A novel process for the ethyl lactate synthesis in a simulated moving bed reactor (SMBR)

A novel approach for the synthesis of ethyl lactate using a simulated moving bed reactor was evaluated by experiments as well as by simulations. A mathematical model considering external and internal mass-transfer resistances and variable velocity due to change of liquid composition was developed to describe the dynamic behaviour of the SMBR and it was validated by the experiments performed; it was observed that the experimental results were well predicted by the model. The effect of operating parameters, as the feed composition, SMBR configuration and switching time on the SMBR performance parameters at the optimal operating points and/or reactive/separation regions was studied. It was shown that the SMBR is a very attractive technology for the production of ethyl lactate, since under appropriate conditions the lactic acid conversion can be driven to completion and productivity as high as and purity of 95% can be obtained.     

食品添加剂乳酸锌生产新工艺研究

本文详细论述了应用乳酸菌发酵生成乳酸,再和锌剂作用,生产食品添加剂乳酸锌的研究过程,对该产品的性状、质量和生物毒性等进行了分析。结果表明:新型乳酸锌生产工艺简便易行,省工、省时、节能,消减了乳酸生产阶段80％的工艺流程。所得乳酸锌产品质量,经检验符合予DB/410000X42015-89标准,产率在94.8％左右,小白鼠毒性实验LD50在4640mg/kg以上。     

SO42-/ZrO2-TiO2催化合成乳酸乙酯的研究

以乳酸和乙醇为原料，在固体超强酸SO4^2-/ZrO2-TiO2的催化下合成乳酸乙酯的工艺进行了实验研究，最佳制备条件为，氧化物配比为ZrO2:TiO2=1:1(摩尔比），浸泡硫酸浓度为1．5mol.L^-1，浸泡时间为24h，焙烧温度为600℃，焙烧时间为1h；最佳酯化反应条件为：醇酸比为1．5：1（摩尔比），催化剂的用量为乳酸质量的2．0％，反应时间为11h，乳酸乙酯产率可达46．76％。     

乳酸铝在医药中的应用研究

综述了乳酸铝在医药方面应用研究的现状 ,并简要叙述了乳酸铝的制备方法 ,为我国医药开发了新原料、新试剂     

Single amino acid substitutions can further increase the stability of a thermophilic L-lactate dehydrogenase

Lactate dehydrogenases are of considerable interest as stereospecificcatalysts in the chemical preparation of enantiomerically pure-hydroxyacid synthons. For such applications in synthetic organicchemistry it would be desirable to have enzymes which tolerateelevated temperatures for prolonged reaction times, to increaseproductivity and to extend then applicability to poor substrates.Here, two examples are reported of significant thermostabilizations,induced by sitedirected mutagenesis, of an already thermostableprotein, the L-lactate dehydrogenase (EC 1.1.1.27 [EC] , 35 kDa permonomer subunit) from Bacillus stearothermophilus. Thermal inactivationof this enzyme is accompanied by irreversible unfolding of thenative protein structure. The replacement of Argl71 by Tyr stabilizesthe enzyme against thermal inactivation and unfolding. Thisstabilizing effect appears to be based on improved interactionsbetween the subunits in the core of the active dimeric or tetramericforms of the enzyme. The thermal stability of L-lactate dehydrogenasevariants with an active site Arg residue, either in the 171(wild-type) or in the 102 position, is further increased bysulfate ions. The two stabilizing effects are additive, as foundfor the Argl71Tyr/ Gln1O2Arg double mutant, for which the stabilityof the protein in 100 mM sulfate solution reaches that of L-lactatedehydrogenases from extreme thermophiles. All mutant proteinsretain significant catalytic activity, both in the presenceand absence of stnhilfoing salts, and are viable catalysts inpreparative scale reactions.     

以淀粉废水为原料的乳酸钙发酵工艺研究

对利用小麦淀粉废水发酵生产乳酸钙的工艺条件进行了研究，确定了小麦淀粉双酶法糖化、乳酸发酵和产品提取的最适工艺条件     

Synthesis of triptorelin lactate catalyzed by lipase in organic media

Triptorelin lactate was successfully synthesized by porcine pancreatic lipase (PPL) in organic solvents. The effects of acyl donor, substrate ratio, organic solvent, temperature, and water activity were investigated. Under the optimum conditions, a yield of 30% for its ester could be achieved in the reaction for about 48 h.     

Antibacterial Action of Haw Pectic Oligosaccharides

Haw pectic oligosaccharides, lactic acid, sodium lactate, and tea polyphenol showed dose and pH dependent antibacterial activity against E. coli. The activity of haw pectic oligosaccharides could be enhanced by combination with lactic acid, sodium lactate, or tea polyphenol. However, combination of haw pectic oligosaccharides with nisin resulted in no significant enhancement of antibacterial activity against E. coli. These results revealed that haw pectic oligosaccharides is valuable as a food preservative, and lactic acid or sodium lactate could be used to enhance its antibacterial activity, allowing for further improvement in its efficiency, likely leading to a reduction in the dosage necessary for food preservation.     

Microbiological and Sensory Changes in Minced Beef Treated with Potassium Lactate and Sodium Diacetate during Refrigerated Storage

The effect of potassium lactate and sodium diacetate on the microbiological changes and sensory properties of vacuum-packaged minced beef was investigated. The meat samples both with a preservative (in the amounts 0.65% and 1.3%) and without were stored at temperatures of 0–1°C and 5–6°C. The influence of storage time on changes in total bacteria count (TBC), lactic acid bacteria (LAB), Brochothrix thermosphacta, and the microbes of the Enterobacteriaceae family was investigated, as well as changes in pH and sensory quality. It was found that the addition of the preservative to the minced meat caused a significant extension (p < 0.05) of the lag phase and an inhibition of microbial growth rate, depending on temperature, storage time, and its concentration. The antibacterial effect was significantly higher (p < 0.05) at a temperature of 0–1°C than at 5–6°C and most susceptible to it were the bacteria belonging to the Enterobacteriaceae. The study results showed that the minced beef containing the preservative which had been vacuum stored at 0–1°C, presented a better sensory quality and had a shelf-life of about 6 days longer, in relation to the quality and shelf-life of the control samples. For each of the refrigeration storage temperatures however, there was no statistically significant change (p < 0.05) in the pH for the various storage periods and preservative quantities present.     

鸡蛋壳制备乳酸钙的研究

对蛋壳的壳膜分离及综合利用制取乳酸钙进行了研究 .采用酸浸法分离壳膜 ,高温煅烧分解蛋壳 ,中和法制备乳酸钙 ,产率可达 90 .8%