不同发酵方式对樟芝真菌多糖产量的影响研究

通过深层发酵法,对比研究了连续、分批、补料分批3种培养方式对樟芝真菌菌体,胞内外多糖产量的影响,研究表明,补料分批相对于连续培养,菌体最大产量提高5.51%,胞内多糖最大产量提高11.25%。胞外多糖最大产量提高21.70%,补料分批培养优于连续培养和分批培养。     

Effect of pH,aeration and feeding non‐sterilized agave juice in a continuous agave juice fermentation

BACKGROUND: Continuous cultures have been used since the 1950s in beer and wine fermentations due to their higher productivities compared to traditional batch systems; nevertheless, the tequila industry has not taken advantage of the possible improvements that continuous fermentations could offer. In this work, the effect of pH, aeration and feeding of non‐sterilized medium, on the fermentative capability of two Saccharomyces cerevisiae strains (S1 and S2) cultured in continuous fermentation, using agave juice as the fermentation medium, were studied. RESULTS: In continuous cultures, the control of the medium pH (set point at 4) did not have a significant effect on fermentation efficiency compared to fermentations in which the pH was not controlled (pH 2.5 ± 0.3). Conversely, aeration of the cultures of both strains improved biomass production and consumption of reducing sugars and ammonium. The aeration also significantly augmented ethanol production only for S1 cultures (P < 0.05). Furthermore, the feeding of medium, either sterilized or not, did not show significant differences on the production of ethanol for S1 cultures. Higher concentrations of acetoin, succinic acid and diacetyl were found in the cultures fed with non‐sterilized medium. CONCLUSIONS: Compared to S2, S1 has a better fermentative performance in continuous non‐sterilized medium fermentations. Not controlling the pH during the cultures could prevent the possibility of microbial contamination as a result of the extreme medium acidity (pH 2.5 ± 0.3). This work showed the possibility of scaling up agave juice continuous fermentation feeding non‐sterilized medium with no control of pH. Copyright © 2010 Society of Chemical Industry     

固定化酵母用于白酒丢糟降解液乙醇发酵的研究

为了提高白酒生产中废弃物的资源化利用效率,探讨了利用固定化酵母实现丢糟降解液连续发酵生产乙醇的工艺。采用固定化的LR3.1300酵母菌株(Saccharomyces sp)进行丢糟降解液的批次和连续乙醇发酵试验。批次发酵试验结果显示,固定化酵母在白酒糟降解液与葡萄糖混合液中发酵的底物利用和产酒效率都较高。在固定化酵母连续发酵中,当固定化酵母液为60 mL,降解糖液进料速度为15 mL/h时,还原糖利用率为83.7%,流出液酒精度达到了3.97%vol,乙醇发酵的效率与前期的游离酵母发酵相比提高了43%。     

Kappa-Carrageenan Gel Immobilisation of Lager Brewing Yeast

Kappa-carrageenan has been found to be a suitable carrier for yeast immobilisation for continuous fermentation systems due to its unique properties. Brewing lager yeast immobilised in kappa-carrageenan beads was studied both in batch and in a continuously fermenting gas lift bioreactor. The cells were monitored over a six month period of continuous fermentation. Viability (methylene blue), immobilised cell concentration and distribution, and the morphological characteristics of the cells (electron microscopy) were investigated. Viability of cells within the beads was found to decline to less than 50% after six months of continuous wort fermentation and maximum bead population did not exceed 10⁹ cells/mL of gel bead.     

在模型化基础上对青霉素补料分批发酵过程中经济效益的预测

在研究发酵动力学、生物过程反应计量学、代谢流分布和代谢流控制的基础上 ,结合专家知识、实验及生产数据 ,对生产规模的青霉素反复补料分批发酵 (即半连续发酵 )的全过程进行了数学模拟 ,建立了一套包含 2 5个过程变量和一系列经济学变量的改良机理模型 .根据这一模型 ,预测了一些工艺参数和经济学参数的改变对发酵过程经济效益的影响 ,发现在保持最大生物质浓度、稀释速率 ,及其它工艺条件不变的情况下 ,中间放料间隔时间、初始发酵液体积以及葡萄糖和电力的价格对经济效益产生较大的影响 .模拟运算结果表明 ,葡萄糖和电力的价格降低 5 % ,全年利润可分别提高 6 .35 %和 3.75 % ;中间放料间隔时间由 2 4h缩短为 12h和 1h(接近于连续发酵 ) ,全年利润可分别提高 7.2 2 %和 14 .11% ;初始发酵液装罐体积分数由 75 %提高到 85 % ,全年发酵利润可提高 5 .4 8% .     

