酚类物质和硅胶对啤酒中敏感蛋白的吸附选择性研究

啤酒中的混浊活性蛋白（敏感蛋白）富含脯氨酸。对0℃、37℃以及室温下分离的啤酒混浊物质进行氨基酸分析后发现,不同贮藏温度条件下产生的混浊物质中脯氨酸含量差异很大,依次为13．22％,11．30％和10．44％（均为摩尔百分含量）,原因是不同贮藏温度下啤酒中的多酚物质氧化聚合情况不同,造成其对敏感蛋白的选择性差异;0℃贮藏条件下,多酚物质对敏感蛋白选择性最高,37℃次之,室温保藏最差：对硅胶吸附的蛋白质进行氨基酸分析后发现,硅胶吸附蛋白质的脯氨酸含量比啤酒总蛋白所含脯氨酸要高出许多,说明硅胶对敏感蛋白有一定的选择性吸附,且不同硅胶产品对敏感蛋白的吸附选择性也有差异,可以把硅胶吸附蛋白质的脯氨酸含量作为评价硅胶产品质量的一个参考性指标。     

Isolation of beer foam polypeptides by hydrophobic interaction chromatography and their partial characterisation

Beer foam polypeptides have been separated into five groups based on their relative hydrophobicity. Foam stability increases with increasing hydrophobicity of the polypeptide groups. The most hydrophobic polypeptide group contains a large proportion of Coomassie blue-binding polypeptides. Analysis by SDS-PAGE reveals that each polypeptide group is composed of several differently-sized polypeptides. Further purification by anion-exchange chromatography results in five fractions, each of which has a different polypeptide profile on SDS-polyacrylamide gels.     

The Influence of Ethanol on the Foaming Properties of Beer Protein Fractions: A Comparison of Rudin and Microconductivity Methods of Foam Assessment

The effect of ethanol on the foaming properties of beer protein fractions was studied using a microconductivity method and nitrogen gas to generate the foam. Increasing the ethanol concentration resulted in a decrease in foam stability. Interfacial studies including thin film drainage and dilational elasticity measurements indicated that ethanol reduced the rigidity of the adsorbed protein layer resulting in accelerated drainage from the foam lamellae and increased probability of film rupture. These results conflict with data from the Rudin method (using nitrogen gas to generate the foam) which indicate that, at low concentration, ethanol improves foam stability. These apparently conflicting results may be explained by the foam positive effects of a decline in bubble size and increase in bulk viscosity observed for the Rudin method, contrasted with the negative influence of a reduction in surface viscosity observed for the microconductivity foam assessment method.     

AN IMMUNOCHEMICAL ANALYSIS OF BEER FOAM

Beer foam produced in a continuous foaming tower in volumes representative of commercial dispense, was analysed by immunoelectrophoretic and immunoblotting techniques to identify antigens involved in foam structural stability. In crossed immunoelectrophoresis (CIE), only one antigen precipitated from foam in the homologous foam antiserum. This antigen was shown to be of malt origin by rocket-line immunoelectrophoresis and was also present in 11 commercial beers (5 bitters, 4 lagers and 2 stouts). However, the foam preparation separated into more than 20 polypeptides by SDS polyacrylamide gel electrophoresis. Immunoblotting showed that at least 12 of these reacted with foam antiserum and that they originated from either malt or yeast. Similar polypeptides were also identified in the antigen precipitated in CIE, suggesting that these polypeptides were probably present in the foam as a complex. It is concluded that the stability of foam reflected molecular interactions between these polypeptides (and possibly other components such as carbohydrates) in the liquid film of the bubble structure.     

PGA对纯生啤酒泡沫稳定性的影响研究

在纯生啤酒中添加微量的PGA,可有效地提高纯生啤酒的泡沫稳定性。实验发现,在初过滤之后,终过滤之前,向纯生啤酒中添加35mgPGA/L啤酒,静置5min后,泡持值可从294s平均增加到402s,即泡持值提高了36.7%。经过60d贮藏后,测得其泡持值为390s。     

HORACE BROWN MEMORIAL LECTURE THE ROLE OF NITROGEN IN BREWING

The development of chromatographic methods of analysis in the 1940's and 1950's allowed detailed investigations to be made into the role of nitrogenous compounds in malting and brewing. The development of individual amino acids during malting, their extraction in the brewhouse and assimilation by culture yeasts during fermentation are reviewed as are their effect on the quality of the final beer.     

