Kinetic study and kinetic parameters of lipase-catalyzed glycerolysis of sardine oil in a homogeneous medium

The production of polyunsaturated fatty acids （PUFAs） concentrates by enzymatic catalysis has gained interest due to their stereospecificity and the milder conditions employed compared to the use of inorganic catalysts. The enzymatic glycerolysis of sardine oil by Lipozymeò435 to get PUFA concentrates in the forms of di‐and monoacylglycerols （DAGs, MAGs） in an optimized amount of tert‐butanol as the organic solvent was studied. First, mass transfer limitation of the reaction sys‐tem was analyzed. The effects of different operating variables such as lipase loading, temperature and feed composition were investigated. A semi‐empirical kinetic model based on the reversible elementary reactions of glycerolysis and hydrolysis of the glycerides was employed to correlate the experimental kinetic data. A molar ratio glycerol：oil of 3：1 was the optimum, which produced more than 84 wt%of MAG at 323 K. A comparison with other glycerolysis systems was performed using MAG yield, reaction rate and significance of kinetic parameters.

干红葡萄酒的酸味、苦味与涩味及其相互影响

葡萄酒中的呈味物质为其带来了独特的味觉和口感。消费者在评价葡萄酒质量时,味觉和口感都是关键因素。品酒时,消费者感受到的不是单一的某种味觉或口感,而是味觉和口感的集体呈现。当各种味觉和口感聚在一起时,会相互影响。其中酸味、苦味和涩味在干红葡萄酒的整体口感中起着重要作用。本文简要分析了干红葡萄酒的酸味、苦味和涩味的呈味化合物与觉、口感之间的相互作用,为进一步研究干红葡萄酒的非挥发性呈味化合物提供理论依据。

好风土成就高质量的葡萄酒

不同于碳酸饮料,葡萄酒追求的不是统一和一成不变,而是需要完美地体现其地域特征,即风土。以前,在讨论葡萄酒质量时,更多的是基于酿造技术而不是葡萄。但近年来这一认识发生了变化,葡萄酒的质量更多的被认为是取决于葡萄,且需要天时地利人合,对应起来就是气候、土壤以及选择种植的品种和栽种技术。下面笔者通过简析葡萄酒酿造中的风土,阐明其对高质量葡萄酒的意义。