酱油渣中免疫活性肽水解用酶的筛选

为筛选制备酱油渣免疫活性肽的最适水解酶,采用小鼠巨噬细胞(RAW264.7)增殖和脂多糖（LPS）炎症模型细胞内NO释放量实验,考察了Acalase、Papain、Pepsin、Trypsin与Protamex水解酱油渣蛋白所得到酶解物的免疫活性。结果表明,制备酱油渣免疫活性肽的最佳水解酶为Acalase,Acalase酶解物对小鼠巨噬细胞的增殖指数(SI)为1.09(6.25 μg/mL),且对脂多糖炎症模型中细胞内NO释放量具有极显著抑制作用,抑制率为10.80%（P<0.01）;其酶解物中180～1 000 u的组分占比81.33%,多肽含量及可溶性氮回收率分别为51.47%和89.43%。     

大孔树脂分离红花籽粕酶解产物制备抗氧化肽的工艺研究

为制备红花籽粕抗氧化活性肽,比较不同酶解工艺下产物的抗氧化性,研究AB-8大孔树脂分离工艺,对比分离前后多肽抗氧化性,结果表明:碱性蛋白酶Alcalase酶解产物抗氧化性最佳,测得还原力为1.755,DPPH自由基清除率39.84％,羟自由基清除率26.76％、超氧阴离子自由基清除率25.90％,多肽含量达到10.71...     

Kinetic Study on Peptide‐Bound Pyrraline Formation and Elimination in the Maillard Reaction Using Single‐ and Multiple‐Response Models

Pyrraline, an advanced glycation end product (AGE), is related to some chronic diseases and can be employed as an indicator for heat damage in food processing. In this study, the impact of changing the reactant concentration and ratio on the kinetic parameters describing peptide‐bound pyrraline (pep‐pyr) formation and elimination was evaluated in the Lys‐Gly/glucose model systems, with microwave heating treatment ranging from 120 to 200 °C. The maximum pep‐pyr concentration increased as follows: 200 °C ? 180 °C ? 160 °C ? 120 °C ? 140 °C. First, the pep‐pyr formation and elimination was modeled by using a single‐response modelling. The formation rate constant (k_F) of pep‐pyr was independent of the initial concentration of the reactants and ratios. However, the elimination rate constant of pep‐pyr (k_E) increased with increasing reactant concentrations. Second, a multiresponse modelling was performed to illustrate the pathways of pep‐pyr formation and elimination. Two adapted models can fit to the experimental data with the goodness‐of‐fit ranging from 0.663 to 0.920. Glucose‐to‐fructose isomerization rather than glucose‐to‐mannose epimerization was detected in an equimolar model system and the model system with an excess of any of the reactants. The caramelization reaction was negligible in the equimolar systems and the model systems with an excess of peptide. The reaction rate constant of glucose‐to‐fructose isomerization was independent of the initial reactant ratios. It was more difficult for pep‐pyr elimination in the model system with an excess of peptide than that in the other 2 model systems (the equimolar system and the system with an excess of glucose), whereas a reverse result in pep‐pyr formation was obtained.     

棉籽蛋白源ACE抑制肽的制备过程中脱盐技术的研究

综合比较了001 ×7、201 ×7离子交换树脂、MWCO100透析袋和DA201-C大孔吸附树脂对棉籽蛋白水解液的脱盐效果,分析了DA201-C树脂脱盐对棉籽蛋白水解液ACE抑制活性和氨基酸组成的影响,并对Sephadex G-25分离纯化获得ACE抑制肽各组分进行活性测定.结果表明:DA201-C大孔吸附树脂的脱盐效果最好,控制流速为3 mL/min时,脱盐率可达到94.78％,氮回收率为86.32％,脱盐后疏水性氨基酸得到了有效富集,ACE抑制率显著提高.分离纯化后的ACE抑制肽各组分中,组分Ⅲ的抑制率最高,分子质量小于1000u.     

