超高压均质参数对酵母破壁率的影响

利用超高压均质设备进行酵母破壁实验研究,考察酵母溶液浓度、均质压力和均质时间3个因素对酵母破壁率的影响。通过研究可知:酵母的破壁率随着溶液浓度的增加先增大后减小,浓度在10%左右达到最佳;破壁率随着均质压力的升高而增大,但上升梯度逐渐减小;破壁率随着均质时间的延长而增大并逐渐趋于水平,在超高压操作工况下,短时破壁即可达到较理想的效果。在实验范围内,酵母浓度10%、均质压力172 MPa和均质时间17 min为最佳工艺条件。实验研究为废酵母的加工和利用提供了参考依据。     

锁掷酵母破壁技术的研究

分析比较了酸热法、二甲基亚砜法、细胞自溶法、高压均质法及酶促法对锁掷酵母的破壁效果,及对类胡萝卜素提取率的影响。结果表明,与其他4种破壁方法相比,高压均质法具有破壁效果好（破壁率达72.4%）、类胡萝卜素提取率高（67.3%）、破壁时间短、工艺简单、安全无污染等优点。通过均质压力、均质次数和菌液浓度这3个因素对高压均质法进行工艺优化,发现均质压力80 MPa、均质3次、菌液浓度为8%时,细胞破壁及类胡萝卜素提取效果最佳,分别是78.3%和82.5%。该研究结果为锁掷酵母的开发利用及类胡萝卜素的提取提供了理论依据及技术支持。     

锁掷酵母破壁技术的研究

分析比较了酸热法、二甲基亚砜法、细胞自溶法、高压均质法及酶促法对锁掷酵母的破壁效果,及对类胡萝卜素提取率的影响。结果表明,与其他4种破壁方法相比,高压均质法具有破壁效果好(破壁率达72.4%)、类胡萝卜素提取率高(67.3%)、破壁时间短、工艺简单、安全无污染等优点。通过均质压力、均质次数和菌液浓度这3个因素对高压均质法进行工艺优化,发现均质压力80 MPa、均质3次、菌液浓度为8%时,细胞破壁及类胡萝卜素提取效果最佳,分别是78.3%和82.5%。该研究结果为锁掷酵母的开发利用及类胡萝卜素的提取提供了理论依据及技术支持。     

机械破壁和盐法结合从啤酒酵母中提取RNA

机械破壁法和盐法结合 ,在酵母浓度为 10 % ,高压均质破壁循环两次 ,盐浓度 5 % ,95℃下加热 3h ,RNA平均净得率 >3% ;将上清液回收利用 ,回用到第三次时 ,RNA净得率达 3.6 7%。     

从啤酒酵母中提取RNA新工艺的研究

研究了从啤酒酵母中提取RNA的新生产工艺,即在均质法和氨解法的基础上,将两者结合为均质-　氨解法。得出最佳工艺条件:酵母浓度10%,均质破壁循环2次,氨浓度0.6%,三氯乙酸浓度4%,提取30min。将上清液循环回用,RNA平均净得率>3%,第3次循环时净得率最高。     

微波辅助酵母破壁工艺的研究

研究微波功率、微波作用时间、酵母含量、pH值对酵母细胞破壁的影响。以破壁前后酵母细胞的数量和氨基酸态氮含量来衡量酵母细胞的破壁率,确定最佳破壁条件。通过单因素和正交试验。结果表明,在酵母含量为4%、pH 6.0、微波功率600W条件下,微波处理40min,添加1%的质量比为1∶1的木瓜蛋白酶和中性蛋白酶,3%的NaCl,在55℃恒温自溶2h后即可得到最佳的破壁效果。     

反复冻融和超声协同作用破碎酵母细胞

利用反复冻融法和超声波技术相结合的方法破碎啤酒酵母细胞壁,研究协同作用对酵母细胞破壁率的影响。研究结果表明:啤酒酵母先经反复冻融处理(加水量为25%、冻融4次),然后经过超声处理(超声功率400 W,每次辐射时间11 s,超声总时间14.5 min,酵母浓度20 mg/mL)进行破碎,破壁率达到了89.31%,且破壁率是反复冻融单独作用的2.4倍,是超声波单独作用的1.5倍。     

