影响啤酒酵母自溶的因素分析

酵母自溶是酵母死亡后,胞内物质释放出来的过程。啤酒酵母发生自溶是一个不可避免的过程,本文从细胞、非生物因素、生物因素三个角度来讨论影响酵母自溶的因素。     

理化处理对啤酒酵母自溶的影响

利用酵母自溶动力学方程考察了温度、破壁酶、酵母预处理、酵母初始质量分数、盐等理化因素对啤酒酵母自溶过程的影响.温度对酵母自溶速度有很大影响.通过回归分析得到不同体系中反映自溶温度和速度常数关系的Arrhenius方程及相应的自溶反应的活化能Ea;破壁预处理能显著加速酵母自溶,添加破壁复合酶或食盐均有利于加速酵母自溶反应,但两者复合添加有相互抑制作用;酵母初始质量分数对自溶影响不大.     

减少酵母自溶改善啤酒口味

酵母性能受发酵过程及外部环境等因素的影响而发生变化，如何延长酵母使用寿命，降低因自溶给啤酒质量带来的不良影响．作者谈谈影响酵母自溶的因素和防止自溶的工艺措施。     

啤酒酵母自溶的危害及其影响因素

酵母是啤酒发酵的灵魂,因此酵母的好坏对啤酒发酵起到至关重要的作用。酵母自溶是酵母死亡后,胞内物质释放的过程。啤酒发酵过程中酵母发生自溶是不可避免的。从细胞、非生物因素、生物因素3个角度论述了影响酵母自溶的因素。     

酵母细胞自溶条件优化研究

以啤酒酵母为材料,通过单因素试验在自溶时间、温度、pH值、助溶剂及外加酶等因素中确定对酵母自溶影响关键的因素,然后根据Box-Benhnken的中心组合试验设计原则,选取对酵母自溶影响较大的3个因素,即自溶温度、pH值和加酶量进行试验和响应面分析,得出啤酒酵母自溶的最佳条件为每100g酵母泥中添加NaCl 3g、β-葡聚糖酶0.3g,控制自溶温度55.7℃、pH5.9,经过18h自溶后,酵母自溶液中氨基酸态氮含量可达0.592g/100mL。     

利用啤酒废酵母开发功能性液态调味剂的研究

为了得到利用啤酒废酵母生产功能性调味剂的最佳工艺流程;试验在前期啤酒废酵母的脱苦工艺和自溶条件单因素研究的基础上,对啤酒废酵母的自溶条件进行正交试验,并对功能调味剂的调配进行正交试验;结果表明:废酵母自溶的最佳自溶条件为pH 7.0、自溶温度55℃、自溶时间60h,影响因素依次为自溶时间>pH>自溶温度;功能性调味剂最优调配组合为糖1%、酒精2%、酱色1%,对调味剂风味的影响因素依次为:酒精>酱色>糖。     

响应面法优化啤酒酵母抽提工艺条件的研究

以啤酒酵母为原料,通过单因素试验在自溶时间、温度、pH值及助溶剂等因素中确定对酵母自溶影响最为关键的因素,然后根据Box-Benhnken的中心组合试验设计原则,选取对酵母抽提影响较大的3个因素:自溶时间、自溶温度和pH值进行实验和响应面分析,得出啤酒酵母抽提的最佳工艺条件:在NaCl添加量为3%的条件下,自溶时间18.5h、自溶温度56.8℃和pH6.03,在此条件下酵母抽提液中氨基氮含量可达0.44g/100mL。     

利用活性干酵母制备酵母抽提物的工艺研究

以活性干酵母为原料,采用自溶-酶联技术制备酵母抽提物。以氨基氮得率和抽提物得率为主要指标考察了对酵母自溶影响关键的几个因素,包括自溶温度、酵母悬浮液浓度、自溶pH值、外加破壁酶的种类、外加蛋白酶的种类及添加量、自溶促进剂,并在此基础上对酵母酶联自溶进行正交试验,最后确定了酵母酶联自溶的时间。结果表明:自溶-酶联技术是制备酵母抽提物的理想方法,在最佳工艺条件下制得的酵母抽提物氨基氮得率和抽提物得率分别达到3.19%和51.31%。     

