ROLE OF MICROORGANISMS IN FERMENTED PRODUCTS

PROJECT REPORT
ON
“ ROLE OF MICROORGANISMS IN FERMENTED PRODUCTS ”








ACKNOWLEDGEMENT

I am NITU DOGRA student of M.Sc (Microbiology) (Hons) 1st Semester of LPU Phagwara (Punjab). I feel highly indebted to the persons who cooperated, associated, and extended their support and able guidance to me in preparation of this project work.

I am also highly thankful and express my gratitude to Dr Ravinder Nagpal for his expert and valuable guidance.

I feel it as my proud privilege to express my heartfelt feelings and regards to my beloved parents for their esteemed love, affection, and guidance extended to me for preparation of not only this project work but leading to me on right path to achieve my ultimate goal.

But most importantly I would like to express that above all I am so thankful for the willpower given to me by Almighty GOD and without his grace it would not have been possible to complete this project work.

Historical Overview



Fermentation and Fermented Foods:
The Mingling of History and Culture
The origin of fermented foods is lost in antiquity, but fermentation is one of man’s oldest attempts at food preservation and preparation. There are biblical references to fermented wine production and recorded indications of Assyrian king Ashurbanipal (668-626 BCE) on what he considered to be the best wines of his time. Fermentation, however, predates even these early writings. It is suspected that the natural fermentation processes for grains and dairy led to the development of beer, wine, cheese and yogurt about the time early man moved away from a hunter-gatherer society into an agriculture-based society. To survive, ancient man had to harness nature. Food begins to spoil the moment it is harvested, but food preservation enabled man to put down roots, live in one place, and form communities. He no longer had to consume the kill or the harvest immediately. Fermentation became popular at the dawn of civilization not only because it preserved food, but also because it provided a variety of tastes and food forms.
The astonishing fact about food preservation is that, historically, it has permeated every culture. The cultural heritage of virtually all civilizations includes fermented foods made by the souring action of microbes. Fermented foods are consumed in every country throughout the world and have played an important role in our diet for centuries. Similar foods can be found in every culture, with only the name changing, indicating that fermentation has universal application and appeal. Additionally, there are nutritional benefits from fermented foods.
Historical, Cultural Fermentation
Fermenting food occurred among various native peoples, and was propagated through oral communication. During the Middle Ages, various fermented foods and drinks depended upon raw materials, environmental conditions, and the local taste preferences. Among the vegetables preserved through lacto-fermentation—using lactobacillus (and lactic acid)—cabbage has been preferred. In China, records date that cabbage has been fermented for over 6,000 years. In Europe and today in North America, the principal lacto-fermented vegetable food is cabbage—in the form of sauerkraut. Described in historical Roman texts, sauerkraut was prized for its delicious taste and medicinal properties. Tiberius carried a barrel of sauerkraut with him during long voyages to the Middle East because the Romans knew that the lactic acid it contained protected them from intestinal infections.
Captain James Cook, during his sailing trips (1768 to 1780), forced his crew to eat sauerkraut. He became well known for the extraordinary survival record and health of the shipmates on board his ships. The sauerkraut provided vitamin C to protect the entire crew from scurvy—with no cases occurring during the 27-month voyages. Russia and Poland use pickled green tomatoes, peppers and lettuces. Lacto-fermented vegetables form part of Asian cuisines as well. The peoples of Japan, China and Korea make pickled preparations of cabbage, turnip, eggplant, cucumber, onion, squash and carrot. Korean kimchi, for example, is a lacto-fermented condiment of cabbage with other vegetables and seasonings and is eaten daily. Early American tradition includes many types of relishes, developed primarily to mask the taste and odor of less than fresh food. In India, varieties of chutneys, all of which were originally lacto-fermented products, are traditional foods.
One striking observation of ethnic cuisines is that it is rare when meals are eaten without at least one fermented food. In France if one were to take away bread, cheese, wine and beer—all produced through fermentation—meals would be much impoverished. In Japan, it’s not a complete meal without miso, soy sauce and pickles—all fermented foods. In India soured milk is consumed at practically every meal. In Indonesia tempeh is eaten regularly, and in Africa porridge of fermented millet, corn, cassava, and sorghum are daily staples. In Moslem countries they consume fermented-grain breads and milk products.
Fermented foods are usually produced as a means of preserving perishable ingredients such as milk, vegetables, and fish when refrigeration is unavailable or too costly. Beyond its use as a valuable food preservation method, unique nutrient complexes are also created during fermentation. The abundant microorganisms in the fermentation process produce vitamins, enzymes, antioxidants, beta-glucans, and phytonutrients.

