酶法制备不同水解度高温豆粕水解产物的理化特性研究

采用Alcalase酶和木瓜蛋白酶分别对高温大豆粕进行酶解,通过控制酶解反应得到水解度为5%、10%和15%的6种水解产物,研究两种酶对不同水解度的水解产物理化特性的影响。结果表明,Alcalase酶和木瓜蛋白酶均可产生6种不同分子量范围的水解产物,但各部分比例具有显著差异(P0.5),其平均分子量随水解度的增加逐渐减少,Alcalase酶的水解产物中小于2562 Da小分子量肽所占比例更高。豆粕蛋白的疏水基团在酶解反应中发生暴露与断裂的数量差,导致其表面疏水性随水解度增加呈现先下降再上升的变化,即水解度为10%的表面疏水性最低。zeta电势的绝对值随水解度不断上升,分子间的斥力增大,相同水解度下两种酶对zeta电势的影响并不显著。此外,在pH值为3、5、7和9时,水解产物的溶解性随着水解度的增加而逐渐增高,乳化活性和乳化稳定性则逐渐降低。     

鲢鱼蛋白酶法水解产物的功能性质

采用复合蛋白酶对酸法提取的鲢鱼蛋白进行水解改性。以水解鲢鱼蛋白为原料,与未酶解的鲢鱼蛋白作对照,考察其溶解性、起泡性、乳化性、持水性油性及流变学特性。结果表明：经酶解后的鲢鱼蛋白在pH2～10的范围内溶解度均在90%以上,较未酶解蛋白有明显的改善;起泡性增加不明显,仅为1.85%,泡沫稳定性延长了60min;乳化性是未酶解蛋白的8倍,乳化稳定性增加;持水、持油性降低,黏度减小。该酶法水解对鲢鱼蛋白质的部分功能性质有一定的改善效果。     

碱性蛋白酶限制性水解对高温菜籽粕蛋白功能性质的影响

为改善高温菜籽粕蛋白质的功能性质,用碱性蛋白酶对其进行限制性水解,并研究不同水解度(DH)高温菜籽粕蛋白功能性质及相对分子质量分布。结果表明：碱性蛋白酶限制性水解高温菜籽粕蛋白的溶解度、乳化性和吸油性均有所改善,其中溶解度随水解度增加而增加,pH7.0 时DH为10% 的高温菜籽粕蛋白的溶解度达63.82%,是原蛋白溶解度的2.1 倍;DH 为2.0% 的水解蛋白乳化性最好,pH6.0 和pH8.0 时乳化指数分别为0.43 和0.49,比原蛋白乳化指数分别高0.13 和0.11;DH 为8% 的水解蛋白吸油性最好,为4.39g/g。水解后高温菜籽粕蛋白的某些功能性质与其相对分子质量分布有一定的关系,需控制高温菜籽粕蛋白水解度以获得某种良好的功能性质。     

酶解小麦面筋蛋白及其组分功能特性研究

利用木瓜蛋白酶对谷朊粉功能特性进行改良,在pH7.0的条件下,研究时间对水解度的影响以及水解度对乳化活性和溶解度的影响,水解度为2.4%时,乳化活性可以达到72.5%.通过响应面实验,研究酶浓度、底物浓度、pH值、反应时间、反应温度对谷朊粉乳化活性和溶解性的影响,探索木瓜蛋白酶水解谷朊粉提高乳化性和溶解性的最佳反应条件,分析发现5个因素对谷朊粉乳化性的影响由强到弱的顺序为酶浓度、谷朊粉浓度、时间、温度和pH值.最佳水解条件为:酶浓度0.475%、反应温度60℃、反应时间1.63 h、pH6.6、底物浓度4%,此时的水解度为4.32%、乳化活性为63.4%、溶解度则为19.04%.经过超滤(10 ku)后得到的截留组分乳化活性与酶解面筋蛋白接近.     

水解胶原蛋白的溶解性和乳化性研究

采用复合酶从皮边角余料中提取得到分子量分布在4.2×104～8.5×104的水解胶原蛋白样品,对其溶解性和乳化性进行了系统研究.结果发现,水解胶原蛋白的溶解度随pH值与等电点的差值的绝对值增加而增加,但即使等电点时,也高达91.4%;在低于20℃时,其溶解度随温度的升高而增大,在20～60℃内,其溶解度高达100%,故水解胶原蛋白水溶性好,使用酸度和温度范围宽.水解胶原蛋白的乳化能力和乳化稳定性都随其浓度增加而增大,但浓度越大,乳化能力和乳化稳定性增大幅度越小;酸、碱性溶液中水解胶原蛋白都有较高乳化能力和乳化稳定性,碱性环境的乳化能力略高于酸性环境,而乳化稳定性却在酸性环境中更高.在等电点附近,乳化能力和乳化稳定性最差;水解胶原蛋白的乳化能力和乳化稳定性先随NaCl浓度升高而增大,但当NaCl浓度达到一定值时,胶原蛋白的乳化能力和乳化稳定性又随NaCl浓度升高而减小.实验还发现浓度达5%以上时,溶液pH值,外加电解质的量对其乳化能力和乳化稳定性几乎无影响.     

