豌豆蛋白酶法水解及产物特性研究

为研究豌豆蛋白质酶解前后功能特性变化,利用Alcasase2.4L碱性蛋白酶对其限制性酶解,对酶解水解度动态变化、蛋白质回收率及酶解产物功能特性等方面进行研究。试验结果表明,Alcasase2.4L碱性蛋白酶能够有效酶解豌豆蛋白,蛋白质回收率可达84%,与豌豆原蛋白相比,在pH 2～12范围内,不同水解度的酶解产物溶解性均有明显改善,最高可达95%左右。5%水解度的酶解产物乳化性、乳化稳定性、起泡性和泡沫稳定性相比豌豆蛋白均较好,但随着酶解的进一步进行,其乳化和起泡特性均呈下降趋势。     

Pepsin-induced changes in the size and molecular weight distribution of bovine casein during enzymatic hydrolysis

Bovine casein was digested with pepsin at pH 2.0 in a batch-stirred tank reactor. To investigate the effect of peptic digestion on the aggregate size and molecular weight distribution of bovine casein, the resulting hydrolysates were examined by size-exclusion chromatography coupled with multiangle laser light scattering and dynamic light scattering. Casein was resolved by size-exclusion chromatography into 2 major peaks corresponding to aggregates and monomers, both of which showed a continuous decrease as hydrolysis proceeded. However, the ratio of aggregates to monomers was maintained at almost 1 (2:2.5) during the initial 30-min hydrolysis, indicating that the caseins in solution were in a type of equilibrium between aggregates and monomers. Upon peptic hydrolysis, casein aggregates increased in size and molecular weight, and exhibited a decrease in intermolecular repulsion. This finding was confirmed by dynamic light scattering measurements, which traced the changes in the hydrodynamic radii and light scattering intensities of casein hydrolysates. In addition, the release kinetics of peptide fractions with different molecular weights was also examined. It was concluded that the increase in hydrophobic attraction and the reduction in intermicellar repulsion might promote the growth in aggregate size of bovine casein during the limited hydrolysis.     

烘烤和酶解处理对花生蛋白功能性及抗氧化性的影响

首先采用烘烤处理花生仁,粉碎、脱脂后采用碱性蛋白酶水解制备活性肽,比较烘烤和酶解处理对花生蛋白水解度、功能特性和抗氧化性的影响。实验结果表明,烘烤处理降低了花生蛋白的溶解性、乳化活性,而增大了其体外消化性、乳化稳定性、羟自由基清除能力、亚铁离子螯合能力。碱性蛋白酶水解处理可提高花生蛋白的溶解性、乳化稳定性、羟自由基清除能力和亚铁离子螯合能力。脱脂生花生粉或熟花生粉与碱性蛋白酶分别酶解8h和6h的酶解物清除羟自由基的能力最强。这表明,烘烤的花生蛋白或脱脂花生粕可采用酶解法制备活性多肽。     

风味蛋白酶水解制备豌豆蛋白抗氧化酶解产物工艺条件优化

采用风味蛋白酶水解豌豆蛋白,对制备豌豆蛋白酶解产物清除DPPH.清除率进行研究;通过单因素实验和响应面回归分析,得到制备酶水解产物最佳酶解工艺条件:酶解温度48.8℃、酶解时间3.1 h、pH 5.5、加酶量4.0%、底物浓度6.0%,在此条件下,风味蛋白酶酶解产物对DPPH.清除率为60.10%。     

Physicochemical and bitterness properties of enzymatic pea protein hydrolysates

ABSTRACT:  The effects of different proteolytic treatments on the physiochemical and bitterness properties of pea protein hydrolysates were investigated. A commercial pea protein isolate was digested using each of 5 different proteases to produce protein hydrolysates with varying properties. After 4 h of enzyme digestion, samples were clarified by centrifugation followed by desalting of the supernatant with a 1000 Da membrane; the retentates were then freeze-dried. Alcalase and Flavourzyme™ produced protein hydrolysates with significantly higher ( P < 0.05) degree of hydrolysis when compared to the other proteases. Flavourzyme, papain, and alcalase produced hydrolysates that contained the highest levels of aromatic amino acids, while trypsin hydrolysate had the highest levels of lysine and arginine. Papain hydrolysate contained high molecular weight peptides (10 to 178 kDa) while hydrolysates from the other 4 proteases contained predominantly low molecular weight peptides (≤ 23 kDa). DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity of the Flavourzyme hydrolysate was significantly ( P < 0.05) the highest while alcalase and trypsin hydrolysates were the lowest. Inhibition of angiotensin converting enzyme (ACE) activity was significantly higher ( P < 0.05) for papain hydrolysate while Flavourzyme hydrolysate had the least inhibitory activity. Sensory analysis showed that the alcalase hydrolysate was the most bitter while papain and α-chymotrypsin hydrolysates were the least. Among the 5 enzymes used in this study, papain and α-chymotrypsin appear to be the most desirable for producing high quality pea protein hydrolysates because of the low bitterness scores combined with a high level of angiotensin converting enzyme inhibition and moderate free radical scavenging activity.     

