Etiket Arşivleri: lactic acid bacteria

Antimicrobial Activity of Lactic Acid Bacteria on Pathogens in Foods ( Prof.Dr. Dilek HEPERKAN )

Antimicrobial activity of lactic acid
bacteria on pathogens in foods
Why succesful?
How succesful?

Prof.Dr. Dilek Heperkan

Istanbul Technical University,

Faculty of Chemical and Metallurgical
Engineering, Dept. of Food Engineering

Food Technology2014 21-23 July, Las Vegas

Microorganisms especially bacteria can be used for a number of beneficial purposes. Among them some are more prominent like Lactic acid bacteria (LAB) and bifidobacteria.

Lactic acid bacteria have been used as natural food-grade preservatives against a variety of undesirable microorganisms.

LAB has been used for production of fermented foods for many years. As a matter of fact fermented foods existed long before mankind discovered microorganisms.

During their activity in production of fermented foods their inhibitory potential on pathogenic bacteria have been recognised and they gained increasing interest in the scientific community.

Thus LAB has been used as a tool to produce antimicrobial compounds and to control undesirable microorganisms.

Antibiotics;

On the other hand, acute diarrhea due to the loss of normal intestinal microbiota, drug-resistant strains and chronic toxicity due to widespread use of antibiotics are well known negative effects of antibiotics.

Pesticides;

The risks of toxic residues in foods, as well as contamination of soil and water due to the use of xenobiotics in food production chain are considered negatively by the public.

Lab producing a wide range of antimicrobial metabolites thus, the last two decades have seen pronounced advancements in using LAB and their metabolites for natural food preservation, as well as crop protection, and health protection.


Fermentation Lab Sheets‎ > ‎Cucumber Pickling ( FE 411 )

PURPOSE

To practice the production of cucumber pickling. By the way, to measure some parameters of the pickle.

THEORY

Pickle is a product that produced from vegetables and fruits are fermented by lactic acid bacteria in a brine has a specific salt concentration or in their self juice. Any kind of vegetables and fruits can be used for pickling. But, in whole world the most known and manufactured pickle type is cucumber pickle.

Lactic acid fermentation is the most important step occurs in the pickling. The fermentation occurs in anaerobic conditions, generally at 18-20 OC, for 2-8 weeks according to pickle’s content. While fermentation occurs, there is a transition between brine and raw material. The salt in brine passes into raw material and various compounds in raw material like minerals, sugars, and nitrogenous substances pass into brine. Lactic acid bacteria ferment the sugars.

Lactic acid bacteria ferment sugars with different pathways. Homofermentative lactic acid bacteria (Lactobacillus plantarum etc.) which are dominant in fermentation use the EMP pathway and produce only lactic acid. This kind of bacteria forms almost all lactic acid and end the fermentation. Heterofermentative lactic acid bacteria (Leuconostoc mesentereoides etc.) which generally start the fermentation use the HMP pathway and produce lactic acid, ethanol, CO2, acetic acid. Thanks to other compounds exception lactic acid by formed these bacteria; the pickle gets its taste and flavor.

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