β-葡聚糖和工艺条件对啤酒膜过滤效能的影响

本试验采用0．45μm膜进行过滤试验，研究了β-葡聚糖、剪切力、pH、酒精含量和储藏时间对过滤性能的影响。结果表明，β-葡聚糖的存在会降低啤酒过滤性。通过膜过滤器的最大啤酒过滤能量Vmax和初始过滤速度Qinit随着大分子量β-葡聚糖浓度的增加而降低。剪切啤酒(0—10℃)的Vmax和Qinit较低。pH值较高时可以改善啤酒的过滤能力。和无醇啤酒相比，酒精含量在5％和10％(v/v)的啤酒呈现出较低的Qinit和较高的Vmax值。然而，和不含β-葡聚糖的啤酒样品相比，在含有β-葡聚糖的啤酒中添加5％和10％的酒精会降低相对Vmax。结果还表明在4℃冷储藏两周不会影响β-葡聚糖处理过的啤酒的过滤性。     

β-葡聚糖在糖化过程中的分解

适量的β-葡聚糖是构成啤酒酒体和泡沫性能的主要成分,β-葡聚糖含量过高,导致麦汁和啤酒过滤困难。对于质量较差的麦芽,可通过添加β-葡聚糖复合酶来改善麦汁质量。     

啤酒边滤与稳定性的关系

啤酒稳定性和过滤密切有关,过滤是一种分离过程,通过过滤,将啤酒中存在的酵母细胞和其它混浊物分离出去,提高啤酒的感官质量。1 影响啤酒过滤降低过滤速度的因素1)发酵液黏度大,β-葡聚糖含量高;2)原料质量较差,糖化不完全,存在淀粉质多糖和糊精;3)酵母沉降不好,细胞数偏高;4)冷凝固物分离不全及硅藻土的粗细土添加比例不当;5)硅胶添加不当;     

β-葡聚糖酶在啤酒生产中的应用研究

针对大麦胚乳细胞中的β-葡聚糖残留会影响啤酒的质量,进行了在糖化阶段添加β-葡聚糖酶的试验,通过头号麦汁过滤情况比较、麦汁组分的分析、发酵液相关指标对比分析、发酵液过滤情况的分析和成品啤酒保质期试验,结果表明:β-葡聚糖酶对β-葡聚糖的降解效果是非常理想和显著的,可增加啤酒产量,改善啤酒质量.     

高效β-葡聚糖酶对麦汁过滤速度的影响

对添加高效β-葡聚糖酶对麦汁过滤速度的影响进行了研究。结果表明,添加β-葡聚糖酶可提高过滤速度2～3倍;添加木聚糖酶对过滤速度也有提高;β-葡聚糖酶的最适用量为110g,木聚糖酶用量为20g,两种酶复合应用效果较好;添加酶制剂对啤酒的外观及口味无不良影响,不会影响啤酒的风味;添加β-葡聚糖酶可缩短麦汁生产时间,提高生产效率。（孙悟）     

β-葡聚糖对啤酒酿造过程的影响及控制

在啤酒酿造过程中，由于使用麦芽的不同，β-葡聚糖含量也有差别。如果糖化过程有大量的阻葡聚糖释放，将导致醪液黏度上升，麦汁或啤酒过滤速度缓慢，降低生产效率。β-葡聚糖含量过高的啤酒也影响其非生物稳定性，啤酒易发生浑浊。笔者就生产过程影响β-葡聚糖的因素进行较系统的概述。     

β-葡聚糖酶的应用及研究现状

β-葡聚糖酶的应用在啤酒工业中的应用 目前,β-葡聚糖酶广泛应用于啤酒发酵工业.美国、日本、丹麦、德国、澳大利亚、加拿大等国均已采用β-葡聚糖酶作为啤酒工业的主要酶制剂;我国每年生产啤酒约2200多万吨,其消费量呈上升趋势,但在该酶制剂的研制和应用方面起步较晚.在啤酒的酿造过程中,大麦胚乳细胞中β-葡聚糖不能充分降解,β-葡聚糖的残留是造成啤酒酒体混浊、泡沫持久力减少和挂杯力不强的主要原因之一.β-葡聚糖酶(E.C.3.2.1.73)可以专一分解粘度很高的各种大麦β-葡聚糖,能够疏松大麦胚乳细胞壁,促进细胞内容物的外溢,提高原料利用率,使麦芽汁粘度降低,大大缩短麦芽汁和啤酒的过滤时间,增加啤酒产量,改善啤酒的质量.     