酵母自溶对啤酒生产的影响及预防措施

发酵过程实际是酵母代谢过程，酵母性能受发酵条件等因素影响不可避免出现酵母衰老、死亡与自溶。如何减少酵母自溶，是保证啤酒质量稳定的基础。     

不同促溶剂对酵母细胞在发酵液中自溶的影响

通过添加不同促溶剂研究酵母细胞在发酵液中的自溶情况。对影响酵母细胞内容物的溶出率的各因素进行单因素试验,并设计正交试验进行各因素参数优化。正交试验结果表明,以NaCl为促溶剂的酵母发酵液内的自溶条件为pH5.0、温度50℃、时间48h、NaCl添加量为9%,测得酵母细胞在发酵液内自溶率达到49.30%;以β-葡聚糖酶为促溶剂的酵母发酵液内的自溶条件为pH6.5、温度55℃、时间24h、酶添加量为0.6%,测得酵母细胞在发酵液内自溶率达到49.98%;以木瓜蛋白酶为促溶剂的酵母发酵液内的自溶条件为pH 6.0、温度60℃、时间72h、酶添加量1%,测得酵母细胞在发酵液内自溶率达到51.53%。     

啤酒酵母自溶条件的优化及其抽提物的挥发性风味成份

本文研究了添加硫胺素、葡萄糖、缓慢加热对啤酒酵母自溶的影响,正交试验表明:pH5.5、温度57℃、添加硫胺素0.10％(W/W)、升温时间60分可使自溶时间缩短至6～8小时。 本文还研究了添加中性蛋白酶1398的酵母自溶。在正交试验选出的条件下,自溶时间及蛋白质、氨基酸得率都不及前述工艺。 用SDE分离得到自溶抽提物的挥发物,并用GC-MS鉴定了63化合物。其中含硫化合物20个。     

Yeast autolysis in sparkling wine – a review

Sparkling wine produced by the traditional méthode champenoise requires a second in-bottle alcoholic fermentation of a base wine, leading to the sparkling wine. This second fermentation is followed by prolonged ageing in contact with yeast cells (lees). The autolysis of yeast occurs during the ageing of sparkling wines. During this process, the yeast releases different compounds that modify the organoleptic properties of the wine. The ageing period is required to give these wines their roundness and characteristic aroma and flavour. Autolysis products also influence the foaming properties of sparkling wine. Yeast autolysis is characterised by the hydrolysis of intracellular biopolymers by yeast enzymes activated after cell death. This results in the release of low molecular weight products. This article reviews the recent advances in understanding the yeast autolysis mechanism, the factors affecting autolysis, the nature of the released compounds and their effects on sparkling wine quality.     

Autolysis of Squid Mantle Muscle Protein as Affected by Storage Conditions and Inhibitors

Autolysis of squid mantle muscle was investigated under various conditions using muscle homogenate as a model system. Cleavage of myosin into heavy and light meromyosin was prominent during autolysis. Storage conditions such as NaCl concentration and temperature affected not only the rate of autolysis but also the products formed. Conditions for maximal autolysis were: NaCl concentration 0.3M, pH 7 and temperature 40°C. Autolysis was well inhibited by ethylenediaminetetra acetic acid and Na-pyrophosphate at <25°C and by phenyhnethylsulfonyl fluoride and chymotrypsin inhibitor extracted from potato tuber at >35°C suggesting two different types of proteinases were involved.     

Autolysis of Lactobacillus sanfranciscensis

 Autolysis of Lactobacillus sanfranciscensis in phosphate buffer was strain-dependent and maximal in the exponential growth phase and at pH 5.6. It decreased to 15% of the maximum at pH 4.5. In culture medium, autolysis did not correspond to the cell death rate because the low pH reached after fermentation limited it markedly. Appreciable autolysis was only found when buffering citrate or fumarate were added to the culture medium. Leakage of peptidases from cells to the culture medium confirmed the autolysis. Renaturating SDS-PAGE showed an autolytic profile composed of four clean lytic bands of ca. 102, 87, 76.5 and 61.5 kDa. This profile was observed in all strains and did not vary with the growth phase or with the use of the crude cell-envelope or crude extracts. Sourdough fermentations lasting 24–48 h showed no differences in the leakage of peptidases when strains which differed greatly for autolysis were compared. However, if citrate was added to the dough it enhanced the release of intracellular peptidases by fast autolytic strains because of the less acidic conditions which favored microbial autolysis during sourdough fermentation. Received: 5 February 1999     

Autolysis of shrimp head by gradual temperature and nutritional quality of the resulting hydrolysate

