热处理辅助木瓜蛋白酶改善蛋清蛋白的起泡特性

为获得起泡特性优良的蛋清蛋白制品,试验以新鲜鸡蛋蛋清为原料,采用热处理辅助木瓜蛋白酶有限酶解的方法来改性蛋清蛋白,通过单因素实验,分析了底物浓度、酶的添加量、酶解时间、酶解温度、酶解pH等因素对起泡能力、泡沫稳定性的影响,并在单因素实验的基础上,以起泡能力和泡沫稳定性为响应值,通过响应面分析和方差分析得出热处理辅助木瓜蛋白酶改性蛋清蛋白的最佳工艺条件:底物质量分数3%、热处理温度90℃、热处理时间10 min、酶的添加量3 500 u/g、酶解时间2.5 h、酶解温度55℃、酶解pH 7。在此条件下,蛋清蛋白的起泡力为1741.38%,泡沫稳定性为93.38%。与未改性的蛋清蛋白相比,起泡力提高了112.97%,泡沫稳定性提高了93.27%。泡沫流变学特性结果表明改性蛋白的泡沫储存模量G′是未改性蛋白的1.5倍,泡沫更加稳定。     

酶解对蛋清蛋白液起泡性能和乳化性能的影响

利用碱性蛋白酶水解蛋清蛋白,主要研究了酶用量、底物浓度和酶解时间对蛋清蛋白液起泡性能和乳化性能的影响。实验结果表明,酶解条件对蛋清蛋白液的起泡性能和乳化性能有一定程度的影响,当碱性蛋白酶酶解温度为45~50℃,pH6~8.5时,其最佳酶解条件为酶用量4%,底物浓度3%,酶解时间6h。在此最佳酶解条件下获得的蛋清蛋白酶解液起泡性为27.65%,发泡能力178.26,泡沫稳定性60.33%,乳化容量37.86%,乳化稳定性127.23,乳化活性指数134.53,乳状液稳定指数1.83。     

响应面法优化木瓜蛋白酶脱除茁霉多糖发酵液蛋白质工艺

对木瓜蛋白酶脱除茁霉多糖发酵液蛋白质工艺进行研究。在单因素实验的基础上,通过响应面设计进行工艺优化。结果表明:pH、酶解温度、酶添加量以及pH与酶解时间、pH与酶添加量的交互作用对蛋白脱除率有显著影响。木瓜蛋白酶脱除茁霉多糖发酵液蛋白质的最佳工艺条件为:pH5.2,酶解时间2.5h,酶解温度49℃,酶添加量1.5%,在此条件下蛋白脱除率为64.09%,多糖损失率为13.05%。     

纤维素酶处理对花生蛋白起泡性的影响

用纤维素酶酶解花生蛋白以提高其起泡性。通过对纤维素酶作用的pH、温度和加酶量的控制,可以提高酶解花生蛋白的起泡性。正交试验确定的最佳酶解条件为:pH 5.5,酶解温度40℃,加酶量0.4%。最佳条件所得酶解花生蛋白比原料花生蛋白的起泡性提高了39%。     

酶改性大豆分离蛋白起泡性能的研究

使用碱性蛋白酶对大豆分离蛋白进行改性,以改善蛋白质的起泡性能。探讨酶水解过程中的酶解时间、酶解温度、底物浓度、加酶量、p H对蛋白起泡能力和泡沫稳定性的影响,在此基础上通过正交实验确定了碱性蛋白酶水解大豆分离蛋白提高起泡能力的最优水解条件:时间40 min、温度50℃、底物浓度8%、加酶量0.04%、p H8,提高泡沫稳定性最佳水解条件:时间30 min、温度40℃、底物浓度6%、加酶量0.04%、p H9。测定上述条件下大豆分离蛋白的起泡能力和泡沫稳定性分别为217.50%和93.10%。改性前后蛋白质起泡能力和泡沫稳定性均有所改善,与未改性蛋白相比起泡能力和泡沫稳定性分别提高了61.11%和20.38%。     

