普鲁兰酶对木薯淀粉糖化的影响

普鲁兰酶对木薯淀粉糖化的影响￥华南理工大学＠温其标＠陈玲＠罗发兴＠颜盛发＠张力田普鲁兰酶对木薯淀粉糖化的影响华南理工大学（５１０６４１）温其标陈玲罗发兴颜盛发张力田１前言在淀粉糖工业和许多食品发酵工业中都以淀粉为原料，经水解制成葡萄糖作为工厂的产品或者半成...     

普鲁兰酶的应用对柠檬酸发酵的影响研究

通过10L发酵罐试验,研究了普鲁兰酶的应用对柠檬酸发酵的影响.研究结果表明:在原料处理中按0.01%加普鲁兰酶,产酸率提高1.1%,转化率提高8.2%,发酵周期缩短12h.     

木薯粉酒精浓醪发酵条件的优化

以木薯粉为原料进行浓醪酒精发酵,在前期优化液化糖化条件的基础上,分析了培养基成分以及温度,pH值等条件对发酵的影响.实验结果表明,在优化的液化糖化条件下进行木薯粉浓醪酒精发酵,氮源和无机盐的最适添加量为尿素0.25%(w/w),MgSO4·7H2O 0.45g/L,KH2PO4 1.50g/L,CaCl2 0.20g/L,发酵最适温度为33℃,最适初始pH4.5,酵母接种量100,6(v/v),发酵时间48h.在此条件下发酵成熟醪酒精浓度高达17.2%(v/v),淀粉利用率达91%.     

木薯粉酒精浓醪发酵条件的优化

以木薯粉为原料进行浓醪酒精发酵,在前期优化液化糖化条件的基础上,分析了培养基成分以及温度,pH值等条件对发酵的影响。实验结果表明,在优化的液化糖化条件下进行木薯粉浓醪酒精发酵,氮源和无机盐的最适添加量为尿素0.25%(w/w),MgSO4·7H2O0.45g/L,KH2PO41.50g/L,CaCl20.20g/L,发酵最适温度为33℃,最适初始pH4.5,酵母接种量10%(v/v),发酵时间48h。在此条件下发酵成熟醪酒精浓度高达17.2%(v/v),淀粉利用率达91%。     

普鲁兰酶对大麦麦汁发酵度的影响试验

本文主要对于普鲁兰酶对大麦麦汁发酵度的影响进行了试验。实验结果表明,添加普鲁兰酶在一定程度上可提高大麦麦汁的发酵度,当添加量为120U/Kg时能提高麦汁发酵度至75%,预测啤酒发酵度可达72%以上。     

木薯酒精浓醪发酵中液化条件的优化

利用木薯进行酒精浓醪发酵,对其中液化过程中的条件进行了优化,得出最佳液化条件为:液化pH值5.0～6.0,液化酶加入量为10U/g木薯粉,液化温度和时间分别为105℃、2h。     

普鲁兰酶水解制备抗消化性和低回生性木薯淀粉的研究

研究普鲁兰酶水解前后木薯淀粉的消化性、回生性的变化情况。试验结果表明,当加酶量为120 U/g时,木薯淀粉的易消化淀粉和缓慢消化淀粉分别降低至25.45%和31.32%,抗性淀粉含量可由不加酶的16.20%升高到43.22%(P0.05)。糊化的酶解木薯淀粉,在4℃保存21 d后经DSC扫描,糊化焓由原来的8.75 J/g降至2.77 J/g(P0.05)。普鲁兰酶水解后的木薯淀粉,有较低的消化性和回生性。     

高浓发酵和酸洗对酿造酵母的影响

用磷酸类杀菌物质来洗涤接种酵母,以避免细菌污染是许多啤酒厂通用的方法,使用不正确的方法洗涤酵母将使其发酵特性下降并产生不良影响。酵母酸洗后接种于１２Ｐ麦汁,发酵特性没有明显下降;而接种于２０Ｐ麦汁,在发酵的第一个２４小时,酵母的活力就有所下降,但酵母的发酵特性没有变化。     

