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16日星期五
Temperature sterilization effect
Generally use 45 ℃ warm water dissolve 100 ℃ high temperature sterilization 40-60min heat treatment method, although this method causes the emulsion darken from white into a cream, but bactericidal effect, sterilization time in this range do not affect the emulsion stability, and milk drinks made with a special thick milk flavor, milky yellow color special appearance during storage than white as well. Zinc lactate se of UHT sterilization method (about 135 ℃ ,3-10s), although this method has little effect on the emulsion composition, but enough for its bactericidal effect (relative activity of lactic acid bacteria fermentation of condition), the emulsion microbial strains the number of clusters more after inoculation with lactic acid bacteria buffered lactic acid survive competition, the impact will also affect the final fermentation fermented milk flavor. On the other hand, after the preheat treatment (usually 80-100 ℃) of raw milk, precipitation are relatively small, and without preheating more precipitate (milk with no preheat treatment and the preheat treatment between difference), the choice of raw materials required to consider this point.
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