FNB News - Microbial food cultures - Probiotics and starter cultures

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Microbial food cultures - Probiotics and starter cultures

Saturday, 27 February, 2021, 14 : 00 PM [IST]

Abhilasha Shingote & Dr Surendra Sadawarte

Probiotics
Probiotic means simply life for originating from the Greek words ‘pro’ and ‘bios’. The most commonly quoted meaning was brought out by Fuller in 1989. Probiotics are live microbial feed supplement which beneficially affects the host animal by improving its intestinal balance. This correct definition is still commonly referred to, despite continual contention.

Today, probiotics are quite every day in health-promoting ‘functional foods' for humans, as well as therapeutic, prophylactic growth supplements in animal production human health. Other commonly studied probiotics include the spore-forming Bacillus spp.Bacillus spp. holds an added interest in probiotics as they can be kept in the spore form and therefore stored indefinitely on the shelf. It is often reported that a probiotic must be adherent and colonise within the gastrointestinal tract (GIT), it must replicate to high numbers, it must produce antimicrobial substances, and it must withstand the acidic environment of the GIT. The most commonly used probiotic is LAB, namely, lactobacilli spp. are usually characterised by Gram-positive, nonmotile, nonsporulating bacteria that produce lactic acid as their main by-product due to fermentation.

Some features of bacterial species as probiotics

Type of probiotic bacteria	Benefits
B. animalis/ bifidusregularis	Gut health, digestion
B. longum	Digestion, irritable, bowel syndrome
B. animalis	Immune system, digestion, irritable bowel, colds
L. acidophilus	Irritable bowel, diarrhea, antibiotic-induced diarrhea, lactose intolerance, immune system, pollen allergies
L. paracasei	Travelers diarrhea, ulcers
L. plantarum	Irritable bowel, immune system, colds
L. caseiimmunitas	Immune system, colds and flus, diarrhea
L. caseishirota	Immune system, digestion
L. lactis	Immune system
P. acidilactici	Ulcerative colitis
S. boulardii	Antibiotic-induced diarrhea, acne, irritable bowel

Starter cultures
Introduction
Food fermentation has been used for centuries as a method to preserve perishable food products. The raw materials traditionally used for fermentation are as diverse as: fruits, cereals, honey, vegetables, milk, meat and fish. It is possible to obtain a large variety of different food products by selecting different raw materials, starter cultures and fermentation conditions. The diversity covers, but is not limited to products as: wine, beer, vinegar, bread, soy sauce, kochujang, sauerkraut, kimchi, pickled olives, fermented milk products as buttermilk and yoghurt, a variety of cheeses and sausages.

Starter culture is a microbial preparation of large numbers of cells of at least one microorganism to be added to a raw material to produce a fermented food by accelerating and steering its fermentation process. The group of lactic acid bacteria (LAB) occupies a central role in these processes, and has a long and safe history of application and consumption in the production of fermented foods and beverages.

They cause rapid acidification of the raw material through the production of organic acids, mainly lactic acid. Also, their production of acetic acid, ethanol, aroma compounds, bacteriocins, exopolysaccharides, and several enzymes is of importance. In this way they enhance shelf life and microbial safety, improve texture, and contribute to the pleasant sensory profile of the end product.

The production of lactic acid, by fermenting lactose is the major role of dairy starters. The acid is responsible for development of characteristic body and texture of the fermented milk products, contributes to the overall flavour of the products, and enhances preservation. Diacetyl, acetaldehyde, acetic acid, also produced by the lactic starter cultures, contribute to flavour and aroma of the final product. Most of the cultured dairy products are produced using commercial starter cultures that have been selected for a variety of desirable properties in addition to rapid acid production. These may include flavour production, lack of associated off flavours, bacteriophage tolerance, ability to produce flavour during cheese ripening, salt tolerance, exopolysaccharide production, bacteriocin production, temperature sensitivity, etc.

Types of fermented foods and their starter cultures

Product	Raw material	Starter culture
Beer	Cereals	Yeast
Wine	Grape juice	Yeast, lactic acid bacteria
Bread	Grains	Yeast, lactic acid bacteria
Soy sauce	Soybeans	Mould (Aspergillus), lactic acid bacteria
Sauerkraut, Kimchi	Cabbage	Lactic acid bacteria
Fermented Sausages	Meat	Lactic acid bacteria
Pickled vegetables	Cucumbers, olives	Lactic acid bacteria
Fermented milks	Milk	Lactic acid bacteria
Cheese	Milk	Lactic acid bacteria

The manufacturers of fermented foods have the choice of either acquiring the starter culture in a ready to-use, highly concentrated form, or to make a propagation of the culture in the factory. The choice between the two types of process will be influenced by a number of factors as: the number of different products produced, degree of automation, presence of expertise in microbiology and finally the economy. The highest level of safety and flexibility is achieved by using a commercial starter culture for direct inoculation. Such cultures are supplied either as frozen or freeze-dried highly concentrated and highly active cultures.

(The authors are M. Tech. research scholar, College of Food Technology, VNMKV, Parbhani and assistant professor, College of Food Technology, VNMKV,Parbhani. They can be reached atshingoteabhi27@gmail.com)