Effect of whey protein enzymatic hydrolysis on the rheological properties of acid-induced gels

A protein dispersion blend of β-lactoglobulin and α-lactalbumin was heat-denatured at pH 7.5, hydrolyzed by α-chymotrypsin and then acidified with glucono-δ-lactone to form gels at room temperature. Heat treatment induced the formation of whey protein polymers with high concentration of reactive thiol groups (37 μmol/g). The reactive thiol group concentration was reduced by half after 40 min enzymatic hydrolysis. It was further reduced after enzyme thermal deactivation. During acidification, the first sign of aggregation for hydrolyzed polymers occurred earlier than for non hydrolyzed polymers. Increasing the hydrolysis duration up to 30 min resulted in more turbid gels characterized by an open microstructure. Elastic and viscous moduli were both reduced, while the relaxation coefficient and the stress decay rate constants were increased by increasing the hydrolysis duration. After one week storage at 5 °C, the hardness of gels made from hydrolyzed polymers increased by more than 50%. The effect of polymer hydrolysis on acid-induced gelation is discussed in relation to the availability and reactivity of thiol groups during gel formation and storage.     

超高压协同酶法条件下不同分子量大豆分离蛋白水解肽乳化性及抗氧化性研究

目的研究不同分子量分布对大豆分离蛋白水解肽乳化性及抗氧化性的影响。方法采用超滤技术将超高压协同酶解制备的大豆分离蛋白水解物分离得到5个分子量肽段,即分子量（Molecular weight, Mw）<3500 u、3500 u< Mw <7000 u、7000 u< Mw <10000 u、10000 u< Mw <20000 u和Mw >20000 u。通过测定乳化活性、乳化稳定性、电势、粒径、还原力、以及对 2,2-联苯基-1-苦基肼基(2,2-diphenyl-1-picrylhydrazyl, DPPH)和 2,2''-联氮-双(3-乙基苯并噻唑-6-磺酸)（2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS）自由基清除率,分析不同分子量水解肽的乳化性及抗氧化性变化。结果7000 u< Mw <10000 u的水解肽具有较高的乳化活性、电势和较小的粒径,而10000 u< Mw <20000 u的水解肽则表现出较优的乳化稳定性,但与7000 u< Mw <10000 u的组分差异不显著(P＞0.05);水解肽的抗氧化性随肽段分子量的减小呈逐渐增大趋势,且不同分子量肽段与还原力和DPPH自由基清除能力均呈极显著负相关性（P＜0.01）,与ABTS自由基清除能力呈显著负相关性(P＜0.05)。结论 超高压协同酶法制备的大豆分离蛋白水解肽,乳化性和抗氧化性与其分子量分布有密切关联,这为相关功能性产品的开发提供了较为切实的理论依据。     

Modifications of soy protein isolates using combined extrusion pre-treatment and controlled enzymatic hydrolysis for improved emulsifying properties

Effects of combined extrusion pre-treatment and controlled enzymatic hydrolysis on the physico-chemical properties and emulsifying properties of soy protein isolates (SPI) have been investigated. Results showed that extrusion pre-treatment caused a marked improvement in the accessibility of SPI to enzymatic hydrolysis, resulting in changes in degree of hydrolysis (DH), protein solubility (PS), surface hydrophobicity (H₀) and molecular weight distributions (MWD) for ESPIH (extrusion pre-treated SPI hydrolysates). It was observed that emulsion systems formed by control SPI or SPIH (SPI hydrolysates) (20% v/v oil, 1.6% w/v emulsifier, and pH 7.0) were unstable over a quiescent storage period of 21 days, due to bridging flocculation and creaming. However, ESPIH (9.1% DH) was capable of producing a very fine emulsion (d₃₂ = 0.42 μm, d₄₃ = 2.01 μm) which remained stable over a long term quiescent storage. Various surface properties of ESPIH products have also been studied in relation to DH and emulsifying functionalities. It was suggested that significantly increased protein solubility and decreased molecular weight could be the main reasons for the greatly improved emulsifying capability of ESPIH. This study demonstrated that modified soy protein could be an excellent emulsifying agent for food and other applications. It also demonstrated that combined extrusion pre-treatment and enzymatic hydrolysis could be a highly effective method for functionality modification of globular proteins.     

