酿造工艺对啤酒中有机酸的影响

有机酸是啤酒中重要的风味物质,其组成与含量同酿造工艺有着密切的关系.采用离子色谱法探索了不同酵母菌种、酵母接种景、发酵温度、麦汁pH值以及原麦汁浓度5个因素对啤酒中有机酸的影响.结果表明,酵母菌种、酵母接种量以及原麦汁浓度是有机酸组成和含量的主要影响因素;啤酒最终的pH值和总酸受原麦汁浓度的影响显著,且呈正相关性.     

不同配比麦芽的麦汁中有机酸含量差异及酿造过程中变化规律的研究

研究试用300L啤酒中试设备,添加不同比例焦香麦芽制备麦汁并发酵,采用抑制型离子色谱法对麦汁及啤酒酿造过程中的有机酸含量进行检测。其结论是麦汁中的有机酸含量随焦香麦芽添加量的增多而增加,发酵过程中有机酸含量呈规律变化。     

小麦啤酒有机酸组成的优化研究

分别考察了酵母种类和小麦芽品种对成品小麦啤酒有机酸组成的影响。基于德国品牌小麦啤酒的有机酸组成,确定了小麦啤酒主要有机酸的较佳组成范围,并且通过L9(33)正交实验设计,最终确定了较佳的发酵工艺参数:麦汁pH5.5;接种量为1.0×107个/mL;主酵温度10℃。研究表明,选择产酸合理的酵母菌株和优良的小麦芽以及使用较佳发酵工艺,可以有效地降低乙酸、琥珀酸含量和增加柠檬酸含量,进而优化小麦啤酒的有机酸组成,这对改善小麦啤酒的酸感和风味都有很大的指导意义。      

啤酒中有机酸及其对啤酒风味的影响

啤酒中有机酸即羧酸类物质，主要来源于酿造原料、麦芽生产、糖化麦汁制备及啤酒酿造过程中。啤酒中的有机酸是构成酵母细胞组织的重要物质，有利于酶作用，是组成啤酒风味物质成分之一。但是，若啤酒中的脂肪酸含量过多则会对啤酒风味稳定性不利，有机酸在啤酒中的含量、比例都将使啤酒风味产生重大影响。应控制好啤酒中的有机酸含量使之达到“酸而不露”。方法：①控制原料质量；②调节糖化用水；③调pH值，宜用乳酸、磷酸两种混合酸；④麦汁过滤一定要清亮；⑤严格控制好每道工序的工艺卫生；⑥选用优良的酵母菌种，并加强酵母管理。（丹妮）     

浅谈麦汁糖类组成对啤酒发酵度的影响

本文从酵母吸收糖类顺序的生理特性，阐述增加麦汁中葡萄糖等单糖含量对提高发酵度的重要性；并从10°P干啤酒中麦汁糖类组成的分析情况进一步说明其副发酵度的影响。我们通过添加淀粉酶及调整糖化工艺，提高了麦汁中可发酵性糖含量，改变了麦汁中葡萄糖、麦芽糖、麦芽三糖的比例，使三者比例约为65：23：12，而普通啤酒一般为10～15：67～72：18～22，显然增加了葡萄糖含量。并从发酵中证实麦汁糖类组成对提高发酵度是关键要素，使用普通酵母也能生产高发酵度的干啤酒。     

酯——啤酒酿造中最重要的风味活性物质

酯类物质是啤酒风味物质体系中的重要组成部分。它们能够对啤酒质量和稳定性产生积极或消极的影响。麦汁浓度、澄清度和糖组成对酯类的形成具有一定程度的影响。在高浓度麦汁中，高麦芽糖含量比高葡萄糖含量更能够使酯类物质的含量显著降低。在相似的发酵条件下，不同的酵母菌株产生不同的酯含量。     

控制发酵过程提高发酵质量

啤酒发酵过程正常与否,将直接影响啤酒风味物质含量和组成,最终影响啤酒质量。所以发酵过程控制历来是酿造的重中之重。 1麦汁组分控制 合适的麦汁组成是保证酵母正常发酵的基础。应有效控制原料质量和糖化效果,每批次麦汁组成应均匀。     

酵母发酵副产物与啤酒风味

啤酒生产中的副产物有高级醇、有机酸、联二酮、酯类、醛类等物质 ,其含量受酵母菌种、麦汁成分、工艺条件等因素的影响。高级醇赋予啤酒醇厚感、泡沫细腻 ,使啤酒丰满 ,但含量太高会破坏啤酒酒体及风味 ;在啤酒中有机酸含量为5.0×10-4～1.5×10-3。双乙酰在啤酒中含量高 ,阈值低 ,对啤酒风味影响很大。酯是啤酒香气的主要载体。乙醛是啤酒中含量最高的醛类 ,硫化物主要代表物是硫化氢和二甲基硫 ,对啤酒风味影响很大。(孙悟)     

