Lecture 5: Food Fermentation

Lecture 5: Food Fermentation

• Food fermentation is a crucial method for producing various food types.
• Fermentation technology is essential for global food security.
• Many common foods like bread, vinegar, cheese, and yogurt rely on fermentation.
• Microorganisms play a critical role in food fermentation.

Objectives

• Understand the significance of fermentation processes.
• Define fermentation.
• Identify key microorganisms used in food fermentation.
• Recognize the beneficial effects of fermentation.
• Explore ways to enhance food fermentors.

Importance of Fermentation

• Fermentation has been a vital food production method for centuries.
• It remains a key method for producing diverse food types.

Fermented Foods

• Bread/baked goods
• Cheeses
• Miso
• Soy sauce
• Cocoa
• Tea
• Coffee
• Tempeh
• Yogurt
• Tofu
• Kefir
• Vinegar

Contemporary Fermentation Technology

• Modern fermentation technology ensures food security for millions.
• Public awareness of fermentation's role in food preparation is relatively low.

Enhancement of Functional Foods

• Fermentation boosts the health benefits of functional foods.
• Functional foods contain significant amounts of beneficial components.
• These components enhance health beyond basic nutritional needs. Examples include tempeh and miso.

Defining Fermentation

• Fermentation involves the breakdown of substances by microorganisms.
• This process often includes effervescence and heat generation.
• Fermentation is essentially anaerobic respiration.
• Bacteria, yeasts, molds, and combinations of these organisms drive fermentation.
• Enzyme activity during fermentation causes the associated changes.

Anaerobic Respiration

• Anaerobic respiration is an organism's way of creating usable energy without oxygen.
• It's a type of respiration occurring in the absence of oxygen.

Important Microorganisms for Food Fermentation

• Yeasts and lactic acid bacteria are the main food fermenting organisms.
• These organisms ferment sugars in substrates to gain energy.

Lactic Acid Bacteria

• Lactic acid bacteria are central to many fermented foods.
• Olives, pickles, yogurt, and cottage cheese are examples of foods relying on these bacteria.

Fermentative Yeasts

• Fermentative yeasts produce ethanol and carbon dioxide from sugars.

Additional Food Production Processes

• Certain foods like bread and vinegar are created using fermentative processes followed by oxidative actions.

Diagram Comparing Respiration and Fermentation

• ATP and pyruvic acid are produced by fermentation.
• Yeasts produce enzymes converting pyruvic acid to ethanol.
• The transformation of compounds by cellular enzymes is fermentation.
• The following details summarize different fermentation pathways with their products using a table format*

ATP (Adenosine Triphosphate)

• ATP is the major energy source in living organisms.
• It's produced in aerobic respiration (with oxygen).
• It's also produced by fermentation (without oxygen).

Lactic Acid Fermentation Details

• Lactic acid fermentation produces 2 ATP molecules per glucose.
• No atmospheric oxygen is required.
• Specific bacteria are involved in yogurt production.

Lactic Acid Fermentation Equation

• C₆H₁₂O₆ (glucose) → 2 CH₃CHOHCOOH (lactic acid)
• Reactions involving water are shown separately for clarity

Yogurt Production via Lactic Acid Fermentation

• Several methods exist for yogurt production.
• Two bacteria types (Streptococcus thermophilus and Lactobacillus bulgaricus), ferment milk at roughly 45°C.
• Streptococcus creates acidic conditions (pH drops to around 3).
• Lactobacillus shapes the flavor and aroma.
• The entire process is relatively fast.

Alcoholic Fermentation

• Alcoholic fermentation is a different metabolic pathway.
• It primarily involves yeast.
• Alcoholic fermentation starts with glucose conversion to pyruvic acid, followed by ATP generation.

Alcoholic Fermentation Breakdown

• Pyruvic acid is broken down to form carbon dioxide and ethanol, with energy release.
• The process necessitates no atmospheric oxygen.
• C₆H₁₂O₆ (glucose) --> 2 CH₃CH₂OH (ethanol) + 2 CO₂ + Energy
• Crucial in beer, wine, and bread production.

Acetic Acid Formation

• This process follows alcoholic fermentation.
• The bacterium Acetobacter oxidizes ethanol to produce acetic acid and water, producing additional ATP.
• Acetic acid is essential to vinegar's taste and aroma.
• Examples of foods produced this way include vinegar and kombucha

Vinegar Production

• Yeasts ferment apple cider into ethanol.
• Acetobacter bacteria then oxidize the ethanol to acetic acid (vinegar).
• CH₃CH₂OH + O₂ -- Ethanol
• -----> CH₃COOH + H₂O + Energy Acetic acid
• Vinegar production employs both fermentation and oxidation.
• Starches and sugars from grains and fruits form sour tasting vinegar.

Fermentation's Beneficial Effects

• Microorganisms produce energy.
• Additional metabolic changes improve flavor, digestibility, shelf life, and nutrition of the food.
• Increased flavor and variety of foods can be achieved.

Additional Functions of Fermentation

• Fermentation processes provide food components.
• Proteins, essential amino acids, fatty acids, vitamins, carbohydrates, and antioxidants are generated.

Nutritional Value of Fermented Foods

• Traditional fermented protein-rich foods are beneficial.
• Examples include improved nutrition of people in tropical countries (like Aspergillus niger helping improve cassava). -Iron content in cereals becomes more available by germination & fermentation, which can combat anemia in tropical regions.

Removal of Anti-Nutritional Factors

• Many fruits and vegetables contain toxins and anti-nutritional compounds.
• These are often removed by fermentation processes.
• Fermentation serves as a critical process in making cassava safe to eat.

Digestibility of Fermented Foods

• Microorganisms produce enzymes, like cellulases and pectinases, unavailable in humans, enhancing digestibility.
• Cellulose and starch are broken down into sugars aiding human digestion.
• Food digestibility is increased in fermented foods.

Medical Benefits of Fermentation

• Fermentation can reduce microbial contamination in food products.
• Studies suggest lower diarrhea risk in children consuming fermented gruels (compared to unfermented). -Lowers pH, inhibits bacteria growth, destroys pathogens. -Some lactic-acid bacteria and molds produce antibiotics and bacteriocin.
• Beneficial health effects of fermentation on intestinal flora are apparent.
• Substances in fermented foods may have protective effects against cancer.

Fermentation Facts

• Fermentation is an anaerobic process independent from oxygen.
• Yeast favors fermentation even in the presence of oxygen if enough sugar is present.
• This process occurs in the human digestive system.

Specific Medical Conditions & Fermentation

• Gut fermentation syndrome (auto-brewery syndrome) causes ethanol production related intoxication in the digestive tract.
• This fermentation process occurs in human muscles as they can consume ATP faster than oxygen supply.

Explore the vital processes of food fermentation, a crucial technique that has shaped food production for centuries. This quiz covers the significance of fermentation, key microorganisms involved, and the diverse products it generates, including bread, cheese, and yogurt. Gain insights into contemporary fermentation technology and its role in global food security.