法夫酵母色素提取方法的研究

对法夫酵母色素的提取方法进行了研究。实验结果表明:在工业化生产中酸—热法是法夫酵母破壁较理想的方法。其最佳工艺条件为盐酸浓度3mol/L、盐酸用量9mL/g干细胞、浸泡时间20min、沸水浴时间4min,丙酮是较优越的色素浸提溶剂。在此条件下,法夫酵母破壁率达到95.8%,细胞碎片经丙酮浸提后,几乎为无色。     

甲醇酵母细胞破壁与蛋白纯化工艺研究

利用碱溶、离心、破壁、酸沉对甲醇蛋白粗品进行纯化。研究了适合于甲醇酵母细胞破壁及胞内蛋白纯化的条件。结果表明:热碱与高压均质联合处理法较生物酶解处理法、热碱处理法及高压均质处理法对细胞破壁效率高;采用p H 10.0、60℃热处理2 h,100 MPa压力均质3次,细胞破壁率可达87.6%;在p H 4.5时,破壁后上清液蛋白沉淀量最大,所得纯化甲醇蛋白中粗蛋白质含量达到82.5%,纯化效果较为理想。     

不同发酵法对油菜蜂花粉破壁的影响

采用自然发酵法、干性酵母直接发酵法、酵母发酵-酶解法对油菜蜂花粉进行破壁,比较3种破壁方法的破壁率、破壁花粉营养成分可溶性糖、游离氨基酸、总黄酮、维生素C及风味改善,从而筛选出最佳的破壁方法.结果表明,采用干性酵母直接发酵法、酵母发酵-酶解法得到的破壁率、营养成分及风味改善优于自然发酵法,从经济方面来考虑酵母发酵法为油菜蜂花粉的最佳破壁法.     

啤酒酵母中提取核糖核酸的研究

本实验采用食盐破壁法和高压均质破壁法提取啤酒酵母中的核糖核酸(RNA)。结果表明:在盐浓度为8%,温度为121℃,时间为30min,沉淀pH2的工艺条件下,RNA提取率为2.21%。高压均质压力为70MPa,均质3次的工艺条件下,RNA提取率为3.08%。     

Microfiltration of whey proteins adsorbed on yeast cells

Soluble whey proteins (WPs), adsorbed on yeast cells, were recovered by a crossflow microfiltration (MF) technique using a cellulose nitrate membrane with a pore size of 0.45 μm. The crossflow velocity was 1.5 m s^?1 with a transmembrane pressure of 200 kPa at 25 °C. A series of protein rejections occured at various pH values ranging from 2 to 8. WPs adsorbed more on to yeast cells at low pH (pH < 4) than at high pH values, probably because they were positively charged at low pH. It was also shown that permeate flux increased and Modified Membrane Fouling Index values decreased at low pH levels. When the yeast concentration was 50 g L^?1, the flux decreased five times compared with that in the absence of yeast. Protein recovery increased with increasing yeast concentrations. The highest protein recovery was found to be 85% at a yeast concentration of 50 g L^?1 at a steady state flux rate of 10^?6 m s^?1 at 25 °C. When diluted solutions of whey were used, the same rejection of protein, adsorbed on yeast cells, was achieved at ten times lower amounts of yeast cells. This technique not only provides for the recovery of protein but also may give rise to the direct use of yeast cells, which are rich in protein, in the baking industry. WPs absorbed by yeast cells can be used to produce nutritionally rich products in areas where yeasts have been already used.     

Characterization of membrane bioreactor for dry wine production

Characteristics of yeast growth and ethanol fermentation were examined in membrane bioreactor using a grape juice. After inoculation, batch fermentation was carried out for 24 h. When yeast growth reached the stationary phase, continuous fermentation was initiated. In continuous fermentation, a linear relationship was observed between cell concentration and dilution rate. In single-vessel membrane bioreactor, the cell concentrations of 18.7 g/l and 76.9 g/l (15 and 60 times higher than that of the batch fermentation, respectively) were observed at dilution rates of 0.1 h(-1) and 0.3 h(-1), respectively. The residual sugar concentration was higher than 10 g/l at the dilution rate of 0.1 h(-1), 0.2 h(-1) or 0.3 h(-1), therefore the single-vessel membrane bioreactor was not suitable for producing dry wine (sugar concentration: 4 g/l or less). In the double-vessel membrane bioreactor, it is most suitable to set the recycle ratio at 0.15 for keeping the sugar concentration below 4 g/l. The productivity of dry wine in the double-vessel membrane bioreactor was 28 times higher than that in the batch fermentation.     