Introduction

Preservation of foods by fermentation is a widely practiced and ancient technology. Fermentation ensures not only increased shelf life and microbiological safety of a food but also may also make some foods more digestible and in the case of cassava fermentation reduces toxicity of the substrate. Lactic acid bacteria because of their unique metabolic characteristics are involved in many fermentation processes of milk, meats, cereals and vegetables. Although many fermentations are traditionally dependent on inoculation from a previous batch starter cultures are available for many commercial processes such as cheese manufacture thus ensuring consistency of process and product quality. This review outlines the role of lactic acid bacteria in many such fermentations and the mechanisms of antibiosis with particular reference to bacteriocins and gives a brief description of some important fermented foods from various countries. It is anticipated that the contribution of the advances in lactic acid bacteria research towards improvement of strains for use in food fermentation will benefit both the consumer and the producer.
For centuries microbial organisms have been part of nature, assuring a number of naturally occurring fermentation processes. Today micro-organisms are used in industrial food and feed production and the interest of the industry is safeguarded through the European Food and Feed Cultures Association (EFFCA).
Main categories of micro-organisms
Micro-organisms responsible for the majority of food fermentations are classified into 3 categories:
• Yeasts
- Yeasts are fungi, a division of thallophytes - non-vascular plants with little or no mycelium. They ordinarily reproduce by budding. They live in sugary solutions and ferment sugar. Among the yeasts used in food production one can mention as examples:
- genus Saccharomyces, common in bread, wine or beer making as well as in the dairy industry (such as Sereveisae used in blue mould cheeses),
- genus Debaromyces, also used in the dairy industry.
• Moulds

Moulds are also fungi, but contrary to yeasts, they feed on organic matter and reproduce by means of spores. In this family, Penicillium roqueforti in Roquefort cheese and P. candidum in Camembert cheeses are well known.
• Bacteria

Bacteria are typically one-celled and multiply by simple division. They occur in three main forms: spherical (cocci), rod-shaped (bacilli) and spirilla.
• Among the immense family of bacteria one can give as examples:
- Genus Micrococcus present in the meat industry,
- Genus Oenococcus in the wine industry,
- Genus Lactococcus - also known as lactic bacteria - used in the dairy industry.
Micro-organisms can work alone, but they usually work in associations comprising a large number of gena, species and strains.
Lactic bacteria

Lactic bacteria include a great variety of micro-organisms used in the food industry. They are primarily used in the dairy industry but can also be used in a number of other applications. Although classification remains difficult and some times changes, one can distinguish at least a dozen of different types such as streptococcus, lactococcus, intrococcus, pediococcus, leuconostoc, bifido bacterium and lactobacillus.
Applications
Fermentation
• Traditional view: The process for the production of alcohol or lactic acid from glucose
• A broader definition:
An enzymatically controlled transformation of an organic compound.

