斑点叉尾鮰下脚料蛋白酶水解工艺优化

以蛋白质水解度为考察指标,从木瓜蛋白酶、复合蛋白酶、风味蛋白酶、中性蛋白酶、碱性蛋白酶中筛选水解斑点叉尾鮰下脚料的适宜蛋白酶,并通过单因素试验和正交试验优化工艺条件。结果表明：5种蛋白酶中复合蛋白酶的水解度最高;复合蛋白酶酶解斑点叉尾鮰下脚料的最佳酶解条件为温度55 ℃,时间4 h,pH 9.0,酶质量浓度2 500 U/g,料液比1∶3,在该条件下,蛋白质的水解度为53.26%。     

桉木氨水浸渍预处理响应面优化提高酶解效率

采用氨水中温浸渍（SAA）方法对桉木进行预处理,以期提高其后续酶水解效率。以响应面法主要预处理条件进行优化,以期筛选出SAA预处理的最优工艺条件。结果表明：最佳预处理工艺为氨用量80％、时间11h、温度90℃,在此条件下预处理物料的后续酶解转化率可达31．7％。对预处理物料的分析表明：在SAA预处理过程中,可在不损失纤维素的前提下脱除木素51％,而且主要是紫丁香基型和愈疮木基型木素降解溶出,半纤维素主要是木聚糖也有部分降解溶出。木素及半纤维素的降解、纤维素结晶度的降低都有利于后续的酶水解。     

A Comparative Study of the Difference Method and the Enzyme-Hydrolyzed Casein Method for Determining True Amino Acid Digestibilities and Endogenous Amino Acid Losses in Duck Feed

In this study,we examined the variations between the difference method and the enzyme-hydrolyzed casein method for determining endogenous amino acid loss and the true amino acid digestibility in ducks fed normal protein-containing diets.These methods were compared to the nitrogen-free(N-free)diet method.The difference method was based on soybean meal as the only protein source,with the experimental diets containing crude protein levels at 15% and 20%.The enzyme-hydrolyzed casein method was based on enzyme-hydrolyzed casein meal as the protein source,with the experimental diet containing a crude protein level of 17.5%.The N-free diet was prepared with starches and paper fibers.In each method,64 Tianfu meat drakes(7-weeks-old)with an average body weight of 2.77±0.16 kg were used and divided into four groups,and fed four different diets.Each group contained four replicates of four drakes and they were force fed trial diets according to the Sirbald method for detecting their apparent amino acid digestibility,endogenous amino acid loss and true amino acid digestibility.The results demonstrated that using the difference,enzyme-hydrolyzed casein and N-free diet methods,endogenous amino acid losses were 0.9946,1.2243 and 0.9297 mg/g dry matter intake(DMI),respectively.The true amino acid digestibility measured by the difference method was 88.93%±4.43%.Using the enzyme-hydrolyzed casein method with two dietary crude protein levels of 15% and 20%,the digestibility was 91.15%±4.33% and 91.97%±4.16%,respectively,and by the N-free diet methods with two dietary crude protein levels of 15% and 20%,it was 88.55%±4.29% and 88.82%±4.61%,respectively.The results suggested that when the dietary protein level was 15% to 20 %,the true amino acid digestibility and endogenous amino acid loss as determined by the difference method was more accurate than the values determined by the enzyme-hydrolyzed casein method.     

A Comparative Study of the Difference Method and the Enzyme-Hydrolyzed Casein Method for Determining True Amino Acid Digestibilities and Endogenous Amino Acid Losses in Duck Feed

In this study, we examined the variations between the difference method and the enzyme-hydrolyzed casein method for determining endogenous amino acid loss and the true amino acid digestibility in ducks fed normal protein-containing diets. These methods were compared to the nitrogen-free (N-free) diet method. The difference method was based on soybean meal as the only protein source, with the experimental diets containing crude protein levels at 15% and 20%. The enzyme-hydrolyzed casein method was based on enzyme-hydrolyzed casein meal as the protein source, with the experimental diet containing a crude protein level of 17.5%. The N-free diet was prepared with starches and paper fibers. In each method, 64 Tianfu meat drakes (7-weeks-old) with an average body weight of 2.77 ± 0.16 kg were used and divided into four groups, and fed four different diets. Each group contained four replicates of four drakes and they were force fed trial diets according to the Sirbald method for detecting their apparent amino acid digestibility, endogenous amino acid loss and true amino acid digestibility. The results demonstrated that using the difference, enzyme-hydrolyzed casein and N-free diet methods, endogenous amino acid losses were 0.9946, 1.2243 and 0.9297 mg/g dry matter intake (DMI), respectively. The true amino acid digestibility measured by the difference method was 88.93% ± 4.43%. Using the enzyme-hydrolyzed casein method with two dietary crude protein levels of 15% and 20%, the digestibility was 91.15% ± 4.33% and 91.97% ± 4.16%, respectively, and by the N-free diet methods with two dietary crude protein levels of 15% and 20%, it was 88.55% ± 4.29% and 88.82% ± 4.61%, respectively. The results suggested that when the dietary protein level was 15% to 20 %, the true amino acid digestibility and endogenous amino acid loss as determined by the difference method was more accurate than the values determined by the enzyme-hydrolyzed casein method.     