纯生啤酒的泡沫稳定性及原因分析

利用中国国标测定方法,分析比较市场上销售的普通熟啤酒和纯生啤酒的泡沫稳定性,跟踪其在3个月货架期的泡沫稳定性的变化。结果表明,在3个月的货架期内,熟啤酒泡沫稳定性变化不大,纯生啤酒的泡沫稳定性随时间逐渐下降;贮藏条件对泡沫稳定性有影响,贮藏温度越高,纯生啤酒泡沫稳定性下降越快;对全国啤酒市场上的不同品牌的纯生啤酒进行了泡沫稳定性的跟踪检测,表明泡沫稳定性差是纯生啤酒的共同问题;蛋白酶A是导致纯生啤酒泡沫稳定性问题的关键因素。     

啤酒冷混浊蛋白的分析及硅胶、PVPP吸附效果比较

利用SDS—PAGE电泳对3种不同品牌的啤酒中的冷混浊蛋白进行分析,结果表明,引起啤酒冷混浊的蛋白分为醇溶性蛋白和水溶性蛋白。其中醇溶性冷混浊蛋白占总含量的70％左右,分子量在43～50kDa之间。水溶性冷混浊蛋白的分子量在8～14kDa之间。另外,比较硅胶、PVPP的吸附效果,经二者处理后的样品浊度都有明显的下降,但经硅胶处理后的样品浊度更低一些。比较硅胶吸附前后样品的泡持时间没有很大的变化,而经PVPP处理后的样品泡持时间有一定的改变。因此,在啤酒生产过程中添加硅胶,能够有效地除去啤酒冷混浊蛋白,而且不会影响啤酒的泡持性。     

啤酒中异-α酸和蛋白质含量对啤酒泡持性的影响

研究以11°P不同品牌的啤酒为研究对象,分别利用国标法、反相高效液相色谱法(RP-HPLC法)、二喹啉甲酸法(BCA法)和十二烷基磺酸钠-聚丙烯酰胺凝胶电泳技术(SDS-PAGE技术)检测了啤酒泡持性、异-α酸含量、泡沫蛋白质的浓度及蛋白质Z与脂转移蛋白(LTP)含量.结果显示,异-α酸中的异合葎草酮及总蛋白质含量与泡持性关系较密切,但是单一蛋白质Z或LTP含量与泡持性不太密切.     

蛋白酶A对纯生啤酒泡持性的影响研究

该文研究蛋白酶A活力对纯生啤酒泡持性的影响,同时建立初始成品纯生啤酒及过滤前发酵液蛋白酶A活力限量值。结果表明,随着贮存时间的延长,纯生啤酒蛋白酶A活力和泡持值均呈下降趋势,最终残留蛋白酶A活力是影响其货架期泡持值的主要因素。纯生啤酒泡持值与蛋白酶A活力呈显著负相关（P＜0.01）。为了保证成品纯生啤酒在货架期内泡沫稳定性,发酵液出罐滤酒前的蛋白酶A活力应＜24×10-5 U/mL,相应成品纯生啤酒初始蛋白酶A活力应＜15×10-5 U/mL。该内控标准能为纯生啤酒生产企业控制泡持性提供指导。     

纯生啤酒泡沫稳定性的研究

纯生啤酒的泡持随着货架时间的延长会逐渐衰减 ,严重影响啤酒的外观质量。大量的文献资料证实 ,纯生啤酒泡持性的下降是由酒液中存在的蛋白酶A造成的。通过对成品酒泡持性的跟踪测定 ,重点讨论了发酵及啤酒过滤过程控制对泡持衰减趋势的影响。     

