Questions and Answers
What is the primary objective of the 4MCB 322 Biotechnology course?
To prepare various items of food by microbial fermentation.
Which of the following is NOT a product of microbial fermentation?
The bacteria responsible for sauerkraut production are mainly lactobacilli and leuconostocs.
True
The process of fermentation adds flavor and aroma to the final product, which has appeal to the _____.
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What is the temperature range for incubating yogurt during fermentation?
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What does the addition of lactic acid bacteria do to milk during yogurt production?
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Which of the following materials is NOT required for yogurt production?
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How long should you incubate the yogurt mixture?
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What is the purpose of using a pH meter in the yogurt preparation process?
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What is the main purpose of microbial fermentation in the context of food production?
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Which of the following fermented food products is NOT typically prepared using a starter culture?
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Which of the following is NOT a product of fermentation in sauerkraut production?
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What is the primary reason for heating the skim milk to 85℃ for 15 minutes in the yogurt production process?
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What is the role of powdered skim milk in the yogurt production process?
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What role does carbon dioxide play in the production of sauerkraut?
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Why is it important to use starter cultures in the production of yogurt, acidophilus milk, and some cheeses?
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Why is it important to cool the milk to 40℃ to 42℃ before adding the yogurt starter culture?
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What is the primary reason for the claimed health benefits associated with consuming fermented dairy products like yogurt and acidophilus milk?
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Which of the following best describes the appearance of the final yogurt product?
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Which of the following is NOT a characteristic of a starter culture used in food fermentation?
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What is the purpose of checking the pH of the final yogurt product?
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What is the primary reason why microbial fermentation is a valuable method for food preservation?
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Which of the following is NOT a factor that influences the quality of the final yogurt product?
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Study Notes
Objective
- Prepare various food items through microbial fermentation.
Overview of Microbial Fermentation
- Traditional method for preparing and preserving foods.
- Examples include sauerkraut, brined pickles, olives, soy sauce, yogurt, and buttermilk.
- Chemical changes during fermentation enhance flavor and aroma, increasing consumer appeal.
- Fermented dairy products like buttermilk and yogurt contain beneficial lactic acid bacteria, potentially improving health.
- Fermentation utilizes naturally occurring bacteria found on vegetables, such as cabbage or cucumbers.
- Stater cultures are commonly used for producing yogurt, acidophilus milk, and certain cheeses.
- Stater cultures contain specific microorganisms to ensure high-quality fermentation and can be sourced from specialized companies.
Key Microorganisms
- Lactobacilli and Leuconostocs are primary bacteria in sauerkraut production, fermenting sugars in cabbage juice.
- Lactic acid, acetic acid, ethanol, mannitol, and carbon dioxide are byproducts of fermentation, contributing to flavor and preservation.
- Yogurt production relies on lactic-acid bacteria, especially Streptococci and Lactobacilli, which ferment lactose leading to the coagulation of milk proteins.
Yogurt Production Procedure
-
Materials Required:
- Fresh plain yogurt or commercial stater culture
- Fresh skim milk (100 ml)
- Powdered skim milk (3 g)
- LBS (Lactobacillus selection) medium
- 250 ml beaker, plastic cup, hot plate, thermometer, pH meter
-
Procedure Steps:
- Measure and heat 100 ml of fresh skim milk in a 250 ml beaker to 85°C for 15 minutes while stirring.
- After heating, add 3 g of powdered skim milk and stir until dissolved.
- Cool the mixture to 40°C to 42°C, then add 2 teaspoons of yogurt starter culture or fresh yogurt for every 100 ml of milk.
- Transfer the mixture to a plastic cup, cover with foil, and incubate at 40°C to 42°C for 18 to 24 hours.
- Post-incubation, check the pH, consistency, flavor, and aroma of the final yogurt product.
Objective
- Prepare various food items through microbial fermentation.
Overview of Microbial Fermentation
- Traditional method for preparing and preserving foods.
- Examples include sauerkraut, brined pickles, olives, soy sauce, yogurt, and buttermilk.
- Chemical changes during fermentation enhance flavor and aroma, increasing consumer appeal.
- Fermented dairy products like buttermilk and yogurt contain beneficial lactic acid bacteria, potentially improving health.
- Fermentation utilizes naturally occurring bacteria found on vegetables, such as cabbage or cucumbers.
- Stater cultures are commonly used for producing yogurt, acidophilus milk, and certain cheeses.
- Stater cultures contain specific microorganisms to ensure high-quality fermentation and can be sourced from specialized companies.
Key Microorganisms
- Lactobacilli and Leuconostocs are primary bacteria in sauerkraut production, fermenting sugars in cabbage juice.
- Lactic acid, acetic acid, ethanol, mannitol, and carbon dioxide are byproducts of fermentation, contributing to flavor and preservation.
- Yogurt production relies on lactic-acid bacteria, especially Streptococci and Lactobacilli, which ferment lactose leading to the coagulation of milk proteins.
Yogurt Production Procedure
-
Materials Required:
- Fresh plain yogurt or commercial stater culture
- Fresh skim milk (100 ml)
- Powdered skim milk (3 g)
- LBS (Lactobacillus selection) medium
- 250 ml beaker, plastic cup, hot plate, thermometer, pH meter
-
Procedure Steps:
- Measure and heat 100 ml of fresh skim milk in a 250 ml beaker to 85°C for 15 minutes while stirring.
- After heating, add 3 g of powdered skim milk and stir until dissolved.
- Cool the mixture to 40°C to 42°C, then add 2 teaspoons of yogurt starter culture or fresh yogurt for every 100 ml of milk.
- Transfer the mixture to a plastic cup, cover with foil, and incubate at 40°C to 42°C for 18 to 24 hours.
- Post-incubation, check the pH, consistency, flavor, and aroma of the final yogurt product.
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Description
Learn about the role of microbial fermentation in preparing and preserving various food items, including sauerkraut, pickles, soy sauces, and more.