培养基及培养条件对普鲁兰酶的影响

从土壤中分离出一株产普鲁兰酶的菌株,初步鉴定为芽孢杆菌．通过优化发酵培养基及发酵培养条件,在２５０ｍＬ的摇瓶中可达到４．５μｍｏｌ／（ｍｉｎ·ｍＬ）的普鲁兰酶酶活．优化后的发酵培养基成分如下：玉米支链淀粉２ｇ／ｄＬ,蛋白胨２ｇ／ｄＬ,牛肉膏１．５ｇ／ｄＬ,ＮａＣｌ０．５ｇ／ｄＬ,ＭｎＳＯ４２μｍｏｌ／Ｌ．摇瓶发酵工艺条件：接种量１７％,温度３７℃,摇瓶转速２２０ｒ／ｍｉｎ,ｐＨ６．０,发酵周期３２ｈ．通过２Ｌ容积的发酵罐批式发酵,酶活可稳定在３．３μｍｏｌ／（ｍｉｎ·ｍＬ）左右     

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。     

马铃薯酒精浓醪发酵工艺条件的研究

酒精浓醪发酵是生产燃料乙醇的一个重要步骤,为了提高发酵醪的酒精度,研究了不同因素对马铃薯浓醪发酵的影响。以发酵醪的酒精度为指标,通过单因素实验和正交实验,得到马铃薯酒精浓醪发酵的最佳条件为:料水比1∶3.0,糖化酶添加量150U/g,初始pH值4.5,接种量6%,得到发酵醪的酒精度为14.90%(v/v)。     

Effects of wheat gluten hydrolysates fractionated by different methods on the growth and fermentation performances of brewer's yeast under high gravity fermentation

Wheat gluten hydrolysates (WGH) were fractionated through ultrafiltration membrane with molecular weight (Mw) cut‐off of 3 kDa and ethanol precipitation, respectively. WGH and their fractions were used to examine their effects on the growth and fermentation performances of brewer's yeast under high gravity fermentation. Results showed that WGH and their fractions exhibited significant differences in biomass accumulation, viability, ethanol yield, free amino nitrogen and sugar consumptions under high gravity fermentation. Compared to WGH, the fractions with Mw < 3 kDa and the supernatant of WGH treated with ethanol precipitation showed better fermentation performance for brewer's yeast. The relatively lower molecular weight and the higher levels of Leu, Lys, His and Arg in these two fractions might be responsible for their bioactivity for brewer's yeast. Thus, both ultrafiltration and ethanol precipitation could be used as efficient methods for enriching peptides with significant growth‐ and fermentation‐promoting activity for brewer's yeast under high gravity fermentation.     

高浓酿造法生产高辅料啤酒的研究

该文通过试验研究,确定了75%高辅料的糖化工艺、麦汁16°P高浓度的发酵工艺、高浓稀释工艺。采用上述工艺不仅生产的产品质量达到GB4927标准,而且感官指标和风味都比较稳定。从而提高了现有设备的利用率,增加了产量,降低了成本,提高了企业的经济效益。     

Influence of temperature on continuous high gravity brewing with yeasts immobilized on spent grains

Flavor compounds’ formation and fermentative parameters of continuous high gravity brewing with yeasts immobilized on spent grains were evaluated at three different temperatures (7, 10 and 15 °C). The assays were performed in a bubble column reactor at constant dilution rate (0.05 h⁻¹) and total gas flow rate (240 ml/min of CO₂ and 10 ml/min of air), with high-gravity all-malt wort (15°Plato). The results revealed that as the fermentation temperature was increased from 7 to 15 °C, the apparent and real degrees of fermentation, rate of extract consumption, ethanol volumetric productivity and consumption of free amino nitrogen (FAN) increased. In addition, beer produced at 15 °C presented a higher alcohols to esters ratio (2.2–2.4:1) similar to the optimum values described in the literature. It was thus concluded that primary high-gravity (15°Plato) all-malt wort fermentation by continuous process with yeasts immobilized on spent grains, can be carried out with a good performance at 15 °C.     

Characterisation of fermentation of high-gravity maize mashes with the application of pullulanase,proteolytic enzymes and enzymes degrading non-starch polysaccharides

