Role of lactic acid bacteria

Role of lactic acid bacteria

Some lactic acid bacteria are able to produce flavor compounds that contribute to the organoleptic qualities of cheeses. Most aroma compounds are derived from the metabolism of citrate: acetoin and diacetyl are the most important.

- Production of exopolysaccharides
Some strains of lactic acid bacteria have the ability to synthesize and excrete, during their growth, sugar polymers called exocellular polysaccharides or EPS, which improve the texture and viscosity of the finished product. In general, the presence of polysaccharides in fermented products, such as yogurts, increases the homogeneity of the product and makes its presentation more pleasant

- Role in conservation
Lactic acid bacteria play an essential role in the conservation of food products, they are able to produce a variety of inhibitory products whose effects can affect the lactic flora itself but also the undesirable or pathogenic flora.

- Acid production and pH decrease
Organic acids are produced by lactic acid bacteria during the fermentation process and inhibit the growth of yeasts and other bacteria that can not grow at acidic pH. The inhibitory effect of these organic acids is mainly caused by the undissociated molecules that diffuse through the lipid layers of the membranes of the microorganisms thus causing a lowering of the pH in the cytoplasm which results in the destabilization of the cells.

-Production of hydrogen peroxide
The production and accumulation of hydrogen peroxide create a toxic environment for cells not equipped with a protective system capable of degrading this compound. Its accumulation is inhibitory vis-à-vis the strains that generate peroxide but also vis-à-vis other microorganisms

- Production of bacteriocins
Bacteriocins are substances of a protein nature synthesized by bacteria and which have an antibacterial power directed against bacteria taxonomically close to the producing microorganism.
These antibacterial peptides have an action against Gram-positive bacteria associated with the deterioration of the hygienic quality of food and certain human pathologies. Other antimicrobial agents are produced: carbon dioxide (CO2), acetic acid, diacetyl, and acetaldehyde.

Be careful to not confuse professional and pre-biotic! Prebiotics are soluble, non-digestible dietary fibers that stimulate the multiplication or activity of useful bacterium.
The term probiotic derives from 2 Greek words "pro" and "bios" and virtually means that "in favor of life" A probiotic may be a living being that's once eaten in the comfortable amount it's a positive result on health.
In most cases, farm products like yogurts, hard milk, cheeses, milk powders, and ice creams are chosen as the most popular vehicles for probiotic cultures. On the opposite hand, a very important property of probiotic bacterium lies in their ability to stick to the enteric walls.
Lactic acid bacterium are more and more utilized in human and animal nutrition for his or her probiotic effects. Among these effects we are able to mention:

Lactic acid bacterium exerts Associate in Nursing restrictive result on the event and synthesis of poisons by alternative morbific microorganisms.
Inactivation or inhibition of cancer compounds within the GI tract.
-The hindrance and treatment of looseness of the bowels because of gi infections.
-The decrease in sterolemia by reducing the enteric absorption of endogenous and exogenous cholesterol and also the reduction of its synthesis within the liver

-two beverage ferments:

Since yore, humans have used the principles of fermentation to preserve their food, whether or not supported milk, meat, fruits or vegetables. In fact, long before their presence was suspected, the micro-organisms were used for the assembly of hard products like dish, food, and cheese.
In cheese, as an example, the natural process was meted out from milk that was hard ad libitum by a bacterium that had contaminated the milk on the farm or at the farm. Towards the top of the nineteenth century, some researchers incontestable that it absolutely was doable to provide the product of constant quality exploitation pure cultures of microorganisms. Currently, starters or beverage ferments ar outlined as pure cultures or mixtures of carboxylic acid bacterium hand-picked and used for the manufacture of hard products. Among these cultures, there are natural ferments, typically mixtures of the many strains of a bacterium whose precise composition is indeterminate mixed ferments, composed of 5 or six strains fastidiously hand-picked and cultivated on an individual basis up to the stage of mother culture or ferment. throughout fermentation, bacterium multiply and manufacture compounds giving the food its organoleptic properties like acidity, flavor, aroma, and texture.