Flavourzyme蛋白酶酶解牛骨制备低聚肽的处理条件研究

采用酶法可有效地将骨中蛋白质水解成低分子肽,提高其营养价值和功能特性。实验采用酶制剂Flavourzyme蛋白酶对牛骨粉进行水解,测定水解率和氮溶出率,确定了水解最佳处理条件。结果表明,牛骨粉经121℃,30min的加热预处理显著提高水解度和氮溶出率。风味酶在pH7.0、温度50℃、底物浓度9%、酶量与底物蛋白量之比为50LAPU/g的条件下,水解5h,水解产物的水解度和氮溶出率分别为20.6%和95.5%,且水解产物在不同pH条件下氮溶解指数均达90%左右,三氯乙酸氮溶解指数为90.1%,可见,采用风味酶水解牛骨粉,其酶解产物绝大部分为小分子肽且具有高的溶解性,可直接作为营养强化剂应用于食品中。     

羊胎盘素提取新工艺及其营养成分的分析测定

本文研究了从新鲜羊胎盘提取羊胎盘素的新工艺，并对其生物活性及营养成分进行了分析测定。结果表明：用本文所报道工艺提取的羊胎盘素中氨基酸和微量元素含量丰富，其中必须氨基酸亮氨酸、赖氨酸含量较多。该产品具有较大的开发价值和经济效益。而且原料易得。为开发利用羊胎盘素制品提供了科学依据。     

大豆蛋白肽在肉糜中乳化机理的研究

研究了Acalase酶水解分子质量1000～2000Da的大豆蛋白肽添加到乳化肠中的乳化机理。通过扫描电镜发现大豆蛋白肽可在脂肪球表面形成亲水蛋白膜,从而起到乳化作用;在巴氏杀菌温度(72～82℃)下大豆蛋白肽不凝固,稳定了肉糜的脂肪-蛋白质-水体系,且比大豆分离蛋白的乳化效果好。     

双酶法制备混合蛋白肽的研究

利用双酶法同步水解动植物混合蛋白(大豆蛋白和虾粉)制备蛋白肽,最佳酶解条件为:大豆蛋白粉和虾粉混合蛋白(按照3∶2的比例混合)作为底物,底物浓度为12.0%、Flavourzyme风味蛋白酶的添加量为1.27%、Protamex复合蛋白酶的添加量为0.64%、水解温度55℃,起始pH值7.0,酶水解时间4h,此条件下水解度为29.0%。     

鸡骨胶原蛋白肽抗氧化性的研究

选取具有代表性的·OH、DPPH·、O2·三种自由基体系和铁离子还原体系,以不同浓度鸡骨胶原蛋白肽的抗氧化作用作为指标,评价鸡骨胶原蛋白肽的抗氧化性能。结果显示：鸡骨胶原蛋白肽对三种自由基都具有明显的清除作用,在相应浓度范围内,·OH 最大清除率为99.74%,半抑制浓度IC50 为 4.85mg/ml;DPPH·最大清除率为80.24%,IC50= 32.06μg/ml;O2·最大清除率为53.71%,IC50=16.48μg/ml。同时,对铁离子还具有显著的还原能力。     

Interaction of MDpep9, a novel antimicrobial peptide from Chinese traditional edible larvae of housefly,with Escherichia coli genomic DNA

Antimicrobial peptides from edible insects may serve as a potentially significant group of food preservatives. In the present work, the mode of action of a novel antimicrobial peptide MDpep9 from Chinese traditional edible housefly larvae was investigated. MDpep9 was shown to bind to bacterial DNA from the results of gel retardation and fluorescence quenching experiments. Further investigations confirmed that MDpep9 could bind with the phosphate group of DNA and intercalate into the base pairs in a helix of DNA or locate in hydrophobic environment of DNA. The previous and present results demonstrated that MDpep9 has dual mechanisms of bactericidal activity: disrupting bacterial cell membranes and binding to bacterial genomic DNA to inhibit cellular functions, ultimately leading to cell death. The results of DNA-binding mode may be contributive in designing new and promising antimicrobial peptides for food preservatives.