The aim of the research was to assess the possibility of the fermentation productivity rising through the increase in corn mashes extract from 16–17 to 20–21°Balling, yet keeping a 3-day fermentation period. The second goal was to obtain the highest possible utilization of starch in the raw material through deep enzymatic degradation and utilization of available sugars and simultaneous maintenance of high quality spirit. It was found that fulfilling the above during the 3-day fermentation period was possible with the application of pullulanase as an additional amylolytic enzyme. Adding pullulanase resulted in the acceleration of the starch hydrolysis degree, which led to lower amounts of unhydrolyzed dextrins and higher ethanol yield. When the supportive enzymes complex (pullulanase, protease and cellulase) was used, the final ethanol concentration reached 10.86 ± 0.04% v/v, with ethanol yield at 68.41 ± 0.23 dm³ of absolute ethanol (A₁₀₀) per 100 kg of starch, which was 95.25 ± 0.32% at the theoretical value. The acceleration of starch enzymatic degradation and the application of a proteolytic preparation visibly shortened both initial and main fermentation phases. This in turn increased the time of the final fermentation phase and resulted in more extensive utilization of substrates by yeasts with simultaneous reduction of the final concentration of acetaldehyde (26.0 ± 0.5 mg/dm³A₁₀₀) and diethyl acetal of acetaldehyde (2.5 ± 0.5 mg/dm³A₁₀₀). The quality of spirit obtained was positively verified also in terms of relatively low concentration of higher alcohol (3912.2 ± 9.8 mg/dm³A₁₀₀). Preliminary analysis of costs (without raw-material) of 1 l distillate production indicated the possibility to reduce the costs by 18–20%.     

利用木薯淀粉为原料发酵生产丁二酸的研究

利用木薯粉为原料发酵生产丁二酸,将先糖化后发酵(SHF)和同步糖化发酵(SSF)2种发酵模式进行比较,发现SSF发酵模式在工艺上、产量上均优于SHF,进而对SSF的一些工艺条件进行摇瓶优化,得到SSF的最适发酵温度为37℃,糖化酶添加量为1000U/g,最适底物浓度60g/L.在7L发酵罐中进行放大实验,用木薯粉同步糖化发酵45h,最终丁二酸浓度为61.2g/L,乙酸浓度为4.66g/L,生产强度达到1.36g/(L·h),丁二酸转化率为89%.     

法夫酵母高密度培养条件的优化

本文采用正交试验对法夫酵母高密度培养条件进行了研究,得到其优化培养基组成为:葡萄糖35g/L、酵母膏9g/L、KNO30.6g/L、(NH4)2SO4 0.5g/L、KH2PO4 1.5g/L、MgSO4 0.2g/L,最适摇瓶装液系数为10%。在10L罐上的实验结果表明:采用优化后的培养基在48h细胞总数就可以达到1.5×109个/mL,与初始培养基相比细胞总数提高了88.7%,到达最高菌体浓度提前了12h。     

高浓度蔗糖酒精发酵的初步研究

高产量酒度和快速发酵一直是酒精发酵产业所追求的,而酵母直接利用高浓度蔗糖发酵酒精未见有文献报道.文中所用酿酒酵母能直接发酵30%(w/v)的蔗糖溶液,发酵周期只有2d～3d,其最终产生的酒精可以达到17.08%vol,对发展蔗糖酒精是个很好的契机.     

木薯半连续同步糖化发酵乙醇

研究了用木薯为原料,半连续同步糖化发酵生产乙醇的工艺。工艺条件为:原料粉碎粒度:Φ1.5mm,料水比:1∶2.3,α-淀粉酶、糖化酶的添加量分别为9U/g木薯粉,120U/g木薯粉,95℃下蒸煮90min～110min,60℃下前糖化35min～40min。前期发酵温度28℃,中后期发酵温度32℃,总发酵时间69h。在此条件下酒精度达到13.5%vol,半连续发酵17d,为进一步研究以木薯为原料生产乙醇工业化提供了依据。     

高浓度发酵中酵母菌性能调控及优化

高浓度发酵能有效提高乙醇发酵的经济效益,但反应过程中高浓度基质和产物对酵母菌性能抑制作用是限制最终乙醇产率的关键因素。文中通过分析比较了不同基质及产物浓度下的发酵中基质浓度、菌体浓度、乙醇产量的变化规律,确定酵母菌对抑制物的耐受浓度。并对比内源和外源乙醇对于发酵初始12 h酵母菌平均比增长速率和平均乙醇发酵速率的影响,揭示内外源乙醇抑制作用的差异。结果表明,在实验浓度范围内,该酵母菌株发酵基质最大投加浓度为160 g/L,所产乙醇最大浓度为55 g/L;产物乙醇是发酵过程中的首要抑制因素,菌体对发酵初始时所添加乙醇的耐受浓度为70 g/L,内源乙醇对酵母菌的抑制作用大于外源乙醇。