PVA共固定化双菌种发酵葛根酒的研究

采用PVA为载体共固定化酿酒酵母和产香酵母发酵葛根,酿造葛根酒。对游离细胞与固定化细胞的分批发酵和连续发酵的动力学进行了研究并建立了相应的发酵动力学方程。实验结果表明:酿酒酵母和产香酵母二种菌种菌量的最佳配比为3(1,发酵温度20℃,共固定化细胞分批发酵和连续发酵凝胶粒的充填系数分别为0.25和0.5,游离混合细胞的发酵时间为7d,共固定化细胞连续发酵稀释速率0.12/h其发酵时间为0.5d左右。经2000d连续发酵实验,PVA固定化细胞粒子的机械强度良好.     

酵母流加发酵过程中的模糊控制器

通过分析酵母发酵过程中的影响因素,建立了控制酵母发酵过程中流加速率的模糊控制器.该模糊控制器的模糊规则可以根据专家经验方便地修改以提高控制效果.实验表明在模糊控制器控制下酵母产量比恒速流加时提高了一倍.     

基于主元分析和模糊模型的链霉素发酵过程建模

基于主元分析和模糊模型 ,提出了一种简单而有效的链霉素发酵过程产物浓度的预报方法 .该方法采用主元分析压缩关联程度高且含有测量噪声的实际工业生产数据 ,筛选出影响产物浓度的主要过程变量 ,构造了模糊分段线性模型的产物浓度估计器 .与线性多元回归模型相比 ,模糊模型更适合作为间歇发酵过程的状态估计器 .     

L-色氨酸营养缺陷型高产菌株的发酵工艺研究

目的以L-色氨酸营养缺陷型高产菌HX22-118为出发菌株,研究探讨L-色氨酸补料分批发酵工艺。方法通过对L-色氨酸补料分批发酵工艺中不同初糖浓度、不同补料方式、碳氮源比例、不同p H值调节方式、添加L-苯丙氨酸、L-酪氨酸对发酵的影响进行了研究。结果通过补料分批发酵工艺能有效地解除了高糖对菌体生长的抑制,促进菌体生长产酸,选择初糖淀粉浓度为90 g/L,保持葡萄糖总浓度160 g/L,在发酵第24 h开始连续流加剩余的糖,并于发酵第12 h和24 h分2次补加各50 mg/L的L-苯丙氨酸、L-酪氨酸,同时用氨水与Na OH控制发酵过程的p H,发酵产酸较分批发酵的33.5 g/L提高49.5%,达到50.1 g/L,缩短了发酵周期,提高了原料利用率。结论形成一套先进的L-色氨酸工业化发酵生产工艺技术,产酸高,生产运行稳定。     

培养基与分割发酵优化促进Nisin生物合成

为了提高乳酸乳球菌（Lactococcus lactis）细胞生长和乳酸链球菌素（Nisin）的合成效率,以正交优化法研究培养基分批发酵和分割发酵方式对Nisin生物合成效率的影响。结果表明,优化发酵培养基配方为：5%蛋白胨,3%蔗糖,2%玉米浆,1%酵母浸粉。在此优化条件下,摇瓶培养（11 h）峰值生物量为4.9×109 CFU/mL,较对照提高43%;10 L发酵罐分批发酵峰值生物量、Nisin效价及Nisin合成速率■q分别为7.75×109 CFU/mL、2 573 IU/mL、151.4 IU/（mL·h）,较优化前分别提升38.0%、56.6%、38.2%。分批发酵培养18 h Nisin达到峰值后[■q为147 IU/（mL·h）],以不同比例分割发酵并继续培养7 h,第二次分割（25%）为Nisin合成最适发酵方式,其Nisin平均合成速率达到294 IU/（mL·h）,较分批发酵提高了100%。     

