Pure lactic acid is a colorless liquid, is a colorless to pale yellow liquid. Odorless, hygroscopic. The relative density of 1.2060 (25/4 ℃). Melting point 18 ℃. Boiling point 122 ℃ (2kPa). Refractive index nD (20 ℃) ??1.4392. With water, ethanol, glycerin, insoluble in chloroform, carbon disulfide and petroleum ether. Heating under normal pressure, concentrated to 50%, part of the anhydride into milk, thus products often contain 10% -15% of the milk anhydride.
2013年8月14日星期三
Highest lactate dehydrogenase activity
Zinc lactate from the highest activity of Lactobacillus DSM20196 confusion cells obtained in D-lactic acid dehydrogenase, a non-optically active pyruvate as substrate D-lactic acid can be obtained.
Industrial production of lactic acid fermentation method and the method is mainly synthesis. Because fermentation process is simple, abundant raw materials, develop and become more mature earlier lactic acid production methods, lactic acid potassium lactate for about 70 or more, but long cycle, only batch or semi-continuous production and quality of domestic non-lactic fermentation to international standards. Chemical method can achieve large-scale continuous production of lactic acid and lactic acid synthesis has also been the U.S. Food and Drug Administration (FDA) approval, but the raw materials are generally toxic, does not meet the requirements of green chemistry. Enzymatic process is complex, and its industrial application needs further study.
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