Prediction model,experimental optimization,and verification for yield of high-pressure crystallization: a case study of citric acid

ABSTRACT

Yield is one of the most important quality indexes for the crystal produced by high-pressure crystallization such as supercritical antisolvent (SAS) crystallization. In this study, a prediction model of yield of the SAS crystallization was proposed in the first place. Then, an experiment that prepares the citric acid particle crystallization was conducted through SAS batch device. With the help of a uniform design method, the maximum yield (0.86) was obtained under the combination of process parameters (the initial concentration of solution 0.35 g/mL, the operating temperature of 33°C, the operating pressure of 12.5 MPa, and the holding time of 3.5 h), the regression equation between yield of crystallization and four factors was obtained, and the effects of each factor on the yield are as follows: initial solution concentration > operating pressure > operating temperature > holding time. Finally, the prediction model was verified by an experiment, and the results show that the average relative error between the values calculated by prediction model and the experimental ones is 9.77%.     

5-甲氧基色胺类衍生物的合成及抗痒活性评价

以5-甲氧基色胺为基本骨架,与肉桂酸衍生物或苯乙酸衍生物进行酰胺化反应,得到3个新型的5-甲氧基色胺衍生物Ca1、Ca2、Ca3。化合物结构通过IR、1H NMR和元素分析进行确证,并且测试了目标化合物对瘙痒模型小鼠的抗痒活性。抗痒活性测试结果表明,化合物Ca3具有较强的抗痒活性,有望成为新型的抗痒药物。     

Sesamin modulation of lipid class and fatty acid profile in early juvenile teleost, Lates calcarifer, fed different dietary oils

Sesamin, a major sesame seed lignan, has diverse biological functions including the modulation of molecular actions in lipid metabolic pathways and reducing cholesterol levels. Vertebrates have different capacities to biosynthesize long-chain PUFA from dietary precursors and sesamin can enhance the biosynthesis of ALA to EPA and DHA in marine teleost. Early juvenile barramundi, Lates calcarifer, were fed for two weeks on diets rich in ALA or SDA derived from linseed or Echium plantagineum, respectively. Both diets contained phytosterols and less cholesterol compared with a standard fish oil-based diet. The growth rates were reduced in the animals receiving sesamin regardless of the dietary oil. However, the relative levels of n-3 LC-PUFA in total lipid, but not the phospholipid, increased in the whole body by up to 25% in animals fed on sesamin with ALA or SDA. Sesamin reduced the relative levels of triacylglycerols and increased polar lipid, and did not affect the relative composition of phospholipid subclasses or sterols. Sesamin is a potent modulator for LC-PUFA biosynthesis in animals, but probably will have more effective impact at advanced ages. By modulating certain lipid metabolic pathways, sesamin has probably disrupted the body growth and development of organs and tissues in early juvenile barramundi.     

丙交酯合成工艺影响因素的分析

丙交酯是合成聚乳酸的主要原料,其收率和纯度制约着聚乳酸的成本和质量。介绍了聚乳酸的市场概况,重点综述了两步法丙交酯合成工艺的影响因素,分析了反应温度、压力、催化剂等对乳酸缩聚和解聚的影响以及粗丙交酯精制方法的优劣;分析了国内生产企业存在的问题和发展方向,提出丙交酯合成技术发展的关键在于开发高效手性催化剂、高收率的精制技术以及连续化生产工艺等。     

大豆粗脂肪酸值检测方法的改进

以大豆粗脂肪酸值检测方法为研究对象,对GB/T 14488.1-2008《植物油料含油量测定》与GB/T 5530-2005的标准测定方法进行改进,减少称量步骤、缩短抽提时间,以提高检测效率。试验结果表明:改进后的大豆粗脂肪酸值检测方法在保证检测结果准确性的前提下,可大幅缩短检测时间,提升检测效率。     

Biodegradable organic acid-crosslinked alkali-treated gelatins with anti-thrombogenic and endothelialization properties

Abstract

Gelatins were crosslinked with organic acids and treated with alkali to impart to them endothelialization and anti-thrombogenic properties. These matrices were characterized by biochemical and physicochemical techniques. The amounts of residual amino groups in the matrices decreased with increasing crosslinker concentration. The matrices with the highest crosslinking densities showed excellent endothelial cell adhesion and proliferation. In addition, the adhesion of platelets and formation of fibrin networks on the matrices were suppressed with increasing crosslinker concentration. The matrices also exhibited excellent biodegradability, and the degradation rate decreased with increasing crosslinking density. All the organic acid-crosslinked alkali-treated gelatins showed excellent anti-thrombogenic and endothelialization properties, superior to those of glutaraldehyde-crosslinked alkali-treated gelatins.     