固、液态发酵生产微生物脂肪酶

目前脂肪酶生产主要有固、液态两种发酵方法。该文对两种发酵方法进行详细对比,概述固、液态发酵生产脂肪酶菌种及发酵底物,并对分批、补料分批、连续发酵等技术进行对比;介绍数学模型在脂肪酶生产中应用,并展望利用酶工程技术和数学模型改良脂肪酶生产。     

Ageing vessel configuration for continuous redox potential-controlled very-high-gravity fermentation

The development of continuous very-high-gravity (VHG) fermentation is hindered by ineffective glucose uptake in order to result in zero discharge in the effluent stream. To overcome the problem, we proposed a continuous redox potential-controlled fermentation configuration, consisting of a Chemostat vessel connected with two ageing vessels installed in parallel, and the relevant design criteria are also specified. The Chemostat vessel is subjected to redox potential control to maintain yeast viability, and the ageing vessels are used to completely utilize glucose before discharging to next process unit. Two ageing vessels are scheduled alternatively, resulting in continuously-like operation. The size of ageing vessel is governed by the Chemostat size, dilution rate and filling time. The guideline to choose proper dilution rate is provided and the selection criterion of the proposed continuous configuration over batch fermentation is derived. The excess ethanol produced by the proposed continuous configuration over batch fermenter is quantified. As an illustration, a bio-ethanol plant is typically operated 8000 h per annum and the downtime between batches is 6 h. Given that the fermenter size of 100 m³ for both batch fermenter and Chemostat vessel, and glucose fed at 300 g/l, if the proposed continuous redox potential-controlled fermentation configuration (operated at 0.028 h^− 1 and controlled at − 50 mV) is selected, it will take 191 h for this configuration to outperform the batch counterpart, and the excess amount of ethanol being produced will be 1142 t.     

Effects of magnesium ions on both VHG batch and continuous fruit wine fermentations

In Poland, fruit wines or aromatized fruit wines are semi‐sweet or sweet and contain approximately 15–16% (v/v) ethanol. Their production can be classified as a very high‐gravity (VHG) fermentation. Magnesium has a beneficial effect on VHG fermentations as it protects the yeast cells against ethanol, osmotic and temperature stress. The effect of the magnesium concentration in an apple must, containing 32% sugars, on the fermentative parameters of batch and continuous fermentations was assessed. In the batch process, a magnesium concentration of ~8.5 mg/L resulted in decreased the ethanol production in comparison to a magnesium concentration of ~250, 490 and 970 mg Mg²⁺/L. The highest amount of Mg also caused a metallic taste. A continuous fermentation was carried out for 2.5 months in a four‐column packed‐bed fermentor. The medium contained ~50, 250 and 490 mg Mg²⁺/L and the yeast was immobilized on foam glass. During the continuous fermentation, no differences at p ≤ 0.05 in terms of fermentative parameters were seen with magnesium additions. The same beginning amount of magnesium ions in the medium led to a similar use of this element, both in batch and in continuous fermentation. The more Mg²⁺ that was present in the medium, the more Mg²⁺ was used by the yeast. The results suggest that the minimal dose of magnesium, under the described conditions, is 50 mg/L, corresponding to the amount of Mg in the medium prepared using concentrated apple juice and tap water. This finding has industrial significance, as Polish wine companies prepare their fruit musts using tap water. Copyright © 2014 The Institute of Brewing & Distilling     

A Review of Flavour Formation in Continuous Beer Fermentations*

The attractive prospect of a continuous beer fermentation system consists mostly of the accelerated transformation of wort into beer. Although continuous beer fermentation has been studied as a promising technology for several decades, the number of industrial applications is still limited. The major obstacle hindering the extensive industrial exploitation of this technology is the difficulty in achieving the correct balance of sensory compounds in the short time typical for continuous systems. This paper offers an integral view on the particularities of continuous systems, which may impart beer a sensorial character distinct from conventionally fermented counterparts. The main groups of flavour active compounds are discussed from the perspective of possible control strategies by means of process parameters and strain selection.     