酵母细胞破壁技术研究与应用进展

随着啤酒行业的发展,啤酒生产中带来的废酵母数量与日俱增,造成了环境污染,废酵母的再利用成为人们关注的焦点。酵母细胞内具有丰富的营养物质,充分利用这些营养物质需要对酵母细胞进行破壁,因而破壁技术就显得尤为重要。系统论述了当前破碎酵母细胞壁的方法和原理,以及各种方法的优缺点和应用现状,对酵母破壁技术的应用前景进行展望。     

Immobilised yeast grape must deacidification in a recycle fixed bed reactor

Maloalcoholic fermentation (MAF) of grape must by Schizosaccharomyces pombe immobilised in calcium‐alginate double‐layer beads (ProMalic^®) was studied in Erlenmeyer flasks and in a total recycle fixed‐bed reactor operating in batch mode. The reaction is pseudo‐first order with respect to l ‐malic acid and under similar conditions deacidification is faster in the recycle reactor. This was attributed to mass transfer limitations which were confirmed in the recycle reactor by studying the influence of yeast load on the rate of MAF. Mass transfer limitations are also responsible for the lower activation energy of fermentation with the immobilised yeast (67 ± 9 kJ mol^?1) in comparison with the free cells (126 ± 19 kJ mol^?1). Alcoholic fermentation and MAF were performed simultaneously, both in the recycle reactor and in the industrial trials, confirming the efficacy of immobilised S. pombe to reduce grape must acidity without interfering with the main fermentation. Altogether, the present results are useful for the scale‐up of a recycle reactor to process large volumes of grape must.     

Advanced Method for Measuring Proteinase A in Beer and Application to Brewing*

Proteinase A, excreted from yeast cells into beer during fermentation in the brewing process, has been shown to degrade foam-active proteins and to decrease foam stability. In order to improve the measurement of this enzyme in beer, a new fluorescent peptide, MOCAc-Ala-Pro-Ala-Lys-Phe-Phe-Arg-Leu-Lys (Dnp)-NH₂, was synthesised and applied to the accurate and rapid estimation of proteinase A in commercial beer and fermenting wort. This novel substrate is several hundred times more sensitive to proteinase A than other previously reported synthetic substrates or native protein substrates. The concentration of proteinase A in beer is closely related to foam stability and proteinase A activity was found to increase gradually during fermentation. The concentration of proteinase A excreted from yeast cells is also closely related to the vitality of pitching yeast cells. This new method was successfully applied to the evaluation of yeast vitality and the development of optimum yeast handling procedures.     

压力对啤酒酵母生长及某些发酵性能的影响

以气体为加压介质,研究了不同压力下酵母细胞生长及压力对酵母发酵性能的影响.高压对酵母细胞的生长代谢有明显的影响:压力使酵母细胞的比生长速率和生物量降低,细胞的倍增时间延长;电子显微镜显示,压力使酵母菌细胞的形态发生明显的改变;压力也导致酵母的发酵速度、耗糖率、乙醇生成量、双乙酰的生成和还原速率下降.     

压力影响酵母海藻糖生成的初步研究

初步探讨了压力对酵母菌生成海藻糖的影响，研究发现处理压力、处理时间、处理温度、pH值及酵母菌培养时间均对酵母胞内海藻糖的生成有显著影响，而且胞内海藻糖含量与菌体存活率之间呈一定的相关性；同时发现高压CO2对酵母海藻糖生成的影响是酸化作用、厌氧、压力多个因素综合作用的结果。     

利用固定化酵母进行黄酒主发酵的初步研究

该文以海藻酸钙凝胶为固定化载体,从酵母浓度、海藻酸钠浓度、氯化钙浓度3方面来探究黄酒主发酵阶段的最佳固定化条件,确定了酵母浓度为109个/mL,海藻酸钠浓度为2.0%,氯化钙浓度为4%。同时将其与传统游离酵母的发酵曲线进行对比,并且在实验室条件下连续进行了12次固定化酵母发酵,结果显示主发酵结束时酒样的酒精度在7.4%vol左右(与游离发酵结果类似),稳定性较为理想。