Microorganisms in Food Production

This section explains microorganisms in food production. Microorganisms, which include bacteria, yeasts, and moulds, play a significant role in food production. While many microorganisms can cause foodborne illnesses or spoilage, others are used beneficially in the production of a wide variety of foods. Understanding how microorganisms can both negatively and positively affect food is crucial in ensuring food safety and quality.

Types of Microorganisms Used in Food Production

    Bacteria:

Certain types of bacteria are used in the fermentation process to produce foods like yoghurt, cheese, and pickles. These bacteria help to break down sugars and other compounds in food, which leads to changes in flavour, texture, and preservation.

        Examples of beneficial bacteria include:

• Lactobacillus (used in the fermentation of yoghurt and other dairy products)
• Streptococcus thermophilus (used in making yoghurt)
• Lactococcus lactis (used in cheese production)

        Role in Food Production:

• Fermentation: Bacteria ferment lactose (milk sugar) into lactic acid, which thickens milk and gives it a tangy flavour. In cheese production, bacteria break down milk proteins and fats, giving cheese its distinctive texture and flavour.
• Preservation: The production of lactic acid by bacteria in fermented foods lowers the pH, making the food more acidic and preventing the growth of harmful microorganisms.

    Yeasts:

Yeasts are fungi that are widely used in food production, especially in the making of bread, beer, and wine. Yeasts convert sugars into alcohol and carbon dioxide in a process called fermentation.

        Example: Saccharomyces cerevisiae (the most common baker's yeast) is used to leaven bread and produce alcoholic beverages like beer and wine.

        Role in Food Production:

• Fermentation in Bread: Yeasts in bread dough consume sugars in the flour and release carbon dioxide gas. This causes the dough to rise, giving bread its light, airy texture.
• Alcoholic Beverages: In brewing and winemaking, yeast ferments sugars in barley, grapes, or other fruits to produce alcohol and carbon dioxide. The carbon dioxide is often released, but the alcohol remains in the final product.

    Moulds:

Moulds are fungi used in the production of certain types of cheese, soy sauce, and fermented foods. While moulds can spoil food, controlled use of moulds in food production is common.

        Example: Penicillium roqueforti is the mould used in the production of blue cheese, where it contributes to the characteristic flavour and appearance of the cheese.

        Role in Food Production:

• Cheese Production: Moulds such as Penicillium species are intentionally introduced to cheeses like Camembert and Brie. They grow on the surface or throughout the cheese, creating the distinctive flavour, texture, and rind of the cheese.
• Soy Sauce Production: Moulds are used in the fermentation process of soy sauce, where they help break down the soybeans and wheat, leading to the development of rich flavours.

The Use of Microorganisms in Food Production

Microorganisms are deliberately used in food production for various beneficial processes, such as fermentation, preservation, and flavour development. Below are some key examples of how microorganisms are harnessed in the food industry:

    Fermentation:

Definition: Fermentation is a metabolic process where microorganisms break down sugars (such as glucose) to produce by-products like alcohol, carbon dioxide, and organic acids. This process is used to produce many staple foods and drinks.

        Examples of Fermented Foods:

• Bread: Yeast fermentation causes dough to rise, producing carbon dioxide, which gives bread its airy texture.
• Yoghurt: Lactic acid bacteria ferment lactose in milk, producing lactic acid, which thickens the milk and gives yoghurt its tangy flavour.
• Cheese: Lactic acid bacteria ferment milk sugars, while certain moulds and other bacteria help develop the flavour, texture, and appearance of different types of cheese.
• Beer and Wine: Yeast ferments sugars from barley (beer) or grapes (wine) into alcohol and carbon dioxide, resulting in alcoholic beverages.
• Sauerkraut and Kimchi: Lactic acid bacteria ferment the sugars in cabbage, creating tangy, sour-flavoured products.

    Preservation:

• Lactic Acid Bacteria (LAB): In foods such as pickles, sauerkraut, and kimchi, LAB ferment sugars and produce lactic acid. This makes the food acidic, which acts as a preservative and inhibits the growth of spoilage microorganisms.
• Alcoholic Fermentation: The production of alcohol by yeast also preserves food by preventing the growth of harmful microorganisms. The alcohol in beer, wine, and spirits acts as a preservative.
• Vinegar Production: Acetic acid bacteria are used to ferment ethanol (alcohol) into acetic acid, which is the main component of vinegar. The acidity of vinegar helps preserve pickled vegetables, fruits, and other foods.

    Flavour Development:

• Microorganisms can alter the flavour of food by producing various compounds during fermentation.
• Cheese Flavours: The bacteria and moulds used in cheese production break down proteins and fats, creating complex flavours in cheeses such as cheddar, blue cheese, and brie.
• Sourdough Bread: In addition to yeast, wild bacteria in sourdough fermentation contribute to the distinctive sour flavour by producing lactic acid.
• Fermented Soy Products: In the production of tempeh and miso, microorganisms such as fungi (Rhizopus oligosporus) and bacteria produce unique flavours that are integral to the foods' characteristics.

    Nutritional Benefits:

• Probiotics: Certain bacteria used in the fermentation of dairy products (such as Lactobacillus and Bifidobacterium) are considered probiotics. These beneficial bacteria contribute to gut health by supporting the balance of the microbiome in the digestive system.
• Increased Nutrients: Fermentation can increase the bioavailability of certain nutrients, such as B vitamins and minerals. For example, fermentation of soybeans increases the bioavailability of iron and calcium.

Controlling the Use of Microorganisms in Food Production

The growth of microorganisms in food production must be carefully controlled to ensure the desired outcome (e.g., fermentation) while preventing spoilage or harmful pathogens from contaminating the food. The following factors are important for controlling microorganisms in food production:

    Temperature Control:

Microorganisms grow at specific temperatures, and these temperatures must be carefully controlled. For instance, fermentation processes are often carried out at warm temperatures (25°C to 30°C) to encourage the growth of yeast or beneficial bacteria.

• Too high or too low temperatures can kill the microorganisms or prevent them from growing.

    Time Control:

Fermentation and other microbial processes often require specific time periods for optimal results. For example, sourdough bread may take several hours to ferment, while yoghurt requires an incubation period of 4-12 hours.

    Oxygen Control:

• Some microorganisms, such as yeast, require oxygen for growth, while others (e.g., some lactic acid bacteria) grow best in anaerobic conditions (without oxygen).
• In processes like fermentation, controlling the amount of oxygen can influence which microorganisms dominate and affect the final flavour and texture of the product.

    Sterilisation and Pasteurisation:

• Pasteurisation (e.g., heating milk to kill harmful microorganisms) is commonly used in food production to prevent spoilage and ensure safety.
• Some foods may undergo sterilisation (e.g., in canning) to destroy harmful microorganisms and preserve food for long-term storage.

By understanding how microorganisms are used in food production, both in terms of beneficial fermentation and control of harmful microbes, food safety can be better managed. Proper handling, temperature control, and hygiene are essential for ensuring that microorganisms contribute to the production of high-quality, safe food products.