啤酒生产过程中脱氧雪腐镰刀菌烯醇的控制研究

以感染镰孢霉属真菌的大麦为原料,确定了NaHSO3溶液浸泡的化学脱毒方法(浸泡浓度为10g/L和浸泡时间为50min)和在第一次浸麦阶段接种白地霉孢子106个/g大麦的微生物脱毒方法,并对比研究了两种脱毒方法的效果。对制麦和酿造过程中DON变化及相关理化指标的比较发现,添加白地霉G4的脱毒效果较NaHSO3溶液浸泡好,而采用NaHSO3溶液浸泡处理方法所制得的麦芽、麦汁和啤酒的理化指标相对较好。两种脱毒方式所制得的麦芽的理化指标均符合QB/T1686-2008中啤酒麦芽的要求,成品啤酒的常规理化指标均符合GB4927-2008中淡色啤酒的理化要求。     

利用白地霉提高低发芽率大麦溶解性能的研究

采用恒温和升温两种发芽工艺,研究了第一次浸麦过程中添加NaOH和接种5株具有高水解酶活力的白地霉菌株对低发芽率大麦溶解性能的影响.结果表明:在不同工艺下添加NaOH和接种白地霉菌株均能提高低发芽率大麦的溶解性能,特别是在升温发芽工艺下接种白地霉菌株G4能更好地改善麦芽的溶解指标,与对照样品相比,其成品麦芽β-葡聚糖酶酶活提高了6.2倍,木聚糖酶酶活提高了8.9倍,糖化力提高了21.5%,其它理化指标也均符合QB1686-93的标准.     

生物制麦中白地霉的筛选及其特性的研究

以甘啤3号大麦为原料,从中分离得到了2株生长能力较强的菌株,通过对该菌产生的β－葡聚糖酶、木聚糖酶、纤维素酶和糖化酶的酶活情况进行研究及生理生化鉴定得出该菌株为白地霉,分别为白地霉GQG28．1和白地霉GQG28．2。对筛选到的白地霉GQG28生长特性的初步研究表明,该菌最适生长温度为25℃,生长温度范围为5℃～37℃,其最适生长pH5．6,最低生长pH值为3．2,最高生长pH值为11．0,利用该白地霉制得麦芽综合指标为206．15,所制麦芽糖化力为308．5WK、α-氨基氮为186mg／100g、浸出物相对质量分数为87．1％。     

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。     

利用根霉提高国产麦芽质量的研究

用AS3．904，AS3．948，AS3．866，AS3．28934株根霉作为实验茵株，研究利用根霉改善国产麦芽质量的可行性。结果表明，AS3．866具有较好的效果。以AS3．866为种根霉，考察了接种量、接种时间、孢子活化对制麦效果的影响。制得的根霉麦芽中β-葡聚糖含量降低了33％，β-葡聚糖酶和木聚糖酶酶活分别提高了1150％和690％，其他许多参数也有明显的改善。     

利用响应面优化生物制麦工艺

利用白地霉菌株作为生物制麦添加物改造传统制麦工艺.以麦芽糖化力、α-氨基氮(α-AN)、浸出物相对质量分数为衡量指标,采用单因素对比分析与响应面结合的实验方法,研究白地霉添加量、浸麦温度、浸麦pH对麦芽综合品质的影响.结果表明:在白地霉接种量104个/g大麦、浸麦温度15℃、浸麦pH为4.0的最优制麦工艺下,所制麦芽综合指标实际值为206.15,糖化力为308.5WK,α-AN为186mg/100g,浸出物相对质量分数为87.1％,均高于轻工业行业标准QB/T 1686-2008中优级产品的指标,且所制麦芽中均未检测出真菌毒素.     

不同干燥工艺条件下β-葡聚糖酶活性与麦牙品质关系的研究

以甘啤4号大麦为实验材料,对麦芽干燥工艺过程的凋萎初始温度和焙焦温度,进行二因素三水平全面试验,通过分析测定麦芽关键品质指标,对啤酒大麦芽β-葡聚糖酶活与麦芽品质的关系进行了研究.结果表明:影响β-.葡聚糖酶活力的工艺参数主次顺序为:焙焦温度凋萎初始温度;凋萎初始温度48℃、焙焦温度78℃时大麦芽β-葡聚糖酶活力最高.麦芽中β-葡聚糖酶活与麦芽α-淀粉酶活力、蛋白酶活力、浸出物含量、α-AN和库尔巴哈值指标间存在极显著正相关关系,与麦汁黏度、糖化时间以及β-葡聚糖浓度间存在极显著负相关关系.     

霉菌对麦芽品质影响的研究

麦芽是啤酒酿造的主要原料,其表面附着了各类微生物,尤其是受霉菌侵染的麦芽可能引起β-葡聚糖、可溶氮和麦汁黏度升高等问题.本文研究了三种大麦在制麦过程中添加已筛选的大麦自身携带的四种霉菌对麦芽质量的影响,发现链格孢霉和镰孢霉对大麦细胞壁降解和细胞内基质溶解有明显的负作用,导致β～葡聚糖酶活力降低,β～葡聚糖含量增加,麦汁的浊度升高;其中镰孢霉对Gairdner的麦汁浊度影响最大,增加220％;添加镰孢霉的三种麦芽中蛋白酶活力和库值都有所降低,其中国产内蒙麦芽库值下降最多,下降了7.2％.     

