Fermentation production method for xylitol

Abstract

The invention relates to a fermentation production method for xylitol, which is based on the mastery of principle of preparing the xylitol through fermentation of Pachysolen tannophilus. According to the method, the fermentation process comprises two stages of Pachysolen tannophilus proliferation and xylitol fermentation, at the first stage, fermentation liquor dissolved oxygen is improved through filling large amounts of oxygen so as to increase the proliferation speed of the Pachysolen tannophilus and shorten the fermentation time; and at the second stage, the oxidation-reduction potential of fermentation liquor can be adjusted through controlling feeding glucose amount, so as to improve the conversion efficiency of the xylitol. According to the invention, the production is carried out in a fermentation tank of 5000 L, the fermentation time is shortened to 36 hours, the xylose consumption rate is 95 percent, the xylitol conversion rate is 99 percent, and the production speed rate of the xylitol is 7.23 g / liter per hour. Compared with a conventional fermentation, the xylitol conversion rate is improved by 10 percent; the production speed rate is improved by 7 percent. The method integrates fermentation and regulation and control, has the advantages of being controllable, accurate and economical, and has a wide market prospect.

Description

technical field [0001] The invention belongs to the technical field of xylitol production, in particular to a method for producing xylitol by fermentation. Background technique [0002] Xylitol is a five-carbon polyol, an intermediate product of xylose metabolism, and is mainly used as a sweetener and food additive. In recent years, the market demand for xylitol has continued to expand, and the annual output value of xylitol in China has reached 1.2 billion yuan. At present, the industrial production of xylitol is mainly the chemical hydrogenation method, and the yield from xylose to xylitol is only about 50-60%. The bioconversion method is to use the hemicellulose hydrolyzate rich in xylose to convert xylose into xylitol through a biological method. The process does not need to purify xylose, nor does it need high-pressure equipment. It is easy to separate and purify, and reduces production costs. Produce good social and economic benefits. [0003] At present, there are ...

AI Technical Summary

Problems solved by technology

The dissolved oxygen level in the fermentation process directly regulates the production rate of xylitol. Since microbial aerobic fermentation technology must be adopted, it is difficult to meet the requirements of this process in industrial production. In actual industrial production, it affects the dissolved oxygen in the fermentation broth. There are many factors, especially under low dissolved oxygen conditions, it is difficult to fine-tune dissolved oxygen through aeration, and the oxygen level in the fermentation liquid cannot be accurately controlled; Xylitol dehydrogenase gene, thereby inhibiting the conversion of xylitol to xylulose, but in the reaction process, a large amount of relatively expensive glycerol needs to be added as a substrate to maintain the normal growth and metabolic activities of cells, and the residual glycerol is serious Interfering with the subsequent separation and purification of xylitol, the industrial value is not high

At present, the highest yield of xylose into xylitol is 70%~80%, and there is no economical and mature method for the optimal control of strains, which affects the economical and large-scale production of xylitol