β-葡聚糖酶及其在啤酒生产中的应用

应用在啤酒糖化中的β-葡聚糖酶有改善过滤性能、提高麦汁收得率及降低粮耗等作用。本文对大麦中β-葡聚糖酶在制麦芽和糖化过程中的变化、外源添加微生物β-葡聚糖酶的研究进展及目前国内啤酒酿造用β-葡聚糖酶产品进行了简要的介绍。     

酵母β-葡聚糖与肌球蛋白互作及对蛋白质风味吸附特性的影响

研究酵母β-葡聚糖与鲅鱼肌球蛋白的相互作用,及其对蛋白质风味吸附能力的影响。采用Zeta电位分析、荧光、紫外、拉曼光谱及气质谱联用技术,研究不同酵母β-葡聚糖添加量对肌球蛋白结构及风味结合能力的影响。结果表明,随着酵母β-葡聚糖添加量的增加,肌球蛋白的溶解度、Zeta电位绝对值、表面疏水性和活性巯基含量均呈先升高后降低的趋势,内源荧光强度逐渐下降,紫外吸收峰强度逐渐增强。酵母β-葡聚糖添加量在0~2%时,α-螺旋含量显著降低(P < 0.05),而β-折叠含量显著增加(P < 0.05);当添加量大于2%时,α-螺旋含量又逐渐升高,β-折叠含量逐渐降低。添加酵母β-葡聚糖促使肌球蛋白结构展开,增强了蛋白质与所选风味物质的结合能力,而当其添加量超过2%,结合能力增加不显著。     

影响啤酒过滤速度的因素及改进措施

本文分析了啤酒过滤过程中影响啤酒过滤速度的因素,并提出了解决措施。过滤工序是一个纯物理过程,它是控制啤酒清亮度的关键点之一。过滤后的啤酒,不仅浊度有所降低,而且胶体及风味稳定性都有很大提高。就此我们对影响啤酒过滤速度的因素进行分析,并提出解决措施。1 引起啤酒过滤困难的原因分析滤酒困难的原因主要有下列几个方面:1)发酵液黏度大,β-葡聚糖含量高;2)原料质量较差,不均一或操作不细,造成糖     

β-GLUCANASE: THE SUCCESSFUL APPLICATION OF GENETIC ENGINEERING

The now well established principles of genetic engineering are described in relation to the solution of problems associated with β-glucans in beer. The application of these techniques has enabled the isolation of a Bacillus subtilis endo-1, 3–1, 4-β-D-glucanase gene which expresses a biologically active enzyme in yeast.^15,16 Although this enzyme is capable of hydrolysing beer β-glucans during fermentation, thereby enhancing beer filtration, insufficient β-glucanase is produced in yeast to enable successful commercial implementation. The requirements for the efficient production of β-glucanase in genetically manipulated brewing yeast are described.     

酵母自溶的成因及其对啤酒质量的影响

酵母自溶由酵母胞内蛋白分解酶外泄引起，影响酵母自溶的因素有：(1)酵母菌种；(2)麦汁营养成分组成不合理；(3)酵母使用代数过高；(4)酵母添加量过多；(5)温度、压力、pH值等发酵工艺条件控制不当；(6)酵母回收时间、方法、压力、酵母贮存条件；(7)微生物污染。酵母自溶会影响啤酒风味稳定性，使啤酒苦味、涩味加重；啤酒双乙酰含量增加；啤酒的泡持性下降；啤酒总酸偏高；啤酒pH值升高；增加啤酒过滤成本。防止酵母自溶的方法有：(1)选择优良强壮的出发菌株；(2)控制酵母添加量和使用代数；(3)制备营养丰富、组成合理的麦汁；(4)严格发酵工艺奈件；(5)加强酵母质量管理；(6)加强卫生管理，保证纯种发酵。     

山药啤酒的研制

以山药、麦芽为原料,酶法糖化制汁,接种啤酒酵母发酵研制了山药啤酒。将新鲜山药制备成山药粉,与麦芽在复合酶的作用下糖化制汁。采用正交试验设计研究复合酶的添加量、添加阶段、作用时间、山药粉添加量对山药、麦芽mix中还原糖量、α-氨基氮含量的影响。结果表明,酶法制备山药、麦芽混合汁的最佳工艺条件为酶的添加量0.36%,添加阶段45℃,作用时间17min,山药粉添加量35%。于此工艺下制备的山药、麦芽混合汁经酵母菌代谢后,高级醇含量为55.8mg/L,双乙酰0.06mg/L,酒精度3.91%(W/W),真正发酵度66.4%。酿制的啤酒不仅具有大麦芽啤酒的风味,并且还富含了山药中多种氨基酸和抗癌物质,不失为一种较好的功能性饮品。     

压力对啤酒发酵的影响

啤酒发酵过程中,随着压力的升高,发酵速度、耗糖率、乙醇生成量、双乙酰的生成和还原速率有所下降;风味物质中的醇类、脂类下降,而乙醛含量却上升。压力还使酵母细胞形态产生了变化。     

