基于BP神经网络模型的梨醋发酵产酸量的预测

研究不同发酵条件(发酵温度、乙醇体积分数、接种量和梨的添加量)对梨醋总酸含量的影响,并且建立BP神经网络预测模型。神经网络模型能够根据发酵条件,准确预测总酸含量,总酸相关系数为0.986。在梨醋发酵中,发酵温度对总酸含量影响最大。与传统的模型比较,BP神经网络误差小,构建简单,拟合性高。     

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.     

啤酒发酵过程对重要醇酯影响的研究

风味物质的含量决定啤酒的品质,其特征会直接决定啤酒口感和其市场竞争力。研究了麦汁浓度、主酵温度和接种量对啤酒中风味物质的影响。在不同的发酵条件下,以全麦芽为原料,经下面发酵生产啤酒。采用顶空气相色谱法检测啤酒中高级醇和酯类的浓度。研究发现麦汁浓度对高级醇和酯的影响最大,且提高麦汁浓度能够同时增大啤酒中高级醇和酯的含量,当麦汁浓度从11°P提高到15°P,乙酸乙酯的含量提高了34%。在相同接种量和麦汁浓度下,主酵温度越高,异戊醇含量越高,异丁醇的含量却有所降低。在较高的发酵温度下乙酸乙酯、辛酸乙酯和乙酸异戊酯的含量升高,但是己酸乙酯的含量变化无规律。研究结果显示接种量对醇和酯的影响都不显著。     

金柑果醋生产工艺优化

以金柑为原料酿制果醋,对金柑果醋的酿造工艺条件进行了优化.响应面分析实验结果表明,酿造金柑果醋的最适宜工艺条件:酒精发酵阶段糖度为18.7％,接种量0.2％,发酵温度为32℃,发酵时间144 h;醋酸发酵阶段,接种量11.3％,初始酒精浓度8.2％,发酵温度为33℃,得到果醋酸度接近4.8g/dL.     

响应面法优化桃子果醋生产工艺的研究

研究桃子果醋的酿造工艺条件,利用响应面分析实验并得到最佳工艺条件.结果表明,酿造桃子果醋的最适宜工艺条件为:酒精发酵阶段糖度为15.9％,接种量0.3％,发酵温度为25℃,发酵时间7天,醋酸发酵阶段,接种量11.4％,底物浓度7.8％,醋酸菌的适宜生长温度为30℃,果醋酸度达到4.53％.     

发酵工艺参数对嫩啤酒抗氧化力的影响

为提高啤酒的抗氧化力及改善其风味稳定性,系统研究了麦汁发酵过程中抗氧化力的变化及发酵工艺参数包括麦汁浓度、酵母接种量、酵母代数与发酵温度对嫩啤酒抗氧化力的影响。结果表明:麦汁发酵过程中DPPH自由基清除活性、氧自由基吸收能力和还原力分别提高了6.27%、3.46%和31.38%。麦汁浓度从6°P增加到12°P,嫩啤酒的DPPH自由基清除活性、氧自由基吸收能力与还原力升高显著,浓度超过12°P后,抗氧化指标增速减缓或略有下降。酵母接种量在800～3200万个/mL之间的嫩啤酒抗氧化力随酵母接种量的增加而升高。1、2、4和5代酵母发酵嫩啤酒的抗氧化力随酵母代数的增加呈降低趋势。9、12和15℃发酵嫩啤酒的抗氧化力随发酵温度的升高而降低。因此,优化发酵工艺参数是提高啤酒抗氧化力的有效措施。     

啤酒的高浓度酿造试验

啤酒酿造的传统方法是将糖化后的麦汁在常规浓度下(如10～12％麦汁)进行发酵,得到含乙醇4～5％(v/v)的啤酒。为了提高生产效率,降低成本,增加产量,尤其是在不需要增加糖化、发酵设备的条件下大幅度增产,可采用高浓度发酵工艺,然后在啤酒过滤工段将发酵成熟的高浓度啤酒用脱氧碳酸水稀释到正常浓度。用高浓度酿造法可使生     

石榴果醋发酵工艺的研究

研究以石榴为原料酿造石榴果醋.通过正交实验,确定了石榴果醋发酵的最佳工艺参数.实验结果表明:石榴果醋酒精发酵的最佳工艺参数为:活性干酵母接种量0.10％、糖度16％、发酵温度28℃;石榴果醋醋酸发酵的最佳工艺参数为:醋酸菌接种量12％,酒精浓度8％,发酵温度34℃.     