活性干酵母在淀粉质酒精发酵生产中的应用

本文利用市售活性干酵母代替培养酒母,分别进行淀粉质酒精间歇发酵、半连续发酵和连续发酵大型生产,均取得了发酵速度快、出酒率高的好效果。     

食醋生产操作方式的研究进展

食醋生产工艺经历了固态发酵和液态发酵,液态发酵又由表面静止发酵向深层发酵发展。目前,食醋液态生产的操作方式有批式、半批式、反复半批式操作和半连续法四种操作形式,其中批式操作和半批式操作在食醋生产也已不常用,但在日益自动化的今天,随着计算机控制技术和传感器的发展及它们在食醋连续发酵的应用,在不久的将来食醋连续发酵将会取代反复半批式操作和半连续法,这也将是食醋生产工艺操作方式的又一次历史性变革。     

菠萝蜜果酒分批发酵动力学模型研究

为了研究菠萝蜜果酒分批发酵过程中酵母菌体生长、还原糖基质消耗和乙醇产量生成的动力学变化规律,每隔24 h测定菠萝蜜果酒发酵过程中的酵母菌数、还原糖含量和酒精度,采用经典的Logistic、SGompertz、Boltzmann和DoseResp模型进行非线性拟合,构建菠萝蜜果酒的分批发酵动力学模型。结果表明,在酵母菌体生长动力学模型中,采用Boltzmann模型拟合效果最佳,拟合系数R 2为0.99396;在乙醇产量生成动力学模型中,SGompertz和Boltzmann模型的R^2分别为0.99905和0.999,2种模型均能产生很好的拟合效果;在还原糖基质消耗动力学模型中,DoseResp和Boltzmann模型的R^2都为0.98705,拟合系数一致,说明2种模型均可用于较好地描述发酵过程还原糖的消耗情况。所选模型拟合发酵过程是可行的,为菠萝蜜果酒工业化发酵工艺控制提供理论基础。     

微胶囊技术在啤酒生产中的应用研究

介绍了微胶囊固定化啤酒酵母细胞的原理以及研究了影响微胶囊稳定性的几个关键因素,阐述了微胶囊技术在啤酒连续生产应用中的可行性,结果表明连续发酵生产的啤酒与分批发酵相比,风味、口感都比较接近.     

指数流加模型在乙醇气提发酵过程中的应用研究

通过实验选择并考核了一个指数流加模型 ,同时也对比地考察了均速流加方式的发酵效果。结果表明 ,指数流加相比匀速流加过程的细胞生物量平均浓度增加了 1 2 2倍 ,乙醇生产速率和糖消耗速率分别提高到 3 0 1 g/(h·L)和 6 2 1g/(h·L) ,是匀速流加时的 1 2倍和 1 1 9倍。研究表明 ,在乙醇气提发酵过程中 ,如果选用适当的指数流加模型 ,就能够消除发酵过程中底物和产物的双抑制作用 ,简单而有效地改进现有的在线分离乙醇的连续发酵工艺 ,提高乙醇生产速率     

Fermentation characteristics of corn‐, triticale‐, and wheat‐based dried distillers' grains with solubles in barley‐based diets determined using continuous and batch culture systems

BACKGROUND: Dried distillers' grains with solubles (DDGS) are becoming increasingly available and popular as an alternative livestock feed. This study used continuous and batch culture techniques to compare the in vitro fermentation characteristics of diets containing corn‐, triticale‐ or wheat‐based DDGS at 200 g kg^?1 diet dry matter (DM) against a barley grain‐based control diet. RESULTS: In continuous fermentation of wheat DDGS diet, total volatile fatty acid (VFA) concentration was decreased by 15.7% across sampling times and NH₃ concentration was quadrupled compared with control, whereas fermentations of corn‐ and triticale‐DDGS diets were similar to the barley‐based control. In batch cultures, corn DDGS differed from control only in increased culture pH. Compared with control diet, triticale DDGS yielded lower total gas production (140.94 versus 148.78 mL g^?1 DM) and in vitro DM digestibility (IVDMD; 0.509 versus 0.535). Wheat DDGS diet yielded decreased total gas production (123.49 mL g^?1 DM) and IVDMD (0.468), as well as total VFA production (105.84 versus 134.20 mmol L^?1) and substantially increased ammonia concentration (151.61 versus 58.34 mg L^?1) and acetate:propionate ratio (2.94 versus 1.11). CONCLUSION: Corn‐ and triticale‐ DDGS diets exhibited fermentation characteristics similar to the barley based control diet, consistent with in vivo findings that these diets yielded no adverse effects on production. In vitro ruminal fermentation of wheat DDGS diet differed significantly from control in several aspects including 2.6 to 6X higher ammonia concentrations. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd