啤酒老熟助剂—α-乙酰乳酸脱羧酶

<正> 传统的啤酒发酵工艺有下面发酵和上面发酵两大类型。目前,国内外大多数啤酒生产厂家都采用下面发酵工艺。传统的下面发酵啤酒的发酵过程通常可分为主发酵和后发酵(包括贮藏)两个阶段:     

科技园地

啤酒是一种营养丰富的低酒精度饮料.城乡消费者对啤酒的需要量越来越大.而传统的发酵工艺,生产周期比较长,产量低,不大量增加投资和设备,就难以满足广大群众的需要.     

前锥后卧二次发酵有关工艺的探讨

一、前言随着科学技术的发展,先进设备的引进,啤酒技术也日趋先进与完善,一些啤酒厂家先后废除了一些旧设备、旧工艺,比如,前酵工艺及前酵池的废除后,后发酵工艺也随之变化,大多数厂家采用了锥形罐的一次发酵工艺,即是将啤酒发酵的主发酵、后发酵、贮酒,这三个阶段全过程,在同一锥罐中完成,具有投资省、单位占地面积小、啤酒产量大、啤酒成熟快、发酵周期短便于自动化控制等优点,对于我厂来说,新扩建的18个容量为1032立方米的大卧罐不能被废掉,所以我厂技术人员根据本厂的资金情况,在原有卧罐的基础上,摸索出一条符合我厂情况的新工艺——前…     

生产10°BX超干啤酒

生产10~oBX 超干啤酒的关键是要使啤酒达到一定的发酵度(≥72%),同时又要啤酒口味纯正,清淡爽口,无杂味。一、提高啤酒的发酵度,在工艺上可采用:(1)提高麦汁可发酵糖含量。(2)采用高发酵度的酵母菌种。我们采用低温糖化工艺62—63℃,调整糖化醪的 PH 值使其适合β-淀粉酶的作     

微机控制系统在啤酒发酵过程中的应用

一、概述ＹＤＨ－Ｉ型啤酒发酵集散式微机控制系统是为啤酒发酵工艺过程自动化设计的,主要是完成根据啤酒发酵工艺要求的温度自动控制、压力自动控制、液位显示等控制过程使其达到最佳稳定状态。二、自动控制方案的确定１啤酒发酵的工艺要求在啤酒生产过程中啤酒发酵是...     

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。     

高浓发酵后稀释啤酒质量的改善

近年来,高浓发酵后稀释工艺被越来越多的啤酒厂所采用,市场涌现出大量低浓度啤酒.高浓发酵后稀释工艺与常规酿造相比,具有可在不增加糖化、发酵设备的基础上大幅度提高啤酒产量的优势.但高浓发酵后稀释工艺也存在明显缺陷,如稀释后的低浓度啤酒泡持性较差、口味较淡、风味不协调等.该文分析了上述缺陷的形成原因,并提出了后修饰等改善措施.     

小麦啤酒生产工艺的研究

本文利用现有10万吨啤酒的生产设备,对小麦啤酒的主要工艺条件进行了研究探讨,研究内容包括糖化、菌种培养、混合发酵、上面发酵等主要生产工艺。糖化工艺采用一次煮出糖化法,在糖化过程中采用程序升温进行蛋白质休止,增加一次分醪煮沸对强化蛋白质分解,促进凝固氮的去除非常有利。煮沸时酒花分三次添加,加量约8‰,发酵工艺采用了两种方式,即混合发酵方式(二罐法)与上面发酵方式(一罐法),以上面发酵工艺研究较为详细。发酵采用22～23℃的高温,其发酵速度快,双乙酰还原迅速。此发酵工艺所生产的啤酒新颖独特,风味上较普通大麦啤酒有显著特色。     

金桔香橙风味小麦精酿啤酒的工艺研究

金桔不但具有丰富的营养,还具有很强的保健功能。以小麦艾尔啤酒的酿造工艺为基础,采用添加鲜金桔汁、鲜香橙汁的方式,研究金桔香橙小麦精酿啤酒的发酵工艺。试验结果可知,最佳的糖化工艺是分步糖化工艺,第一步糖化:温度45℃、时间60min;第二步糖化:温度67℃,时间60min。金桔香橙小麦精酿啤酒在发酵过程中,最佳的发酵工艺为:金桔汁的添加量为5%、香橙汁的添加量为10%,主发酵10天后进行二次发酵,二次发酵时间为10天,获得一种具有金桔香橙风味的小麦精酿啤酒。     