Effectiveness of a peracetic acid-based disinfectant against spores of Bacillus cereus under different environmental conditions

A peracetic acid based disinfectant was tested for its efficacy against spores of different Bacillus cereus -strains (DSM 318, 4312, 4313 and 4384). To determine the influence of different factors like exposure-time, temperature and presence of protein quantitative and qualitative suspension tests were performed. Spore suspensions of B. cereus were treated with various concentrations of a representative peracetic acid based disinfectant at three temperatures (10, 15 and 20 °C), with protein load and with different exposure times (5, 30 and 60 min). Temperature, level of concentration and exposure-time had a significant influence on reduction of spores of B. cereus (p < 0.05). The susceptibility of spores of different strains greatly differed. A treatment of spores of DSM 4384 with 2.0% for 30 min even at 10 °C inactivated all present spores (initial number 6.18–6.71 log CFU/ml). Spores of B. cereus strain DSM 4313 had only reductions of 0.16–0.97 log CFU/ml at same treatment conditions. The presence of inactivated bovine serum as interfering substance had no significant influence on reduction (p > 0.05).     

小芒森甜白葡萄酒质量指标分析

以龙眼、贵人香、雷司令和玫瑰香甜白葡萄酒为参照对象,采用气相色谱、液相色谱及感官品评等技术分析小芒森甜白葡萄酒质量指标的特点。结果表明,小芒森葡萄酒中的2-甲基-1-丁醇、3-甲基-1-丁醇、乙酸乙酯、丁二酸二乙酯、咖啡酰酒石酸含量高于其他类型的甜白葡萄酒;咖啡酸、酒石酸、苹果酸、对位香豆酸和对羟基苯甲酸在小芒森甜白葡萄酒中的含量也相对偏高,上述成分是影响小芒森甜白葡萄酒风味的关键性指标。感官品评结果表明,在色泽和香气方面,小芒森甜白葡萄酒明显优于其他几种类型的甜白葡萄酒,很可能与其含量较高的酸类、醇类和酯类等成分有关。     

Whole soybean as probiotic lactic acid bacteria carrier food in solid-state fermentation

For the purpose of preparing lactic acid bacteria (LAB) carrier food, the solid-state fermentation of whole soybean was performed using Bifidobacterium animalis 937, Lactobacillus casei Zhang and Lactobacillus plantarum P-8 mixed with Bacillus subtilis natto, respectively. The physicochemical properties, the amino nitrogen content and peptide molecular weight distribution of the fermented whole soybean products were examined during this process. After 48 h of fermentation, the viable counts of the three samples were 1.41 × 10⁸ CFU/g (B. animalis 937), 1.74 × 10¹⁰ CFU/g (L. casei Zhang) and 2.19 × 10¹⁰ CFU/g (L. plantarum P-8), with the pH declined rapidly from 6.32 to 5.78, 5.60 and 5.44 at the early stage of the fermentation and increased to 6.71, 6.47 and 6.60 at the later stage of the fermentation. The fermentation caused a sharply increase in the content of the free amino nitrogen from 99.7 μmol/g to 301.9 μmol/g, 390.1 μmol/g and 529.1 μmol/g in the solid fermented soybean products, due to the multiplication of microorganism and the effect of enzyme system. Furthermore, the levels of soybean peptide with molecular weight less than 1000 Da increased 30.7%, 71.2% and 81.3% relative to that of the control group at 48 h. The result of the present work implied that whole soybean fermented by LAB can provide the different probiotics for the host, and there is potential to develope nutritious fermented soybean products.