限制性酶解乳清蛋白功能性质研究

探究乳清蛋白在碱性蛋白酶限制性水解下功能性质变化。以乳清蛋白的溶解性,乳化性、乳化稳定性,起泡性、起泡稳定性为考察指标,确定乳清蛋白的等电点及分析不同水解度下乳清蛋白功能性质在p H调控下的变化。结果表明:乳清蛋白的等电点为4.8。乳清蛋白进行限制性酶解后功能性质有了很大提高,其中溶解性在DH14、p H10下达到最大值,较原蛋白提高了14.55%;起泡性在DH14、p H4下达到最大值,较原蛋白提高了107.5%;起泡稳定性在DH4、p H4下达到最大值,比原蛋白提高了8.66%;乳化性在DH14、p H12下达到最大值,比原蛋白提高了56.1%;乳化稳定性DH4、p H12下达到最大值,比原蛋白提高了50.42%。      

Effect of cold plasma on the techno-functional properties of animal protein food ingredients

Proteins, as food ingredients, are employed in the food industry, not only for their high nutritional value, but also because of their techno-functional properties. Modifications of their native structure due to the action of external factors such as pH, temperature or processing by emerging technologies, can lead to changes in their functionality; and consequently, their applicability. The present study investigates the effects of cold atmospheric air plasma on the techno-functional properties of two common food ingredients (haemoglobin and gelatine from pork), and a novel source of functional proteins extracted from a meat co-product (bovine lung protein). Significant effects were found for their functional, rheological and gelling properties. However, the effects were found to depend on the native structure and nature of the protein. The findings point to the specific nature of plasma-protein interactions and the need for individual proteins to be studied as a function of plasma conditions.Industrial relevance textCold plasma is increasingly being investigated as a non-thermal technology for food and other biological applications such as primary agriculture and medicine. In addition to microbial and pest decontamination, it can be also be used to modify the functionality of food ingredients to achieve the desired properties of a specific food product.     

大豆蛋白的酶水解产物研究

大豆蛋白含有多种蛋白成分,其酶水解物非常复杂.为探索其中规律,采用Protamex酶对大豆蛋白进行有限水解,测定了水解液中氨基氮含量、三氯乙酸中可溶性氮含量随水解度的变化曲线,并采用凝胶层析过滤色谱分析了不同水解时间水解物分子量的变化,发现大豆分离蛋白中存在一些Protamex不容易水解成分,大豆分离蛋白的Protamex水解过程是一个不均匀的过程.     

海参体壁蛋白ACE抑制肽酶解工艺及产物分子量分布研究

以血管紧张素转化酶(ACE)抑制率和水解度为指标,筛选出适合海参体壁蛋白水解的酶。采用单因素和响应面法优化最优酶的水解条件,确定其最佳水解工艺,进而采用HPLC法探讨酶解产物的分子量分布。结果表明:中性蛋白酶在50℃、p H7.5、酶量3000 U/g、酶解5 h条件下,所得酶解产物的ACE抑制率最高,达到56.5%。此条件下酶解产物经HPLC分析,200~1000 Da(2~10肽)的海参多肽占44.1%。      

Application of emerging technologies to obtain legume protein isolates with improved techno-functional properties and health effects

Current demand of consumers for healthy and sustainable food products has led the industry to search for different sources of plant protein isolates and concentrates. Legumes represent an excellent nonanimal protein source with high-protein content. Legume species are distributed in a wide range of ecological conditions, including regions with drought conditions, making them a sustainable crop in a context of global warming. However, their use as human food is limited by the presence of antinutritional factors, such as protease inhibitors, lectins, phytates, and alkaloids, which have adverse nutritional effects. Antitechnological factors, such as fiber, tannins, and lipids, can affect the purity and protein extraction yield. Although most are removed or reduced during alkaline solubilization and isoelectric precipitation processes, some remain in the resulting protein isolates. Selection of appropriate legume genotypes and different emerging and sustainable facilitating technologies, such as high-power ultrasound, pulsed electric fields, high hydrostatic pressure, microwave, and supercritical fluids, can be applied to increase the removal of unwanted compounds. Some technologies can be used to increase protein yield. The technologies can also modify protein structure to improve digestibility, reduce allergenicity, and tune technological properties. This review summarizes recent findings regarding the use of emerging technologies to obtain high-purity protein isolates and the effects on techno-functional properties and health.     