口蘑多糖啤酒发酵工艺优化

为开发新款啤酒,以大麦芽和口蘑多糖提取液为原料,酿造口蘑多糖啤酒。以酒精度和感官评分为指标,采用单因素试验考察主发酵温度、口蘑多糖提取液添加量和口蘑多糖提取液加入阶段对口蘑多糖啤酒的影响,在此基础上,采用响应面确定口蘑多糖啤酒发酵的最佳工艺。结果表明最佳酿造工艺条件为主发酵温度16℃、口蘑多糖提取液添加量为4.4 mL、主发酵阶段加入口蘑多糖提取液,在此条件下酿造的口蘑多糖啤酒风味协调,口感醇正。     

固定化酵母笼架生物反应器发酵啤酒的研究

笼架生物反应器放在主发酵池中,用于分批式生产啤酒。反应器由4级组成,每级反应器约填加12kg固定化酵母凝胶球。啤酒主发酵时间从传统工艺的七天缩短为一天半。啤酒发酵周期缩短50％以上,固定化酵母成品啤酒质量达到传统啤酒水平。固定化酵母在生物反应器内的实际使用寿命为二个月。     

BIOLOGICAL AND BIOCHEMICAL ASPECTS OF TOWER FERMENTATION*

Biological and biochemical aspects of continuous fermentation in a Tower fermentor operated on a commercial scale are described with particular reference to the rate of utilization of α-amino nitrogen and carbohydrate. Under stable conditions, well defined gradients exist in the Tower fermentor and a fully fermented beer, indistinguishable from the conventional batch beer, is produced. Breakdown of these gradients leads to unstable conditions with a resultant increase in effluent gravity. Yeast growth in the Tower has been shown to be comparable to that of a conventional batch fermentation. No mutation of the yeast has been observed over a period of 3 years, during which time little trouble was experienced from infecting organisms.     

固定化酵母薯干原料酒精发酵中试研究

本文论述了固定化酵母薯干原料带渣酒精发酵的中试结果。中试生物反应器容积为１０００Ｌ，采用改性海藻酸钙凝胶为固定化酵母细胞的载体。中试研究中设计了较合理的中试工艺流程，优选出较佳的发酵条件，并考察了生物反应器的性能。试验获得了如下结果：中试装置已运转１９２天，固定化酵母仍保持高活力，并可继续运转；发酵成熟醪酒精含量达６．５～８．０％（ｖ），它比同期传统式酒精发酵高出０．３～０．４％；淀粉利用率达９１～９２％；固定化酵母生物反应器的乙醇生产能力为９．５ＫｇＥｔＯＨ／Ｍ￣３·ｈ，它可比传统式发酵罐的生产能力提高１０～１２倍。     

Acid Washing and Serial Repitching a Brewing Ale Strain of Saccharomyces cerevisiae in High Gravity Wort and the Role of Wort Oxygenation Conditions†

Acid washing pitching yeast is an effective method for removing bacterial contamination, but if the yeast is washed incorrectly decreased fermentation performance and beer quality problems may result. Various factors can affect the acid resistance of yeast strains during brewery fermentations. Yeast from shaking flask experiments was more resistant to the combination of high gravity and acid washing conditions than yeast cropped from static fermentations. Yeast harvested from static high gravity wort (20° Plato; 1.083 OG) fermentations was more adversely affected by acid washing than yeast from standard gravity (12° Plato; 1.048 OG) wort. Wort oxygenation resulted in enhanced yeast fermentation performance and healthier yeast crops when yeast was serially repitched into 20° Plato wort. Yeast cropped from fermentations with air saturated high gravity wort responded poorly when acid washed. These results suggest that the structure of the plasma membrane particularly the sterol and fatty acid composition, may have an important role in tolerating high gravity wort and acid washing conditions.     

PRODUCTION OF BEER USING IMMOBILIZED YEAST ENCODING α-ACETOLACTATE DECARBOXYLASE

Genetically modified brewer's yeast encoding α-acetolactate decarboxylase (α-ALDC) was tested in immobilized yeast bioreactors for main fermentation of beer. The α-ALDC enzyme produced by the transformant catalyzes the direct conversion of α-acetolactate to acetoin without formation of diacetyl. The long lagering period required for beer maturation in conventional brewing can thus be shortened or even omitted. Three different packed bed bioreactors were employed, with volumes of 1.6 dm³, 5 dm³ and 25 dm³. The 5 dm³ column had a slightly conical geometry in contrast to the others which had cylindrical shapes. Sintered glass beads were chosen as the carrier material on the basis of experiments with the parent strain. The brewing performance of the transformant compared well with that of the parent strain in the immobilized system. Fermentation, utilization of amino acids (including isoleucine, valine and leucine) and flavour formation were practically identical with both strains, the only difference being a marked decrease in the formation of diacetyl by the transformant. Small differences were, however, observed in the long-term biochemical stability. By using yeast encoding α-ALDC in the immobilized yeast system the total (primary and secondary) fermentation time could be reduced to approximately 2–6 days, compared with 3–6 weeks in a conventional batch process.     

