Functionalities and antioxidant properties of protein hydrolysates from the muscle of ornate threadfin bream treated with pepsin from skipjack tuna

Functional properties and antioxidant activities of protein hydrolysates prepared from ornate threadfin bream (Nemipterus hexodon) muscle, using skipjack tuna pepsin, with different degrees of hydrolysis (DH: 10%, 20% and 30%), were evaluated. Emulsifying and foaming properties of hydrolysates were governed by their DH and concentrations used. Hydrolysates with 20% DH had the highest scavenging activities for ABTS and DPPH radicals. However, chelating activity of hydrolysates for ferrous ion increased as DH increased. Size exclusion chromatography of the hydrolysate with 20% DH using Sephadex G-25 revealed that antioxidative peptides with molecular weight of approximately 1.3 kDa exhibited the highest ABTS radical-scavenging activity. In vitro simulated gastrointestinal digestion indicated that ABTS radical-scavenging activity of the antioxidative peptides was not affected by pepsin hydrolysis, whilst further digestion by pancreatin enhanced the activity. Therefore, protein hydrolysate from the muscle of ornate threadfin bream produced by skipjack tuna pepsin can be used as a promising source of functional peptides with antioxidant properties.     

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.     

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.     

不同蛋白酶水解棉籽蛋白制备抗氧化多肽的研究

利用6种蛋白酶对棉籽蛋白进行酶解,测定了各酶在水解过程中的水解度及其变化,对酶解产物的抗氧化活性进行了分析比较。研究表明,各蛋白酶在水解的前2h内,水解度迅速增加,2h之后水解曲线变得平缓。其中胃蛋白酶的水解能力最强,其4h水解产物水解度最大,为30.40%;胰蛋白酶的水解能力最差,最终水解产物的水解度为17.61%。中性蛋白酶水解产物的抗氧化活性较强,经测定其DPPH清除能力为54.95%,羟自由基清除能力为68.98%,超氧阴离子自由基清除能力为58.38%。     

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。     

Influence of degree of hydrolysis on functional properties,antioxidant activity and ACE inhibitory activity of peanut protein hydrolysate

Functional properties, antioxidant and Angiotensin-converting enzyme (ACE) inhibitory activities of peanut protein isolate (PPI) and peanut protein hydrolysate (PPH) prepared using Alcalase, at different (10%, 20%, 30% and 40%) degrees of hydrolysis, (DH) were investigated. Hydrolysis (at DH > 10%) significantly (p < 0.05) improved the solubility (>80%) of PPI, especially in the pH range of 4–6. However, PPI showed better emulsifying and foaming properties than PPH (p < 0.05). As DH increased, ferrous ion chelating activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and ACE inhibitory activity of PPH increased, while reducing power decreased (p < 0.05). Bleaching of beta-carotene by linoleic acid was suppressed better by PPI and PPH at 10% DH than of PPH at higher DH. Thus, the results reveal that DH affects functional properties, antioxidant and ACE inhibitory activities of peanut protein.     

Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe

Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe, hydrolysed by Alcalase 2.4 L (RPH) with different degrees of hydrolysis (DH) at various concentrations were examined. As DH increased, the reduction of DPPH, ABTS radicals scavenging activities and reducing power were noticeable (p < 0.05). The increases in metal chelating activity and superoxide scavenging activity were attained with increasing DH (p < 0.05). However, chelating activity gradually decreased at DH above 30%. All activities except superoxide anion radical scavenging activity increased as the concentration of hydrolysate increased (p < 0.05). Hydrolysis using Alcalase could increase protein solubility to above 80% over a wide pH range (2–10). The highest emulsion ability index (EAI) and foam stability (FS) of hydrolysates were observed at low DH (5%) (p < 0.05). Concentrations of hydrolysates determined interfacial properties differently, depending on DH. The molecular weight distribution of RPH with 5%DH (RPH5) was determined using Sephadex G-75 column. Two major peaks with the molecular weight of 57.8 and 5.5 kDa were obtained. Fraction with MW of 5.5 had the strongest metal chelating activity and ABTS radical scavenging activity. The results reveal that protein hydrolysates from defatted skipjack roe could be used as food additives possessing both antioxidant activity and functional properties.     

