酸催化半干微波法水解蚕蛹蛋白的研究

以酸为催化剂,采用半干微波法水解蚕蛹蛋白制备氨基酸。在适宜条件下,20min内氨基氮生成率达52.4％,产品收率为43.7％,游离氨基酸收率为34.0％。与常规酸水解法相比,反应时间大大缩短,能耗大幅度下降,产品收率和纯度提高。     

水解鱼蛋白对大菱鲆幼鱼消化率的影响

设计5组等氮等脂等能的饲料, 在室内流水系统进行68d的养殖实验, 探讨高植物蛋白饲料中添加不同分子量水解鱼蛋白对大菱鲆Scophthalmus maximus L.（16.050.03） g幼鱼消化能力的影响。分别在高植物蛋白饲料中添加5.4%超滤水解鱼蛋白（UF）、5.5%未经超滤水解鱼蛋白（FPH）、5.5%超滤截留水解鱼蛋白（RF）, 其均占饲料蛋白的10%, 以及不添加水解蛋白（PP）, 以上各组鱼粉含量均为18%, 对照组（FM）鱼粉含量为67.5%。研究结果表明, FM组的大菱鲆特定生长率与UF、FPH及PP组无显著差异（P0.05）; 饲料效率、蛋白质效率和蛋白质沉积率在FM组与UF组无显著差异（P0.05）, 但显著高于FPH、RF及PP组（P0.05）; 饲料干物质和蛋白质消化率在UF、FPH及RF组显著高于PP组（P0.05）, 但显著低于FM组（P0.05）, 在UF组显著高于FPH和RF组（P0.05）; 不同处理对饲料氨基酸和牛磺酸的消化率均产生显著影响（P0.05）, 趋势为FM组最高, 其次为UF组, PP组最低; 半胱氨酸和牛磺酸的消化率在添加水解鱼蛋白的3组（UF、FPH和RF组）和不添加水解鱼蛋白的2组（FM和PP组）呈相反的趋势。上述结果表明, 在高植物蛋白饲料中添加低分子量水解鱼蛋白（UF）, 大菱鲆幼鱼的生长和饲料利用有升高的趋势, 但UF、FPH以及RF都显著提高了大菱鲆对饲料干物质、蛋白质和氨基酸的消化率, 且UF效果优于FPH和RF。此外, 添加不同分子量水解鱼蛋白都降低了牛磺酸的消化率。       

在高植物蛋白饲料中添加水解鱼蛋白对牙鲆幼鱼的影响

研究采用酶解技术水解太平洋鳕鱼肉, 制备不同分子量组分的两种水解鱼蛋白产品(Fish protein hydrolysate,FPH-A 和FPH-B)。在牙鲆幼鱼高植物蛋白饲料配方中, 以水解鱼蛋白产物1.2%和3.7%两个梯度替代饲料中的鱼粉蛋白, 在室内流水养殖系统中进行了为期60d 的生长实验。研究了高植物蛋白饲料中添加水解鱼蛋白对肉食性鱼类牙鲆(Paralichthys olivaceus)生长性能和饲料利用的影响。结果表明, 添加3.7%的水解鱼蛋白显著促进了牙鲆幼鱼的生长, 特别是添加了富含低分子量组分的水解蛋白产品(FPH-A)后实验鱼的特定生长率最高。各实验处理组牙鲆摄食率没有显著差异。摄食添加3.7% FPH-A 的牙鲆鱼体粗蛋白含量显著高于对照鱼粉组。添加水解鱼蛋白显著提高了牙鲆幼鱼的蛋白质消化率、蛋白质效率和蛋白质沉积率,摄食3.7% FPH-A 实验鱼蛋白质消化率、蛋白质效率和蛋白沉积率最高, 显著高于其他各组。实验表明, 高植物蛋白饲料中添加低分子量组分的水解鱼蛋白可显著提高牙鲆幼鱼的生长和饲料蛋白利用。     

胃蛋白酶和木瓜蛋白酶水解核桃蛋白工艺研究

以核桃粕为原料,以水解度为考察指标,研究胃蛋白酶和木瓜蛋白酶对核桃蛋白的水解作用.结果表明：木瓜蛋白酶为酶解核桃蛋白最佳酶,其最佳酶解条件为底物浓度4％、酶质量分数5％、酶解 pH 值为7．0、酶解温度50℃、酶解时间4 h;在该条件下,木瓜蛋白酶酶解核桃蛋白水解度可高于25．76％.     

