Angiotensin converting enzyme inhibitory activity of proteolytic digests of peanut (Arachis hypogaea L.) flour

Defatted raw and roasted peanut flour were hydrolyzed with alcalase or sequentially with pepsin and pancreatin, and then the hydrolyzates were fractionated by RP-HPLC and tested for hypotensive potential. This research revealed that proteolytic peanut digests have an inhibitory effect on the activity of angiotensin converting enzyme (ACE). Three fractions from the hydrophobic end of the chromatogram of each hydrolyzate were the most potent for inhibiting ACE activity in comparison to seven other fractions. These potentially potent fractions were then assayed for IC₅₀. Fractions from the alcalase digestion of raw peanut exhibited IC₅₀ values of 8.7-122 μg/ml, and those from roasted flour exhibited values of 12-235 μg/ml. IC₅₀ values of 7.9-65.9 μg/ml, and 11-36 μg/ml for raw and roasted peanut, respectively, from the pepsin-pancreatin system were observed. These values compare to the IC₅₀ value of 0.36 μg/ml of a known commercial ACE inhibitor (pGlu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro).     

PARTIAL CHARACTERIZATION OF A WHEY PROTEIN CONCENTRATE AND ITS ENZYME HYDROLYSATES

A whey protein concentrate (WPC) was produced from fresh whey by ultrafiltration (MW cut off 10 kDa) and lyophilization. Enzymatic hydrolysis was performed with three enzyme systems: pancreatin (PA), protamex (PR) or alcalase 0.6L (AL) to produce hydrolysates with 20% degree of hydrolysis (DH). The peptide profiles of the hydroly sates were determined by high performance capillary electrophoresis (HPCE). The relationship between enzyme system and preferential protein substrate could be established. The alcalase hydrolysate (ALH) differed from the other two hydrolysates, and the enzyme showed the lowest specificity for β‐lactaglobulin. Considering the protein content from WPC the pancreatin hydrolytic system was the most efficient leaving only 4.69% unhydrolyzed protein in the final hydrolysate (PAH). For 20% degree of hydrolysis alcalase left 7.98% unhydrolyzed protein, while protamex left 9.81% unhydrolyzed protein in the final hydrolysate.     

Preparation and characterization of a protein hydrolysate from an oilseed flour mixture

A novel protein hydrolysate was prepared from the mixture of oilseed flours (soybean, sesame and peanut) and determined physicochemical & functional properties along with comparison of individual oilseed flour hydrolysate of soybean. Mixed flour obtained from oilseed flours viz. soybean, sesame and peanut by using calculated amounts in the ratio of 1.1:1.7:0.7, respectively was used as a starting raw material having balanced amino acid profile. Protein hydrolysates were prepared from mixed flour and soybean flour by a double enzyme treatment method to a level of 40% degree of hydrolysis. The dried protein hydrolysate prepared from the mixed flour had 72% crude protein. This protein was characterized by gel filtration chromatography and SDS-PAGE. Comparison of the amino acid profile of the protein hydrolysate from mixed flours and soyabean flours showed a significant increase in the former one with respect to amino acid contents usually deficient of single oilseed flour hydrolysate. The product is creamish yellow in colour and had a solubility of >90% over a wide pH range of 2–10. The mixed flour protein hydrolysate showed better functional attributes such as foaming, as compared to that from soybean flour alone.     