Microbial Fermentation Products
• Pyruvic Acid
• Saccharomyces Lactic acid
• Streptococcus
• Lactobacillus Ethanol,CO2
• Bacillus
• Clostridium Butanol, Acetone
• E. coli
• Salmonella Lactic Acid, Ethanol, Acetic acid
Microbial Growth
• Growth of individual cells
• Increase in size and mass of all components within the cell
• Cells continually grow and divide
• Limitation by nutrient or toxic metabolites
• Growth of the entire population
• Total mass of the entire population
• Population is asynchronous
Fermentation
• Microorganisms convert raw materials into useful products
• Type of microorganisms:
• Wild Type
• Mutants
• Genetically Engineered
• Media components
• Metabolites
Some common products of microorganism activities
• Scotch
• Wine
• Beer
• Yogurt
• Pickles
• Cheese
• Amino acid
• Vitamins
• On October 15, 1980 Genentech shares went from $35 to $ 89 producing Insulin from microbial fermentation. This was the first recombinant DNA product
Specialty Chemicals
• The chemical industry is a + $ 100 Billion
• US market is $250 Million for amino acids
• 20 amino acid, 10 are essential, must be supplied in the diet
• Animal Food supplement 50% of the market
• Food fortifications 25% of the market
• Pharmaceuticals $30 Million
• Specific therapy:
o Glutamic acid in epilepsy
o In cosmetics - Serine
o In intravenous infusion 1% of the market (18% of the revenues)
Other Fermentation Products
• Vitamins
• Sweeteners
• High fructose corn syrup 3 million tons at 7cents/pound while saccharine costs $4.00/pound
• Beverage industry uses 750,000 tons/year
• Americans consume 130 pound of sugar/ capita/yr
• Enzymes
• World wide sales $300 Million
• US sales $100 Million
Substances of Significant Economic Value Derived from Microorganisms
• Antibiotics
• The Brewing Industry
• The Wine Industry
• Amino Acids
• Vitamins
• Recombinant DNA Products: Insulin
Animal Cell Culture Technology
• Why people grow animal cells in cultures
• Variety of research studies
• Production of biopharmaceutical
• Products derived from Animal cells
• Viral vaccines
• Monoclonal antibodies
• Complex Enzymes and Proteins
• In vitro skin growth-clinical practice
Tissue Engineering
• A collaboration of biologists and engineers
• Biological substitutes to be implanted into the body
• Making of non biologic materials that are compatible with the body
• Development of materials that promote the remodeling of tissue
• Artificial Skin Bioartificial organs
• Blood substitutes Neurological implants
• Tissue engineered vascular grafts
• Various orthopedic devices


Development of Animal Cell Culture
• Organ Culture
• Tissue Culture
• Cell Culture and development of cell lines
• Most widely used presently especially for the production of biopharmaceutical products

Industrial usage
The lactobacilli are present almost everywhere in nature and are widely used in the food industry where they assure a consistent production of high-quality food products.
a. Dairy industry
In the cheese manufacture, the starter culture plays a crucial role during all phases of the cheese making and maturing process. As the culture grows in the milk, it converts lactose to lactic acid. This ensures the correct pH and it also assures the final moisture level and yield in the cheese. During ripening, the culture assures a balanced aroma, taste, texture and, if required, eye formation. Depending on the cheese type produced, the selection of the correct mixture of culture is essential in order to obtain a high quality product.
In yoghurt and other fermented milks the culture assures the development of the taste and texture of the final product. Depending on the level of pH, the product can be either mild or strong in taste. Depending on the amount of polysaccharides produced, the product can be more or less viscous.
Dairy products have long been valued as a source of healthy nutrition. Probiotic cultures in particular are known for this positive effect. These cultures are carefully selected strains; there are strong indications that they help improve digestion, balance the intestinal flora and safeguard the immune system.