Physicochemical and antioxidant properties of buckwheat (Fagopyrum esculentum Moench) protein hydrolysates

The enzymatic hydrolysis of common buckwheat (Fagopyrum esculentum Moench) protein isolate (BPI) by Alcalase and some physiochemical and antioxidant properties of the resulting hydrolysates were characterised. The hydrolysis resulted in remarkable decrease in the globulins or protein aggregates and concomitant increase in peptide fragments. The surface hydrophobicity of the hydrolysates decreased with increasing degree of hydrolysis (DH) and reached a minimum at DH 15%, but increased at further hydrolysis, whereas their amino acid compositions were unchanged. The polyphenol content of the hydrolysates gradually decreased with DH increasing from 0% to 15%, while it on the contrary increased upon further hydrolysis. The hydrolysates exhibited excellent antioxidant activities, including DPPH radical scavenging ability, reducing power and ability to inhibit linoleic acid peroxidation. The antioxidant activities of these hydrolysates were closely related to their polyphenol contents. The results indicated that polyphenol-rich buckwheat proteins are unique protein materials for the production of the hydrolysates with good nutritional and antioxidant properties.     

Antioxidant and biochemical properties of protein hydrolysates prepared from Silver carp (Hypophthalmichthys molitrix)

The antioxidant and biochemical properties of enzymatically hydrolyzed silver carp (Hypophthalmichthys molitrix) protein were studied. The molecular weight of the main peaks of the hydrolysates by both Alcalase and Flavourzyme was lower than 5000 Da. The hydrolysates treated by Alcalase for ?1.5 h (hydrolysis time) showed that the relative proportion of <1000 Da fraction was more than 60%. For the biochemical properties, hydrolysis by both enzymes increased protein solubility to above 75% over a wide pH range; and when the hydrolysis time was prolonged (>3 h), the colour of the hydrolysates turned yellowish. The protein hydrolysates exhibited significant hydroxyl radical-scavenging activity and inhibited linoleic acid peroxidation. For Alcalase treatment, the hydroxyl radical-scavenging activity and the inhibition of linoleic acid peroxidation of hydrolysates appeared to reach a maximum level for 1.5, 2.0 h of hydrolysis, respectively; and their antioxidant activity was close to that of α-tocopherol in a linoleic acid emulsion system, and carnosine in the 2-deoxyribose oxidation system. The hydrolysate with lower molecular weight distribution possessed stronger Fe²⁺ chelation ability at a sample concentration of 5.0 mg/mL. The results suggested that the antioxidant activity of silver carp protein hydrolysates were related to its degree of hydrolysis (DH), hydrolysis time and molecular weight.     

Enzymatic preparation and functional properties of wheat gluten hydrolysates

The water-insolublity of wheat gluten is one of the major limitations for its more extensive use in food processing. Wheat gluten was enzymatically hydrolyzed by several commercially available proteases (Pancreatin Trypsin 6.0S, Porcine pepsin, Pancreatin and Alcalase 2.4L) with protein recovery varying from 42.5 ± 0.7% to 81.3 ± 0.1%. The hydrolytic efficiency of these proteases on wheat gluten was also compared. Alcalase served best for the preparation of wheat gluten hydrolysates (WGHs). Thus, Alcalase-assisted hydrolysates of wheat gluten (AWGHs) with different degrees of hydrolysis (DH 5.0, 10.0 and 15.0%) were further assessed for their functionalities. All the AWGHs had excellent solubility (>60%) over a pH range of 2–12. The emulsifying and foaming properties of AWGH with relatively low DH (5.0%) were remarkably higher compared to the original gluten. However, extensive hydrolysis of gluten resulted in remarkable reduction in emulsifying and foaming properties.     

Influence of degree of hydrolysis on functional properties and angiotensin I‐converting enzyme‐inhibitory activity of protein hydrolysates from cuttlefish (Sepia officinalis) by‐products

BACKGROUND: In Tunisia the cuttlefish‐processing industry generates large amounts of solid wastes. These wastes, which may represent 35% of the original material and constitute an important source of proteins, are discarded without any attempt at recovery. This paper describes some functional properties and the angiotensin I‐converting enzyme (ACE)‐inhibitory activity of protein hydrolysates prepared by hydrolysis of cuttlefish (Sepia officinalis) by‐products with crude enzyme extract from Bacillus licheniformis NH1. RESULTS: Cuttlefish by‐product protein hydrolysates (CPHs) with different degrees of hydrolysis (DH 5, 10 and 13.5%) were prepared. All CPHs contained 750–790 g kg^?1 proteins. Solubility, emulsifying capacity and water‐holding capacity increased while fat absorption and foaming capacity decreased with increasing DH. All hydrolysates showed greater fat absorption than the water‐soluble fraction from undigested cuttlefish by‐product proteins and casein. CPHs were also analysed for their ACE‐inhibitory activity. CPH3 (DH 13.5%) displayed the highest ACE inhibition (79%), with an IC₅₀ value of 1 mg mL^?1. CONCLUSION: Hydrolysis of cuttlefish by‐product proteins with alkaline proteases from B. licheniformis resulted in a product with excellent solubility over a wide pH range and high ACE‐inhibitory activity. This study suggests that CPHs could be utilised to develop functional foods for prevention of hypertension. Copyright © 2010 Society of Chemical Industry     