降低高浓啤酒发酵中高级醇含量的研究

为降低高浓啤酒发酵中高级醇的生成量,研究18°Bx麦汁啤酒酿造过程中的加糖浆方式、酵母接种量和麦汁中α-氨基氮含量对啤酒高级醇生成量的影响。结果表明：18°Bx麦汁发酵高级醇生成量显著高于12°Bx麦汁;分两次加入制备18°Bx麦汁所需的糖浆量、控制18°Bx麦汁的酵母细胞接种量为3×107个/mL以及麦汁中α-氨基氮含量为230mg/L麦汁时,均有利于降低18°Bx高浓啤酒发酵过程中高级醇的生成量。     

响应面法优化帝国世涛啤酒酿造工艺的研究

以感官评分为主要评价指标,通过单因素和响应面试验,对帝国世涛啤酒酿造工艺参数（原麦汁浓度、发酵温度、白砂糖添加量）进行优化。结果表明,原麦汁浓度对帝国世涛啤酒品质的影响最大;帝国世涛啤酒的最佳工艺参数为：原麦汁浓度16 °P,发酵温度21 ℃,白砂糖添加量5.1%。在此最佳工艺条件下,帝国世涛啤酒的感官评分为95分,各项理化指标均符合啤酒国家标准;所酿造的帝国世涛啤酒呈现浓黑色,泡沫绵密而扎实,复合香气协调浓郁,酒体厚重,余味绵长,同时具有很强的包容性。     

Predicting acetic acid content in the final beer using neural networks and support vector machine

Most acetic acid found in beer is produced by yeast during fermentation. It contributes significantly to beer taste, especially when its content is higher than the taste threshold in beer. Therefore, the control of its content is very important to maintain consistent beer quality. In this study, artificial neural networks and support vector machine (SVM) were applied to predict acetic acid content at the end of a commercial‐scale beer fermentation. Relationships between beer fermentation process parameters and the acetic acid level in the fermented wort (beer) were modelled by partial least squares (PLS) regression, back‐propagation neural network (BP‐NN), radial basis function neural network (RBF‐NN) and least squares‐support vector machine (LS‐SVM). The data used in this study were collected from 146 production batches of the same beer brand. For predicting acetic acid content, LS‐SVM and RBF‐NN were found to be better than BP‐NN and PLS. For the comparison of RBF‐NN and LS‐SVM, RBF‐NN had a better reliability of model, but lower reliability of prediction. SVM had better generalization, but lower reliability of model. In summary, LS‐SVM was better than RBF‐NN modelling for the prediction of acetic acid content during the commercial beer fermentation in this study. Copyright © 2013 The Institute of Brewing & Distilling     

高浓高温对啤酒酵母发酵性能的影响

以啤酒酵母S-6为实验菌株,研究了主发酵温度和原麦汁浓度对啤酒发酵的残糖、酒精度、风味物质和絮凝性等性能指标的影响。结果表明,原麦汁浓度一定时,主发酵温度对高级醇和乙酸酯的含量影响较大,主发酵温度由10 ℃提高至16 ℃时,高级醇含量提高了10%～20%,乙酸酯含量提高了8%～16%,但CO2累积质量损失、残糖、酒精度和絮凝性基本不受温度的影响;主发酵温度一定时,原麦汁浓度对酵母絮凝性影响较大,原麦汁浓度越高,酵母絮凝性越低,将高浓（18 °Bx）发酵液稀释50%至常浓（12 °Bx）,残糖、酒精度和高级醇的含量与常浓发酵液基本相同。该研究为选育高温高浓发酵低产高级醇同时强絮凝性酵母菌株提供了重要依据。     

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。     

混合微生物发酵生产啤酒醋及饮料开发

以大麦芽为主要原料,进行啤酒醋发酵,调配制备麦香啤酒醋饮料。优化后的啤酒醋发酵工艺条件为：麦芽糖化后接种啤酒酵母进行酒精发酵,24 h后接种生香酵母,继续发酵4 d,啤酒酵母和生香酵母的添加比例为4∶1;醋酸发酵阶段醋酸菌接种量为10%,30 ℃条件下发酵,发酵结束时啤酒醋酸度为（3.21±0.09） g/100 mL,乙醇含量＜0.05%vol。开发麦香啤酒醋饮料,最佳配方为啤酒醋12%,麦芽汁70%,白砂糖3%,橙色素0.04‰,最终产品的酸度为（0.38±0.07） g/100 mL,糖度为（84.32±0.05） g/L,酸糖比为1∶22。感官评定表明,该方法制备的麦香啤酒醋饮料色泽金黄、澄清透明、酸甜爽口,醋香和麦芽香气浓郁。     

