应用电子自旋共振(ESR)法测定猪血浆蛋白水解物抗氧化活性的研究

将猪血浆蛋白(4% 浓度,W/W)用碱性蛋白酶水解0.5～5h。分别用FRAP 法和电子自旋共振(ESR)法测定水解物的还原能力和自由基清除能力。结果显示,水解物的还原能力随着水解度(DH)的增大而显著增强(p ＜ 0.05),并且水解物对DPPH 自由基、羟基自由基以及超氧自由基的清除能力随着水解时间的延长和蛋白浓度的增大而显著增强(p ＜ 0.05)。尽管未水解的猪血浆蛋白也有一定的抗氧化活性,但远远低于水解物的抗氧化活性(p ＜ 0.05)。此外,猪血浆蛋白碱性蛋白酶水解物的抗氧化活性和自由基清除能力与水解度(DH)和蛋白浓度密切相关。由于猪血浆蛋白水解物具有一定的抗氧化活性和自由基清除能力,所以可以作为一种有效的抗氧化剂而应用于食品工业中。     

胰蛋白酶对猪血红蛋白酶解脱色条件优化

以酶解液水解度（hydrolysis degree,DH）、三氯乙酸（trichloroacetic acid,TCA）可溶性氮含量及血红素残留量为评定指标,采用单因素试验比较胰蛋白酶和碱性蛋白酶对猪血红蛋白的酶解脱色效果。在单因素试验基础上,进行4因素3水平正交试验。结果表明：胰蛋白酶水解脱色的效果更好,最佳酶解工艺参数为酶底比7500 U/g、酶解温度45 ℃、pH 7.5、底物质量浓度8 g/100 mL,在此条件下,酶解液DH为25.67%,TCA可溶性氮含量为80.05%,血红素残留量为18.34%,猪血红蛋白多肽粉蛋白含量83.17%;对此条件下制备的猪血红蛋白多肽粉进行分子质量分布分析,分子质量在1 000 Da以下的小肽占比94.20%;最佳酶解脱色条件下,猪血红蛋白多肽粉中TCA可溶性氮含量为80.05%的蛋白占猪血红蛋白多肽粉蛋白含量的96.25%,这与分子质量分布结果比较符合。     

两种酶水解鲢鱼蛋白产物功能性质研究

采用Alcalase 2.4L和Flavourzyme 500L蛋白酶对鲢鱼肉进行水解,研究了水解产物的水解度与体系的pH值对其功能性质的影响。水解产物的溶解度在pH4时最低,碱性时具有较高的溶解度;浊度随pH值变化趋势与溶解度相反,浊度越大,溶解度越小。随水解度的增加,水解产物的乳化活性指数、乳化稳定性、起泡性和泡沫稳定性减小(p<0.05);在水解度相同情况下,水解产物的功能性质取决于所用酶的种类。结果表明,鲢鱼肉蛋白水解产物的功能性质受其水解度和所用酶种类的影响。     

Valorisation of tuna viscera by endogenous enzymatic treatment

Fish processing industry generates a considerable amount of by-products which represent an environmental problem. Only a small portion of these residues is used for the production of low marketable products. Therefore, industrially scalable processes yielding value-added products would be highly desirable. Different to others studies, this work deals with potential valorisation of bullet tuna (Auxis rochei) viscera using its endogenous enzymes without previous separation stage for the production of bioactive hydrolysates. Functional and bioactive properties of hydrolysates produced at different degree of hydrolysis (DH 3%, 6% and 9%) were evaluated. The endogenous enzyme hydrolysates (EH) obtained by the proposed low cost treatment were compared with hydrolysates produced with a well-known commercial enzyme: subtilisin. Regarding functional properties, EH presented similar or even better solubility, emulsifying and oil binding capacities than subtilisin hydrolysate (SH). EH also showed very interesting antioxidative properties, particularly metal reducing and radical scavenging activity. Additionally, the ACE inhibitory activity of EH at low degree of hydrolysis was comparable to SH. According to these results, bullet tuna viscera protein can be value-added by endogenous enzyme hydrolysis.     

