Etiket Arşivleri: Lactic acid fermentation
Lactic Acid Fermentation
Yogurt production demonstrates fermentation by Streptococcus thermophilus and Lactobaacillus bulgaricus
Heated milk is inoculated and maintained at a given temperature causing bacteria to grow and ferment lactose, the suger in milk
The bacteria produce lactic acid which causes the milk to coagulate
Food grade containers, washed
Food grade thermometer
2 cup of milk
1/3 cup nonfat dry milk
2 table spoons yogurt
Combine milk with nonfat dry milk and heat in water bath to 87ºC
Hold at that temperature for 10 to 20 minutes
Cool to 46ºC and record the pH of the mixture
Place the plain yogurt in jar and gradually blend in the warm milk
Cover and place in oven or incubator at 45ºC
Allow to stand undisturbed until the mixture is firm when the jar is gently wiggled
This may take as long as 6 to 8 houres
To practice the production of cucumber pickling. By the way, to measure some parameters of the pickle.
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.