不同蛋白酶水解高温花生粕和低温花生粕及其水解产物抗氧化活性的对比研究

由于高温花生粕中的花生蛋白在高温压榨过程中高度变性,因此在食品工业中蛋白利用率较低。本研究通过对比高温花生粕和低温花生粕经过不同商业蛋白酶(Alcalase 2.4 L,Neutrase,Papain,Protamex及Flavorzyme 500 MG)水解后水解产物特性的蛋白回收率、水解度、分子量分布及抗氧化活性,确定高温花生粕是否适合采用生物酶解的方式利用其中的蛋白质并筛选合适的蛋白酶。结果表明,高温花生粕经不同蛋白酶水解后,其蛋白质利用率均在60.61~67.86%,与低温花生粕相当;水解度及分子量分布方面,高温花生粕Flavorzyme水解产物的DH最高,高达44.92%,且含有较多的3 ku小分子肽及游离氨基酸;此外,高温花生粕不同酶水解产物的DPPH自由基清除活性均高于低温花生粕,这可能是由于高温花生粕水解产物中含有较多具有供电子的小分子肽、游离氨基酸以及高温压榨过程中生成的美拉德反应产物。     

水酶法从花生中提取油和水解蛋白

研究在蛋白酶Alcalase作用下，花生油得率和水解蚕白得率与水解度的关系，并对不同水解度下水解蛋白的相对分子质量进行测定。分析了乳状液中的蛋白质相对分子质量，并初步探讨了酶对花生蛋白的作用机理。     

质谱法分析烘焙对花生过敏原Ara h 1潜在致敏性的影响

为研究烘焙对花生过敏原Ara h 1潜在致敏性的影响,采用高离液序列盐溶液从鲜花生和烘焙花生中提取总蛋白,通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析烘焙前后蛋白条带变化情况,并对其中的花生主要过敏蛋白Ara h 1条带进行质谱和Swiss-Model模型分析.十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果显示,烘焙花生蛋白出现...     

多宝鱼不同水解物肽段组成及体外抗氧化活性比较

为研究熟化、模拟消化和酶解对多宝鱼肉水解物抗氧化活性的影响,本研究分别采用碱性蛋白酶和胃蛋白酶-胰蛋白酶水解多宝鱼生肉和熟肉,制备生肉碱性蛋白酶水解物、熟肉碱性蛋白酶水解物、生肉体外模拟消化产物和熟肉模拟消化产物,并评价其水解度、相对分子质量分布、氨基酸组成、肽段组成和体外抗氧化活性的差异。结果表明:生肉碱性蛋白酶水解物的水解度最高,为20.18%;4种水解物的分子质量分布差异明显,共有肽段仅有1条,但氨基酸组成没有显著性差异;碱性蛋白酶水解物以肽段小于1000 Da的组分为主,2～4肽的含量达64.57%～51.73%,而模拟消化产物中1000～3000 Da的组分占比超过50%,以多肽(>10)为主,熟化过程会减少小肽(<6)的比例;体外抗氧化活性分析显示,碱性蛋白酶水解物的抗氧化活性均高于模拟消化样品,熟化会降低生肉碱性蛋白酶水解物的抗氧化能力,生肉碱性蛋白酶水解物具有最高的超氧阴离子和羟基自由基清除能力,以及最佳的铁离子还原能力。因此,碱性蛋白酶是优于模拟消化的多宝鱼蛋白水解方式,鱼肉的熟化总体上会降低水解物的抗氧化能力。     

Separation of iron-binding protein from whey through enzymatic hydrolysis

Whey protein concentrate (WPC) was hydrolyzed by nine proteolytic enzymes to examine the effectiveness of the hydrolysates to bind iron. Degree of WPC hydrolysis was higher with pancreatin (13.91%), alcalase (13.60%), and flavourzyme (12.80%) compared with other enzymes (esperase, neutrase, papain, pepsin, protease and trypsin). Tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse-phase high performance liquid chromatography analyses revealed maximum hydrolysis of α-LA and β-LG with alcalase. Molecular masses of peptides derived from alcalase hydrolysate were smaller than 6.5 kDa. Iron-binding by alcalase hydrolysate was the highest (97.6%) of all other hydrolysates. Using ion-exchange chromatography alcalase hydrolysate was eluted at a 0.25 m NaCl gradient concentration with higher iron-binding ability. This eluted fraction had higher Lys (18.09%), Ala (17.24%), and Phe (16.58%) contents. Alcalase showed noticeably better effectiveness than other enzymes to produce a hydrolysate for the separation of iron-binding peptides derived from WPC.     

