鲢酶解物对羟自由基的清除作用

通过测定酶解物对Fenton体系产生的羟自由基的清除效果，从胰蛋白酶、木瓜蛋白酶、胃蛋白酶、枯草杆菌蛋白酶和复合蛋白酶5种酶中，筛选出木瓜蛋白酶和胰蛋白酶作为酶解鲢制备具有较高清除羟自由基活性酶解物的理想水解酶；用正交试验L9(3^4)对两种酶的水解条件进行了优化，并对最佳酶解条件下得到的酶解物进行Sephadex G-25凝胶柱分离，洗脱液分别在波长280nm处比色，测定酶解物中主要抗氧化活性肽的分子量分布。结果表明，木瓜蛋白酶在温度50℃、酶解时间15min、pH=6．5、酶质量分数1．50％、底物：水=1：2的水解条件下，酶解物对羟自由基清除效果较好，清除率为88．2％；胰蛋白酶在温度55℃、酶解时间60min、pH=8．0、酶质量分数0．25％、底物：水=1：2的水解条件下，酶解物对羟自由基清除效果较好，清除率为84．2％。木瓜蛋白酶酶解物在最大洗脱峰时有最大羟自由基清除率峰，清除率为95．1％，在最大峰处酶解物中活性肽的分子量为2．2kDa；胰蛋白酶酶解物在最大洗脱峰时也有最大羟自由基清除率峰，其清除率为89．6％，该峰处活性肽的分子量为14．2kDa。     

缢蛏蛋白肽制备工艺优化及其清除羟自由基作用

以缢蛏为试验材料,采用羟自由基清除率为评价指标,从胰蛋白酶、胃蛋白酶、木瓜蛋白酶、碱性蛋白酶和中性蛋白酶5种蛋白酶中筛选最适水解用酶,在单因素试验基础上使用响应面法优化酶解工艺条件,考察缢蛏蛋白肽的羟自由基清除能力并通过Sephadex G-15凝胶层析测定其分子质量分布。结果表明,碱性蛋白酶酶解制备的缢蛏蛋白肽清除羟自由基能力明显强于其他蛋白酶,优化后的碱性蛋白酶水解缢蛏蛋白工艺条件为底物浓度6mg/ml、加酶量3%、pH8.0、温度55℃、酶解时间4h,蛋白肽的羟自由基清除率为76.60%,IC50值为1.89mg/ml,蛋白肽中80%以上是分子质量小于1500Da的小分子肽。     

沙丁鱼下脚料酶解物功能性及抗氧化性

利用Alcalase酶水解沙丁鱼下脚料,制备沙丁鱼蛋白水解物,分析不同水解度的蛋白水解物的功能性及抗氧化性。结果表明沙丁鱼蛋A水解物的溶解性随着水解度的增加而增加,水解度为10．16％的水解物在pH6～10的范围内,具有极好的溶解性。而其乳化性和起泡性随着水解度的增加而降低。不同水解度的沙丁鱼蛋白水解物都体现出高于50％的抑制亚油酸的过氧化活性。水解度为10．16％的沙丁鱼蛋白水解物具有较高的DPPH清除能力,DPPH自由基清除能力达到43％。酶解处理是利用沙丁鱼下脚料的一种有效方法。     

鳙鱼蛋白酶解液清除自由基的研究

以鳙鱼肉为原料,通过对水解度的分析和对可溶性短肽的测定研究了不同蛋白酶的酶解效果,并分别利用分光光度法、Deoxyribose筛选法及邻苯三酚氧化法对鳙鱼蛋白酶解液在体外清除自由基的能力进行了比较。试验结果表明:鳙鱼蛋白经酶解后可提高对自由基DPPH.、.OH和O2.-的清除活性,水解至一定时间后酶解液的清除活性达到最大,随后减少;不同的酶对清除能力的影响不同,碱性蛋白酶Alcalase的酶解液清除能力较强;酶解液对不同的自由基表现出不同的清除活性,提示酶解液对不同自由基存在着不同的抗氧化机制。     

海洋活性胶原肽酶解液的脱色脱腥工艺

以富含胶原的海产品下脚料为原料,用海洋碱性蛋白酶894水解,得到具有清除羟自由基活性的酶解液.采用一次正交回归实验设计及结果分析,建立回归方程,研究了活性炭、β-环糊精、酵母三者用量及温度、pH和作用时间6因子及其可能存在交互作用的变化关系对该酶解液综合脱色脱腥效果的影响.结果表明,在给定取值范围内,pH对综合脱色脱腥效果影响高度显著,酵母添加量、pH与酵母添加量的交互作用影响显著,其它因子及其可能的交互作用影响不显著,得最佳工艺为:温度37℃、pH 4.0、活性炭0.8%、β-环糊精和酵母分别为0.1%,作用30 min.此时,综合脱色脱腥效果值为90.90,蛋白回收率为98.02%,羟自由基清除率的IC50浓度从原来的1.42 mg·mL-1增加到1.62 mg·mL-1.     

