high in thiamine, riboflavin, niacin, vitamin B6, and vitamin B12 when fortified.

Ans:  a. Streptococcus thermophilus

Explanation: Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, among other lactic acid bacteria, generate yoghurt, a popular fermented dairy product. These bacteria create lactic acid, which lowers the pH and causes the milk protein to coagulate during the creation of yoghurt. Cultured milk with living bacteria is used to make modern yoghurt. Lactic acid is produced by the bacteria, which causes the milk proteins to coagulate, resulting in thick, sour yoghurt.

Ans: a. neutral pH

Explanation: The majority of bacteria are neutrophils, which means they thrive at pH levels between 5 and 8, which is one or two pH units below neutral. E. coli, staphylococci, and Salmonella spp. are among the most common bacteria. Fungi, on the other hand, likes pH values of 5.0–6.0, which are somewhat acidic.

Ans:  b. Acidified potato glucose agar

Explanation: For fungal cultivation, Acidified potato glucose agar is employed. Acidified potato glucose agar is a yeast and mould growth medium that can be treated with acid or antibiotics to prevent bacterial growth. Plate counting procedures for foods, dairy products, and cosmetics testing are all advised. It can be used to produce yeast and moulds that are clinically important.

Ans:  d. fats

Explanation: The bacteria can be grown as a protein-rich big cell crop using industrial wastes or by-products as fertilisers. In France, Japan, Taiwan, and India, bacterial cells cultured on hydrocarbon waste from the petroleum industry are used as a source of protein.

Ans:  d. 40-50%

Explanation: Microbial cells have a very high protein content. Protein content in yeast cells ranges from 40 to 50%. This high-protein component can be used to boost the protein content of food products. Yeast protein is seen as a decent source of protein by 83% of people. Nutritional yeast, often known as nooch, is a deactivated yeast that is offered commercially as a food product. It is usually a strain of Saccharomyces cerevisiae. It's available in the bulk section of most natural food stores in the shape of yellow flakes, granules, or powder.

Ans:  d. All of the above

Explanation: MacConkey Broth, Violet Red Bile agar, and Eosin Methylene blue agar are used to cultivate gramme negative, lactose fermenting bacteria and as a coliform organism presumptive test. The presence of coliform organisms in food, water, milk, and other sanitary materials can be detected using this broth.

Ans:  d. All of the above

Explanation: These are elements that are present in the food itself. Fish, for example, have properties that may encourage the growth of specific microbes. Intrinsic variables include those that are unique to the food product, such as nutritional content, pH levels, water activity, redox potential, and other antimicrobial components that serve as antimicrobial defence mechanisms. 

Ans:  c. Bulgarian milk

Explanation: Sour milk is a favourite among the herds' people all year, although it is more readily available during the summer months when the most milk is produced. Bulgarian milk should not be sweetened or flavoured in any way. The distinctively zingy flavour of natural Bulgarian sour milk, or 'kiselo mlyako,' is due to the region's unique characteristics, including climate, air, and water. 

Ans:  d. All of the above

Explanation: Standard plate count, aerobic mesophilic count, total plate count, or aerobic colony count are all terms used to describe the aerobic plate count (APC). The bacterial population in a food sample is estimated using the APC. The total number of bacteria that can develop in an oxygenated or aerobic environment is referred to as the Aerobic Colony Count (ACC). It's one of the most widely used tests to determine the microbiological quality of food, not its safety. Large levels of germs could indicate a lack of cleanliness, as well as issues with process control or ingredient quality. APC is naturally high in some products, such as those made by fermentation.

Ans: c. Either A or B

Explanation: The number of individual live microorganisms in a sample is determined through enumeration in microbiology. Enumerating microorganisms, or determining their numbers, is required to calculate rates of microbial growth and death. It's also common to need to figure out how many germs are in a sample.