Effects of high solid concentrations on the efficacy of enzymatic hydrolysis of yeast cells and the taste characteristics of the resulting hydrolysates

Effects of solid concentrations on enzymatic hydrolysis of yeast cells and the taste characteristics of the resulting hydrolysates were examined. Results showed that increased solid concentrations ranging from 10% to 30% resulted in a mild increase in degree of hydrolysis (DH) of hydrolysates during the whole hydrolysis process, whereas an obvious inhibition effect on DH was found at hydrolysates with 40% of solid concentration. The levels of amino nitrogen and total nitrogen of supernatant with 40% of solid concentration were six‐fold higher than those of hydrolysates with 10% of solid concentration at all hydrolysis time. After 21 h of hydrolysis, there was no significant difference in molecular weight distributions of hydrolysates with different solid concentrations, while a significant increase in amino acid contents of hydrolysates with high solid concentrations was found. Results from sensory evaluation showed that the intensities of umami, mouthfulness and continuity in umami solution could be significantly improved by supplementing with the resulting hydrolysates with high solid concentrations.     

Hemoglobin hydrolysates from porcine blood obtained through enzymatic hydrolysis assisted by high hydrostatic pressure processing

The purpose of this work was to obtain discoloured hemoglobin (Hb) hydrolysates from porcine red blood cells fraction by combining enzymatic hydrolysis and high hydrostatic pressure (HHP) treatments. Samples of Hb were submitted to treatments of enzymatic hydrolysis by trypsin (EC 3.4.21.4) or pepsin (EC 3.4.23.1), under controlled conditions of temperature and pH, for 2, 6 and 24 h, and pressurization at 400 MPa, at 20 °C for 15 min, after the addition of the proteases. To evaluate the effects of the proteolysis reactions, the effectiveness of discolouration, the extent of hydrolysis as the percentage of non-protein nitrogen, and the SDS-PAGE electrophoretic profiles of the hydrolysates were determined. The results showed that HHP had a significant influence on enzymatic hydrolysis of Hb by trypsin, whereas did not improve the extent of proteolysis in the case of pepsin. The main conclusion derived from this study is that pressurization of Hb samples after the addition of trypsin enhanced enzymatic hydrolysis of the Hb, hence permitting a decrease in the incubation time.

Industrial relevance

The present study is focussed on assessing the effects of enzymatic hydrolysis with trypsin or pepsin assisted by HHP treatment on the discolouration of Hb from porcine blood. HHP treatment was able to increase the activity of trypsin and to enhance discolouration effectiveness of Hb with pepsin. The results from this work corroborate the potential of the application of HHP processing combined with enzymatic treatments on the development of food ingredients from porcine blood.     

鳕鱼和鲅鱼鱼肉蛋白酶解产物功能特性及抗氧化性

采用风味蛋白酶对鳕鱼和鲅鱼鱼肉进行酶解,研究水解度、pH值及酶解时间对酶解产物功能特性和抗氧化活性的影响.结果表明:随着酶解时间延长,鳕鱼和鲅鱼鱼肉酶解产物的水解度、亚铁离子螯合力逐渐增加,DPPH自由基清除能力逐渐下降;不同pH值下,鳕鱼和鲅鱼鱼肉蛋白酶解产物均具有良好的溶解性和热稳定性;鲅鱼酶解产物的水解度、溶解性、热稳定性和亚铁离子螯合力显著高于鳕鱼酶解产物.     

猪血浆蛋白水解物抗氧化作用模式的研究

将猪血浆蛋白(4%浓度,W/W)分别用碱性蛋白酶水解0.5～6h。用pH-Stat方法测定其水解度;同时测定水解物还原能力、金属离子(Cu2+和Fe2+)鳌合能力以及对DPPH自由基清除能力来分析猪血浆蛋白水解物的抗氧化作用模式。结果表明,5h的猪血浆蛋白碱性蛋白酶水解物具有较高的还原能力、合成抗氧化剂所没有的金属鳌合能力以及较强的清除自由基的能力。通过比较不同浓度的水解物抗氧化性实验发现,随着水解物浓度的增高,其抗氧化活性显著增强(p＜0.05)。尽管未水解的猪血浆蛋白也有一定的抗氧化活性,但远远低于水解物的抗氧化活性(p＜0.05)。由于猪血浆蛋白水解物具有一定的抗氧化活性,所以可以作为金属离子鳌合剂、氢供体和自由基稳定剂用以抑制脂质氧化。     