果啤与啤酒组分差异比较研究

采用气相色谱和高效液相色谱的分析方法,分析了市售同一品牌菠萝果啤、啤酒的风味成分、有机酸、糖的组成及含量,结果表明,果啤中酯含量类物质的种类相对普通啤酒丰富,组成协调,高级醇含量低。有机酸含量果啤高于啤酒,柠檬酸积累较多。果啤中蔗糖消耗大,而果糖和葡萄糖含量有所升高。     

用实验室最终发酵度定性判断麦汁组份的合理性及其意义

麦汁组份合理是广大酿造工作者追求的目标。合理的麦汁组成会使发酵过程有一个令人满意的结果,在绝大多数啤酒厂家,通常是沿用长期以来的实验手段,即通过非糖比非糖、氨基酸含量这两项指标来判断麦汁组份的合理性,尽管如此,还常常出现发酵异常,如双乙酰还原不好、     

100%大麦啤酒酿造过程中老化Strecker醛的研究

分别采用上面发酵工艺与下面发酵工艺进行100%大麦啤酒及100%麦芽啤酒的酿制,并对其麦汁的氨基酸含量、老化Strecker醛、自由基以及新鲜啤酒中老化Strecker醛的含量等进行了对比分析。研究发现,就麦汁而言,100%大麦麦汁中老化Strecker醛的含量都明显低于100%麦芽麦汁;同样的麦汁,上面发酵方式还原Strecker醛的能力明显优于下面发酵方式。就啤酒而言,经酵母还原后,新鲜啤酒中的老化Strecker醛含量较麦汁含量低,且100%大麦啤酒中老化Strecker醛的含量低于100%麦芽啤酒中的含量。100%麦芽麦汁的自由基含量是100%大麦麦汁的近3倍。这都预示着100%大麦啤酒的风味稳定性（新鲜度）明显好于100%麦芽啤酒。     

Application of Plackett–Burman experimental design for investigating the effect of wort amino acids on flavour‐active compounds production during lager yeast fermentation

Aroma‐active higher alcohols and esters are produced intracellularly in the cytosol by fermenting lager yeast cells, which are of major industrial interest because they determine aroma and taste characteristics of the fermented beer. Wort amino acid composition and their utilization by yeast during brewer's wort fermentation influence both the yeast fermentation performance and the flavour profile of the finished product. To better understand the relationship between the yeast cell and wort amino acid composition, Plackett–Burman screening design was applied to measure the changes in nitrogen composition associated with yeast amino acids uptake and flavour formation during fermentation. Here, using an industrial lager brewing strain of Saccharomyces pastorianus , we investigated the effect of amino acid composition on the accumulation of higher alcohols and volatile esters. The objective of this study was to identify the significant amino acids involved in the flavour production during beer fermentation. Our results showed that even though different flavour substances were produced with different amino acid composition in the fermentation experiments, the discrepancies were not related to the total amount of amino acids in the synthetic medium. The most significant effect on higher alcohol production was exercised by the content of glutamic acid, aromatic amino acids and branch chain amino acids. Leucine, valine, glutamic acid, phenylalanine, serine and lysine were identified as important determinants for the formation of esters. The future applications of this information could drastically improve the current regime of selecting malt and adjunct or their formula with desired amino acids in wort. Copyright © 2017 The Institute of Brewing & Distilling     

以未发芽大麦替代麦芽酿造啤酒及其麦香改善研究

本文研究了利用酶制剂Ondea Pro进行大麦啤酒的生产,对其麦汁糖谱、氨基酸谱、蛋白质区分、α-氨基氮和大麦啤酒理化成分及风味物质等指标进行了检测,特别是对麦香物质呋喃酮、2-乙酰吡咯、2-乙酰-1-吡咯啉、麦芽酚、2-甲基吡嗪、乙基吡嗪、乙酰呋喃和甲基糠醛等化合物进行了分析,并邀请专业品酒委员进行了感官品评。研究结果发现,利用Ondea Pro酶生产的麦汁,能够满足酵母发酵需求,然而大麦啤酒存在明显的麦香缺陷。通过额外添加不同比例的焦香麦芽,分析大麦啤酒中主要麦香物质的变化规律,结合感官品评,结果表明添加1%的焦香麦芽酿造而成的大麦啤酒,其主要麦香物质和品评口感与麦芽啤酒接近。添加少量焦香麦芽生产的大麦啤酒市场潜力具大,极具推广价值。      

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。     

啤酒高浓酿造中氨基酸对酵母发酵性能和啤酒色值的影响

探讨在24?°P高浓啤酒发酵过程中8?种氨基酸（Met、Phe、Trp、Arg、His、Ile、Leu、Lys）的不同添加量（分别为原麦汁中相应氨基酸含量的0.5、1?倍和2?倍）对酵母生理特性、发酵性能和啤酒色值的影响。结果表明：8?种氨基酸的补充可显著提高麦汁发酵度、乙醇产量,促进酵母生长,提高酵母活细胞率,改善啤酒色值。其中,补充1?倍氨基酸的高浓麦汁发酵性能较好,与对照组相比,发酵度、乙醇产量、最大悬浮酵母细胞数和发酵结束时的酵母活细胞率分别提高了6%、17%、11%和10%。添加氨基酸的高浓酿造啤酒经稀释后,啤酒色泽依然鲜亮,且添加1?倍氨基酸酿造而成的啤酒经稀释后色差（ΔE）最小,色泽最接近青岛纯生啤酒。     