Mechanical properties of mammalian and fish gelatins based on their weight average molecular weight and molecular weight distribution

Acid porcine skin gelatins (type A), lime bone gelatins (type B) and gelatin from different cold water fish species were compared on the basis of low deformation mechanical properties, Bloom value, weight average molecular weight, molecular weight distribution and isoelectric point. The dynamic storage modulus and Bloom value for all types of gelatin increased with increasing weight average molecular weight. Type A and type B gelatins with similar weight average molecular weight exhibited different dynamic storage modulus (G′) and different Bloom values. This is most probably due to a different molecular weight distribution as well as the presence of different hydrolytic fragments. The present study suggests that it may be possible to improve the mechanical properties by removing low molecular weight molecules from a gelatin sample. The Bloom values for gelatin from haddock, saithe and cod were determined to be 200, 150 and 100 g from a linear correlation between G′ and Bloom.     

不同酶切方式对乳清蛋白疏水性和乳化性的影响

采用不同的蛋白酶对乳清蛋白进行水解,考察了肽键断裂方式对乳清蛋白肽疏水性和乳化性的影响,以及乳清蛋白不同酶解产物的疏水性和乳化性的关系。结果表明:不同蛋白酶作用于乳清蛋白得到的水解产物疏水性不同,6种蛋白酶解液的疏水性均随水解度的增大而降低,其中以胰凝乳蛋白酶酶解液的疏水性下降的最慢。研究还发现,乳化性随着水解度增加而先升高后下降,以双酶复合酶解液最差。不同蛋白酶水解液的乳化性指数随疏水性指数的降低而升高,乳化性指数与疏水性氨基酸质量分数成正相关。     

酶解法制备豌豆抗氧化肽及其稳定性的研究

以DPPH自由基清除率为指标,研究了豌豆蛋白经过碱性蛋白酶酶解后的豌豆多肽的抗氧化活性,并研究了温度、p H及胃肠模拟消化条件下对豌豆抗氧化肽活性的影响。试验结果表明,在p H为7,温度为37℃条件下,豌豆抗氧化肽的DPPH自由基清除率保持稳定。高温、过酸或过碱条件均可大幅度降低豌豆抗氧化肽的DPPH自由基清除率。胃蛋白酶处理对豌豆抗氧化肽的活性无显著影响,胃蛋白酶和胰蛋白酶共同处理后,豌豆抗氧化肽的活性显著提高(P0.05)。豌豆蛋白是潜在的制备抗氧化肽的优质资源。     

限制性酶解对豆粉相关性质的影响

为降低豆粉的致敏性,扩大其应用,采用限制性酶解制备豆粉。以木瓜蛋白酶、风味蛋白酶和碱性蛋白酶为限制性酶解用酶,研究不同的酶制剂及酶解时间对豆粉的致敏性、溶解性、表面疏水性及乳化性的影响,并对豆粉进行感官评价。结果表明:随着酶解时间的延长,豆粉的致敏性降低,溶解性、表面疏水性、乳化活性和乳化稳定性增加;其中利用木瓜蛋白酶酶解30 min制备的豆粉致敏原含量最低,为1. 95%,溶解性最高,为88. 55%,乳化活性及乳化稳定性最大,分别为182. 4 m2/g和120. 8 min;利用SDS-PAGE电泳发现,酶解作用使豆粉蛋白质中的7S和11S降解,生成小分子的肽类,从而降低豆粉的致敏性;利用木瓜蛋白酶酶解20 min制备的豆粉口感与传统市售豆粉相似。     

低限度酶水解对醇法大豆浓缩蛋白分散性的影响

以大豆浓缩蛋白的分散时间和分散稳定时间为主要指标,研究了大豆浓缩蛋白经过Alcalase酶低限度水解后,分散时间和分散稳定时间的变化情况,并考察了低限度酶水解对分子量分布的影响。      

低限度酶水解对醇法大豆浓缩蛋白分散性影响

以大豆浓缩蛋白分散时间和分散稳定时间为主要指标,研究大豆浓缩蛋白经过Alcalase酶低限度酶水解后,分散时间和分散稳定时间变化情况,并考察低限度酶水解对分子量分布影响。