鲤鱼鱼肉蛋白酶水解物抗氧化性及功能特性

采用碱性蛋白酶对鲤鱼鱼肉蛋白进行酶解,制备不同水解度的水解物。测定水解物的抗氧化活性以及不同pH值条件下水解物的功能特性。结果表明:随着水解度的逐渐升高,水解物的抑制脂质氧化能力、D PP H自由基清除能力、还原能力以及金属离子(Cu2+和Fe2+)螯合能力逐渐增加(P<0.05);同时,水解物的溶解性、乳化性和起泡性都在pH值为4.0(等电点)时达到最低,而后溶解性和乳化性随着pH值升高而增大(P<0.05),而起泡性随着pH值的升高先上升后又下降。因此,鲤鱼鱼肉蛋白碱性蛋白酶水解物可以提高蛋白质的抗氧化活性和溶解性,但是较高的水解度会在一定程度上降低其乳化性和起泡性。     

水解度对牡蛎酶解液特性的影响

利用胰蛋白酶限制性酶解牡蛎肉,研究水解度(degree of hydrolysis,DH)对牡蛎酶解液的感官评分、肽分子量分布和游离氨基酸组成的影响。实验结果表明,随着水解度的增大,牡蛎酶解液的鲜味、酸味和甜味先增加后降低,而咸味和苦味则一直增加;分子量>10 kDa和5~10 kDa肽比例逐渐减少,3~5 kDa肽比例先增加后减少,1~3 kDa和<1 kDa肽比例逐渐增大。<1 kDa和1~3 kDa肽比例最高的是DH62.02%酶解液。6种水解度牡蛎酶解液中各游离氨基酸含量、游离氨基酸总量、必需氨基酸含量随着水解度的增大而升高。鲜味氨基酸、甜味氨基酸和苦味氨基酸含量均随着水解度的增大而增加,芳香族氨基酸含量先增加后降低。随着水解度的增大,6种酶解液中TAV>1的氨基酸数量逐渐增多。6种水解度牡蛎酶解液中谷氨酸TAV值均大于1,且随着水解度的增大TAV值逐渐增大。     

Effect of ultrasonic pretreatment on the antioxidant properties of porcine liver protein hydrolysates

In this study, the effect of ultrasonic pretreatment on the antioxidant activity of porcine liver protein hydrolysates (PLPHs) was investigated. The results showed that the degree of hydrolysis (DH) and peptide contents of the PLPHs increased as the time of ultrasonication increased. The hydrolysate pretreated with ultrasonication for 60 s exhibited the highest DH and peptide contents. The hydrolysate pretreated with ultrasonication for 45 s exhibited the highest ferrous ion chelating ability and reducing power. The hydrolysate pretreated with ultrasonication for 30 s exhibited the highest 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity and the higher inhibitory activity in the linoleic acid autoxidation system. The molecular weight of peptides in the hydrolysates was less than 6.2 kDa. The results clearly demonstrated that ultrasonic pretreatment enhances the antioxidant activities of the PLPHs in a short period of time (15–30 s).     

鳄鱼皮酶解产物功能特性及抗氧化活性

为了解鳄鱼皮酶解产物功能特性和抗氧化活性,采用2种商业蛋白酶(木瓜蛋白酶、碱性蛋白酶)在各自最适反应条件下分别酶解鳄鱼皮,研究水解度(DH)、酶种类及pH值对酶解产物功能特性及抗氧化活性的影响.结果显示:随着酶解时间延长,鳄鱼皮水解度逐渐增加,鳄鱼皮在碱性蛋白酶酶解作用下水解度较高,水解4h时可达12％;木瓜蛋白酶酶解产物与碱性蛋白酶酶解产物的溶解性差异不显著(P＞0.05).相同水解度下,碱性蛋白酶酶解产物的热稳定性在pH4时优于木瓜蛋白酶酶解产物.酶解时间在1h之内,木瓜蛋白酶酶解物亚铁离子螯合力明显增强;随着时间延长,酶解产物亚铁离子螯合能力变化不显著(P＞0.05).酶解3h后碱性蛋白酶酶解产物亚铁离子螯合能力高于木瓜蛋白酶酶解产物,但木瓜蛋白酶酶解产物具有较强的清除DPPH自由基能力.综上表明,碱性蛋白酶水解作用的鳄鱼皮水解度较高,其酶解产物乳化活性和热稳定性优于木瓜蛋白酶酶解产物;鳄鱼皮酶解产物抗氧化能力较强,有较高的开发利用价值.     

