Method for improving survival ratio of lactobacillus after freeze drying by liquid nitrogen prefreezing

Abstract

The invention discloses a method for improving the survival rate of lactobacilli after freeze drying by using prefreezing with liquid nitrogen, which comprises the following steps: (1) collecting well-cultivated bacterial sludge of lactobacilli and adding a protective agent according to a certain mixing ratio; (2) dripping the bacterial sludge into liquid nitrogen for prefreezing; (3) freeze drying the pre-frozen bacterial sludge; and (4) collecting product for storage under vacuum. The method of the invention effectively increases the number of live bacteria after freeze drying by replacing the conventional prefreezing method with prefreezing with the liquid nitrogen, and adopting the certain compound protective agent at the same time, is simple in related materials and convenient operation, and has high industrial implementation performance.

Description

The method of improving the survival rate of lactic acid bacteria after freeze-drying by using liquid nitrogen prefreezing technical field The invention relates to a freeze-drying pre-freezing method, in particular to a pre-freezing method for improving the survival rate of lactic acid bacteria after freeze-drying. Background technique With the improvement of people's quality of life requirements, freeze-dried products are becoming more and more popular. However, due to the fact that the technology of vacuum freeze-drying microorganisms in China is not perfect enough, the number of viable bacteria in freeze-dried products is not high enough, and the freeze-drying technology is still in the development stage. The direct-throwing freeze-dried starter has a high content of viable bacteria, is convenient for storage and transportation, has a high degree of mechanization, and is convenient for industrialized mass production. It is the main development direction of high-efficie...

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Problems solved by technology

At the same time, if the freezing speed is too slow, it will also cause partial freezing of the extracellular solution, so that the concentration of solute in the unfrozen solution outside the cell is too high, resulting in solute damage; when the freezing speed is too fast, the water in the cell has no time to leak out. Larger ice crystals will be formed, which will damage the cell membrane and organelles and cause mechanical damage to the ice crystals in the cells.

There are also research reports that when the freezing rate is between 5°C / min and 180°C / min, the intracellular water will completely leak out of the cells during the freezing process, no crystallization will occur in the cells, and the cell survival rate is high; when the freezing rate is greater than At 5000°C / min, the intracellular water quickly forms crystals, no extravasation occurs, and the cell survival rate is relatively high; but if the freezing speed is between 180°C / min and 5000°C / min, the intracellular water is easy to flow during the extravasation process. mechanical damage to cells

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