利用代谢组学方法分析不同糖化条件对酿酒酵母代谢途径以及啤酒中风味物质形成的分析

在啤酒发酵过程中，麦汁的好坏会直接影响啤酒的品质。为了探究不同的糖化工艺对发酵后酒品质的影响，运用代谢组学的方法，分析了不同糖化条件对麦汁成分造成的差异，从代谢水平上解释了啤酒发酵过程中不同糖化工艺产生的麦汁对酿酒酵母代谢途径的影响。通过对质谱检测后所得的数据经过进行主成分分析和偏最小二乘判别分析，确定了不同糖化工艺产生的麦汁会影响酿酒酵母的氨基酸代谢、有机酸代谢以及脂质和脂肪酸代谢等代谢途径；主要涉及精氨酸的生物合成，苯丙氨酸、酪氨酸和色氨酸生物合成，缬氨酸、亮氨酸和异亮氨酸生物合成，甘氨酸、丝氨酸和苏氨酸代谢，D-氨基酸的代谢，赖氨酸降解，以及脂肪酸生物合成等途径，这些途径对啤酒风味有较大影响，研究结果为啤酒中风味物质的调控提供了一定的理论指导。     

The Gel Filtration Chromatographic‐Profiles of Proteins and Peptides of Wort and Beer: Effects of Processing — Malting,Mashing, Kettle Boiling,Fermentation and Filtering

Barley and malt proteins, of infusion (IoB) and decoction (EBC) mashing worts as well as commercial wort and beer, obtained from the Castlemaine Perkins brewery, Brisbane, were gel filtered, with or without further treatments. A general, similar pattern of protein and peptide profiles emerged from barley malt and beer. This confirmed the widely assumed fact that beer proteins descend from barley, some transformed and others perhaps mostly unchanged by processing. In the gel‐filtrate profiles, a maximum of 8 or 9 fractions were discerned. These fractions were collected and quantified for protein contents and amino acid compositions. The first four fractions contained the proteins and polypeptides of molecular weight higher than 14,000. Consequently, the remaining fractions contain the smaller peptides (<14,000), that were completely removed by dialysis. The effects of processing on proteins and peptides varied contingent upon the type of processing step considered and the pre‐chromatographic treatment. Malting was the most effective process remarkably increasing the soluble protein contents, especially the smaller peptide fractions and the colour development. This is the first report, as far as we are aware of, on the gel filtration profiles of wort and beer low molecular weight peptides including those of barley wort. The importance of the smaller peptides in foam formation and retention cannot be overemphasised. The amino acid composition of the fractions revealed much more diversity than was observed in the comparison of the profiles. Proline content of fraction 1 resembled that of barley soluble proteins while fractions F2, F3 and F4 that of glutelin and only fraction 8 that of hordein. The latter, suggests that hordeins or, at least the peptide products rich in proline, are likely to be completely digested to amino acids, during malting.     

酿造水中的锌离子对啤酒酿造的影响

啤酒中的锌离子来源于麦芽、大米、酿造用水、酒花。实验表明在啤酒酿造过程中,锌离子可激活酶的活性、提高酶的催化作用,促进糖化、发酵;提高麦汁中糖、氨基酸的含量;促进双乙酰的还原,降低双乙酰的含量;激活乙醇脱氢酶,降低乙醛,提高酵母活力,降低酵母死亡率;提高发酵度,缩短发酵时间。     

Impact of Dark Specialty Malts on Extract Composition and Wort Fermentation

Dark specialty malts are important ingredients for the production of several beer styles. These malts not only impart colour, flavour and antioxidative activity to wort and beer, they also affect the course of wort fermentations and the production of flavour‐active yeast metabolites. The application of considerable levels of dark malt was found to lower the attenuation, mainly as a result of lower levels of fermentable sugars and amino acids in dark wort samples. In fact, from the darkest caramel malts and from roasted malts, practically no fermentable material can be hydrolysed by pilsner malt enzymes during mashing. Compared to wort brewed with 50% pilsner malt and 50% dark caramel malt or roasted malt, wort brewed with 100% pilsner malt contained nearly twice as much fermentable sugars and amino acids. Reduced levels of yeast nutrients also lowered the fermentation rate, ranging from 1.7°P/day for the reference pilsner wort of 9 EBC to 1.1°P/day for the darkest wort (890 EBC units), brewed with 50% roasted malt. This additionally indicates that lower attenuation values for dark wort are partially due to the inhibitory effects of Maillard compounds on yeast metabolism. The application of dark caramel or roasted malts further led to elevated levels of the vicinal diketones diacetyl and 2,3‐pentanedione. Only large levels of roasted malt gave rise to two significant diacetyl peaks during fermentation. The level of ethyl acetate in beer was inversely related to colour, whereas the level of isoamyl acetate appeared to be affected by the use of roasted malt. With large levels of this malt type, negligible isoamyl acetate was generated during fermentation.