瑞士乳杆菌水解乳清蛋白发酵条件的研究

利用益生菌发酵制备具有生物学功能特性的发酵乳制品,特别是在构建功能性食品方面,对人类的健康及人体内共生菌群的开发具有重大意义。以瑞士乳杆菌(Lactobacillushelveticus)为研究菌种,对瑞士乳杆菌利用乳清粉的发酵条件进行了系统的研究,并对发酵条件进行了优化。实验结果表明,瑞士乳杆菌在33℃,发酵液的初始pH为5.5,接种量为1.5%时蛋白酶活力最强,发酵液中游离氨基酸含量为3.004μg/ml活菌数达到108cfu/ml。通过对瑞士乳杆菌的发酵动力学的研究,确定了该菌生长特性,以及乳清蛋白水解进程曲线和产酸情况。     

微波高压罐水解法在氨基酸分析中的应用简报

本文报导了采用微波高压罐水解技术快速水解食物蛋白质,并测定其１７种氨基酸含量的方法。研制的高压罐具有密闭性、微波穿透性好,耐热、耐压、耐腐蚀等特点。采用该高压罐研究了微波强度及作用时间等条件对氨基酸稳定性的影响,在微波输出功率１００Ｗ３５～４５分钟水解了３份食品样品,其氨基酸含量测定结果与传统的１１０℃２２左水解基本相符,１７种氨基酸５次平行测定结果ＣＶ值均＜１０％。     

扇贝边蛋白资源酶法水解条件的优化

以扇贝边为原料,首先分析了其营养成分,结果表明,扇贝边干物质中蛋白质的含量为67.6%。然后用ASI,398枯草杆菌中性蛋白酶通过液体发酵对扇贝边蛋白资源进行了酶解条件优化,实验了酶解温度、酶的用量、酶水解时间和底物浓度等4因素对酶解效率的影响,确定了扇贝边的最佳水解条件:即酶解温度为50℃,蛋白酶的加入量为0.5%,即250U·ml^-1,底物浓度为6%,酶解时间为3h。     

乳状鱼蛋白的营养评价

乳状鱼蛋白是以鱼类为原料采用酶水解方法制作的一种鱼蛋白制品。以低值淡水鱼鲢鱼整鱼为原料制作的乳状 鱼蛋白,其营养成分和氨基酸组成具有如下特点:蛋白质含量丰富,脂肪含量较高(质量分数分别为18.4%和7.1%),其组成 中不饱和脂肪酸质量分数约占70%,且EPA和DHA的总量达到12.1%;此外,铁、锌含量较高,质量分数分别为30.7mg/k 和42.2mg/kg。组成蛋白质的各必需氨基酸除甲硫氨酸和胱氨酸外,其他均接近或超过FAO/WHO模式或全蛋蛋白。由大鼠 生长试验结果表明,其蛋白质的PER和NPR均高于酪蛋白,因此可以认为乳状鱼蛋白是食品加工的良好的蛋白质源。     

Halobacterium sp. SP1(1) as a starter culture for accelerating fish sauce fermentation

Aims: Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation. Methods and Results: Traditional fish sauce fermentation was mimicked using Halobacterium sp. SP1(1) as starter culture. Protease activity, peptide release and α‐amino content (parameters used to monitor the progress of the fermentation) were high at day 10 in tests and day 20 in un‐inoculated controls. The total protein and nitrogen contents were also high in tests compared with controls. The amino acid profile observed at the end of fermentation in experimental samples, when compared with the commercial sauce preparation, was found to be better with respect to flavour and aroma contributing amino acids as well as essential amino acid lysine. Microflora analysis of the final fish sauce revealed the absence of any nonhalophilic or halotolerant micro‐organisms. The protease‐producing halophilic isolates obtained from the fish sauce of eviscerated and uneviscerated controls were identified as Halobacterium sp. F1 and F2, respectively, by 16S rDNA sequence analysis. Conclusions: Exogenous augmentation of Halobacterium sp. SP1(1) accelerated the fish sauce fermentation process with an additive effect on the existing natural microflora present in the fish during fermentation. Halobacterium sp SP1(1), therefore, can be used as an important starter culture for accelerating the fish fermentation process, which is attributed to its extracellular protease. Significance and Impact of the Study: The present study is the first report on use of Halobacterium species as a starter culture for accelerating fish sauce fermentation. Use of halobacterial starter cultures may revolutionize the process in fish sauce industries by reducing the fermentation time and making the process more economical with improved nutritive value of product.     

固定化脂肪酶选择性水解废弃鱼油富集DHA和EPA甘油酯

以鱼油下脚料为原料．以固定化Geotrichum sp．脂肪酶为催化剂,选择性水解粗鱼油,使目标脂肪酸EPA和DHA富集于甘油骨架上,显著提高了甘油酯中EPA和DHA的质量分数。通过单因素试验和响应面分析得出最佳水解条件：2g粗鱼油,2．5g水,221．3U脂肪酶,30℃,反应11．7h。最佳条件下的水解度为42．1％。EPA和DHA质量分数分别为7．8％和41．1％。经过二次水解后,水解度提高到45．9％,EPA和DHA质量分数分别提高到8．5％和42％。与初始鱼油相比,分别提高了2倍和2．2倍。     

Efficiency of 2.45 and 5.80 GHz microwave irradiation for a hydrolysis reaction by thermostable β-Glucosidase HT1

Microwave irradiation at different frequencies gave unique results for the hydrolyses of glycosyl bonds by β-Glucosidase HT1. With the observed relative complex permittivity data for the reaction buffer, 2.45?GHz microwave radiation affected both waters and ions, while 5.80?GHz only affected waters. We, here, propose that would be one of the unique “microwave nonthermal effects”.     