酱油沉淀控制酶解制备高起泡蛋白的研究

研究了pH值、蛋白浓度、水解度对酱油沉淀蛋白控制酶解制备起泡蛋白的影响,并探讨了黄原胶的添加对酱油沉淀蛋白泡沫性质的改善效果。结果表明:酱油沉淀蛋白的起泡性随着pH值的升高而提高,但沉淀蛋白水解物的起泡性呈现相反的变化趋势,其在pH 5时起泡性和泡沫稳定性最佳,酶解3h水解物的起泡性和泡沫稳定性分别达到59.00%和43.55%;当黄原胶添加量为0.05%～0.1%时,能显著提高沉淀蛋白水解物的泡沫稳定性,但添加量过大会影响起泡性。在pH 5时,添加0.05%的黄原胶,3h水解物的起泡性和泡沫稳定性可达到54.00%和81.81%。以粘度、表面疏水性、ζ-电位为指标探讨了影响酱油沉淀蛋白泡沫性质的机理,蛋白泡沫性质的呈现与它们的综合效应有关。     

响应面法优化鲟鱼精蛋白肽的酶解提取

对鲟鱼-甲骨板加工副产物精巢组织进行酶法提取,建立最佳提取工艺,从而得到功能活性鱼精蛋白肽。实验发现木瓜蛋白酶对鱼精蛋白的酶解度显著高于胃蛋白酶和胰蛋白酶。在以木瓜蛋白酶添加量、液料比、pH值、酶解时间和酶解温度值等条件为对象的单因素实验基础上进一步通过响应面法利用Box-Behnken试验设计原理构建鱼精蛋白肽的酶解提取模型,并得到最佳提取工艺条件:液料比为39.72,木瓜蛋白酶添加量3%,酶解pH 7.0,温度55℃,时间8.22 h。该条件下鱼精蛋白水解度达5.44%,且该鱼精蛋白肽对大肠杆菌和金黄色葡萄球菌抑制显著。     

蕨麻粗多糖酶法脱蛋白工艺

摸索蕨麻粗多糖脱蛋白工艺条件,为蕨麻粗多糖的纯化提供理论依据。实验选取了木瓜蛋白酶、中性蛋白酶、胰蛋白酶进行蕨麻粗多糖脱蛋白实验,采用正交试验研究了酶添加量、酶解温度、酶解时间、pH值对蕨麻粗多糖脱蛋白工艺的影响。选取胰蛋白酶进行脱蛋白实验,最佳脱蛋白条件为酶添加量0．25g、酶解温度30℃、酶解时间4h、pH值7．8。     

结合型虾青素酶法水解工艺的研究

利用木瓜蛋白酶将克氏原螯虾虾壳中的结合型虾青素水解,获取游离虾青素。以虾青素提取量为评价指标,考察了蛋白酶添加量、酶解温度、溶液pH值及酶解时间等因素对水解效果的影响。通过单因素和正交试验确定了酶解工艺的最佳条件为:木瓜蛋白酶添加量10%、酶解温度45℃、溶液p H值5.5、酶解时间5 h,在此条件下,虾青素的提取量为97.26μg/g;各因素对虾青素提取量的影响依次为溶液pH值酶解温度酶解时间木瓜蛋白酶添加量。     

猴头菌丝多肽的制备及抗氧化活性研究

以还原能力、清除自由基能力以及多肽的含量为评价指标,采用木瓜蛋白酶、酸性蛋白酶、碱性蛋白酶和中性蛋白酶分别水解猴头菌液体发酵菌丝蛋白。结果表明效果最佳的是木瓜蛋白酶。通过控制木瓜蛋白酶加入量、酶解时间、酶解温度以及pH值4个因素的变化,进行4因素3水平的正交试验优化猴头菌丝蛋白的酶解工艺参数。结果表明,影响猴头菌丝抗氧化肽制备的因素为加酶量〉pH〉酶解时间〉温度。确定猴头菌丝抗氧化肽制备的最佳酶解工艺条件：加酶量80 U/mL,酶解时间1 h,酶解温度50℃,酶解pH 6.0,在此条件下猴头菌丝多肽的还原力最强,多肽含量最高。     

Studies on the effects of enzymatic hydrolysis on functional and physico-chemical properties of arachin

Arachin, the major protein fraction isolated from groundnut (Arachis hypogaea L.) was enzymatically modified to get desired degree of hydrolysis (DH) using papain, alcalase and fungal protease. The measured DH of arachin obtained with different proteases under optimum conditions suggested that the effectiveness followed the order fungal protease>papain>alcalase. The solubility in pH range 4-4.5 was 14-16% with a low DH compared to 55-60% with high DH. Emulsification capacity of arachin improved with low DH; papain was more effective compared to alcalase and fungal protease. The foam capacity of alcalase modified arachin with low DH was remarkably high compared to papain and alcalase modified arachin. Limited proteolysis did not bring about significant improvement in foam stability. However, extensive hydrolysis of arachin resulted in remarkable reduction in emulsification, foaming capacity and stability. The gel electrophoretic analysis of modified arachin suggested that the low molecular weight subunits were resistant to enzymatic attack initially and disappeared after 1 h hydrolysis.     