Antioxidant activities and functional properties of grass carp (Ctenopharyngodon idellus) protein hydrolysates

BACKGROUND: Grass carp, with an annual production exceeding 4 × 10⁶ t in China in 2009, has not been developed into a high‐value product. In this study the antioxidant activities and functional properties of grass carp protein hydrolysates prepared with Alcalase 2.4L (HA) and papain (HP) were investigated. The hydrolysate with strongest radical‐scavenging activity and reducing power was assessed further for changes in its antioxidant activity during simulated gastrointestinal digestion. RESULTS: As the degree of hydrolysis (DH) increased, the metal‐chelating activity of both HA and HP increased while their reducing power and 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH^?)‐scavenging activity decreased (P < 0.05). At the same DH, HP possessed higher DPPH^?‐scavenging activity and reducing power than HA (P < 0.05). The metal‐chelating activity of HP with 10% DH was significantly increased after in vitro gastrointestinal metabolism (P < 0.05). Regarding their functional properties, all hydrolysates were more than 81% soluble over a wide range of pH (3–8). At the same DH, HP showed higher emulsion activity index but lower solubility and foaming capacity than HA. CONCLUSION: Grass carp protein hydrolysates showed high solubility over a wide pH range and could be used as natural antioxidants in food systems. Copyright © 2011 Society of Chemical Industry     

具有金属螯合活性的蚕豆蛋白酶解物的制备

目的探究蚕豆蛋白酶解物的金属螯合活性,研究其金属螯合活性与其抗氧化活性的关系。方法分别采用碱性蛋白酶、中性蛋白酶、木瓜蛋白酶对蚕豆蛋白进行酶解,并测定其水解物的抗氧化活性与金属螯合活性,选用碱性蛋白酶为酶解蚕豆蛋白制取金属螯合肽的最适酶,以酶解产物的水解度、抗氧化活性及金属螯合活性为测定指标获得合适的水解条件。结果 3种蛋白酶的蚕豆蛋白酶解产物都有金属螯合活性和抗氧化活性,碱性蛋白酶为酶解蚕豆蛋白的最适酶,最适酶解时间为4 h时,得到的酶解产物金属离子螯合率为88.22%,抑制羟自由基能力为220.70 U/mg,总还原力为0.03 U/mg。结论蚕豆蛋白酶解物具有一定的金属离子螯合活性与抗氧化活性,水解度对蚕豆蛋白酶解物的金属离子螯合活性及抗氧化活性有明显的影响,蚕豆蛋白酶解物的金属螯合活性与总还原力及抑制羟自由基能力呈现显著的正相关性,相关系数分别为0.925、0.968(P0.01)。     

2种蛋白酶酶解曲拉干酪素条件优化及抗氧化性比较

以曲拉干酪素为原料、水解度为指标,在酶解时间、酶解温度、pH值、曲拉干酪素质量浓度、酶添加量单因素试验基础上,采用响应面试验对碱性蛋白酶和胰蛋白酶酶解工艺条件进行优化,并对2 种酶解液的1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、超氧阴离子自由基、羟自由基清除率,Fe2＋、Cu2＋螯合能力和还原力等抗氧化性指标进行比较。结果表明,碱性蛋白酶和胰蛋白酶分别在酶解时间3.8、2.5 h,酶解温度49.8、47.8 ℃,曲拉干酪素质量浓度60、35 g/L,pH 8.5、7.5,酶添加量140、2 900 U/g时水解度最大,为24.25%和13.57%。碱性蛋白酶解液超氧阴离子自由基清除率、Fe2＋螯合能力显著低于胰蛋白酶解液（P＜0.01）;羟自由基清除能力高于胰蛋白酶解液（P＞0.05）;2 种蛋白酶酶解液在酶解液质量浓度1～5 mg/mL时,Cu2＋螯合能力、DPPH自由基清除率和还原力随质量浓度均呈上升趋势,Cu2＋螯合能力低于Fe2＋螯合能力（P＞0.05）,DPPH自由基清除率和还原力二者差异显著（P＜0.01）。2 种蛋白酶对酶解物抗氧化性指标影响不同,碱性蛋白酶酶解物抗氧化性相对较优。     

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.     

