Protamex蛋白酶水解大豆分离蛋白的研究

以大豆分离蛋白为底物,通过响应面分析,确定了用Protamex蛋白酶水解的最佳条件。最佳酶解条件为:大豆分离蛋白浓度6.0%,加酶量2.4%,酶解温度51℃,酶解时间4h,pH7.0。在最佳条件下,可得到水解度为12.94%的酶解液。     

热烘改性对大豆分离蛋白功能性的影响

研究了利用热处理对大豆分离蛋白(SPI)进行改性。热烘改性对SPI的吸水性、吸油性、发泡性和泡沫稳定性无显著性影响,常温粘度、高温粘度、耐热性、凝胶性和保水性分别比对照提高了118%、135%、108%、81%和83%。比较适宜的热烘改性条件为10min/85℃。     

高压均质对大豆分离蛋白功能性质的影响

为了了解高压均质技术对大豆分离蛋白（SPI）功能性质的影响,采用不同的均质压力、均质次数和料液比对大豆分离蛋白溶液进行了高压均质处理,并分析处理前后SPI功能性质的变化.结果表明：高压均质可在一定程度上提高SPI的溶解性、乳化活性及其稳定性和起泡性及泡沫稳定性.均质压力在0～70 MPa的范围内升高时,SPI的溶解性、乳化稳定性、起泡性和泡沫稳定性得到了相应的改善,而乳化活性在压力为40 MPa时达到最高;均质次数由1次向3次增加时,SPI的乳化稳定性、起泡性及泡沫稳定性得到了提高,而溶解性和乳化活性则降低;均质物料料液比在1∶16～1∶8 （g∶mL）的范围内逐步增大时,SPI的各项功能性质均有不同程度的提高,并在料液比为1∶8时达到了最高值.     

Evaluation of bitterness in enzymatic hydrolysates of soy protein isolate by taste dilution analysis

ABSTRACT:  Although enzymatic hydrolysates of soy protein isolate (SPI) have physiological functionality, partially hydrolyzed SPI exhibits bitter taste depending on proteases and degree of hydrolysis (DH). To determine proteolysis conditions for SPI, it is important to evaluate bitterness during enzymatic hydrolysis. Taste dilution analysis (TDA) has been developed for the screening technique of taste-active compounds in foods. The objectives of the present study were to evaluate bitterness of enzyme-hydrolyzed SPI by TDA and to compare bitterness of SPI hydrolysates with respect to kinds of proteases and DH. SPI was hydrolyzed at 50 °C and pH 6.8 to 7.1 to obtain various DH with commercial proteases (flavourzyme, alcalase, neutrase, protamex, papain, and bromelain) at E/S ratios of 0.5%, 1%, and 2%. The DH of enzymatic hydrolysates was measured by trinitrobenzenesulfonic acid method. The bitterness of enzymatic hydrolysates was evaluated by TDA, which is based on threshold detection in serially diluted samples. Taste dilution (TD) factor was defined as the dilution at which a taste difference between the diluted sample and 2 blanks could be detected. As DH increased, the bitterness increased for all proteases evaluated. Alcalase showed the highest TD factor at the same DH, followed by neutrase. Flavourzyme showed the lowest TD factor at the entire DH ranges. At the DH of 10%, TD factor of hydrolysate by flavourzyme was 0 whereas those by protamex and alcalase were 4 and 16, respectively. These results suggest that TDA could be applied for the alternative of bitterness evaluation to the hedonic scale sensory evaluation.     

