ROLE OF MICRO-ORGANISMS IN FOOD PRODUCTION

The first realization that microorganisms were involved in food production processes was in 1837, when scientists discovered the role of yeast in an alcoholic fermentation. Later, when the world renowned French chemist and biologist Louis Pasteur was trying to explain what happened during the production of beer and vinegar in the 1860es, he found that microorganisms were responsible. However, it wasn’t until after the Second World War that the food industry began to develop the biotechnological techniques we rely on today to produce a wide variety of better, safer foods under controlled conditions.

Components of food

Food is a nutritive substance taken by an organism for growth work, repair and maintaining life processes. It is a kind of fuel for the living things. The components of food are certain organic substances and minerals found in food, called nutrients. The major components of our food are Carbohydrates, Fats, Proteins, Mineral (salts), Roughage, Water and Vitamin.

Food processing serves the following purposes:

1. It helps in preventing spoilage of food.

2. It helps in retaining the nutritive value of food.

3. It ensures the availability of food throughout the year.

4. It ensures the availability of food even at distant or remote places.

5. It makes the food more palatable.

Micro-organisms in Foods

Microorganisms, in relation to food, can have one of these 3 roles:

1. Pathogenic microorganisms can cause infections or intoxications
2. Saprophytic microorganism play a role in biodegradation and cause food spoilage
3. Cultured microorganisms like probiotic bacteria are used in food processing.

Safety of food

When we discuss the relative safety or potential for spoilage of a food, we need to focus on two things:

1. What are the total number of microorganisms per gram or ml?

2. What types of organisms are represented in this number?

Safety includes control of both chemical and microbiological characteristics of the product.

Food safety is a major focus of food microbiology. Pathogenic bacteria, viruses and toxins produced by microorganisms are all possible contaminants of food. However, microorganisms and their products can also be used to combat these pathogenic microbes. Probiotic bacteria, including those that produce bacteriocins, can kill and inhibit pathogens. Alternatively, purified bacteriocins such as nisin can be added directly to food products. Thorough preparation of food, including proper cooking, eliminates most bacteria and viruses.

If we know what kinds of organisms are associated with plant and animal foods in their natural state, then we can usually predict the general types of microbes that will occur on these foods at some later stage in processing and the types of spoilage that may occur.

Another safety concern in food processing is the use of food additives

MICROBIAL ASPECT OF SAFETY

Processes that are aimed at prevention of growth include:

•Refrigeration

•Pasteurization

•Freezing

•Sterilization (canning)

•Control of water activity (addition of salt sugars, polyols, etc.)

•Membrane processing

ROLE OF MICRO-ORGANISMS

Nature uses microorganisms to carry out fermentation processes, and for thousands of years mankind has used yeasts, moulds and bacteria to make food products such as bread, beer, wine, vinegar, yoghurt and cheese, as well as fermented fish, meat and vegetables.

Most commonly used microorganisms are yeast, bacteria, moulds, or a combination of these. A good example of microorganism usage in food production is the process of fermentation, which results in the production of organic acids, alcohols and esters. These help to either preserve the food or to generate distinctive new food products

Microorganisms are involved in producing many foods and beverages. Fermentation produces characteristic flavors, aromas, and consistencies of various foods.

v  Bacteria in food production

Bacteria are used to make a wide range of food products. The most important bacteria in food manufacturing are Lactobacillus species, also referred to as lactic bacteria.

§  Fermented milk products: Lactobacillus, Lactococcus, Bifidobacterium

§  A variety of foods including Indian dosa, rabri: fermentation by Leuconostoc mesenteroides, S. faecalis

§  Probiotics: are live food supplements used in yoghurt and other fermented milk products. It includes Lactobacillus acidophillus and Bifidobacterium bifidum. A minimum of 10⁸bacteria per 1 ml must get to the colon alive to have any significant effect. These bacteria improve the microbial spectrum in the gut and thus contribute to the following effects:

1.    Influence immunity and hence prevent or make diarrheal diseases milder

2.    Decrease the risk of colon cancer

3.    Decrease cholesterol absorption

4.    Produce acids that decrease the pH in the gut and thus increase the absorption of minerals such as calcium and phosphorous.

v   Yeast in food production

Yeasts have two main uses in food production: baking and making alcoholic beverages. They have been used in this way since ancient times – there is evidence that ancient Egyptians used yeast in bread making, and we have been making fermented drinks like beer and wine for millennia.

Through the process of fermentation, yeast converts sugars into carbon dioxide and alcohol. These two byproducts make yeast an extremely useful tool in food production.

Records of using yeast as a leavening agent date back to the ancient Egyptians, though the form of yeast used has changed over time. Baked goods like bread rise because of the presence of yeast as a raising, or leavening, agent. The most common yeast used in bread making is Saccharomyces cerevisiae.

One of the most common is Saccharomyces cerevisiae, the same strain used in bread making; this is used to make ale-type beers and is known as a top-fermenting yeast as it forms a foam on the top of the brew. Bottom-fermenting yeasts, such as Saccharomyces pastorianus, are more commonly used to make lagers. They ferment more of the sugars in the mixture than top-fermenting yeasts, giving a cleaner taste.

The alcohol in wine is formed by the fermentation of the sugars in grape juice, with carbon dioxide as a byproduct. Yeast is naturally present on grapeskins, and this alone can be sufficient for the fermentation of sugars to alcohol to occur.