啤酒中β-葡聚糖的研究

β-葡聚糖是大麦半纤维素和麦胶物质的主要成分，对大麦加工及啤酒酿造造成重大影响。本文介绍了β-葡聚糖在谷物中的含量、结构、理化性质、在啤酒酿造中的影响以及β-葡聚糖酶在啤酒工业中的应用。     

制麦过程中大麦β-葡聚糖的变化及对麦汁和啤酒中β-葡聚糖含量的影响

观察制麦过程中大麦β-葡聚糖溶解度的变化,研究糖化条件对麦汁和啤酒中β-葡聚糖含量的影响。发芽4～5天后,绿麦芽中可溶性β-葡聚糖部分显著提高。然而,如果麦芽的内源性酶活经加热处理后被抑制,发芽前3天β葡聚糖的溶解一直增加,在之后的阶段开始降低。当提取温度从室温提高到45℃时,可溶性β-葡聚糖部分显著增加。溶解良好和溶解不良的麦芽在不同糖化温度下随着温度从45℃增加到75℃,麦汁中可溶性β-葡聚糖数量增加并最终在啤酒中残留。在任何温度下,由溶解不良麦芽所得麦汁和啤酒中的β-葡聚糖含量都非常高。甚至在低糖化温度下内源性酶也难以完全溶解这些葡聚糖。     

CONTROLLING MALTING LOSSES WITH ANOXIA,CARBON DIOXIDE,AND SULPHUR DIOXIDE

Micromalting trials were used to evaluate the effectiveness of various treatments with anaeroblosis, carbon dioxide or sulphur dioxide in controlling malting losses with grain treated with gibberellic acid. Periods of increasing anoxia, with carbon dioxide accumulation as in Kropff malting, produced malt with a reduced malting loss and a lower hot water extract than control malting. Covering germinating barley with atmospheres containing various partial pressures of carbon dioxide reduced malting losses, but the resulting malts were usually inferior in quality to the controls. Sulphur dioxide gas, applied to moist germinating barley three days after casting, reduced malting losses by almost 3%, and increased the hot water extract by about 3 lb./Qr. relative to control malts. The treated malt occupied less space than the control, and the heat output was reduced. Sulphur dioxide treatment and only 4 days' germination produced a malt in high yield, with an extract identical to that of a control malt germinated for five days. The sulphur dioxide malts yielded worts with lower pH and higher soluble nitrogen values than the control and the fermentability of the worts was normal.     

Control of Superoxide Dismutase Activity during Malting Using Plackett‐Burman and Box‐Behnken Experimental Design and Its Effect on Reducing Power of Wort

The Plackett‐Burman multifactorial design was employed to screen the important malting parameters for superoxide dismutase (SOD) in final malt of Ganpi‐3. The eight factors screened for SOD were steeping temperature, steeping time, peroxide hydrogen concentration in steeping water, germination temperature, germination time, withering temperature, drying temperature and kilning temperature. Variance analysis showed that steeping time, germination temperature and kilning temperature were significant for SOD activity. Box‐Behnken experimental design was further used to optimize the levels of the above three factors. By response surface methodology and canonical analysis, the optimal malting factors for higher SOD activity in final malt were: steeping time 42.2 h, germination temperature 16.9°C and kilning temperature 82.9°C. Under these conditions, the model predicted a SOD activity of 2234 U/g of dry weight malt. Verification of the optimization showed that a SOD activity of 2220 U/g was observed under optimal conditions. It showed that the experimental data could be reliably predicted by the polynomial model. Besides Ganpi‐3, three other barley varieties including Ganpi‐4, Ken‐2 and Hamelin were malted under optimal and common conditions under laboratory conditions. To some extent, SOD activities were higher in malts from the optimal malting process than those from the common malting process. Especially, SOD activities in Ganpi‐3 and Hamelin increased by 18.8% and 15.3%, respectively. Furthermore, twenty‐nine samples of malts, including eleven imported malts and eighteen domestic malts, were used. Relationships between SOD activity in malt and the reducing power of wort were examined. There was significant correlation between SOD activity and the reducing power of wort (R² = 0.8069).     

VARIATION IN pH AND LACTATE LEVELS IN MALTS

Malt pH, defined as the pH of worts prepared by the Institute of Brewing Methods of Analysis, was examined in commercial malts from a single malting plant over four crop years, 1990 to 1993. Batch to batch variability was found, in addition to a distinct pattern within two of the years, with a gradual decrease in the winter months following commencement of malting of the new crop barley, followed by a subsequent increase in the late summer. Variability in pH and the longer term trend were not related to any measured processing variables or characteristics of the barley used for malting. Possible reasons for the differences in pH were examined and a negative relationship between malt pH and wort lactate content was demonstrated in a selection of malts from two crop years. A method is proposed for extraction and purification of lactate directly from malt and using this method it was shown that lactate in wort derives mainly from malt with only small amounts being produced during mashing.     