COLD STERILE FILTRATION: A SMALL SCALE FILTRATION TEST AND INVESTIGATION OF MEMBRANE PLUGGING

Beer brewed from 24 commercially and bag malted samples by a small scale brewing method was assessed by a micro-filtration efficiency (MFE) test designed to emulate the cold-sterile (membrane or micro-) filtration process. The level of malt derived beer components with the potential to reduce MFE, such as β-glucan, arabinoxylan, protein and polyphenol, were consistent over duplicate beer batches suggesting that beer quality was reproducible using the small scale method. The small scale MFE test was able to differentiate (P<0.001) between beer brewed from distinct malt samples in a reproducible fashion, suggesting that the test is effective in assessing beer MFE in the laboratory. Subsequently, the effects of various malt derived beer components on micro-filtration were investigated. MFE (measured as <i>V_max) was negatively correlated with beer arabinoxylan content (r=–0.62, P<0.01), suggesting that the arabinoxylan content of malt, and subsequently beer, may influence MFE. Total beer β-glucan was not significantly related to beer MFE (r=-0.36). However, it was likely that β-glucan molecules of high molecular weight influenced MFE more so than the total β-glucan content. Beer viscosity, which was correlated to both beer β-glucan and arabinoxylan content (r=0.86, P<0.001 and r=0.68, P<0.05, respectively), correlated with V_max (r=-0.81, P<0.001) .     

菱角啤酒发酵条件的研究

以菱角汁和麦芽汁为原料,接种啤酒酵母,研究了菱角啤酒的发酵条件。在发酵过程中定时取样,测定了酒精度和还原糖的变化,并进行感官评价。试验结果表明：最佳发酵条件为酵母菌接种量0.5%、菱角汁添加量20%、主发酵时间6d、后酵时间13d。在此条件下,酿制的啤酒酒精度为3.52%vol,还原糖含量为1.63g/100mL,口感清爽,风味俱佳,适合大众化口味。     

压力对啤酒酵母生长及某些发酵性能的影响

以气体为加压介质,研究了不同压力下酵母细胞生长及压力对酵母发酵性能的影响.高压对酵母细胞的生长代谢有明显的影响:压力使酵母细胞的比生长速率和生物量降低,细胞的倍增时间延长;电子显微镜显示,压力使酵母菌细胞的形态发生明显的改变;压力也导致酵母的发酵速度、耗糖率、乙醇生成量、双乙酰的生成和还原速率下降.     

固定化酵母啤酒连续后发酵工艺

将主发酵进行完毕后的嫩啤酒先离心除去酵母,再经加热处理,冷却后通入装有木片作为固定化酵母载体的固定床反应罐进行连续后酵。通过试验确定工艺条件,并将连续后酵与传统后酵工艺生产的啤酒进行对比。试验结果表明,室温下,固定化16 h为宜,热处理温度为80℃,时间为10 min;设定后发酵温度为10℃,滞留时间为3.1 h,双乙酰还原速度大为提高,缩短了酒龄;经过风味测定和感官品评得出,采用连续后发酵工艺生产的啤酒,品质上无明显缺陷。     

THE CONCENTRATION AND SIGNIFICANCE OF PYRUVATE IN BEER

Excretion of pyruvate takes place during the yeast-growth phase of fermentation, and, in batch fermentation, the extent of its accumulation varies directly with the extent of growth. Pyruvate excretion is not related to the content of pyruvate decarboxylase in the cells and is not influenced by the addition of thiamine or alanine to the wort; the pH of the wort exerts a slight influence on pyruvate excretion. Pyruvate may be metabolized by yeast towards the end of fermentation and during conditioning, so that the quantity present in beer is influenced by the extent and timing of yeast separation. The addition of sodium pyruvate to beer alters beer flavour by affecting the ‘mouth feel’ aspect of flavour; the minimum quantity required to do this varies in different beers over a range of 50–400 mg/litre.     

The impact of sulphur dioxide and oxygen on the behaviour of 2-furaldehyde in beer: an industrial approach

2‐Furaldehyde is often used as an analytical indicator of beer flavour deterioration. Although 2‐furaldehyde itself has a flavour threshold far above levels generally present in beer, it can be used as a good marker of heat damage of beer. A reversed‐phase liquid chromatographic assay, using ultraviolet‐visible detection, was applied to investigate the behaviour of 2‐furaldehyde throughout the brewing process and during extended storage of beer. The impact of storage temperature, sulphur dioxide and oxygen content on the level of 2‐furaldehyde was studied. It was found that the concentration of 2‐furaldehyde markedly increases during wort boiling and is rapidly reduced by yeast during the first hours of fermentation, emphasising the yeast reducing capacity as a determinant factor for the 2‐furaldehyde content found in the final beer. The results obtained suggest that sulphur dioxide and oxygen content play a key role on the 2‐furaldehyde content in packaged beer. 2‐Furaldehyde increase during ageing is oxygen dependent and sulphur dioxide retards its development by possibly protecting beer against the occurrence of oxidative reactions.