酵母形态指标百分数离散度与啤酒质量的关联性

通过跟踪不同发酵罐相同发酵时间的啤酒发酵液中的酵母形态指标百分数离散度,检测发酵结束后各发酵罐的啤酒的质量指标,得出啤酒酵母指标百分数离散度与啤酒质量的关联性,即酵母形态指标百分数离散度与酒精度、发酵度、总酸这三个啤酒质量指标成负相关,与原麦芽汁浓度、外观糖度、乙醛浓度、pH值、双乙酰这五个啤酒质量指标成正相关.     

啤酒酵母在红薯淀粉麦芽汁中的发酵特性研究

本实验研究了酵母在红薯淀粉做辅料的麦汁中的发酵特性,并与其在大米做辅料的麦汁中的发酵特性作了对比,结果表明其完成主发酵所用的时间、可发酵浸出物的变化、还原糖含量的变化、α-氨基氮的利用情况、双乙酰的生成量等均无明显的区别,而且酵母的生长繁殖正常。红薯淀粉作辅料的啤酒色度较大。     

A study of beer bitterness loss during the various stages of the Romanian beer production process

Beer is one of the oldest known alcoholic beverages produced by a yeast fermentation of a cereal extract that was germinated in water beforehand. The bitter taste of beer comes from the group of substances introduced during wort boiling, which are the extracted components of hops. The aim of this study was to determine some characteristics of beer (original extract, alcohol content, colour, pH, total acidity, carbon dioxide and bitterness values) during the three stages of the beer production process in a typical Romanian brewery. Measurements were carried out on 60 samples of beers, 10 measurements for each step of the process examining wort, unfiltered fermented beer and bottled beer (final product) from two different types of beer (light and dark). Statistical process control of the beer was performed. Losses in the bitterness units during the production process were between 24.7 and 41.54%, reported in terms of final product. Copyright © 2013 The Institute of Brewing & Distilling     

Effect of the respiro-fermentative balance during yeast propagation on fermentation and wort attenuation

Breweries use different yeast strains to create beers with different flavours and aromas. Yeast propagation must produce yeast that performs consistently from the first fermentation to harvesting and re-pitching in subsequent fermentations. Breweries propagate yeast in wort leading to low efficiency fermentative growth in Crabtree-positive yeast. There is limited knowledge on the impact on beer production when fermenting with yeast propagated in sugar limited and nutrient supplemented wort. It was hypothesised that propagating yeast in this way would have a positive impact on subsequent fermentation performance. Saccharomyces cerevisiae was propagated at the laboratory scale in standard wort with a high carbon to nitrogen (C:N) ratio (850) or in modified wort supplemented with yeast extract to achieve a low C:N ratio (100) and at varying sugar concentrations. Propagation in low C:N wort with 2°P sugar yielded a 27% decrease in fermentation efficiency and a 46% increase in cell production compared to 2°P high C:N wort. This suggests nitrogen is critical to the respiro-fermentative balance during growth. Yeast propagated in standard wort resulted in slower fermentations and significant under-attenuation compared to yeast grown in the modified wort with low sugar and high nitrogen. The results of this study suggest the nitrogen and sugar content drive the respiro-fermentative balance during yeast propagation. The metabolism of yeast during propagation induces significant downstream impacts on the subsequent fermentation performance and wort attenuation. © 2020 The Institute of Brewing & Distilling     

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。     

蚕豆泡菜的发酵工艺条件

以新鲜蚕豆为主要原料 ,通过对自然发酵、陈泡菜卤水、人工接种和人工陈卤发酵方法的研究 ,确定了人工陈卤发酵方法为最佳发酵方法 ;采用L9(3 4)正交试验设计 ,研究了食盐含量、食糖含量和接种量对蚕豆泡菜品质的影响 ,结果表明 ,食盐为 4% ,白砂糖为 8% ,接种量为 5 % ,发酵温度为 2 5～ 3 0℃ ,杀菌条件为 85℃、1 5min时 ,可获得令人满意的产品