马来酸酐酰化改性对大豆分离蛋白功能性质的影响

研究马来酸酐酰化改性对大豆分离蛋白功能性质的影响。结果表明:随着马来酸酐用量的增大,大豆分离蛋白的酰化度增大,等电点降低;随着酰化度的增大,大豆分离蛋白构象松散,色氨酸残基的微环境趋向于暴露于水的状态,亲水性增强;经马来酸酐酰化改性后,大豆分离蛋白的溶解性、发泡性、乳化性及乳化稳定性均显著提升,但泡沫稳定性有所下降。研究表明,马来酸酐酰化改性大豆分离蛋白是一种非常有前景的功能性食品添加剂。     

不同来源蛋白酶水解对大豆分离蛋白分散性及溶解性的影响

研究了动物(胰蛋白酶)、植物(木瓜蛋白酶与菠萝蛋白酶)、微生物(碱性蛋白酶和中性蛋白酶)三种来源蛋白酶的低限度水解对大豆分离蛋白(SPI)分散性和溶解性的影响。结果表明,三种来源蛋白酶轻度水解可显著提高SPI的分散性,但却使其溶解性有不同程度的降低。三种来源蛋白酶水解产物的分散度大小依次为:植物来源蛋白酶>微生物来源蛋白酶>动物来源蛋白酶,而其溶解性则相反:动物来源蛋白酶>微生物来源蛋白酶>植物来源蛋白酶。本文对采用酶解的方法制备高分散性与高溶解性SPI具有一定的参考价值。通过对木瓜蛋白酶水解沉淀物进行分析,可以推测酶解使SPI溶解度显著下降的原因可能是SPI被水解后通过疏水作用力和氢键相互聚集形成了不溶性的沉淀。     

Alcalase 2.4L碱性内切酶和Flavourzyme风味酶酶解大豆分离蛋白及脱苦工艺优化

以大豆分离蛋白为原料,选用Alcalase 2.4L碱性内切酶和Flavourzyme风味蛋白酶对大豆分离蛋白进行酶法水解及脱苦工艺研究。以水解度和苦味分值为考察值,对酶解工艺进行优化,确定最佳条件。结果表明:Alcalase2.4L碱性内切酶最佳酶解条件为加酶量14 000 U/g、酶解温度60℃、酶解pH8.5、底物质量分数5%,酶解时间2h,最终水解度为45.34%,此时水解液苦味值为4。Flavourzyme风味蛋白酶对水解液进行二次水解的最优酶解条件为加酶量300 U/g、酶解温度55℃、酶解pH 7.0、酶解时间3 h,此条件下大豆分离蛋白水解液苦味值最低为1.2。Alcalase2.4L碱性内切酶和Flavourzyme风味蛋白酶水解大豆分离蛋白使水解度得到较大提高的同时也解决了水解液的苦味问题。     

酶改性大豆分离蛋白的制备及产品功能性的研究

为了改善碱溶酸沉法大豆分离蛋白产品(简称SPI)的功能性,采用有限酶解的方法,从6种蛋白酶中选出中性蛋白酶(Neutrase)作为改性用酶.通过单因素实验,分析了底物浓度,E/S,反应时间对水解度和氮收率的影响,并通过正交实验确定制备酶改性大豆分离蛋白(简称ESPI)的最佳工艺参数为:底物浓度为3%,E/S为1 200U/g,时间为60 min.得到的ESPI的蛋白含量与SPI相近,但NSI由SPI的90%提高到97%.而且在功能性方面,ESPI也得到了很好的改善,尤其是乳化性和起泡性.     

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     

大豆分离蛋白改性技术的研究与发展趋势

大豆分离蛋白因其高蛋白营养功能和不同的功能特性而广泛应用于食品工业,为了探讨改性大豆分离蛋白的功能特性,综述了近年来大豆分离蛋白改性的研究方法以及改性后功能特性方面的最新研究进展。根据当前的研究现状及存在的问题对今后发展提出几点展望,不同方式的改性可产生合适的功能特性,拓宽大豆分离蛋白的应用领域。     

大豆分离蛋白酶解液体外抗氧化性的研究

以大豆分离蛋白为底物，以抗氧化性为指标，从6种蛋白酶中筛选出碱性内切蛋白酶为最佳水解酶，优化了其最佳水解条件，并测定了碱性内切蛋白酶水解大豆分离蛋白所得酶解液的亚油酸过氧化抑制率和清除氧自由基活力。结果表明，碱性内切蛋白酶最佳水解条件为T=55℃，pH=7．5，E／[S]=5％，[S]=4．5％，水解时间t=3h，其水解大豆分离蛋白所得酶解液的亚油酸过氧化抑制率为28．4％，清除氧自由基活力为45．6％。     

