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Microbial food cultures – Probiotics and starter cultures
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Wednesday, 13 October, 2021, 14 : 00 PM [IST]
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Priyanka Kale& D. R. More
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Microbial food cultures are live bacteria, yeasts or moulds used in food production. Microbial food cultures carry out the fermentation process in food stuffs. As of 1995, fermented food represented between one quarter and one third of food consumed in Central Europe. More than 260 different species of microbial food culture are identified and described for their beneficial use in fermented food products globally showing the importance of their use.
The scientific rationale of the function of microbes in fermentation started to be built with the discoveries of Louis Pasteur in the second half of the 19th century. Extensive scientific study continues to characterise microbial food cultures traditionally used in foodfermentation taxonomically, physiologically, biochemically and genetically. This allows better understanding and improvement of traditional food processing and opens up new fields of applications.
Microorganisms are the earliest form of life on earth, first evolving more than three billion years ago. Our ancestors discovered how to harness the power of microorganisms to make new foods,even if they did not know the science behind what they were doing.
1665-Robert Hooke and Antoni Van Leeuwenhoek first observe and describe microorganisms.
1857–1876 -Louis Pasteur proves the function of microorganisms in lactic and alcoholic fermentation.
1881-Emil Christian Hansen isolates Saccharomycescarlsbergensis, a pure yeast culture, which is today widely used in brewing of lager beers.
1889–1896 - Herbert William Conn, VilhelmStorch and Hermann Weigmann demonstrate that bacteria are responsible for the acidification of milk and of cream.
1897 - Eduard von Freudenreich isolates Lactobacillus brevis.
1919 - Sigurd Orla-Jensen classifies lactic acid bacteria on the basis of the bacteria's physiological response patterns.
Starting from 1970s - production of first industrial concentrated cultures, frozen or freeze-dried cultures, for the direct inoculation of processed milk, improving the regularity of production processes.
Function of microbial food cultures in food
Microbial food cultures preserve food through formation of inhibitory metabolites such as organic acid (lactic acid, acetic acid, formic acid, propionic acid), ethanol, bacteriocins, often in combination with decrease of water activity (by drying or use of salt).Further, microbial food cultures help to improve food safety through inhibition of pathogensor removing of toxic compounds. Microbial food cultures also improve the nutritional value and organoleptic quality of the food.
Probiotics
Probiotics are defined as ‘live microorganisms which when administered in adequate amount confer health benefits to the host. Alternatively, probiotics have been defined as live microbial feed supplements that beneficially affect the host animal by improving its intestinal microbial balance. Probiotics were originally used to improve the health of both animals and humans through the modulation of the intestinal microbiota. At present, several well-characterised strains of Lactobacilli and Bifidobacteria are available for human use to reduce the risk of gastrointestinal (GI), infections or treat such infectionsby improving or restoring the gut flora and stopping undesirable bacteria from overgrowing in the gut.
Gut flora refers to the microorganisms (i.e., invisible to the naked eye), that naturally live in your digestive tract and are important for your health. Two important roles microorganisms play in the body are protection of the immune system and aiding metabolism. Therefore, consuming probiotics can help strengthen the ability of your gut flora to improve your overall health.The terms probiotics and cultures are often used interchangeably. Live food cultures are microorganisms often used to ferment foods and beverages.
Probiotics are live microorganisms that have been shown to have a positive health effect. Live cultures are essential for creating many of the foods known to be rich in probiotics, for example, your favorite cheese. At the same time, cultures are used to create other fermented products like beer, which is not considered rich in probiotics.
Unpasteurised sauerkraut, miso, kimchi, kefir, sourdough bread, and tempeh are all examples of fermented foods belonging to a category that contain ‘live active cultures' that are naturally rich in probiotics or may have added probiotics. Similarly, yogurt also contains probiotics, either naturally or added. Probiotics can also come in capsule, tablet, powder, and liquid forms to be consumed as a dietary supplement. Knowing the many health benefits probiotics can offer, food scientists are also looking at new ways to add probiotics to everyday products like cereals and granola bars.
Examlpes of probiotic foods with microbial culture used
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Probiotic Foods
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Microbial cultures used
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Yogurt
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Lactobacillus bulgaricus and
Streptococcus thermophilus.
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Sauerkraut
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Lactobacillus and Leuconostoc
species.
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Kimchi
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Leuconostoc, Weissella, and
Lactobacillus
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Tempeh
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Rhizopusoligosporus.
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Miso
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Aspergillus oryzae
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Kombucha
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lactic-acid bacteria
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Kefir.
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Lactobacillus acidophilus,
Bifidobacteriumbifidum, Streptococcus thermophilus.
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Green
olives.
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Enterobacteriaceae, Clostridium,
Pseudomonas, Staphylococcus, lactic acid bacteria.
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Pickles
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Lactobacillus plantarum, L. brevis,
Leuconostocmesenteroides and Pediococcus cerevisiae, Pediococcuspentosaceus
and Enterococcus faecalis.
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Traditional Buttermilk
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Lactobacillus acidophilus
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Natto
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Bacillus subtilis
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The Benefits of Probiotics
- Probiotics can help prevent or treat diarrhea caused by infections or antibiotics.
- It can improve systems of irritable bowel syndrome.
- It can boost the immune system.
- Reduce inflammation and allergies.
- Help your body digest food.
- Keep bad bacteria from getting out of control and making you sick.
- Create vitamins.
- Help support the cells that line your gut to prevent bad bacteria that you may have consumed from entering your blood.
- Breakdown and absorb medications.
Starter cultures
Starter cultures are those microorganisms that are used in the production of cultured dairy products such as yogurt and cheese. The natural microflora of the milk is either inefficient, uncontrollable, and unpredictable, or is destroyed altogether by the heat treatments given to the milk.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.One of the aims of the use of starter cultures is to accelerate the production of lactic acid from the fermentation of sugars. The antimicrobial properties of lactic acid result from the establishment of unfavorable conditions that reduce the growth rate of undesirable microorganisms.
A starter culture can provide particular characteristics in a more controlled and predictable fermentation. The primary function of lactic starters is the production of lactic acid from lactose.
Other functions of starter cultures may include the following:
• flavour, aroma, and alcohol production
• proteolytic and lipolytic activities
• inhibition of undesirable organisms
There are two groups of lactic starter cultures:
1. simple or defined: single strain, or more than one in which the number is known
2. mixed or compound: more than one strain each providing its own specific characteristics
Starter cultures may be categorised as mesophilic,
• Lactococcuslactis subsp. cremoris
• L. delbrueckii subsp. lactis
• L. lactis subsp. lactis biovar diacetylactis
• Leuconostocmesenteroides subsp. cremoris
or thermophilic
• Streptococcus salivarius subsp. thermophilus (S.thermophilus)
• Lactobacillus delbrueckii subsp. bulgaricus
• L. delbrueckii subsp. lactis
• L. casei
• L. helveticus
• L. plantarum
(Kale is research scholar, College of Food Technology, VNMKV, Parbhani. More is associate professor and head,Department of Food Business Management College of Food Technology VNMKV Parbhani. They can be reached at Priyankakale665@gmail.com)
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