固定化酵母连续发酵生产香蕉酒的研究

本文进行了固定化酵母连续发酵生产香蕉酒的研究。通过试验,找到了较佳的果胶酵法制取香蕉汁的工艺,制得的果汁澄清透明,香味浓郁。进行了固定化酵母分批和连续发酵果酒的试验研究,确定了较佳发酵条件为:16～18℃,稀释速率0.1h~(-1),反应器内固定化凝胶珠充填系数为0.5,所得的香蕉酒口感醇和,风味较好。主发酵周期从游离酵母的7天缩短到固定化连续发酵的半天。进行了发酵动力学的研究,提出了固定化酵母果酒发酵的数学模型,即产酒速率为:     

德国啤酒酵母和国内啤酒酵母发酵性能的研究

酵母菌种是啤酒酿造的关键，不同的菌种可用来酿造不同类型的啤酒。本试验对德国酵母和国内酵母的发酵性能进行了对比研究，总结出了二者之间的差异。     

固定化后期添加啤酒酵母菌降低啤酒中双乙酰含量的探讨

为探索用后期添加固定化酵母菌降低啤酒中双乙酰的工艺,通过单因素和正交试验,发现后期接入固定化啤酒酵母菌降低双乙酰含量的最佳工艺为:发酵温度为12℃,接入时间为发酵第16d,发酵再次接入固定化酵母菌的接种量为1.0%,此时双乙酰的量为0.083mg/L,啤酒口感达到9.2分。固定化的酵母菌可以重复利用3次,啤酒的双乙酰值和口感维持稳定。该研究表明利用固定化细胞的后期添加可以降低啤酒中的双乙酰含量。     

不同固定化酵母载体对啤酒风味成分影响研究

采用气相色谱分析法,主要考察了山毛榉木片、多孔陶瓷和海藻酸钠3种固定化酵母载体对啤酒风味物质成分的影响。结果表明,不同固定化酵母载体对啤酒风味物质成分的形成有较大影响,其中海藻酸钠载体固定化酵母的牢固程度最好,且载体正丙醇、异丁醇和异戊醇含量分别高于成品啤酒9%、8%和12%,啤酒含醇量较高,适于醇厚型啤酒发酵;山毛榉木载体生成的酯类物质较多,载体乙酸异丁酯、乙酸乙酯、乙酸异戊酯和己酸乙酯含量分别高于成品啤酒20.1%、14.3%、12.5%和17.4%,含酯量较高,适于淡爽型啤酒发酵;与另两种载体相比,多孔陶瓷载体双乙酰含量达到0.14 mg/L,不适合用于啤酒发酵。     

A Comparative Study of Stout Beer Batch Fermentation Using Free and Microencapsulated Yeasts

Because many questions arise regarding the use of immobilization technology to consistently produce a high quality beer, this work focuses on the effects of using an immobilization matrix in the fermentation process. The aim of this study was to explore the feasibility and potential uses of immobilization on sensorial characteristics such as color, flavor, and headspace compounds of stout beer, when using batch fermentation. Batch production of beer was conducted as a standard ale process for stout beer production. For the immobilized yeasts fermentation, cells were microencapsulated in alginate, by using the Thiele modulus procedure for microcapsule design. Glucose concentration, cell multiplication, cell viability, specific gravity, pH, Brix, and ethanol were monitored throughout the fermentation process. Both, sensorial analysis (statistic triangle tests) and instrumental methods (gas chromatography to measure headspace compounds and visible spectrophotometer to quantify the color) were used to evaluate characteristics of the beer that was produced from immobilized and free yeast fermentations. Free and immobilized yeasts fermentation showed no significant difference (p > 0.05) for all variables of interest. The profile of headspace compounds was different, perhaps because of changes in yeast’s behavior and the presence of secondary metabolites. However, immobilization did not have a significant impact on the beer flavor, as detected by the sensorial triangle test.