Food Fermentation - Lecture 5
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Questions and Answers

What is the net production of ATP molecules per glucose molecule during lactic acid fermentation?

  • 2 ATP (correct)
  • 6 ATP
  • 4 ATP
  • 1 ATP
  • Which of the following correctly describes oxygen's role in lactic acid fermentation?

  • It is produced during the process.
  • It is essential for the process.
  • It is utilized to form lactic acid.
  • It is not used in the process. (correct)
  • Which organism is known for producing lactic acid during fermentation in yogurt production?

  • E. coli
  • Lactic acid bacteria (correct)
  • Staphylococcus aureus
  • Yeast
  • What byproduct is formed during lactic acid fermentation?

    <p>Lactic acid</p> Signup and view all the answers

    What role does ATP play in living organisms?

    <p>It serves as the major energy currency.</p> Signup and view all the answers

    In comparison to other fermentation processes, lactic acid fermentation specifically lacks which of the following?

    <p>Oxygen requirement</p> Signup and view all the answers

    In which process is ATP produced in the presence of oxygen?

    <p>Aerobic respiration</p> Signup and view all the answers

    How is ATP generated in the absence of oxygen?

    <p>Using anaerobic fermentation</p> Signup and view all the answers

    Which statement about ATP production is correct?

    <p>Aerobic respiration produces ATP more efficiently than fermentation.</p> Signup and view all the answers

    Which of the following best describes ATP?

    <p>An energy-carrying molecule essential for cellular functions.</p> Signup and view all the answers

    Study Notes

    Lecture 5: Food Fermentation

    • Food fermentation is a crucial method for producing many food items.
    • Key objectives for the lecture include understanding the importance of fermentation, the fermentation process itself, relevant microorganisms for food fermentation, beneficial effects of the process, and methods for improvement.

    Importance of Fermentation

    • Fermentation has been a vital food production method for centuries.
    • Fermented foods such as bread, vinegar, cheese, and yogurt are common examples.

    Fermented Foods

    • Table 1 lists various fermented food products.
      • Bread/baked goods
      • Cheeses
      • Miso
      • Soy sauce
      • Cocoa
      • Tea
      • Coffee
      • Tempeh
      • Tofu
      • Yogurt
      • Kefir
      • Vinegar

    Fermentation Technology

    • Modern fermentation technology plays a major role in ensuring food security for a large global population.
    • Many people are unaware that numerous food items are prepared or preserved via fermentation.

    Functional Foods

    • Fermentation improves the health benefits of functional foods like tempeh and miso.
    • Functional foods consist of significant amounts of active components that provide health advantages beyond basic nutritional needs.

    What is Fermentation?

    • Fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms.
    • This process frequently involves effervescence and heat production.
    • Fermentation, also known as anaerobic respiration, results from the growth of bacteria, yeasts, or molds (or combinations).
    • Microorganism enzymes cause the changes during fermentation.

    Anaerobic Respiration

    • Anaerobic respiration is a metabolic process that enables organisms to produce energy without oxygen.

    Important Microorganisms

    • Yeasts and lactic acid bacteria are the predominant microorganisms used for food production.
    • These microorganisms ferment sugars in the starting material to create energy.

    Lactic Acid Bacteria

    • Lactic acid bacteria are crucial for producing many fermented foods, including olives, pickles, yogurt, and cottage cheese.

    Fermentative Yeasts

    • Fermentative yeasts produce ethyl alcohol and carbon dioxide from sugars.

    Other Fermented Foods

    • Bread and vinegar are examples of foods made through the combined fermentative activities of microorganisms followed by oxidative bacteria.

    Respiration and Fermentation Processes

    • A table showing the steps of Cellular Respiration, Lactic Acid Fermentation, and Alcoholic Fermentation is presented.

    ATP Formation

    • ATP (adenosine triphosphate) is a primary energy source for all living organisms.
    • ATP is produced during aerobic respiration in situations where oxygen is present.
    • ATP is also produced in fermentation when oxygen is absent.

    Lactic Acid Fermentation

    • Lactic acid fermentation has a net production of 2 ATP molecules per glucose molecule.
    • Atmospheric oxygen is not required for lactic acid fermentation.
    • Lactic acid is formed by specific bacteria, commonly used in yogurt production.
    • The equation for lactic acid production from glucose or lactose is shown.
    • Lactic acid fermentation is used for converting lactose into lactic acid in yogurt production.
    • It also occurs in animal muscles when tissues need energy that quickly than oxygen can be delivered.