Modified Soy Proteins with Improved Foaming and Water Hydration Properties

Soy proteins were modified by alkali treatment at pH 10.0, followed by papain hydrolysis. Solubility, water hydration capacity (WHC), surface hydrophobicity, foaming and emulsifying properties of unmodified, alkali-treated, and papain-modified soy protein (PMSP) were compared. PMSP exhibited higher solubility (100% at pH > 7.0), WHC (3.13) and hydrophobicity (40.8) than unmodified soy protein which had solubility 68.5%, WHC 0.21, and hydrophobicity 8.1. The PMSP had foaming capacity (22.0 mL) similar to egg white (21.2 mL) at pH 7.0; and enhanced foam stability (36.4) compared to the unmodified control (32.9). In general, alkali-treated soy had lower functional properties. Emulsifying properties of PMSP and alkali treated soy were unchanged by the modification. PMSP could be used as an egg white substitute in foaming applications at neutral pH.     

高固形物浓度对大豆分离蛋白酸性蛋白酶酶解产物功能特性的影响

本文系统研究了提高固形物浓度对酸性蛋白酶酶法改性大豆分离蛋白分子量分布、氮溶解指数、分散稳定性、持水力、乳化性、起泡性和泡沫稳定性的影响。结果表明:大豆分离蛋白经过酸性蛋白酶控制酶解制备的改性大豆分离蛋白,其产物氮溶解指数、起泡性均有明显提高,分散稳定性略有提高;但持水力、乳化性、泡沫稳定性有所降低。在相同水解度下,随着酶解体系中固形物浓度的提高,改性大豆分离蛋白的分散稳定性、持水力、乳化活性均呈上升趋势,酶解产物中分子量小于10 kDa的肽段以及氮溶解指数呈下降趋势。当水解度小于8%时,低浓度酶解产物起泡性高于高浓度酶解产物,而水解度超过8%时,高浓度酶解产物起泡性大体高于低浓度酶解产物。     

小麦面筋蛋白质酶解产物用作啤酒发泡蛋白的研究

为改善啤酒的泡沫性能,作者分别采用木瓜蛋白酶、胃蛋白酶以及碱性蛋白酶对小麦面筋蛋白进行适度酶解改性,并对其产物用作啤酒发泡蛋白的可行性进行了研究.结果表明,经适度酶解作用后,小麦面筋蛋白在pH 4.5条件下溶解性和泡沫性能得到显著改善(P<0.05),且小麦面筋蛋白酶解产物在啤酒环境中热稳定性较好,经30 min的热处理,含100 mg/L小麦面筋蛋白酶解产物的啤酒浊度与加热前相比增加不显著(p>0.05).小麦面筋蛋白胃蛋白酶酶解产物和碱性蛋白酶酶解产物对啤酒初始泡持性的改善效果都较好,但胃蛋白酶酶解产物对酵母蛋白酶A作用较敏感,对纯生啤酒货架期内泡持性的改善效果不太理想,而碱性蛋白酶酶解产物可明显改善纯生啤酒货架期内的泡沫稳定性.     

Egg yolk protein modification by controlled enzymatic hydrolysis for improved functionalities

Delipidated egg yolk protein (EYP) is produced as a co-product of egg yolk lecithin extraction. This EYP is expected to have poor functionality because of protein denaturation caused by ethanol treatment during lecithin extraction. Two food grade endo-proteases were used to produce EYP hydrolysates (EYPh) with two degrees of hydrolysis (DH), 3% and 6%. Protein solubility was improved as DH increased. Solubility profiles for both EYP and EYPh were relatively less pH-dependent compared with soy protein. Except for foaming capacity, EYPh showed improvement in foam stability, foaming speed, and foam density. Emulsion stability was improved for all EYPhs. Treatments at DH of 6% showed significant increase in emulsification capacity. We have shown quantitatively how controlled enzymatic hydrolysis can be applied to ethanol-treated lipid-free EYP to increase protein solubility, and thus to improve foaming and emulsification properties.     