不同蛋白酶水解牛肉蛋白产物的ACE抑制活力比较

以ACE抑制活力和水解度为指标,考察6种常用蛋白酶（复合蛋白酶、风味蛋白酶、木瓜蛋白酶、菠萝蛋白酶、中性蛋白酶和碱性蛋白酶）对牛肉蛋白酶解产物的影响,比较不同蛋白酶酶解产物经模拟消化前后ACE抑制活力的变化,并分析了不同蛋白酶酶解产物的分子量分布和感官评价。结果表明：碱性蛋白酶最适于酶解牛肉生产降压肽,其酶解液ACE抑制率为51.19%,消化后活性降低幅度小,消化后酶解液ACE抑制率为39.65%,同时水解度为44.76%,大分子蛋白分解程度高。其次是复合蛋白酶和中性蛋白酶,两者的酶解液在消化前后都具有高ACE抑制活力,消化前抑制率分别为67.97%和62.00%,消化后抑制率分别为37.26%和43.12%,水解度分别为37.47%和36.35%,但大分子蛋白的分解程度较低。感官评价结果表明,不同酶解液的外观、气味和滋味与市售商品差异不大,无明显不良风味产生,可用于食品辅料的生产。     

Nutritional and functional characterisation of hydrolysates from quinoa flour (Chenopodium quinoa) using two proteases

The objective was to study the nutritional and functional properties of hydrolysates from quinoa (Chenopodium quinoa) obtained by enzymatic hydrolysis of defatted quinoa flour (DQF). The commercial enzymes alcalase and flavourzyme were used to obtain the hydrolysates defatted quinoa flour hydrolysate with alcalase (DQFA) and defatted quinoa flour hydrolysate with flavourzyme (DQFF), respectively, after 3 h of digestion at 50°C and pH 8. The degree of hydrolysis (47.32%), yield (31.05%) and protein recovery (88.80%) values were higher in DQFA; however, its protein content (48.34%) was lower compared to that of DQFF (55.06%). Also, DQFA had a solubility greater than 57% over a wide pH range (2–10) and good foam stability (70–90%). On the other hand, DQFF presented adequate emulsifying activity (61.30 m²/g), emulsifying stability (158.62 min) and foaming capacity (131%). Due to the high content of macro- and micronutrients and adequate emulsifying and foaming properties, DQFA and DQFF could be used as ingredients in various processed food products and protein supplements.     

THERMAL BEHAVIOR, SOLUBILITY AND STRUCTURAL PROPERTIES OF SOY CONCENTRATE HYDROLYZED BY NEW PLANT PROTEASES

A soy concentrate prepared by alcoholic extraction of defatted soy flour was hydrolyzed with three plant proteases: hieronymin and macrodontin, cysteine proteases, and pomiferin, a serine protease. A commercial microbial protease (alcalase) was included for comparative purposes. Working at optimal conditions for each enzyme, 5–15% degree of hydrolysis (DH) values were obtained. Hydrolysates exhibited a characteristic SDS-PAGE pattern: the plant proteases attacked the polypeptides of 7S and 11S proteins with different intensity and selectivity, especially the A and B polypeptides of the 11S protein. Intermediate molecular weight peptides (24 and 60 kDa) were produced as the hydrolysis progressed. Differential Scanning Calorimetry (DSC) thermograms of flour. concentrate and hydrolysates were analyzed to evaluate the thermal stability and denaturation enthalpies of the major proteins. An increase in the degree of protein denaturation resulting from enzymatic action and a lower thermal stability at low pH were detected. The surface hydrophobicity of all hydrolysates, unlike expected, did not increase. Solubility at pH 7.0 is closely related to the DH, independent of the protease used. Solubility at pH 4.5 appeared to be related to the extent of hydrolysis of polypeptide A by each protease.     