    Yogurt Production

    • Several methods exist for making yogurt, but basic production involves milk fermentation by Streptococcus thermophilus and Lactobacillus bulgaricus, which grow at 45°C.
    • Streptococcus produces significant acid lowering the pH to around 3.
    • Lactobacillus is primarily responsible for the flavor and aroma traits of yogurt.
    • The entire production process takes only a few hours.

    Alcoholic Fermentation

    • This pathway produces ATP from glucose.
    • Yeasts are examples of microorganisms performing alcoholic fermentation.
    • The process starts with glucose breaking down into pyruvic acid and then ATP production.
    • Subsequently, pyruvic acid breaks down into ethanol and carbon dioxide.
    • Alcoholic fermentation doesn't require oxygen.
    • Fermentation of yeast generates ethanol and is used in producing beer, wine and bread.

    Acetic Acid Formation

    • Acetic acid formation is a method subsequent to alcoholic fermentation.
    • The Acetobacter bacterium oxidizes ethanol to create acetic acid and water.
    • Acetic acid provides the characteristic taste of vinegar.

    Vinegar Production

    • Yeasts first ferment sour apple cider into ethanol; afterwards, oxidative bacteria transform the ethanol to acetic acid (vinegar).
    • This process is shown using a chemical equation
    • Vinegars are made from grain or fruit fermentation by sour-tasting vinegar and condiments.

    Vinegar

    • Vinegar is a food that utilises both fermentation and oxidation by microorganisms.
    • Fermentation of a substrate (like apple or grapes) with naturally occurring yeasts produces approximately 12% ethanol.
    • The resulting oxidation by the Acetobacter bacterium is the final step.

    Beneficial Effects of Fermentation

    • The main objective for microorganisms in fermentation is self-energy production.
    • Metabolic and biochemical changes improve food flavor, digestibility, shelf life, and nutritional value.
    • Fermentation generates food substrates with proteins essential amino acids, essential fatty acids, vitamins, carbohydrates and antioxidants.

    Nutritional Value of Fermented Foods

    • Traditionally fermented, high-protein foods improve diets in tropical countries.
    • Growth of Aspergillus niger (a fungus) on cassava flour for a short period significantly improves the protein and carbohydrate content of the final product.

    Removal of Anti-Nutritional Factors

    • Natural toxins and anti-nutrients are present in many fruits and vegetables.
    • During fermentation, microorganisms can remove these compounds.
    • Fermentation can ensure that substances like cassava leaves are safe for human consumption.

    Digestibility

    • Microbial enzymes (like cellulases and pectinases) in fermented foods make them more digestible- as these enzymes are not produced in the human body.
    • These enzymes break down cellulose into sugars for human digestion and soften food texture.

    Medicinal Benefits

    • Fermentation lessens food microbial contamination.
    • Studies reveal that children eating fermented foods have a lower risk of diarrhea than those eating unfermented foods.
    • The lowering of pH during fermentation inhibits the growth of food poisoning bacteria and kills certain pathogens.
    • Some lactic acid bacteria (e.g., Lactobacillus acidophilus) and certain molds produce antibiotics and bacteriocins.
    • Lactic acid bacteria positively impact the digestive tract.
    • Fermented food substances may prevent cancer growth

    Fermentation Facts

    • Fermentation is an anaerobic process, meaning it does not need oxygen.
    • Even with oxygen present, yeasts typically prefer fermentation if ample sugar is available.
    • Fermentation can occur in the digestive systems of humans and other animals

    Fermentation Syndromes

    • The rare medical condition "gut fermentation syndrome," or "auto-brewery syndrome," can result from fermentation processes in the digestive tract leading to ethanol intoxication.

    • This condition occurs because the human digestive tract can produce the same effects as fermentation by yeast.

    • Fermentation also happens in human muscle cells and is necessary to allow for rapid ATP production when oxygen is limited.

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    Food Fermentation Lecture 5 PDF

    Description

    This quiz explores the key concepts presented in Lecture 5 on food fermentation. It covers the importance of fermentation, various fermented foods, and modern fermentation technology. Understand how fermentation has influenced food production practices and the role it plays in global food security.

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