杏仁蛋白Alcalase水解工艺及其体外抗氧化活性的研究

为深入开发利用杏仁蛋白资源,采用Alcalase蛋白酶水解杏仁蛋白,以水解度为指标对酶解过程进行研究,在单因素试验基础上以水解度和DPPH自由基清除率为指标进行酶解正交试验.结果表明制备抗氧化能力较强的杏仁蛋白水解物的最佳条件为:pH 8.0,温度55 ℃,酶底比4%,底物浓度5%.在此条件下进行水解试验,水解度为21.02%,水解物对DPPH自由基的清除率为66.13%.     

鳙鱼鱼肉蛋白的酶解及其对功能性质的影响

为了改善鳙鱼鱼肉蛋白(BCMP)的功能性质以扩大其在食品工业中的应用,以鳙鱼为原料制备了鳙鱼鱼肉蛋白,并利用碱性蛋白酶Alcalase2.4L对其进行水解,得到了3种不同水解度(DH4.5%、DH9.0%、DH13.5%)的酶解物。研究了BCMP及其酶解物的功能性质,包括溶解性、持水性、持油性、乳化性、起泡性。结果表明,与原鳙鱼鱼肉蛋白相比,酶解物的功能性质除持油性以外均有不同程度的提高。此外,DH4.5%的酶解物乳化性和起泡性最高,过度水解(DH9.0%、DH13.5%)反而造成乳化性和起泡性下降。     

Preparation and Functional Properties of Enzymatically Deamidated Soy Proteins

Heat-denatured soy protein was hydrolyzed by Alcalase to 2.0% or 4.0% degree of hydrolysis (DH), heated again at 100°C and deamidated with B. circulans peptidoglutaminase. The extent of deamidation was 6.0% and 8.2% for 2.0 DH hydrolysates and 12.8% and 16.0% for 4.0 DH hydrolysates heated for 15 and 30 min, respectively. Deamidation increased protein solubility and substantially enhanced emulsifying activity under mildly acidic (pH 4–6) as well as alkaline conditions. Deamidation improved emulsion stability and foaming power of heat-denatured hydrolysed soy proteins. Enzymatically deamidated soy protein hydrolysates had improved functional properties compared to nondeamidated hydrolysates and the native soy protein.     

Biochemical properties and antioxidant activity of myofibrillar protein hydrolysates obtained from patin (Pangasius sutchi)

Antioxidant activities of myofibrillar protein hydrolysates (MPH) prepared from patin (Pangasius sutchi) using papain and Alcalase^® 2.4 L with different degrees of hydrolysis (DH) were investigated. With a DH of 65.83%, the hydrolysate prepared with papain exhibited the maximum of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging activity (71.14%) with a reducing power of 0.310. At a concentration of 1 mg mL^?1, the papain‐MPH exhibited a Trolox equivalent antioxidant capacity (TEAC) of 70.50 ± 1.22 μmol g^?1 protein. With a DH of 83.6%, the Alcalase‐MPH had the highest metal‐chelating activity. Low molecular weight peptides showed higher antioxidant activities than high molecular weight peptides. Both papain‐MPH and Alcalase‐MPH contained high amounts of the essential amino acids (48.71% and 48.10%, respectively) with glutamic acid, aspartic acid and lysine as the dominant amino acids. These results suggest that the protein hydrolysates derived from patin may be used as an antioxidative ingredient in both functional food and nutraceutical applications.     

蓝圆鲹蛋白酶解物的螯合矿物离子活性研究

以蓝圆鲹为原料,采用胰蛋白酶、木瓜蛋白酶及碱性蛋白酶对其进行水解,研究酶解产物与钙、亚铁、锌离子的螯合活性。结果表明:蓝圆鲹经胰蛋白酶水解,水解度为23.14%时其产物具有较高螯合铁、锌离子的活性,其螯合率分别高达96.63%和94.28%;蓝圆鲹经木瓜蛋白酶水解,水解度为22.00%时,其产物具有较高螯合钙离子的活性,其螯合率高达96.78%;同时研究表明上述两种酶解物还具有较好的抗氧化活性,其1,1-二苯基-2-三硝基苯肼半抑制浓度值分别为3.74 mg/m L和3.64 mg/m L。此外,氨基酸分析表明蓝圆鲹高螯合矿物离子活性的酶解物中天冬氨酸、谷氨酸、赖氨酸含量较高。