9. Which of the following is often added to wine to inhibit growth of the natural microbial population of grapes?
A. Benzoic acid
B. Lactic acid
C. Carbon dioxide
D. Sulfur dioxide
10. In the brewing process, the sugar and nutrient extract obtained by soaking germinated grain in warm water is called
A. baker's yeast.
1. A small cheese-manufacturing company in Wisconsin is looking for ways to reduce the costs of disposing of the cheese byproduct whey. A company meeting was held to consider what to do with the thousands of liters of whey being produced per month. As a food microbiologist working at the company, what would you suggest that the company do with the whey so they can actually profit from it?
2. A microbiologist is troubleshooting a batch of home-brewed ale that did not ferment properly. She noticed that the alcohol content was only 2%, which is well below the desired level. Microscopic examination showed that the yeast were healthy and numerous. Chemical analysis of the beer showed low levels of sugar, high levels of CO2, and large amounts of protein in the liquid. What did the microbiologist conclude as the probable cause of the beer not coming out properly?
1. It has been argued that the nature of the growth of fungi in Roquefort cheese, indicated by the appearance of bluish-green veins, is evidence that these fungi require oxygen for growth. How does this evidence lead to the conclusion?
2. In the production of sauerkraut, a natural succession of lactic acid bacteria is observed growing in the product. What causes the succession? What does this tell you about the optimal growth conditions of the different species of lactic acid bacteria?
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