The purpose of this experiment was to recognize the kefir culture and to determine the effect of inoculation rate and fermentation time on the kefir production.
Theory:
Kefir is a remarkable culture of about thirty beneficial microbes that is known to have been around for at least a thousand years. They live together in a special structure they create it looks a little bit like like soft bits of cauliflower. They multiply at room temperature between 18 – 30° C (65- 86° F) as they turn milk into kefir. Drinking the cultured milk, called kefir, replenishes the intestinal flora as there are always small ‘grains’ of the kefir microbes passing over to the kefir solution. An improved intestinal flora will alleviate a lot of common ailments. Some scientific tests have shown that kefir can help to reduce cancer and eliminate Candida. I do want to emphasize here that the fermentation of milk by the kefir culture creates a lot of enzymes, which are very important to our health.
Kefir is a mysterious culture. The colony of microbes forms themselves a matrix that is so unique it has its own name. With other cultures, like yoghurt, one can always create a new culture by for example exposing milk to the air (the bacteria in the air enter the milk). But kefir is different. Scientists have never succeeded in recreating a new culture. The microbes never come together to form that unique matrix. Kefir can only be multiplied by dividing the existing culture. People have been dividing it for about a thousand years.
Materials:
kefir culture
a jar with lid
milk
plastic sieve
Procedure:
100 ml pasteurized milk was taken and put in the jar then amount of kefir culture was taken and added to milk at room temperature milk and kefir culture were incubated for 24 hours. After 24 hours kefir separated from milk and washed the kefir culture and then sample was tested according to our sensory properties.
Result and Calculation:
Before incubation; pH = 6, 94 and used amount (ml) of NaOH = 1, 9 ml
After incubation; pH = 4, 93 and used amount (ml) of NaOH = 4, 3 ml
a1*M1*V1 = a2*M2*V2 à 1*0, 1 M*1,9ml = 1*M2*5ml à M2 = 0, 038 M
M2 = n/V à 0, 038 = n / 100*10-3 L à n = 0, 0038
n = m/Mw à 0, 003 = m / 90 g/mol à m = 0, 342 g lactic acid
M1*V1 = M2*V2 à 0, 1 M*4,3ml = M2*5ml à M2 = 0, 086
M2 = n/V à 0, 086 = n / 100*10-3 L à n = 0, 0086
n = m/Mw à 0, 0086 = m / 90 g/mol à m = 0, 774 g lactic acid
Our kefir sample is that;
by the direction of odour = 3
by the direction of flavour = 6
by the direction of bitter test = 1
by the direction of milk taste = 4
by the direction of sour taste = 2
by the direction of acceptability = 6 were evaluated.
Discussion:
In this experiment we studied the kefir culture and kefir production. Kefir is a Russian drink and this drink is consumed at high ratio in Russian.
Kefir includes between 0, 6 – 0, 9 % lactic acid and 0, 2 – 0, 8 % alcohol. Because of carbon dioxide content it has creamy and foamy. For kefir there are different cultures. These are Saccharomyces cerevisae, Saccharomyces propilis, L. brevis etc. after incubation kefir and milk were separated with plastic sieve from each other.
Before incubation pH of kefir and milk mixture was measured as 6, 94 and amount of lactic acid was calculated as 0, 342 g. after incubation pH of kefir was measured as 4, 93 and amount of lactic acid was calculated as 0, 774 g.
According to our result values our kefir sample had acceptable values. By the direction of odour, flavour, bitter taste, milk taste, and sour taste our kefir sample was appropriate to original kefir culture approximately.