响应面试验优化四角蛤蜊调味料风味前体物质酶解制备工艺

以四角蛤蜊肉为原料,利用酶解技术获得四角蛤蜊调味料风味前体物质。以水解度和感官评价为指标,确定酶的种类与比例。在单因素试验的基础上,使用中性蛋白酶和复合风味蛋白酶,通过Box-Behnken响应面分析法,研究双酶酶解四角蛤蜊的工艺条件。研究结果：当中性蛋白酶和复合风味蛋白酶质量比为2∶1时,其酶解液的水解度和鲜度都最佳;双酶酶解最佳条件为酶添加量2.4‰、时间5.5 h、温度52 ℃、料液比1∶4（g/g）、自然pH值,此时酶解液的水解度较大（44.32%）,风味较好。     

Antioxidant activities and functional properties of tea seed protein hydrolysates (Camellia oleifera Abel.) influenced by the degree of enzymatic hydrolysis

Antioxidant activities and functional properties of tea seed protein hydrolysates (TSPH) prepared using alcalase with different (10, 20, 30 and 40%) values of the degree of hydrolysis (DH) were investigated. The effect of hydrolysis time on antioxidant activity was also investigated. As the hydrolysis time was extended, the DPPH radical scavenging activity increased and finally reached a plateau, the copper chelating capacity decreased, and the superoxide radical scavenging and iron chelating activities increased initially, then subsequently slowed. The solubility, foaming properties, and emulsification properties of TSPH were affected by pH and DH. As the DH value increased, the DPPH radical scavenging activity and the reducing power increased and the copper chelating capacity decreased. TSPH at 20 and 30% DH values exhibited higher superoxide radical scavenging and stronger iron chelating activities respectively, than TSPH at other DH values. The DH value of TSPH affected the antioxidant activity and functional properties.     

麦胚蛋白水解物抗氧化活性及其作用模式

采用中性蛋白酶水解麦胚蛋白0.5～6 h,测定水解物的DH(degree of hydrolysis)、硫代巴比妥酸值(TBARS值)、POV值(Prroxide value)、Cu2+螯合能力、二苯代苦味肼基自由基清除能力(DPPH自由基)。结果表明,麦胚蛋白水解度随着水解时间的延长而增加;水解物5 h与未水解的蛋白及0.02%VC相比,在大豆卵磷脂脂质氧化体系(Liposome体系)中具有较强的抑制脂质氧化的能力,还具有较强的Cu2+螯合能力和清除自由基能力,未水解的蛋白具有较弱的抗氧化能力;通过对未水解的麦胚蛋白及不同浓度蛋白水解物的抗氧化指标测定和分析,认为水解物的抗氧化活性与蛋白本身的结构、肽链长短及氨基酸残基有关。     

草鱼肉蛋白酶解物功能特性及质量控制的研究

采用Neutrase对草鱼鱼肉蛋白进行了酶解,得到了水解度(DH)为4.72%、9.80%、13.32%的酶解产物(NH),并分析了pH与水解度对酶解产物功能特性的影响。结果表明,酶解产物的溶解性、乳化性、起泡性在pH为4时达到最低,而后随pH的增大而增加。在pH为3～8的范围内随水解度的增加,酶解产物的溶解性增加,起泡性降低。pH为4时,水解度为4.72%、9.80%、13.32%的酶解产物的热稳定性之间存在显著性差异(P<0.05),且随水解度升高而增大。在pH为3～5的范围内酶解产物的乳化性随水解度升高而降低。酶解产物的溶解性、乳化性、起泡性间存在相关性(P<0.05)。     

Egg yolk protein modification by controlled enzymatic hydrolysis for improved functionalities

Delipidated egg yolk protein (EYP) is produced as a co-product of egg yolk lecithin extraction. This EYP is expected to have poor functionality because of protein denaturation caused by ethanol treatment during lecithin extraction. Two food grade endo-proteases were used to produce EYP hydrolysates (EYPh) with two degrees of hydrolysis (DH), 3% and 6%. Protein solubility was improved as DH increased. Solubility profiles for both EYP and EYPh were relatively less pH-dependent compared with soy protein. Except for foaming capacity, EYPh showed improvement in foam stability, foaming speed, and foam density. Emulsion stability was improved for all EYPhs. Treatments at DH of 6% showed significant increase in emulsification capacity. We have shown quantitatively how controlled enzymatic hydrolysis can be applied to ethanol-treated lipid-free EYP to increase protein solubility, and thus to improve foaming and emulsification properties.     