大豆分离蛋白的特性研究

研究水解后不同分子量范围的大豆分离蛋白功能性方面,分子量在1000～2000D时候乳化活性和乳化稳定性最大,分别为176.9mL/g和120min;持水性方面分子量小于1000D时候最大,为66.2%;黏度方面,分子量大于4000D时候最大,为1.8cp;持油率方面分子量范围在大于4000D范围内最大,为378.42%。     

番茄籽蛋白酶解产物的功能特性研究

以番茄籽蛋白为原料,研究不同蛋白酶对番茄籽蛋白水解物功能性质的影响并与原蛋白的功能性质进行比较。结果表明:不同蛋白酶水解番茄籽蛋白的规律相似,水解度随时间增加而提高,但在相同时间内,不同水解物的水解度不同,说明不同的蛋白酶对番茄籽蛋白的水解效率不同,其中碱性蛋白酶水解效率最高14.48%;木瓜蛋白酶可较高效地回收番茄籽蛋白,蛋白回收率高达81.12%;番茄籽分离蛋白经酶解改性后其表面疏水性降低,但溶解性和乳化性均有不同程度的提高,其中胰蛋白酶水解物的溶解性最好;木瓜蛋白酶水解物的乳化性能最优。因此,酶法水解可改善番茄籽蛋白的功能性质,且不同蛋白酶对蛋白的功能性质的影响不同,可根据实际需要选择蛋白酶。      

Solubility,functional properties,ACE‐I inhibitory and DPPH scavenging activities of Alcalase hydrolysed soy protein hydrolysates

Soy proteins are less soluble at acidic pH value, which impedes their utilisation in acidic beverages. Soy protein isolate (SPI) was hydrolysed using varying Alcalase concentrations (0.0001–2.0 U g^?1 protein) at different pHs (3.0–4.0). Degree of hydrolysis (DH) of soy protein hydrolysates (SPH) at pH 3.0, 3.5 and 4.0 were 5.0–10.7%, 2.3–6.1% and 0–5.4%, respectively, while solubilities ranged from 70.7 to 74.9%, 18.8 to 51.2% and 7.1 to 40.4%, respectively. The highest solubility (74.9%) was observed at pH 3.0 with 1.5 U Alcalase per g protein (DH = 9.2%). Emulsifying activities of SPHs at pH 3.0 and 4.0 ranged from 0.49 to 0.63 AU and 0.19 to 0.24 AU, respectively, while the emulsifying stabilities were 12.2–14.7 min and 18.7–56.0 min, respectively. The foaming capacity at pH 3.0 and 4.0 was 44.9–46.3 mL and 31.2–41.3 mL, respectively, whereas the foaming stability was 25.5–35.2 min and 12.8–15.1 min, respectively. However, hydrolysates had an insignificant effect on ACE‐I inhibitory and DPPH scavenging activities in comparison with SPI.     

Emulsifying properties of soy protein isolate fractions obtained by isoelectric precipitation

Soy protein isolate (SPI) fractions were produced by isoelectric precipitation based on results of isoelectric focusing carried out on the crude soy extract. The fractions were produced from crude protein extract (pH 9.0) sequentially and non‐sequentially at isoelectric points (pIs) of 5.6, 5.1 and 4.5. Emulsions stabilised by soy proteins with pIs between 5.6 and 5.1 had the highest (P < 0.01) emulsion stability index (ESI), while those stabilised with proteins having pIs between 5.1 and 4.5 resulted in the lowest ESI for sequentially precipitated fractions. Non‐sequential fractionation at pI 5.1 produced fractions with higher emulsifying activity index (EAI) than sequential fractionation. SDS‐PAGE profiles indicated that the fractions exhibiting high functionality in terms of ESI and EAI were also richer in 7S globulin protein subunits. © 2001 Society of Chemical Industry     

