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Fermentation is the conversion or transformation of complex biomolecules into simpler compounds by microorganisms and/or by enzymes. During fermentation, microorganisms degrade proteins (proteolysis), lipids (lipolysis) and carbohydrates.
Fermentation could make food more digestible and nutritious, such as cheese from milk, reduce the toxicity of foods (cassava fermentation), deliver probiotic bacteria in products (fermented milk, yogurt) and generate functional compounds (vitamins, antioxidants and other compounds).
However, the original and primary purpose of fermenting food substrates is to preserve highly perishable fresh foods such as meat, fish, milk, fruits and vegetables as fermentation can increase the shelf life and microbial safety of food products. The end products of the fermentation, acids, alcohol and CO2, generated from the oxidation of carbohydrates and related derivatives, determine the preservation of foods as the growth of spoilage microorganisms is controlled by these end-products.
Notably, there are still many parts of the world where fermentation is essential to preserve foods and this is still done traditionally rather than industrial basis. The acquired knowledge and techniques to manufacture unique fermented foods were handed down from generation to generation over the years within local communities. For example, chepa shutki is produced from heavy catches of small fish, and millions of liters of milk is processed into cheese in a single day.
During fermentation, microorganisms handle raw materials in a specific manner to create fermented foods with qualities that are superior to the original substrate and have desirable and organoleptically pleasing characteristics.
An important group of microorganisms for fermentation are the lactic acid bacteria (LAB). Most fermented foods are dependent on LAB.
Because of their unique metabolic characteristics, lactic acid bacteria have a dominant role in the fermentation process of milk, meats, cereals and vegetables. The end-product of carbohydrate catabolism of lactic acid bacteria is lactic acid, which helps in food preservation and contributes to the flavour and texture of the food product.
The writer, a PhD candidate at Wageningen University and Research, the Netherlands, is working as Associate Professor, Department of Human Nutrition and Dietetics, Patuakhali Science and Technology University.
She can be reached at: [email protected]
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