Study On Proliferation Technology Of Kefir Grains And The Physiological Function Characteristic Of Its Fermented Dairy Product

In this article, we make an extensive study on resurgent subculture, purging subculture, proliferation condition, and the optimum technological condition of Kefir yoghurt using the methods such as comparison research, orthogonal experiments, nutrition enrichment, and the animal experiments. Here are the results:The vril of the grainy Kefir grains can reach the highest point under the continuative culture at its 6th generation (pH3.72). Afterwards, the vril begins to decrease as the times of subculture increases, and from the 8~ generation on, after the 7~ generation culture, the vril is stabilized at about 4.2. But the highest vril of flaky Kefir grains can only reach its pH value at 3.94. The acidity of the fermented milk made of the flaky Kefir grains is lower the that of the fermented milk made of the grainy Kefir grains. (pH of the former is 4.74, while pH of the latter is only 4.52). Besides, the fermented milk made of the flaky Kefir grain has the strong irritant sour, the flavor is not mild. After the comparison, we choose the grainy Kefir grain as the object on which we make our study.Purging influences the Kefir grains greatly, the vril of the Kefir grains can only be the vril we need under the continuative culture for 16 generations (pH3.75) even though we purge it every other generation. Under the same technological condition, we draw such a conclusion, so it is of more practical significance for us to use the method of non-purging continuative subculture.The factor which can influence the proliferation of Kefir grains most is the density of milk. Under the optimum culture condition (the density of milk: 12%, culture temperature: 22 ~C, inoculation quantity of Kefir grains: 5%) using non-purging continuative culture for 11 generations, the quality can be doubled, its proliferation rate is 104.73%. In other nutrition enrichment conditions, inorganic salts can have an distinguished effect on the proliferation of Kefir grains, after continuative culture for 10 generations , its proliferation rate can reach 167.85%; sugar and amino acid have a comparative small effect on its proliferation, the proliferation effect obviously decreases during the culture of 2nd generation, as for the 3rd generation , the proliferation is not intensified but withheld.The milk ferment technological condition using cultured Kefir as working ferment is very strict. Only under such conditions as high temperature, large inoculation quantity(temperature: 28~C, inoculation quantity: 12%) and long fermented culturing time, can we obtain the product of high quality. At this time, there are great changes taking place in microorganism colony of Kefir fermented milk from the balance relationship to its vril, if we use this fermented milk, the technological condition will be very strict, and the acidity of the product is comparative low (pH=4.63).In order to study on Kefir functions, we do the animal experiments on rats, measure triglyceride, cholesterol and blood sugar, so this proves that Kefir yoghurt has the admirable function of lowering blood fat and blood sugar (p