����E-Module on�Microbiology of Starter Culture

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Dr.Jitender Kumar

Dept. Biotechnology

HMV ,Jalandhar

Starter Culture

• In microbiology, a starter culture is a deliberate preparation of selected, beneficial microorganisms, such as bacteria or yeast, that is added to a food product like milk to initiate a fermentation process. 
• These cultures convert food components, such as lactose in milk to lactic acid, which creates the desired texture, flavor, and aroma, and also acts as a preservative to prevent spoilage. 
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Role of starter culture

• A fermentation starter is a preparation to assist the beginning of the fermentation process in preparation of various foods and alcoholic drinks. Food groups where they are used include breads, especially sourdough bread, and cheese. A starter culture is a microbiological culture which actually performs fermentation.

Production

• Microorganisms that are used in the production of cultured dairy products such as curd, yogurt and cheese.
• The microorganisms selected for this purpose of need to produce the desired effect in the finished product.
• Starters are a group of active and desirable microorganism capable of bringing about desirable changes in the milk product through the process of fermentation.
• Microorganism act as starter culture.

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Introduction

• These are carefully selected microorganisms that are deliberately added to milk to initiate ("Start') and carry out the desired fermentation in the production of fermented milk products.
• In other words starters bring about the specific changes in the appearance, body, texture and flavor characteristics of the final products.
• Starter culture brings physiological changes.

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History of starter culture

• The pure culture technique in microbiology was developed in the Pasteur era (1860s).
• Lactic acid bacteria (LAB), were identified by Lister in the 1870s.
• Industry developed technique to produce pure cultures only a short time later.
• Storch ( Denmark) ,Weigman (Germany), and Conn (USA) in late 1880s showed that pure cultures could be used to ripen cream, and soon the role of flavor-producing bacteria (i.e., citrate-fermenting diacetyl-producers) was established.

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History of starter culture

• By 1878 Christian Hansen began a culture business that continues even today to be a major supplier of starter cultures for the dairy, meat, brewing, baking, and wine industries.
• Initially, starter strains were prepared by the manufacturer by growing pure strains in heat-sterilized milk. Calcium carbonate was often added as a buffer in order to maintain a neutral pH.
• These liquid cultures remained popular until recently, even though they had a relatively short shelf-life due to the loss of cell viability and fermentative activity.

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History

• Eventually, rather crude dry culture preparations were produced which required several transfers in milk to revive the culture to an active state.
• Freeze-dried cultures also became available, but the early product also required growth in intermediate or mother cultures.
• Frozen cultures, now the most common form for dairy cultures, were not introduced until the 1960s.

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History aspects

• Significant improvements in freezing and freeze-drying technologies have led these types of cultures to dominate the starter culture market.
• The modern starter culture industry provides cultures for nearly every type of fermented food and beverage.
• Most culture houses also produce and sell the media used to propagate starter cultures, the enzymes used to coagulate milk for cheese production, and other ancillary products.

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Commercial development of starter culture

• In addition, the starter culture companies maintain a staff of highly trained microbiologists who provide expert technical service and support when issues or problems related to culture performance arise.
• And although there are many small culture manufacturers throughout the world, specializing in cultures for specific products or applications.
• Standard cultures are little costly.

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NUTRITIONAL ROLE OF FERMENTATION IN FOOD �

• Enrichment of human diet through a wide variety of flavours, aroma and texture of foods.
• Preservation of foods via lactic acid, alcoholic, acetic acid and alkaline fermentations.
• Bio-enrichment of food with proteins, essential amino acids, Essential fatty acids and vitamins.

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ROLE OF FERMENTATION IN FOOD

• Detoxification during food fermentation processing.
• Nutritional and physiological benefits such as Promotion of growth and digestion.
• Settling effect on the GI tract by deceasing harmful bacteria.
• Improvement of bowel movements.
• Suppression of cancer.
• Suppression of blood cholesterol.
• suppression of tumours.
• Suitable for lactose intolerant people.

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CLASSIFICATION / TAXONOMIC GROUPS ( BERGEY'S MANUAL)

Purpose of Propagation, Traditional Methods-Advantage �

• Advantage
• Aim of propagation is to maintain pure cultures and activate cultures without any loss of viability.
• The culture organisms are preserved in small qualities known as stock cultures.
• Fermentation process of any cultured dairy product relies on the 'purity' and activity of the starter culture.

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References

• GENERAL MICROBIOLOGY BY STANIER.
• EXPANDING HORIZON BIOTECHNOLOGY BY B.D.SINGH.
• GENERAL MICROBIOLOGY BY P.TAURO.
• MODERN FOOD MICROBIOLOGY BY JAMES JAY.

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THANKS