Bioactive peptide production by hydrolysis of porcine blood proteins in a continuous enzymatic membrane reactor

BACKGROUND: During slaughter a hog produces approximately 3 L of blood. However, only a small proportion of porcine blood is currently used in food, feed or fertiliser, most of it being treated as waste and discarded. In this study the possibility of hydrolysing porcine blood proteins by enzyme in a membrane reactor for the production of bioactive peptides was investigated. Red blood corpuscles, blood plasma and defibrinated blood plasma were hydrolysed by various proteases, and the hydrolysates were evaluated for bioactive properties. RESULTS: The hydrolysate produced by hydrolysing red blood corpuscles with a mixture of trypsin, chymotrypsin and thermolysin had the highest angiotensin I‐converting enzyme (ACE)‐inhibitory activity (IC₅₀ = 0.58 mg mL^?1) and scavenging effect on α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) (65%) after 6 and 10 h of hydrolysis respectively. When the hydrolysis was carried out in an enzymatic membrane reactor with an enzyme/substrate ratio of 1:5 and a residence time of 100 min, the process reached steady state in 2 h. The ACE‐inhibitory activity of the product during the steady state process was 86% and its scavenging effect on DPPH was 54%. The membrane process also decolourised the enzyme‐hydrolysed product, thus improving the appearance of the product. CONCLUSION: This study demonstrated that hydrolysates of porcine blood possess antihypertensive and antioxidant activities. Using red blood corpuscles as the substrate, the hydrolysis could be carried out in a membrane reactor with a mixture of proteases to produce bioactive peptides continuously. Therefore processing of porcine blood in an enzymatic membrane reactor is a potential method for producing a health‐promoting product. Copyright © 2008 Society of Chemical Industry     

Antioxidative activity and functional properties of protein hydrolysate of yellow stripe trevally (Selaroides leptolepis) as influenced by the degree of hydrolysis and enzyme type

Antioxidative activity and functional properties of protein hydrolysates from yellow stripe trevally (Selaroides leptolepis) meat, hydrolyzed by Alcalase 2.4L (HA) and Flavourzyme 500L (HF) with different degrees of hydrolysis (DH) were investigated. As the DH increased, DPPH radical-scavenging activity and reducing power of HA decreased (p < 0.05) but no differences were observed for HF (p > 0.05). Metal chelating activity of both HA and HF increased with increasing DH (p < 0.05). HF generally had a higher (p < 0.05) chelating activity than had HA at the same DH tested. At low DH (5%), HA exhibited a better DPPH radical-scavenging activity while, at high DH (25%), HF had a higher (p < 0.05) reducing power. For the functional properties, hydrolysis by both enzymes increased protein solubility to above 85% over a wide pH range (2–12). When the DH increased, the interfacial activities (emulsion activity index, emulsion stability index, foaming capacity, foam stability) of hydrolysates decreased (p < 0.05), possibly caused by the shorter peptide chain length. At the same DH, the functionalities of protein hydrolysate depended on the enzyme used. The results reveal that antioxidative activity and functionalities of protein hydrolysates from yellow stripe trevally meat were determined by the DH and by the enzyme type employed.     

响应面法优化猪血红蛋白抗菌肽的制备工艺

以猪血红蛋白为原料,利用筛选出的蛋白酶水解制备抗菌肽,以酶解液抑菌率和水解度为指标,通过单因素试验对酶解温度、加酶量和酶解时间3个主要工艺参数进行研究,在此基础上,通过响应面优化酶解工艺,建立数学模型.结果表明,胰蛋白酶最适合水解猪血红蛋白制备抗菌肽,其最佳条件为酶解温度49.72℃、加酶量2852.81U/g、酶解时间5.19h,酶解产物抑菌率的理论预测值89.70％,实际测量值90.32％.可见,利用胰蛋白酶水解猪血红蛋白能够得到抑菌活性较高的酶解产物,且该模型能够较好的预测抗菌肽制备最佳工艺条件.