水解胶原蛋白的溶解性和乳化性研究

采用复合酶从皮边角余料中提取得到分子量分布在 4.2× 10 4 ～ 8.5× 10 4 的水解胶原蛋白样品 ,对其溶解性和乳化性进行了系统研究。结果发现 ,水解胶原蛋白的溶解度随 pH值与等电点的差值的绝对值增加而增加 ,但即使等电点时 ,也高达 91.4%;在低于 2 0℃时 ,其溶解度随温度的升高而增大 ,在 2 0～ 6 0℃内 ,其溶解度高达 10 0 %,故水解胶原蛋白水溶性好 ,使用酸度和温度范围宽。水解胶原蛋白的乳化能力和乳化稳定性都随其浓度增加而增大 ,但浓度越大 ,乳化能力和乳化稳定性增大幅度越小 ;酸、碱性溶液中水解胶原蛋白都有较高乳化能力和乳化稳定性 ,碱性环境的乳化能力略高于酸性环境 ,而乳化稳定性却在酸性环境中更高。在等电点附近 ,乳化能力和乳化稳定性最差 ;水解胶原蛋白的乳化能力和乳化稳定性先随NaCl浓度升高而增大 ,但当NaCl浓度达到一定值时 ,胶原蛋白的乳化能力和乳化稳定性又随NaCl浓度升高而减小。实验还发现浓度达 5 %以上时 ,溶液 pH值 ,外加电解质的量对其乳化能力和乳化稳定性几乎无影响。     

碱性蛋白酶对谷朊粉改性的研究

利用碱性蛋白酶对谷朊粉进行改性,研究了底物浓度、酶浓度、温度、pH值对谷朊粉乳化性的影响,在此基础上通过正交试验,探索碱性蛋白酶水解谷朊粉提高溶解度、水解度、乳化性及乳化稳定性的最佳反应条件。最佳水解条件为：底物浓度8.0%、pH值8.5、反应温度60℃、酶浓度0.09%。此时谷朊粉的溶解度为24.77%,水解度为12.73%,乳化性为71.43%,酶解效果显著。     

鲢鱼蛋白的酶解及其酶解物功能性质的研究

以鲢鱼肉为原料,以水解度为指标,研究鲢鱼蛋白的酶解及其酶解物的功能性质.用6种不同蛋白酶(胰蛋白酶、风味蛋白酶、中性蛋白酶、木瓜蛋白酶、复合蛋白酶、碱性蛋白酶)酶解鲢鱼肉,结果碱性蛋白酶的水解效果最佳.通过控制碱液用量,用碱性蛋白酶制备鲢鱼鱼肉蛋白(SCMP)在不同水解度(DH4.5%、DH9.0%、DH13.5%、DH18%)下的酶解产物,考察不同酶解产物的功能性质,包括溶解性、持水性、持油性、乳化性、起泡性.与原鲢鱼鱼肉蛋白(SCMP)相比,酶解后的SCMP功能性质(除持油性外)均有不同程度的提高.此外,环境pH值也对酶解产物的溶解性和乳化性有一定影响.鲢鱼蛋白酶解产物作为一种潜在的功能性配料,在食品工业中具有一定的应用前景.     

水解鱼蛋白及其功能特性的研究

用胰蛋白酶对鲢鱼鱼肉蛋白质水解,得到不同水解度的鱼蛋白水解液,并对酶解蛋白酶的溶解度。乳化能力及流变性等功能进行了测定。结果表明酶水解能明显提高鱼蛋白的水溶性,而水溶性随ＰＨ而变化,在ＰＨ４左右溶解性最低,但ＰＨ的影响随水解度的增大而减弱。     

pH对膨化玉米蛋白酶解产物功能性质的影响

采用碱性蛋白酶Alcalase对膨化后的玉米蛋白进行水解,改变产物的pH,研究了不同pH条件下,产物功能性质的变化。玉米蛋白水解产物的溶解性受pH的影响不大,在pH3～9范围内都具有较好的溶解性;在所研究的pH范围内,水解产物粘度都很低;pH大于6时,玉米蛋白水解产物的起泡性及泡沫稳定性、乳化性明显增大,而在pH小于6时却变化不大;产物的乳化稳定性很好,基本不受pH的影响。玉米蛋白水解产物的优良功能性质更有利于其在食品行业中的应用。     

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.     

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)。     

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.     

Production of High-protein Hydrolysate from Poultry Industry Residue and their Molecular Profiles

The use of mechanically deboned poultry meat (MDPM) as a source of raw protein for the enzymatic preparation of hydrolysates was investigated using commercial proteases Alcalase and Flavourzyme. Hydrolysis conditions were optimized by response surface methodology, and the influence of temperature, pH, and enzyme concentration were evaluated to determine the hydrolysis index. For Alcalase, optimal values of temperature, pH, and enzyme concentration were found to be 50°C, 7.5%, and 2.5%, respectively, while for Flavourzyme the optimized variables were at 50°C, 6.0%, and 3.5%, respectively. Compared to raw MDPM, Alcalase produced a very high recovery of 89% of the nitrogen from the hydrolysates, while for Flavourzyme recovery was around 67%. Alcalase was used to produce a spray-dried hydrolysate containing 62% of total protein with molecular weights ranging from 5,807 to 12,000 Da, and had excellent microbiological quality.     