b. Meat industry
The primary application for meat starter cultures is dried fermented products such as salami, pepperoni, chorizo and dried ham. In these products the lactic bacteria provide an optimal development of flavour and colour hereby ensuring correct drying condition and control of fermentation.
In addition a wide variety of moulds are used for surface ripening of sausages hereby preserving the natural quality of the product and assuring a controlled development of flavour.
c. Wine industry
In the wine industry, it is well known that yeasts are responsible for the alcoholic fermentation. Lactic bacteria also play an important role in wine making. They
are responsible for the malolactic fermentation that converts the unstable malic acid naturally present in wine into the stable lactic acid. This conversion is necessary in order to assure the stability that characterises high quality, long-hold wines.
d. Bread industry
In bread making, lactic bacteria are responsible for the fermentation, which is normally known as "sour-dough". This fermentation offers bakers a number of important benefits such as easily handled dough, uniformity, a shorter resting time, good aroma and longer freshness.
e. Agricultural industry
Lactic bacteria are used in the agricultural industry for a number of different applications.
In modern live stock production, pigs, cattle and chickens are often exposed to stressful conditions, which can give rise to imbalances in the intestinal flora with consequent low weight gains, increased diarrhoea incidence and high mortality rates. Lactic acid bacteria have proven very effective in restoring and maintaining a balanced intestinal flora in the animals, hereby ensuring optimal production parameters and improved well being of the animals.
Also in the preservation of silage, which is a fermentation of grass alpha-alpha or corn, lactic acid bacteria are used to assure an optimal preservation of the nutritive elements in these products.
f. Health food industry
In addition to the food and feed applications, lactic bacteria are also used in a wide variety of capsules and tablets specifically targeted at the health food industry. Modern day living often gives rise to imbalances in the intestinal flora of human beings. This imbalance can also be caused by travelling or medical treatment, and lactic acid bacteria can help in restoring and maintaining a balanced intestinal flora, hereby assuring a good quality of life despite changed conditions.
Production process and quality control
Production of lactic bacteria takes place in highly specialised fermentors under strict hygienic conditions. It typically involves a number of different steps:
1. The original strains are preserved in a microbiology laboratory that is responsible for - prior to each production - preparing the inoculation material. This inoculation material is transferred to fermentors in which the culture is allowed to multiply and grow within carefully defined and monitored conditions.
After the fermentation has been finalized, the bio mass is harvested, eg by means of centrifugation, and the resulting bio mass is conserved either in a liquid, frozen or powder form. Finally the product is formulated and packed in the finished product according to the customers' needs.
2. The entire production process is at each individual step carefully monitored by Quality Control laboratories in order to assure that the product remains of the highest quality and is free from contamination.

Importance and Benefits of Fermented Cereals
Fermented foods contribute to about one-third of the diet worldwide (Campbell-Platt 1994). Cereals are particularly important substrates for fermented foods in all parts of the world and are staples in the Indian subcontinent, in Asia, and in Africa. Fermentation causes changes in food quality indices including texture, flavor, appearance, nutrition and safety. The benefits of fermentation may include improvement in palatability and acceptability by developing improved flavours and textures; preservation through formation of acidulants, alcohol, and antibacterial compounds; enrichment of nutritive content by microbial synthesis of essential nutrients and improving digestibility of protein and carbohydrates; removal of antinutrients, natural toxicants and mycotoxins; and decreased cooking times.

Figure 4 – Influence of natural fermentation of cereals on available lysine.
Data from Hamad and Fields (1979)


Figure 5 – Influence of natural fermentation of cereals on the thiamine content.
Data from Chavan and Kadam (1989)
Conclusion
Preservation of foods by fermentation is a widely practiced and ancient technology. Fermentation ensures not only increased shelf life and microbiological safety of a food but also may also make some foods more digestible and in the case of cassava fermentation reduces toxicity of the substrate. Lactic acid bacteria because of their unique metabolic characteristics are involved in many fermentation processes of milk, meats, cereals and vegetables. Although many fermentations are traditionally dependent on inoculation from a previous batch starter cultures are available for many commercial processes such as cheese manufacture thus ensuring consistency of process and product quality. This review outlines the role of lactic acid bacteria in many such fermentations and the mechanisms of antibiosis with particular reference to bacteriocins and gives a brief description of some important fermented foods from various countries. It is anticipated that the contribution of the advances in lactic acid bacteria research towards improvement of strains for use in food fermentation will benefit both the consumer and the producer.

References
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