碱性脂肪酶酶解鲐碎肉脂肪的研究

采用扩展青霉（Penicillium expansum)PF868产生的碱性脂肪酶为酶源，酶解脱酯鲐碎肉，其最适条件为：32－34℃，pH9．3，酶活浓度40u/ml，碎肉的质量与酶液体积比为1g:5ml，脱脂时间50min。鲐碎肉的干基残脂率低于4．0％。     

利用水产蛋白开发酶解降血压肽

据国家卫生部2002年8月在全国范围内开展的“中国居民营养与健康状况调查”显示,我国目前成人高血压患病率为18．6％,全国现有高血压患者1．6亿,比1991年增加7000万,但目前平均的治疗率和控制率分别为24．7％和6．1％,仍处于较低水平。而且随着人民生活水平的提高和社会节奏的不断加快,高血压患者有年轻化趋势且数量正逐年增加,这一严峻形势引起了社会各方的共同关注。     

刺参肠、性腺酶解多肽体外抗氧化作用研究

刺参（Apostichopus japonicus）肠和性腺是刺参加工过程中的副产物,为丰富其高值化利用的基础理论,研究了刺参肠、性腺酶解过程中可溶性蛋白和氨基酸态氮质量浓度变化,分析了酶解多肽对11-二苯基苦基苯肼（DPPH·）、羟基自由基（·OH）和超氧阴离子自由基（O2^-·）的体外清除效果。结果显示,刺参肠和性腺经生物酶水解后,水解度分别为53.63%和63.40%,酶解液中可溶性蛋白质量浓度分别为4.62 mg·mL-1和5.01 mg·mL-1,氨基酸态氮质量浓度分别为0.43 mg·mL-1和0.56 mg·mL-1。刺参肠和刺参性腺酶解多肽清除DPPH·的半抑制质量浓度（IC50）分别为3.31 mg·mL-1和0.88 mg·mL-1,清除·OH的IC50分别为9.53 mg·mL-1和8.81 mg·mL-1,清除O-2·的IC50分别为6.42 mg·mL-1和3.22 mg·mL-1。刺参肠和刺参性腺酶解多肽具有一定的体外抗氧化效果,应用前景广阔。     

沙蜇饮料基料酶解液酶解工艺的研究

以水解度为指标,选用胰蛋白酶、碱性蛋白酶、酸性蛋白酶、中性蛋白酶、风味蛋白酶和胃蛋白酶对沙蜇进行单酶水解,确定胰蛋白酶为水解用酶。通过正交实验确定胰蛋白酶的水解条件为：温度45℃、时间5．5小时、料液比1：4．5、加酶量255U／ml、pH7．5。实验表明,适宜条件下水解度为24．59％。水解液选用柠檬酸为除腥剂,处理后的水解液腥味和涩味都有大幅度降低。     

酪蛋白酶解物在断奶应激中对小肠性能维护试验

为探讨酪蛋白酶解物中活性肽在断奶应激中对小肠性能的维护,在pH=1.4、37℃的条件下,将酪蛋白经胃蛋白酶消化2h。酶解物用于对比试验,发现添加酶解物的仔猪小肠受应激影响小,1周后比对照组绒毛高出26.66%(P<0.01),隐窝低出15.75%(P<0.05);大肠杆菌减少17.21%(P<0.01),乳酸杆菌、双歧杆菌分别增加了6.49%、6.87%(P<0.01)。     

虾夷扇贝内脏多糖的提取及清除羟基自由基作用的研究

通过正交试验确定最佳提取条件为:温度50℃,pH 8.0,加酶量0.25%,料液比1∶45,提取时间2.5 h;最佳条件下提取的虾夷扇贝内脏多糖具有清除羟基自由基的能力。试验结果表明,6.5 mg/m l虾夷扇贝内脏多糖对羟基自由基的清除率可达84.75%。     

Optimization of the Enzymatic Hydrolysis Assisted by Ultra-high Pressure Processing of Alaska Pollock Frame for Improving Flavour

ABSTRACT

In order to improve the flavor of aquatic enzymatic hydrolysate, this study determined the effect of ultra-high pressure processing (UHP) coupled with enzymatic hydrolysis on the flavor of Alaska pollock frame (APF) hydrolysates. The optimal conditions for UHP enzymatic hydrolysis were as follows: pressure time was 60 min, pH value was 7.5, and pressure was 150 MPa. The content of soluble peptide, total-free amino acid, and delicious amino acid (DAA) content of atmospheric pressure and UHP hydrolysates were 11.37 vs 16.70 mg/mL, 5 528 vs 6 234 mg/100 g, and 2145 vs 2411 mg/100 g, respectively. The major compounds in the enzymatic hydrolysates of UHP included seven types of ketones (18.31%), 8 types of aldehydes (6.35%), 3 types of alcohols (2.61%), one type of ester (0.38%), and one type of furan (7.89%). The results of electronic tongue (e-tongue) demonstrated good agreement with gas chromatography-mass spectrometry (GC-MS) analysis. In conclusion, UHP enzymatic hydrolysis can be a potential tool to improve the flavor compounds of hydrolysates.     