Antihypertensive effect of alcalase generated mung bean protein hydrolysates in spontaneously hypertensive rats

Mung bean protein isolates were hydrolyzed by alcalase and neutrase, respectively, and the angiotensin I-converting enzyme (ACE) inhibitory activities of the enzymatic hydrolysates were determined at different hydrolysis times. The highest ACE inhibitory activity recorded was for a hydrolysate generated by alcalase (IC₅₀: 0.64 mg protein/ml) after 2 h of hydrolysis. A significant decrease in systolic blood pressure was observed in spontaneously hypertensive rats following a single oral administration of this hydrolysate at a dose of 600 mg/kg of body weight.     

Effect of enzymatic hydrolysis on the functional,antioxidant, and angiotensin I-converting enzyme (ACE) inhibitory properties of whole horse gram flour

Food Science and Biotechnology - Horse gram hydrolysate (HGH) with different degree of hydrolysis (DH) (20, 25, 35, 40, and 45%) was prepared from whole horse gram flour using alcalase. The amino...     

Allergenicity of roasted peanuts treated with a non-human digestive protease

Peanut allergy is a severe and lifelong type of food allergy triggered by allergenic proteins and peptides in peanuts. This study investigated the effects of ultrasound-assisted alcalase treatment on the concentrations of major allergenic proteins (Ara h 1 and Ara h 2) in roasted peanut kernels and the allergenicity of treated peanut extracts. Peanut kernels were sonicated for 1 h in buffer solution, incubated with different amount of alcalase for various time, then vacuum dried. The variations of Ara h 1 and Ara h 2 contents in soluble and insoluble portions of peanuts treatments were evaluated by sandwich ELISA and SDS-PAGE, respectively. The in vitro IgE-binding capacity of treated peanut extracts was determined by a competitive inhibition ELISA using pooled plasma of 10 peanut allergic patients. Samples with lower in vitro IgE-binding were used for human skin prick tests (SPTs) in peanut allergic individuals. Results indicate that alcalase digestion of sonicated peanuts significantly increased protein solubility while decreasing Ara h 1 and Ara h 2 concentrations in both soluble and insoluble portions of peanuts relative to untreated peanuts. The maximum reductions of Ara h 1 and Ara h 2 levels were obtained following 3 hour digestion with alcalase at concentrations of 4.54 and 6.05 U/100 g. Samples obtained under these conditions showed the lowest in vitro IgE-binding and caused the least allergic response in human SPTs. The current study suggests that the allergenic potential of peanuts could be reduced by postharvest processing such as ultrasound-assisted enzymatic treatment of peanuts kernels.     

酶法制备小黄鱼下脚料调味料的风味前体物质

以小黄鱼下脚料为原料,利用酶解技术获得小黄鱼下脚料风味前体物质,通过单因素及响应面分析,确定碱性蛋白酶(Alcalase)和风味蛋白酶(Flavourzyme)同步酶解工艺,研究料水比、酶解时间、酶用量、初始pH 值和酶解温度对酶解液水解度和感官品质的影响。结果表明,优化的酶解工艺条件为料水比1:7(g/mL)、酶解温度55℃、酶解时间6.5h、初始pH8.0、Alcalase 用量2.5%、Flavourzyme 用量3.0%。在此酶解条件下的水解度为40.11%,所得酶解液中氨基酸含量86.383g/100g,其中必需氨基酸32.785g/100g,鲜味和甘味氨基酸38.384g/100g,与酶解前相比氨基酸含量明显增加,氨基酸总量增加了67.56%,其中必需氨基酸增加了82.02%,呈味氨基酸增加了79.52%,产品具有浓郁的小黄鱼鱼香味。     

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.     

