Biotechnology: Microbial Fermentation in Food Preparation
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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?

  • Soy sauce
  • Sauerkraut
  • Ice cream (correct)
  • Yogurt
  • 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 _____.

    <p>consumer</p> Signup and view all the answers

    What is the temperature range for incubating yogurt during fermentation?

    <p>40℃ to 42℃</p> Signup and view all the answers

    What does the addition of lactic acid bacteria do to milk during yogurt production?

    <p>It results in the coagulation of milk proteins and forms a custard-like curd.</p> Signup and view all the answers

    Which of the following materials is NOT required for yogurt production?

    <p>Vegetable oil</p> Signup and view all the answers

    How long should you incubate the yogurt mixture?

    <p>18 to 24 hours</p> Signup and view all the answers

    What is the purpose of using a pH meter in the yogurt preparation process?

    <p>To measure the pH of the milk and the final product.</p> Signup and view all the answers

    What is the main purpose of microbial fermentation in the context of food production?

    <p>To preserve foods by inhibiting the growth of spoilage microorganisms.</p> Signup and view all the answers

    Which of the following fermented food products is NOT typically prepared using a starter culture?

    <p>Sauerkraut</p> Signup and view all the answers

    Which of the following is NOT a product of fermentation in sauerkraut production?

    <p>Sucrose</p> Signup and view all the answers

    What is the primary reason for heating the skim milk to 85℃ for 15 minutes in the yogurt production process?

    <p>To denature the milk proteins and make them more susceptible to coagulation by lactic acid bacteria</p> Signup and view all the answers

    What is the role of powdered skim milk in the yogurt production process?

    <p>To thicken the yogurt and improve its texture</p> Signup and view all the answers

    What role does carbon dioxide play in the production of sauerkraut?

    <p>It is responsible for the formation of gas bubbles that contribute to the sauerkraut's texture.</p> Signup and view all the answers

    Why is it important to use starter cultures in the production of yogurt, acidophilus milk, and some cheeses?

    <p>Starter cultures introduce specific microorganisms that contribute to the desired flavor and texture of the final product.</p> Signup and view all the answers

    Why is it important to cool the milk to 40℃ to 42℃ before adding the yogurt starter culture?

    <p>To prevent the starter culture from being killed by the high temperature</p> Signup and view all the answers

    What is the primary reason for the claimed health benefits associated with consuming fermented dairy products like yogurt and acidophilus milk?

    <p>The presence of probiotics, which are live bacteria that can improve gut health.</p> Signup and view all the answers

    Which of the following best describes the appearance of the final yogurt product?

    <p>A thick, custard-like substance</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a starter culture used in food fermentation?

    <p>It is a natural byproduct of the fermentation process itself.</p> Signup and view all the answers

    What is the purpose of checking the pH of the final yogurt product?

    <p>To determine if the yogurt has been properly fermented</p> Signup and view all the answers

    What is the primary reason why microbial fermentation is a valuable method for food preservation?

    <p>It creates a hostile environment for spoilage microorganisms, extending the shelf life of the food.</p> Signup and view all the answers

    Which of the following is NOT a factor that influences the quality of the final yogurt product?

    <p>The color of the plastic cup used</p> Signup and view all the answers

    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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    Related Documents

    4mcb 322-yogurt.docx

    Description

    Learn about the role of microbial fermentation in preparing and preserving various food items, including sauerkraut, pickles, soy sauces, and more.

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