Autolysis method was investigated for protein recovery from shrimp head (SH) of white shrimp (Penaeus vannamei). Autolysis of SH by several temperature conditions (40 °C, 50 °C, 60 °C and gradual temperature) at its initial pH showed protein recovery of 43.6%, 73.6%, 50.3% and 87.4%, respectively. Autolysis of SH by gradual temperature (temperature was risen 5 °C every half an hour, from 40 °C to 70 °C) served best for the preparation of autolysis hydrolysate (AH) with the maximum degree of hydrolysis (DH) 48.6% and the maximum protein recovery 87.4%. Subsequently, the chemical components of SH and its AH obtained by gradual temperature were investigated and comparably evaluated. Protein contents of SH and AH by gradual temperature method amounted to 60.6% and 88.8% (dry basis), respectively. Both SH and AH had high contents of tasting or functional amino acids. The contents of essential amino acids (EAA) of SH and AH were 340.26 and 405.30 mg/g protein, respectively. The amino acids scores of SH and AH were 73 and 96, respectively. The EAA of AH covered 96-100% of the FAO/WHO ideal protein. The high performance size exclusion chromatography of AH showed that with the increasing of DH values, there occurred a larger amount of smaller polypeptides with molecular weight <5000 Da. The nutritional value of SH could be greatly enhanced by gradual temperature autolysis.     

酵母自溶研究

该文详细研究了酵母自溶酶类,作用机理,自溶过程中酵母细胞结构的变化,大分子物质的降解模式,为酵母抽提物的生产提供了理论依据。     

酵母天然自溶促进剂筛选

以酵母为研究对象,采用纸片法筛选抗菌物质,七叶一枝花、桔梗、大黄、牛蒡子、八角茴香、秦皮具有抗菌活性。抗菌物质促进菌体蛋白降解为水溶性蛋白,并提高菌体破坏细胞结构相关酶的活性;对将蛋白质完全水解成氨基酸的相关蛋白酶活性影响小,七叶一枝花还有一定抑制作用。八角茴香用量少时,可溶性蛋白含量随着八角茴香水提液用量增加而增加,桔梗对菌体细胞结构破坏相关酶活性的激活作用容易达到饱和,桔梗、八角茴香药食兼用,适合作为酵母天然自溶促进剂。     

Autolysis of selected Lactobacillus helveticus adjunct strains during Cheddar cheese ripening

Cheddar cheeses were manufactured on a pilot scale (500 L vats) with three different Lactobacillus helveticus strains, which showed varying degrees of autolysis, added as adjuncts to the starter. Autolysis of adjunct strains was monitored by reduction in cell numbers, level of intracellular enzymes released into the cheese, and by the consequent changes in the degree of proteolysis and concentration of free amino acids in the cheese. The flavour profiles of the cheeses at 6 months were also determined. Significant variation in viability of the Lb. helveticus strains, which showed a positive correlation with the indicators of autolysis, was observed. However, cheese manufactured with the most autolytic strain did not receive the highest flavour scores. The results indicate that whereas autolysis of adjunct strains is an important factor in Cheddar cheese flavour development, other factors also contribute to the overall flavour improvement observed.     

几种不同来源酵母浸出物对典型酵母菌生长的比较研究

选取5种国内外著名企业生产的酵母浸出物(Yeast Extract,YE)进行组分含量分析,并分别作培养基氮源,研究它们对3株供试酵母菌——葡萄汁酵母(Saccharomyces uvarumBeijerinek)、假丝酵母(CandidaBerkhout)、球拟酵母(Torulopsis Berlese)生长的影响。结果表明:一种国内酵母浸出物总氮、氨基氮及核酸含量最高;在促进三株酵母菌生长方面,一种国产酵母浸出物均优于国外生产的三种酵母浸出物。同时,国产酵母浸出物的售价要远远低于国外产品,这对发酵企业降低生产成本具有重要意义。     

Autolysis of goatfish (Mulloidichthysmartinicus) mince: Characterisation and effect of washing and skin inclusion

Autolysis of goatfish mince and washed mince incubated at different temperatures (30–70 °C) was investigated. The highest autolytic activity was generally observed in mince and washed mince at 60 °C as evidenced by the highest trichloroacetic acid (TCA) soluble peptide content and the greatest disappearance of myosin heavy chains (MHCs). Autolysis of both mince and washed mince was maximised at pH 4, and lower autolytic activity was observed at pH 7. trans-epoxysuccinyl-l-leucyl-amido (4-guanidino) butane (E-64) showed the greatest inhibition of autolysis at pH 4, showing that at least one cysteine protease was active in goatfish muscle. Nevertheless, soybean trypsin inhibitor effectively inhibited the autolysis at neutral pH (pH 7), suggesting that goatfish muscle also contained at least one serine protease. Generally, autolysis of mince was more pronounced than that of washed mince, indicating that washing could lower the autolytic activity of mince. In the presence of skin, a higher autolysis was obtained with the goatfish mince. Therefore, both sarcoplasmic and myofibril-associated proteases in muscle as well as the contamination of skin likely contributed to the degradation of muscle proteins of goatfish.