STARCH HYDROLYSIS IN MALTING AND MASHING

Starch hydrolysis in malting and mashing processes was studied by gel chromatography on Sepharose Cl 4B. The final molecular weight distribution of starch components in malt differs from those in barley. During malting a molecular weight fraction close to the void volume appears as an intermediate product. Minor differences in starch hydrolysis in mashes with different malts is obtained, though the final dextrin composition of the worts is similar.     

A study on malt modification,used as a tool to reduce levels of beer hordeins

Storage proteins from barley, wheat and rye are toxic to gluten sensitive consumers. These consumers include those suffering from coeliac disease, which account for up to 1% of the global population, and non‐coeliac gluten sensitivity that may affect even greater numbers of the population. Codex Alimentarius has published guidelines and limits of gluten in gluten‐free foods, which are applied in Europe, and similar guidelines apply in the rest of the world. The storage proteins present in barley are hordeins. These proteins are broken down and used by the plant as a source of amino acids during germination and growth of the barley embryo. The objective of this study was to extend the germination stage of the malting process and look at the effect on beer hordeins. Standard MEBAK methods were used to develop an extended malting process and produce three different malts, germinated for 3, 5 or 7 days. The quality of malt was assessed and model beers were produced from each malt to test the effect of modification on levels of beer hordeins. Malt germinated for 7 days produced beer 18 mg/kg hordeins corresponding to a reduction of 44% compared with the beer made from malt germinated for 3 days characterized by a hordein content equal to 32 mg/kg. The malting loss was increased during the 7 days of germination but otherwise all malts were of high quality. The results showed that malting conditions have a significant impact on beer hordeins. Copyright © 2018 The Institute of Brewing & Distilling     

INFLUENCE OF MALTING CONDITIONS ON QUALITY OF FINGER MILLET MALT

Effect of processing conditions on dry matter loss and quality characteristics of malt from INDAF-6 variety of finger millet was studied. Increasing the temperature of malting from 15 to 35°C caused increased dry matter loss. Germination at 15–20°C gave malts of higher α-amylase activities than those germinated at 30–35°C. Germination at 20°C for 4–5 days gave malt with maximum enzyme activity and acceptable dry matter loss. Drying the malt to 12% moisture and kilning at 70°C for about 45 min resulted in malt of desired aroma, maximum retention of α-amylase and minimum loss of available lysine. The α-amylase in the malted flour caused the slurries to have low hot paste viscosity.     

The effect of germination and kilning on the cyanogenic potential,amylase and alcohol levels of sorghum malts used for burukutu production

Grain sorghum of the red and white varieties was malted by steeping in water for 18 h, germinated over 5 days and kilned at 50 °C. The malts were analysed for amylase activities and cyanogenic potential and used to produce burukutu, an alcoholic beverage. The alcohol content of the burukutu was recovered by distillation and determined by the refractive index method. α‐Amylase activity peaked on malting day 3 and was higher in the white malts. β‐Amylase activity peaked on day 3 in the red malts and on day 4 in the white malts, but was higher in the red malts. Dhurrinase activity was highest on malting day 4, with a higher activity in the red malts. Kilning at 50 °C reduced the activities of these enzymes. The dhurrin content increased during germination and was consistently higher in the white malts, in which there was evidence of dhurrin mobilisation. In the red malts the dhurrin content increased during germination but decreased progressively after kilning; evidence of dhurrin mobilisation was apparent as from malting day 4. Burukutu produced from the red malts gave higher alcohol contents than that from the white malts. Maximum alcohol yields were obtained on malting day 3 in the red malts and on day 5 in the white malts. © 2000 Society of Chemical Industry     

Effect of malting regimen on diastatic power,cold and hot water extracts of malts from sorghum

In this study, sorghum grains were malted using different malting regimens and the malt qualities were analysed for cold water extract (CWE), hot water extract (HWE) and diastatic power (DP). Results showed that malting regimen produced sorghum malts with peak CWE, HWE and DP within the pre-determined limits of malting regimen. From this, predictive models of sorghum malt quality were developed and tested. Whilst steeping duration interacts significantly with the germination period to cause variations in CWE and HWE, only the germination period significantly influenced the DP of sorghum malts. However, the kilning temperature showed no significant impact on the parameters studied. Besides CWE, HWE and DP correlating positively with each other, the developed predictive models were significant (P < 0.05) and satisfy the quality of fit (R² > 0.70) of the proposed models. The result demonstrated that wort for different purposes can be obtained by varying the malting operational conditions in the predictive model, thus saving time, resources, preliminary studies and research designs. Besides the promotion of a cheaper local alternative material for industrial wort production and brewing purpose, this research provides valuable insight on the brilliant prospect of variable malting regimen in predicting and adjusting the quality characteristics of sorghum malt and wort. Future studies are required to develop models for wort produced from peak CWE, HWE and DP, for predicting wort quality characteristics.