高固形物浓度对风味蛋白酶催化制备改性大豆分离蛋白功能特性的影响

高固形物浓度酶解反应具有终产物浓度高、废水少、冷却和浓缩能耗低、设备尺寸小等优点,是蛋白控制酶解的研究热点之一。本文系统研究了提高固形物浓度对风味蛋白酶酶法改性大豆分离蛋白分子量分布、溶解性、分散稳定性、持水力、乳化性、起泡性和泡沫稳定性的影响。研究结果表明:大豆分离蛋白经过风味蛋白酶控制酶解制备的m SPI,其产物溶解性、分散稳定性、起泡性均提高,持水力、乳化性、泡沫稳定性降低。在相同水解度下,随着固形物浓度的提高,m SPI的分散稳定性、持水力、乳化性均呈上升趋势。当水解度8%时,低浓度酶解产物起泡性高于高浓酶解产物,而水解度超过8%时,高浓酶解产物起泡性大体高于低浓酶解产物。风味蛋白酶制备的m SPI的溶解性与酶解固形物浓度无明显关系。     

EFFECT OF ENZYMATIC HYDROLYSIS ON SOME FUNCTIONAL PROPERTIES OF WHEY PROTEIN

A study was undertaken to further elucidate the functional properties of whey protein with respect to foaming and emulsifying capacities and to observe the effect of enzymatic hydrolysis on these properties. Emulsion capacity decreased as proteolysis continued suggesting there is an optimum mean molecular size of the proteins involved which is lower than that of casein. Heat treatment of the reconstituted protein concentrate was necessary for foam stability; specific volume and foam stability increased directly with temperature of heating. Re effect of pH on whippability, data indicate that the greater the net charge the greater the tendency to foam. A limited amount of hydrolysis appears desirable to increase foaming but greatly decreases foam stability.     

超声辅助碱性蛋白酶提取鸡爪胶原蛋白肽理化性质及功能特性

以超声波辅助碱性蛋白酶提取所得鸡爪胶原蛋白肽作为实验材料,首先研究鸡爪胶原蛋白肽的理化特性（外观色泽、等电点、分子质量分布、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、氨基酸组成及水解度）,进一步对其起泡性和起泡稳定性、乳化性和乳化稳定性等功能特性进行研究。结果表明：鸡爪胶原蛋白肽的分子质量分布范围小于α2-链,小分子质量肽段比例较高;氨基酸种类丰富,甘氨酸和脯氨酸在总氨基酸含量中占比最高;优化提取的鸡爪胶原蛋白肽水解度约28.65%,起泡性和起泡稳定性高达133.33%和126.67%,且具有较好的乳化性和乳化稳定性。     

Effect of Partial Proteolysis and Succinylation on Functionality of Corn Germ Protein Isolate

Corn germ protein isolate (CGPI) was partially hydrolyzed with trypsin and pepsin and succinylated at three levels. Various functional and electrophoretic properties of the native and modified protein were determined. Water absorption and foaming properties of CGPI were Improved by partial hydrolysis with trypsin; emulsifying capacity and nitrogen solubility were reduced; oil absorption was increased only slightly. CGPI pepsin hydrolyzate has decreased oil absorption, nitrogen solubility and emulsifying capacity but improved foaming properties; water absorption was unchanged. Treatment of CGPI with succinic anhydride improved water and oil absorption, nitrogen solubility and foaming capacity but decreased emulsifying capacity; foam stability was unchanged. Succinylation retarded electropohoretic mobility while hydrolysis altered band intensities.     

The foaming properties of proteins isolated from barley

Albumin and hordein protein fractions have been isolated from barley by extraction with salt and aqueous ethanol respectively. Both produce stable foams as assessed by a shaking procedure, and in each case foaming was enhanced by denaturation of the proteins. Foam power was increased rather more for albumin than for hordein, especially by heat, and this was accompanied by an increase in hydrophobic character as assessed by the fluorochrome 1‐anilino‐8‐napthalenesulphonic acid. Iso‐α‐acids and reduced iso‐α‐acids increased the foam stability of both albumin and hordein, with there being a proportionately greater increase for the undenatured proteins. Albumin is resistant to hydrolysis by the cysteine proteinases ficin and papain but is hydrolysed by the serine proteinase trypsin. In the latter instance, hydrolysis is accompanied by a loss of foam stability. By contrast, hordein is resistant to digestion by trypsin but is susceptible to the action of ficin and papain. In these instances, limited proteolysis leads to a substantial enhancement of foam stability from hordein, though prolonged proteolysis is detrimental. Proteinase A from yeast hydrolyses both protein classes and lowers their ability to give stable foams. It is concluded that polypeptides derived from both albumin and hordein could make a contribution to the foam potential of beer. © 2002 Society of Chemical Industry