Lipase-catalyzed hydrolysis of fish oil in an optimum emulsion system

In this study, fish oil was hydrolyzed by lipase in a fish oil-in-water emulsion system in an effort to improve the functional properties of fish oil. Lipase activity was found to depend on the quality of the water/fish oil interface area. We selected several suitable emulsifiers, and their emulsifying activities were evaluated under a variety of conditions, including concentration, water-oil ratios, pH values, and temperature. Among the selected emulsifiers, the emulsifying activity of gelatin was higher than those of carboxymethyl chitin (CM-chitin), bovine serum albumin, and Tween-20, all of which are commercial emulsificers Moreover, the emulsifying activity of the gelatin solution was the highest at 0.5%, and was reduced with increasing concentrations of above 1%. The optimal water-oil ratio, pH, and temperature conditions were 40% (w/v), pH 8.0 and 40°C, respectively. Under these conditions, the emulsifying activity of gelatin solution was 86%. The emulsion structure of the gelatin solution was characterized by high density and small particle size. The degree of sardine oil hydrolysis in the emulsion system was 50% higher than that of the non-emulsion system. The lipid species of the lipase-prepared sardine oil hydrolysates were identified as triacylglycerol, 1,3- and 1,2-diacylglycerol, monoacylglycerol, and fatty acid.     

The Sso7d protein of Sulfolobus solfataricus: in vitro relationship among different activities

The physiological role of the nonspecific DNA-binding protein Sso7d from the crenarchaeon Sulfolobus solfataricus is unknown. In vitro studies have shown that Sso7d promotes annealing of complementary DNA strands (Guagliardi et al. 1997), induces negative supercoiling (Lopez-Garcia et al. 1998), and chaperones the disassembly and renaturation of protein aggregates in an ATP hydrolysis-dependent manner (Guagliardi et al. 2000). In this study, we examined the relationships among the binding of Sso7d to double-stranded DNA, its interaction with protein aggregates, and its ATPase activity. Experiments with 1-anilinonaphthalene-8-sulfonic acid as probe demonstrated that exposed hydrophobic surfaces in Sso7d are responsible for interactions with protein aggregates and double-stranded DNA, whereas the site of ATPase activity has a non-hydrophobic character. The interactions of Sso7d with double-stranded DNA and with protein aggregates are mutually exclusive events, suggesting that the disassembly activity and the DNA-related activities of Sso7d may be competitive in vivo. In contrast, the hydrolysis of ATP by Sso7d is independent of the binding of Sso7d to double-stranded DNA or protein aggregates.     

Specific peptide-bond cleavage by microwave irradiation in weak acid solution

A rapid and selective peptide-bond cleavage in weak acid, induced by microwave irradiation, has been developed. The specific cleavage sites of peptide bonds located only at the carboxyl-and amino-terminal ends of aspartyl residues along the peptide chain. A systematic study including the time course for the cleavage of various aspartyl-containing peptides, the effect of the acidity of the reaction solution on the completeness of peptide-bond cleavage, and the relationship between the power of microwave irradiation and the reaction time of cleavage are studied.     

Characterization of proteolytic activity of proteases

Methods for characterization of protease activity were applied to three Bacillus sp. protease preparations of varying purity. Activities differed by several orders of magnitude between the three proteases. Fractionation by HPLC and assay of peak activity against the two substrates elucidated the presence of 1–4 active fractions in each protease preparation.     

Hydrolysis of industrial substrates by an extremely stable thermolysin-like protease variant obtained by protein engineering

Various industrially used protein substrates were hydrolysed by a recently constructed, thermally stable, thermolysin-like protease variant (Boilysin; Van den Burg et al., Proc. Natl. Acad. Sci. 95: 2056–2060) and three industrial protease preparations. Hydrolysates were analysed by measuring the acid-soluble products and by SDS-PAGE of the breakdown products. The rate and extent of hydrolysis obtained by Boilysin was, in most cases, higher than those obtained with the three commercially available enzyme preperations tested. This suggests that protein hydrolysis with this new protease variant at elevated temperatures can result in improved substrate conversions.     

酶法辅助超声波微波仪从胡桃青皮中提取胡桃醌的工艺研究

以胡桃青皮为原料,在优化酶解与超声波微波萃取仪提取条件下,用硅胶层析法制取胡桃醌,并检测其纯度和含量。经过对多种提取条件的优化,确定其最佳酶解条件为:1%纤维素酶和1%果胶酶各400μL等量混合,固液比1∶20,温度55℃,pH 6.2,时间15 h。最佳提取条件是以氯仿作提取剂,固液比1∶20;在超声波恒定条件下,超声波微波萃取仪处理15 min;设置温度分别为55、60、65℃,超声波功率800、900、1 000 W,微波功率200、250、300 W,超声波频率25 kHz,模式15∶10,电机转速900 r·min-1。硅胶柱干法上样,用氯仿和石油醚分阶段洗脱得到较纯的胡桃醌制品。光度计测得胡桃醌平均含量为0.49%,纯度为81.7%。