Alcalase蛋白酶水解法制备山核桃肽的研究

以脱脂山核桃渣为原料,利用Alcalase 蛋白酶对山核桃蛋白进行水解制备山核桃活性肽,以水解度(DH)表征其反应程度,确定其最佳水解条件为：温度55℃,pH9.0,底物浓度8%,酶质量分数6%,水解时间2.0h。在此条件下水解度(DH)为76.16%。     

酶法制备火麻肽及其血管紧张素转化酶抑制活性研究

以火麻蛋白为原料,在碱性蛋白酶、中性蛋白酶、风味酶和木瓜蛋白酶4种单酶酶解火麻蛋白的基础上,再优选碱性+中性蛋白酶、碱性+风味酶、碱性+木瓜蛋白酶双酶分步对火麻蛋白进行酶解,酶解物(HPH)及其超滤组分的体外血管紧张素转化酶(ACE)抑制活性采用高效液相检测法(HPLC)进行测定。结果得到火麻蛋白最佳酶解组合为碱性+中性蛋白酶,最佳工艺条件为:碱性蛋白酶加酶量8000 U/g,pH10.0,酶解温度50℃,酶解时间4 h;中性蛋白酶加酶量8000 U/g,pH7.0,酶解温度45℃,酶解时间4 h,分步酶解物水解度(DH)和ACE抑制活性分别达74.52%和82.14%,但其与超滤各组分对ACE抑制活性差异并不显著。该研究为产业化制备火麻降血压肽提供理论依据。     

双酶法制备马鹿茸降血糖肽工艺优化及其对α-葡萄糖苷酶的抑制效果

为探索制备马鹿茸降血糖肽的最佳工艺条件,以α-葡萄糖苷酶抑制率为指标,从碱性蛋白酶、风味蛋白酶、中性蛋白酶和胰蛋白酶中筛选出两种酶,根据其体外降血糖效果确定酶的作用顺序,再以水解度、α-葡萄糖苷酶抑制率和蛋白质回收率为指标进行单因素试验和正交试验,优化降血糖肽制备工艺条件。结果表明:碱性蛋白酶和风味蛋白酶比中性蛋白酶和胰蛋白酶更适合用于制备马鹿茸降血糖肽。采用碱性蛋白酶-风味蛋白酶顺序对马鹿茸进行水解,所得酶解产物的α-葡萄糖苷酶抑制率、蛋白质回收率和水解度较高,分别为21.11%、39.12%、19.88%。通过单因素试验和正交试验确定双酶酶解最佳工艺条件为先用碱性蛋白酶在p H 8.0、60℃、底物质量分数12%、加酶量5 000 U/g条件下酶解3 h,再用风味蛋白酶于p H 6.5、45℃、底物质量分数5%、加酶量6 000 U/g条件下酶解1 h。双酶分步水解终产物的α-葡萄糖苷酶抑制率受质量浓度的影响,当质量浓度为3 mg/m L时,α-葡萄糖苷酶抑制率可达94.09%,IC50值为1.82 mg/m L。碱性蛋白酶-风味蛋白酶双酶分步水解马鹿茸可获得高α-葡萄糖苷酶抑制率的降血糖肽。     

响应面法优化大黄花鱼肉蛋白水解工艺及多肽抗氧化性研究

以大黄花鱼为实验材料,利用酶法水解大黄花鱼肉蛋白制备抗氧化肽。以还原力为响应值,通过单因素结合响应面法对中性蛋白酶酶解大黄花鱼肉蛋白的酶用量、酶解温度、底物浓度以及酶解时间进行了优化,结果表明:四种酶中,中性蛋白酶酶解的酶解液水解度(DH)和还原能力最高。最优酶解工艺条件为酶用量为0.4%、酶解温度45 ℃、底物浓度25.0%、酶解时间7 h、体系pH7.0时,还原力为0.951。酶解液DH为37.51%,超氧阴离子自由基清除力(O₂-·)为82.42%。SDS-PAGE(聚丙烯酰氨凝胶电泳)结果显示,酶解7 h大黄花鱼肉蛋白肌动蛋白完全消失,水解形成肌球蛋白轻链分子量为27、15和6 kDa。