The effect of high solid concentrations on enzymatic hydrolysis of soya bean protein isolate and antioxidant activity of the resulting hydrolysates

This study investigated the effect of high solid concentrations on the enzymatic hydrolysis and antioxidant activities of soya bean protein isolate hydrolysates (SPIHs). The soya bean protein isolate at the concentration of 8%, 16%, 24% and 32% was hydrolysed to obtain SPIH with 21.5% degree of hydrolysis (DH), respectively. Results showed that, for the same DH, significant increases in reaction time and decrease in protein recovery were observed as solid concentrations increased. There was no significant difference in molecular weight distribution, but different amino acid compositions in supernatants of SPIH hydrolysed at different solid concentrations. The level of antioxidant amino acids in high solid concentration (32%) was higher than that in low solid concentration group, and antioxidant activity of SPIH increased with the solid concentration increased. Thus, increasing solid concentrations could increase the antioxidant activities and functional properties with low water costs.     

大豆蛋白酶解产物抗氧化活性与水解度相关性研究

利用碱性蛋白酶Alcalase 2.4L水解大豆分离蛋白,研究了底物浓度、加酶量、p H、温度因素对酶解液水解度和还原力的影响,并在此基础上用响应面分析法优化酶水解条件。以还原力为主要指标考察酶解产物的抗氧化活性,通过水解度与还原力的比较,得到Alcalase 2.4L碱性蛋白酶酶解大豆分离蛋白产物的抗氧化活性与水解度之间没有直接线性关系。在实验得到的最佳条件下制备的大豆肽抗氧化活性良好,具有良好的应用前景。     

超声处理对大豆蛋白膜性能和微观结构的影响

研究了超声处理对大豆分离蛋白膜性能和微观结构的影响。结果表明,大豆分离蛋白膜液经超声功率20W、10min的处理,可显著地增加膜的抗拉强度及阻湿性能;红外和扫描电镜结果显示,超声处理改变了膜的空间结构,使膜表面平滑、均匀。     

低温储藏条件对大豆分离蛋白膜理化特性的影响

以大豆分离蛋白为原料制得可食性膜,研究在不同低温储藏条件下其功能特性,包括机械性能和阻隔性能的变化。结果显示:随冷藏温度的升高,其功能特性变化较为缓慢。而随冻藏温度的降低,断裂延伸率下降尤为明显,抗拉强度和脂质阻隔能力变化趋势次之,水蒸气透过率升高缓慢。冷藏时间与断裂延伸率呈显著正相关(p<0.05)。冷藏时间与水蒸气透过率和油脂渗透系数均呈极显著正相关(p<0.01)。冻藏时间与水蒸气透过率和油脂渗透系数呈显著正相关(p<0.05)和极显著正相关(p<0.01)。     

Physicochemical and functional properties of a protein isolate produced from safflower (Carthamus tinctorius L.) meal by ultrafiltration

BACKGROUND: The protein isolate obtained from safflower meal by aqueous extraction and ultrafiltration was evaluated for its physicochemical and functional properties. RESULTS: Protein, ash and moisture contents of the safflower protein isolate were 901, 51 and 45 g kg^?1 respectively. Its water and oil absorption capacities were 2.22 mL H₂O g^?1 protein and 2.77 mL oil g^?1 protein respectively. Least gelation concentration was 20 g kg^?1 at pH 2, 6, 8 and 10 but 100 g kg^?1 at pH 4. Emulsifying properties were also affected by the pH: emulsifying activity and emulsion stability at pH 6 were 82.5 and 100% respectively. The highest foaming capacity (126%) occurred at pH 2; however, it increased by 104% with the addition of 0.25 g glucose g^?1 protein to the foam system. CONCLUSION: In the light of its functional properties found in this study, safflower protein isolate produced by ultrafiltration is recommended for use as an ingredient in food products such as salad dressing, meat products, mayonnaise, cakes, ice cream and desserts. Copyright © 2010 Society of Chemical Industry