Proteinase and exopeptidase hydrolysis of whey protein: Comparison of the TNBS,OPA and pH stat methods for quantification of degree of hydrolysis

Whey protein hydrolysates were generated with Alcalase 2.4L and Debitrase HYW20 which are proteinase and exopeptidase enriched enzyme preparations, respectively. Degree of hydrolysis (DH) values were quantified with the TNBS, OPA and pH stat methods. Poor correlation was observed between the three methods for DH values in Debitrase HYW20 hydrolysates. For Alcalase 2.4L hydrolysates, the OPA method gave DH values that were approximately 15% lower than the pH stat, whereas TNBS DH values were similar to the pH stat method. As whey proteins are relatively rich in cysteine, a weak and unstable reaction between OPA and cysteine was thought to contribute to the under-estimation of DH in whey protein hydrolysates. Since TNBS reacts strongly with cysteine and TNBS DH values were unaffected by the type of enzyme preparation used to generate the hydrolysate, the TNBS method was deemed most suitable for the quantification of DH in whey protein hydrolysates.     

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。     

Proteolysis characteristics of sarcoplasmic, myofibrillar, and stromal proteins separated from grass carp and antioxidant properties of their hydrolysates

Proteolysis of grass carp sarcoplasmic, myofibrillar, and stromal proteins by 5 commercial proteases were studied. Sarcoplasmic and myofibrillar protein could be well hydrolyzed by Alcalase 2.4 L to reach high protein recoveries (PR) (71.86±2.46 and 80.77±3.05%, respectively), while the maximum PR for stromal protein was only 42.83±2.84%. However, stromal hydrolysates, containing mostly 6–10 kDa fraction, exhibited higher ·OH scavenging activities due to its high content of antioxidant-assisting amino acids. Alcalase 2.4 L and pancreatin 6.0, which produced hydrolysates with relative high degree of hydrolysis (DH), were used for further hydrolysis of whole grass carp protein with the assistance of response surface methodology (RSM). The results showed that serine proteases (Alcalase 2.4 L and pancreatin 6.0) could produce sarcoplasmic, myofibrillar, or stromal hydrolysates with relatively high PR, DH, and strong ·OH scavenging activity, which may be used to prepare antioxidant hydrolysates from grass carp.     

Influence of Hydrolysis Degree on the Functional Properties of Salmon Byproducts Hydrolysates

ABSTRACT: Protein hydrolysates from salmon heads were obtained by enzymatic treatment with Alcalase^(r) 2.4L. Response surface methodology (RSM) allowed optimization of temperature, enzyme/substrate, and pH leading to various hydrolysates (11.5% to 17.3% hydrolysis degree [DH]) and protein recovery ranging from 47% to 70%. Size exclusion chromatography of hydrolysates showed that small peptides increased only at high DH. The nitrogen solubility index (NSI) of hydrolysates was higher than 75% over a wide range of pH values, whereas hydrolysates with high DH had the best solubility. Emulsifying capacity, emulsion stability, and fat absorption capacity were better when DH was low.     

不同蛋白酶酶解罗非鱼肉制备蛋白水解液的过程变化规律研究

本文选择五种蛋白酶(木瓜蛋白酶、Alcalase2.4 L、Protamex、Neutrase 1.5MG和Flavourzyme 500MG)对酶解罗非鱼肉制备蛋白水解液的过程变化规律研究.以Cn、Cp值和蛋白质利用率为指标对酶解过程进行分析,说明不同的酶解工艺参数对酶解过程及产物影响较大,其中Flavourzyme 500MG生成游离氨基酸态氮含量最高(12 h后达到4.25 mg/mL);木瓜蛋白酶生成短肽含量最高(5 h后达到39.82 mg/mL);Protamex的蛋白质利用率最高(12 h后达到44.74%).以高含量游离氨基酸的水解液为目的可选用Flavourzyme 500MG、Protamex;以高含量功能性短肽的水解液为目的可选用木瓜蛋白酶、Alcalase 2.4 L.     

糖基化反应条件对鲢鱼鱼肉碱性蛋白酶解产物清除DPPH自由基的影响

为提高鲢鱼鱼肉蛋白酶解产物抗氧化活性,本研究将葡萄糖和低聚异麦芽糖通过糖基化反应分别引入到鲢鱼鱼肉蛋白碱性蛋白酶酶解产物中,利用分光光度计测定其清除DPPH自由基能力。研究结果表明碱性蛋白酶酶解产物与葡萄糖比例为2:1,在60℃时反应得到的产物清除DPPH能力显著高于50℃条件下的反应产物。鲢鱼鱼肉蛋白的碱性蛋白酶酶解物在一定条件下与葡萄糖反应可以提高其清除DPPH自由基能力。