乳酸菌固态发酵酶解对豆粕、棉籽粕和菜籽粕粗蛋白质、pH、酸度及抗营养因子含量的影响

本试验旨在研究乳酸菌和酸性蛋白酶复合固态发酵对豆粕、棉籽粕和菜籽粕粗蛋白质、pH、酸度及抗营养因子含量的影响。以乳酸菌和酸性蛋白酶为发酵剂,对豆粕、棉籽粕和菜籽粕进行固态厌氧发酵,每隔12 h采样1次(其中粗蛋白质测定为每隔24 h采样1次),共发酵72 h。结果表明,乳酸菌固态发酵酶解豆粕、棉籽粕和菜籽粕均能有效提高粗蛋白质含量,降低pH,使酸度增加;乳酸菌固态发酵酶解能有效降解豆粕中胰蛋白酶抑制剂、水苏糖和棉籽糖含量,棉籽粕中单宁及菜籽粕中异硫氰酸酯和唑烷硫酮,而对游离棉酚及植酸的降解能力有限。由此可知,乳酸菌固态发酵酶解能通过提高豆粕、棉籽粕和菜籽粕中粗蛋白质含量、降低pH及对抗营养因子的降解,从而达到改善饲料品质的目的。     

紫苏梗酶解糖化条件优化

[目的]研究复合酶制剂催化水解紫苏梗的适宜条件,为紫苏梗生物质资源化利用提供技术支持.[方法]选用质量比4:25:12的纤维素酶、木聚糖酶和漆酶为复合酶制剂,在单因素试验的基础上,采用响应曲面法,以还原糖含量(Y)为响应值,建立紫苏梗水解糖化的数学模型和优化其工艺参数,并探究复合酶制剂投加量(A)、酶解时间(B)、酶解温度(C)和pH(D)4个因素对复合酶制剂催化水解紫苏梗组织纤维的影响.[结果]建立的紫苏梗催化水解二次多项回归方程为Y=107.28+7.26A+6.88B+3.09C-1.68D-20.57A2-19.41B2-18.42C2-28.26D2-3.63AB-4.98AC-2.93AD+1.93BC-1.20BD-1.33CD,其中复合酶制剂投加量对紫苏梗还原糖含量影响极显著(P<0.01),酶解时间影响显著(P<0.05).复合酶制剂催化水解紫苏梗的最佳工艺条件为:在复合酶制剂投加量1.0 g、酶解温度45℃、pH 5的条件下酶解5.4 h,可水解产还原糖108.8 mg/g,与预测值相差0.1 mg/g.[结论]采用响应曲面法优化获得的复合酶制剂催化水解紫苏梗产糖工艺,具有试验周期短、耗能低等优点,建立的数学模型对优化工艺具有可行性,可用于实际预测.     

4种破碎方法对古尼虫草内含物提取的初步研究

以不溶固形物含量、腺嘌呤含量为指标比较了微波法、酶解法、自溶法和酸热法对交织顶孢霉菌丝体中内含物提取率的差异.结果表明,浓度为0.1%的纤维素酶在50℃条件下处理样品3 h破壁效果最佳,能较好地使细胞内含物包括核苷类物质溶出,其次是微波法.由于纤维素酶的价格较高,不利于大规模工业化生产,从经济角度考虑选用微波低温解冻档处理4 min的细胞破碎方法来提取菌丝体中内含物较理想.     

酶解海蜇胶原蛋白制备抗氧化肽工艺

为优化酶解海蜇胶原蛋白制备抗氧化肽的工艺条件,采用响应面分析法,研究了酶解温度,酶与底物的比值和pH值对此工艺的影响。以羟自由基清除率为响应值,最终确定温度47.3℃,酶与底物的比值2.8%和pH9.1。酶解液的羟自由基清除率为79.07%,与模型预测具有较好的拟合性。此工艺制备的酶解产物含有较高的疏水基氨基酸,相对分子质量主要分布在350～5000u之间,符合水解胶原蛋白的行业要求。     

Plackett-Burman设计及响应面法优化无花果干复合酶解工艺

为探究无花果干复合酶解的最佳工艺参数,在单因素试验的基础上,采用Plackett-Burman设计对影响无花果干复合酶解的7个因素进行评价,筛选出3个显著因素（果胶酶添加量、纤维素酶添加量和酸性蛋白酶添加量）,又采用响应面法Box-Behnken设计进一步优化出无花果干复合酶解工艺主要影响因素的最佳参数水平。结果表明：无花果干复合酶解最佳工艺参数为复合酶添加量0.66‰（果胶酶添加量0.25‰、纤维素酶添加量0.25‰、酸性蛋白酶添加量0.16‰）、料液比1∶20、酶解pH 4.0、酶解温度50℃、酶解时间40 min,此工艺条件下酶解液中可溶性固形物含量为7.73°Bx,酶解效率得到显著提升。     

杉木DNA的快速提取

杉木ＤＮＡ的快速提取黄少甫，赵治芬，陆军，庄杰云关键词杉木，ＤＮＡ提取，酶切分子标记限制性片段长度多态性（ＲｅｓｔｒｉｃｔｉｏｎＦｒａｇｍｅｎｔＬｅｎｇｈＰｏｌｙｍｏｒｐｈｉｓｍ，简称ＲＦＬＰ）和随机扩增的多态性ＤＮＡ（ＲａｎｄｏｍＡｍｐｌｉｆｉｅｄ...