Technological properties of lactic acid bacteria

Lactic acid bacteria are microorganisms that are important from the point of view of the food industry and health. They have been used for centuries in the production of fermented foods and beverages. They contribute to improving the taste, microbiological safety, extending shelf life, improving the texture and sensory profile of the final products. 

It should also be mentioned that they produce lactic acid as the final product of the fermentation process. Types Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Lactosphaera, Leuconostoc, Melissococcus, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus and Weissella they are recognized by LAB  (engl. Lactic acid bacteria). They are widely distributed in nature, and are also found in the human digestive tract. They can provide potential health or nutritional benefits, including: improving the nutritional value of food, controlling intestinal infections, improving lactose digestion, controlling certain cancers, and controlling serum cholesterol levels. Although they are best known for their role in the preparation of fermented dairy products, they are also used for marinating vegetables, baking, winemaking, and drying fish. The laboratory also contributes to the production of fermented sausages, where strains such as L. casei, L. curvatus, L. plantarum, Enterococcus and Pediococcus. Their commitment not only gives sausages unique sensory properties, but also increases their safety and security. Lactic acid bacteria are used all over the world for food production, m.in yoghurts, cheeses, butter, buttermilk, kefir. LABS are either homofermentative or heterofermentative depending on the metabolic pathway. Homofermentative bacteria, such as Lactococcus and Streptococcus, produce two lactates from a single glucose molecule, whereas heteroenzymatic bacteria such as Leuconostoc and Weissella, convert the glucose molecule to lactate, ethanol, and carbon dioxide. Lactic acid bacteria also produce acetic acid, aromatic compounds, bacteriocins and exopolysaccharides, and several important enzymes. For example, acetaldehyde, which provides the characteristic flavor of yogurt, while diacetyl gives a buttery taste to other fermented dairy products, which improves the sensory quality of the product. 

Texturoproductive properties 

Lactic acid bacteria produce a wide range of food-grade exopolysaccharides using glucosyltransferases, which have nutritional and health-promoting properties. Glucanosaccharases are large extracellular enzymes capable of synthesizing glucans from sucrose. These exopolysaccharides are potential therapeutic agents, but are also used as viscosity-enhancing agents, have stabilizing, emulsifying, sweetening, gelling, or water-binding properties. Exopolysaccharides play a key role in the food industry and are attracting increasing interest due to their ability to impart new properties to fermented foods. These substances significantly affect the physiological functions of lactic acid bacteria. Exopolysaccharides offer many applications, especially in fermented dairy products. In addition, other exopolysaccharides have antioxidant properties and have a significant ability to retain water and oil, which makes them promising for the food industry and opens up opportunities for cosmetic applications. This highlights the versatility and benefits of exopolysaccharides in various industries.

A prime example is glucan, an exopolysaccharide that acts as a gelling and stabilizing agent. beta-glucan is a water-soluble fiber that is not digested by enzymes in the human digestive tract, but is broken down by bacteria in the colon. Because of its solubility, glucan is used in the food industry, It is produced by bacteria of the genus Streptococcus, Leuconostoc, Pediococcus and Lactobacillus. It forms viscous aqueous solutions and increases the viscosity of the product. Dextran, on the other hand, is used as a viscosity, texture, or gelling agent in food products. Dextran is produced by: Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus sanfrancisco. As a result of these microbes, dextran is found in small amounts in naturally fermented foods such as sauerkraut, pickled cucumbers, and kefir, where it probably plays the role of a thickener.

Sweetening properties

Lactic acid bacteria can produce polyols (for example, maltitol, sorbitol), which are used as sugar substitutes. Polyols, when added to food, mimic the sweetness of sugar. Sugar alcohols have a lower caloric content than sugar. They are added to chewing gum because they are not destroyed either by saliva or during chewing and therefore do not cause tooth decay. Polyols can be found in foods with reduced energy value, such as mousses, yoghurts, and cookies without added sugar. Maltitol is produced by Leuconostoc fructosum NRRL B-2041. In turn Lactobacillus casei and Lactobacillus plantarum they produce sorbitol. Mannitol produce Lactobacillus leichmanii, Lactobacillus plantarum and Lactococus lactis. 

Preserving properties-bio-preservation of food products

In recent years, a large number of bacteriocins or bacteriocin-like substances synthesized on ribosomes produced by lactic acid bacteria have been identified and characterized. Bacteriocins are biologically active compounds with antimicrobial action. Hence the great interest of bacteriocins in food preservation (bioconservation), which helps to reduce the addition of chemical preservatives and/or the intensity of heat treatment and other physical treatments, thereby satisfying consumer demand for products with minimal processing. Bio-preservation can provide a biological alternative to chemical and physical methods of fixing food that are generally considered unfavorable for the quality of the product, and in some cases also harmful to health. Bio-conservation based on the use of LABS and their metabolites may be associated with increased food safety, as well as other human health benefits, given their ability to improve nutritional value through the production of certain vitamins, organic acids, and other compounds. This vital role of conservation is intertwined with the current trend of consumers redirecting their preferences towards nutritional and health benefits, as well as towards finding more natural and sustainable products. Food safety can also be improved with the help of lactic fermentation bacteria, which leads to a lower pH due to the production of many organic acids, m.in. dairy. 

To sum up

Lactic fermentation bacteria play a significant and multifaceted role in the food industry, actively contributing to the formation of a variety of products through fermentation. These microorganisms are found not only in fermented dairy products, but also have a significant impact on the fermentation of fruits, vegetables and meat. Their impact goes beyond improving taste and texture, as LAB significantly increases the digestibility of food and performs a key function in food fixation. This preserving role is crucial, reducing the risk of food deterioration due to the presence of unwanted microorganisms.