Enzyme immobilization based method for producing lactosucrose through yeast fermentation

Abstract

The invention relates to an enzyme immobilization based method for producing lactosucrose through yeast fermentation. The method comprises the following steps: (1) adding mannitol into 260-280*10<3>U / L beta-fructofuranoside enzyme liquid until the final concentration of mannitol is 1-2mmol / L; mixing the mixed enzyme liquid with 2.4-2.8g / L sodium alginate according to the volume ratio of 1: (1-2), dripping 0.5-0.8mol / L calcium chloride according to the volume ratio of 1: (2-3), carrying out immobilization for 40-50 minutes, filtrating, and then, putting into a 7-8% dialdehyde starch solution for cross-linking for 15-20 minutes, so as to obtain immobilized enzyme; (2) culturing cryptococcus laurentii for 24h in a YPD (Yeast Peptone Dextrose) culture medium at the temperature of 30 DEG C, the revolving speed of 200r / min and the pH of 7.0, centrifuging, washing with water, and recovering yeast; (3) preparing a 580-680mmol / L solution from sucrose and lactose, of which the mass ratio is 1: 1, mixing the 580-680mmol / L solution with the enzyme obtained in the step (1) according to the volume ratio of 1: (1.5-2), reacting for 24h at the pH of 6-7 and the temperature of 25-30 DEG C, adding the yeast, of which the mass percentage is 1-2%, obtained in the step (2) while reacting for 11-12h, and stopping reaction with boiling water bath. According to the method, the content of lactosucrose is 54-58%, the concentration is 160-165g / L, and the conversion ratio of lactose is 56-58%, so that the product purification cost can be reduced.

Description

technical field [0001] The invention belongs to the technical field of bioengineering and relates to a production method of lactulose-oligosaccharide. technical background [0002] Since its development in 1990, LOS has been widely recognized and developed rapidly in Japan. According to the survey in 2005, LOS has become the third largest functional oligosaccharide consumer product in Japan. In recent years, many researchers have found that oligosaccharides have many specific physiological functions, and are expected to become another globally recognized functional food additive after fructo-oligosaccharides and galacto-oligosaccharides. However, due to the low yield of β-fructofuranosidase of most microorganisms and some technical barriers in the synthesis process, only Nippon Salt Harbor Refined Sugar Co., Ltd. can produce it on a large scale. [0003] Lactulooligosaccharides have not yet been industrialized in China, mainly due to the low level of enzyme production by A...

AI Technical Summary

Problems solved by technology

However, due to the low yield of β-fructofuranosidase of most microorganisms and some technical barriers in the synthesis process, currently only Nippon Saltwater Port Refined Sugar Co., Ltd. can produce on a large scale

[0003] Lactulooligosaccharides have not been industrialized in China, mainly due to the low level of Arthrobacter fermentation enzyme production, unclear fermentation mechanism, high production cost of β-fructofuranosidase, and low synthesis yield of enzymatic reaction, oligomeric It is difficult to purify lactulose, etc.