Effect of Pretreatments on Hydrolysis Efficiency and Antioxidative Activity of Hydrolysates Produced from Bighead Carp (Aristichthys nobilis)

ABSTRACT

Effect of pretreatment methods including ultrasonication (US), microwave (MW), and ultrafine milling (UM) on hydrolysis efficiency and antioxidative activity of peptides produced from bighead carp were investigated. The UM peptides showed higher hydrolysis efficiency (higher degree of hydrolysis, nitrogen recovery, and oligopeptide yield; narrower molecular-weight distribution), and higher 1,1-dipheny1-2-pycrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfomic acid) diammonium salt (ABTS) radical scavenging activities, and metal chelating activities than US and MW peptides. The hydrolysis efficiency and antioxidative activity of UM peptides could remain relatively high even when the substrate concentration increased up to 50%. In conclusion, ultrafine milling may be a suitable pretreatment method in the production of peptides.     

Evaluation of the Antioxidant and Antimicrobial Activity of Protein Hydrolysates and Peptide Fractions Derived from Colossoma macropomum and Their Effect on Ground Beef Lipid Oxidation

The objective of this study was to obtain protein hydrolysate from the mechanically separated meat of blackfin pacu to evaluate the influence by ultrafiltration in the antioxidant and antimicrobial activities of the peptide fractions obtained and to apply in ground beef to evaluate the lipid stability. The enzymatic hydrolysis was performed using the enzyme Protamex (pH 7.0, 60°C) for 240 min. The protein hydrolysate was fractionated by ultrafiltration. Then, the antioxidant capacity of the protein hydrolysate and the peptide fractions were evaluated in vitro by the methods of 2,2’-azinobis (3-ethylbenzothiazoline sulfonic acid) radical capture, 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assay, reducing power, and hydroxyl radical scavenging activity. The antimicrobial activity of the samples was evaluated by disc-diffusion against Staphylococcus aureus and Escherichia coli. After evaluation, the peptide fractions did not present higher bioactivities than that shown for the hydrolysate. The protein hydrolysate was applied to ground beef, where the substances reactive to thiobarbituric acid and color were evaluated during 7 days of storage at 4°C. Lipid oxidation was reduced up to 60.9% and there was no modification of the natural coloration. Thus, the protein hydrolysate can be used as an alternative source of antioxidant for the preservation of refrigerated meats.     

Effect of Bacterial Community and Free Amino Acids on the Content of Biogenic Amines During Fermentation of Yu-lu,a Chinese Fermented Fish Sauce

The main objective of this work was to investigate the effects of bacterial community and free amino acids on the content of biogenic amines in Yu-lu during fermentation. Four major biogenic amines (histamine, tyramine, cadaverine, and putrescine) were identified, and the content of tyramine was positively correlated with histamine (R value = 0.9113). Aspartic acid, glutamic acid, histidine, leucine, and lysine were the dominant free amino acids. 16S rRNA sequencing showed that the composition of the bacterial community changed significantly during fermentation of Yu-lu. Principal component analysis revealed the crucial links between microbial community and biogenic amines. For example, Halanaerobium was probably associated with the formation of putrescine, while Halomonas might be associated with the degradation of biogenic amines at the end of fermentation of Yu-lu. This study provided a detailed evaluation of the Yu-lu fermentation process, enabling development of better strategies for biogenic amine control in fish sauce.     

The Effect of Detergents on Solubilization and Activity of the Lipid Peroxidative Enzyme System from the Sarcoplasmic Reticulum of Winter Flounder (Pseudopleuronectes americanus)

Sarcoplasmic reticular (SR) membranes from flounder muscle were solubilized using different ionic and nonionic detergents (Tween-20, Triton X-100, sodium dodecyl sulfate, or sodium desoxycholate). The recoveries of protein and NADH-dependent lipid peroxidative enzyme activity for different detergent treated SR preparations were compared. Triton X-100 was the least detrimental to the activity of the solubilized enzymes system. With Triton X-100, we were able to solubilize 85% of the SR protein and 97% of the phospholipid. Upon removal of the detergent, 98% of the peroxidative activity was recovered.     

Effect of Temperature and Alkaline pH on the Physicochemical Properties of the Protein Isolates Extracted from the Whole Ungutted Lanternfish (Benthosema pterotum)

The aim of this study was to evaluate functional properties of the protein extracted from lanternfish (Benthosema pterotum). Extraction of the fish protein was performed in alkaline pHs (10 and 12) followed by precipitation at its isoelectric pH. The effects of different extraction temperatures (0, 4, 11, 25, and 30°C) were also studied. The results showed that the protein recovery yield was higher when extracted at pH 12 compared to pH 10. Furthermore, some functional properties including water holding capacity, oil holding capacity, emulsifying capacity, foaming capacity, and solubility of the protein isolated at pH 12 were higher than that isolated at pH 10 (p < 0.05). The color evaluation (L*, a*, and b*) of the samples showed protein isolated at pH 12 was lighter (higher L*) than protein isolated at pH 10, but redness (a* value) declined in both samples. Evaluation of different extraction temperatures showed that protein recovery yield and functional properties were improved with increasing temperature. Fish protein isolate can be used in the formulation of value-added products because of their distinctive functional properties.