蛋白酶抑制剂对纯生啤酒泡沫稳定性的影响

在纯生啤酒中加入灵芝真菌蛋白酶A抑制剂，可明显提高纯生啤酒的泡沫稳定性，对其感官指标、理化指标等都不会产生影响。（孙悟）     

啤酒中泡沫活性Z4蛋白质提取参数及与泡持性的关系研究

啤酒泡沫是消费者在接受啤酒时首先考虑的因素之一,也是啤酒的一项重要的感观指标.泡沫活性蛋白质是啤酒泡沫中最重要的组成部分,其中Z4蛋白质约占啤酒泡沫蛋白质Z的70%.主要研究了Z4蛋白质的提取条件,确定了Z4蛋白质的提取参数,为研究泡沫活性Z4蛋白质提供了理论依据.同时,还对泡持性与Z4蛋白质的关系进行了探讨.     

啤酒高分子蛋白检测方法的评估及应用

通过对考马斯亮蓝法检测啤酒高分子蛋白含量的操作方法进行优化,提升其方法的重复性和稳定性,优化后该方法的重复性和稳定性相对标准偏差(RSD)分别为3.68%和3.92%。同时,对该方法检测的高分子蛋白含量与啤酒泡持性进行了相关性分析。结果表明,巴氏杀菌啤酒泡持值与高分子蛋白含量的Pearson相关系数为0.923(P＜0.01);纯生啤酒在贮存3 d、1个月、2个月和4个月的泡持值和其高分子蛋白含量的Pearson相关系数分别为0.700(P＜0.01)、0.739(P＜0.01)、0.899(P＜0.01)和0.883(P＜0.01)。表明该方法不仅能用于啤酒高分子蛋白含量的检测,还能用于巴氏杀菌啤酒和纯生啤酒泡持性的监控。     

RAPID METHODS FOR DETERMINING THE HIGH MOLECULAR WEIGHT POLYPEPTIDE COMPONENTS OF BEER

Size exclusion chromatography and a coomassie blue dye-binding assay were used to investigate the high molecular weight polypeptide fractions of beer. Size exclusion chromatography using small colums of Sephadex G25, G50 (10 ml) and G75 (20 ml) together with an automated FPLC system enabled the rapid isolation of high molecular weight polypeptide fractions of beer. Size exclusion chromatography using small columns of Sephadex was investigated as a method for the determination of the total high molecular weight polypeptides in beer. The results from the analysis of a series of pilot brewery beers produced under standardised brewing conditions showed that the head retention value of a beer correlated with the content of high molecular weight polypeptide material regardless of the molecular weight fraction assayed. Both methods may be used to monitor the high molecular weight polypeptide content, predict the head retention value of a beer and are sufficiently rapid for routine use in the quality control laboratory.     

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.     

APPLICATIONS OF FAST PROTEIN LIQUID CHROMATOGRAPHY (FPLC) TO THE ANALYSIS OF THE NITROGENOUS CONSTITUENTS OF BEER

The nitrogenous constituents of beer were investigated by several Fast Protein Liquid Chromatography (FPLC) techniques. Size exclusion chromatography of dialysed beer material using columns of Superose 6 and Superose 12 suggested that beer polypeptide material was distributed across a wide relative molecular mass (Mr) range with discrete fractions of high Mr (Mr 300 000, Mr 500 000), Mr c60 000, Mr c40 000 and relatively low Mr (Mr 5 000–20 000). The composition of fractions Mr >40 000 and Mr 40 000–60 000 was investigated by ion exchange chromatography. Differences were detected in the elution profiles of fractions prepared from beers brewed from grists comprising 100% malt, 80% malt plus 20% torrfied wheat and 100% malted wheat consistent with differences in the polypeptide composition of these fractions. The Superose 12 column, although designed for the fractionation of high molecular weight components, also provided a method of fractionating low molecular weight nitrogenous materials directly from beer (for example fractions containing purine nucleosides). Reverse phase chromatography was employed in the analysis of beer peptides and demonstrated the complex composition of beer peptide fractions.