微胶囊技术在啤酒生产中的应用研究

介绍了微胶囊固定化啤酒酵母细胞的原理以及研究了影响微胶囊稳定性的几个关键因素,阐述了微胶囊技术在啤酒连续生产应用中的可行性,结果表明连续发酵生产的啤酒与分批发酵相比,风味、口感都比较接近.     

SUPPRESSION OF α-ACETOLACTATE FORMATION IN BREWING WITH IMMOBILIZED YEAST

Immobilized yeast cells extensively produced the diacetyl precursor, α-acetolactate, during alcohol fermentation. The activity of acetohydroxy acid synthetase, which is responsible for the formation of α-acetolactate from pyruvic acid, was high in cell-free extracts of immobilized yeast cells compared with that of free yeast cells. It was suggested that the expression of AHA synthase of immobilized yeast cells was increased during growth in the carrier as compared with free yeast cells. When the initial immobilizing yeast cell concentration was changed from 1.0 × 10⁶ cells/ml to 1.0 × 10⁹ cells/ml, production of α-acetolactate was reduced from 0.94 mg/l to 0.30 mg/l. Furthermore, during continuous fermentation for 10 d, the concentration of α-acetolactate in beer was 0.30 mg/l.     

Naringinase Immobilization in Packaging Films for Reducing Naringin Concentration in Grapefruit Juice

Naringin, a bitter compound in citrus, may be converted to a nonbitter form by enzymic hydrolysis. Our objective was to determine the feasibility of immobilizing naringinase in a food contact approved packaging film. Naringinase from Penicillium sp. was immobilized in cellulose acetate films with up to 23% efficiency at 7°C. Kinetic studies showed that the free enzyme had an optimum pH=3.5 and the immobilized enzyme pH=4.0. Activation energy decreased upon immobilization (from 14.2 to 11.0 Kcal/mol), thus providing an increased catalytic efficiency for immobilized naringinase. The Michaelis constant for immobilized naringinase (K_m=2.1 mM) was lower than for free enzyme (K_mm=3.6 mM). Keeping films under dry storage for 1 mo at room temperature did not cause decreased enzyme activity. A film area/volume ratio (cm²/mL of 10° Brix grapefruit juice) of 7.2 hydrolyzed 60% of the naringin in 15 days at 7°C.     

脂肪酶改良猪油制备功能性脂的研究

我国有丰富廉价的动植物油资源，但这一资源并末得到有效的利用，为了充分利用这些资源，开展了脂肪酶催化猪油与辛酸酸解制备功能性脂的研究工作。脂肪酶筛选实验表明，在所选用的五种脂肪酶中，来自T.languginosa的同定化脂肪酶Liopzyme TL IM的催化效果最好。以Lipozyme TL IM为催化剂，进一步研究了酶量、有机溶剂、底物比率、反心时间和反应温度对猪油中辛酸插入率的影响。反应产物通过高效液相色谱法（HPLC）进行分析。研究结果表明，在正己烷介质中，脂肪酶量为15％（底物重量厅分比），底物比率为1：2（猪油：辛酸）反应时间24h，反应温度为55～60℃时，辛酸插入率最高。     

金属有机骨架载体固定化生物酶的研究进展

金属有机骨架（Metal-Organic Frameworks, MOFs）是金属中心与有机配体通过配位作用自组装形成的多孔晶态材料。MOFs具有稳定性强、大比表面积、高孔隙率、可重复使用等特点,作为一种新型固定化载体材料,具有广泛的应用前景。本文主要从MOFs载体固定化生物酶的合成方法、MOFs-生物酶复合材料的特性和应用等方面进行总结分析,并对MOFs载体固定化生物酶的将来研究方向进行了展望,为后续开发研究和在生物与医药行业应用提供了理论依据。     

固定金属离子亲和膜分离技术：（Ⅱ）研究进展和应用前景

概述了亲和膜及其组件的研究现状以及固定金属离子亲和膜分离技术的研究进展指出了该技术的应用前景．     

Evaluation of immobilized modified lipase: Aqueous preparation and reaction studies in n-hexane

Lipase Saiken 100 (Rhizopus japonicus) and its immobilized form displayed very poor activity (hydrolysis and interesterification) in microaqueous n-hexane solutions. Enzyme modification by the addition of stearic acid or sorbitan monostearate significantly improved activity. A ceramic carrier (SM-10) was used to immobilize modified lipase Saiken (stearic acid, sorbitan monostearate, and lecithin) and was found to further enhance hydrolysis and interesterification rates in n-hexane. In addition, the biocatalysts were re-used for four consecutive batch reactions with no significant shortfall in activity. Reaction rates were also greatly affected by the total reaction water content. Careful control of the biocatalyst water content prior to use and additional reaction water were required to optimize activity and minimize hydrolytic diglyceride byproducts. Hydrolysis and interesterification reaction rates were favored with immobilized biocatalyst water contents of 6.25 and 0.43 wt% with additional reaction water contents of 600 and 20 mg/L, respectively.     

Immobilized lipase reactors for modification of fats and oils—A review

This review focuses on the use of immobilized lipase technology to effect hydrolysis, ester synthesis, and interesterification reactions. The various immobilization procedures, reactor configurations, and process considerations are all reviewed and discussed.     

Synthesis of a new chitosan immobilized with β‐cyclodextrins and its adsorption properties for bilirubin

A new chitosan derivative of chitosan immobilized with β‐cyclodextrins (CTC) has been synthesized by the reaction of chitosan and allyl‐substituted β‐cyclodextrins (ASC). Its structure has been proved by Fourier transform infrared spectral analysis, X‐ray powder diffraction analysis, and chemical analysis. Its adsorption of bilirubin has been also studied. By the experiment, it has been found that this new product has good adsorption ability on bilirubin. At initial 2 h, the adsorption increased largely. The adsorption mechanism was also dealt with. It predicted that this new chitosan derivative could have application in removing the bilirubin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1264–1268, 2006     

Adsorption of bismuth(III) by bayberry tannin immobilized on collagen fiber

The adsorption behavior of collagen fiber‐immobilized bayberry tannin towards Bi(III) at acidic pH values was investigated. The adsorption capacity of the adsorbent towards Bi(III) was 0.348 mmol g^?1 at 303 K, and increased with the rise in temperature. The adsorption isotherms of Bi(III) were in the shape of so‐called type II isotherms and could be described by an empirical equation, ln q_e = k + (1/n)C_e, which implies that chemical adsorption is predominant at lower concentrations of Bi(III) and that physical adsorption is involved at higher concentrations. The adsorption kinetics of Bi(III) on the immobilized bayberry tannin could be well described by the pseudo‐second‐order rate model, and the adsorption capacities calculated by the model were almost the same as those determined by actual measurements. The adsorbent could be regenerated by using 0.02 mol dm^?3 ethylenediaminetetraacetic acid (EDTA) solution after adsorption of Bi(III). The adsorption selectivity of the immobilized bayberry tannin towards Bi(III) in a Cu(II)–Bi(III) binary solution in acidic medium was remarkable. Therefore, it is strongly suggested that the immobilized bayberry tannin could be applied to the removal of Bi(III) from crude Cu(II) samples under proper conditions. Copyright © 2006 Society of Chemical Industry