The influencing factors of yeast and cell death

Summary: in beer brewing beer yeast is of vital importance. Due to many environmental factors in the process of brewing, there will be a part of the yeast death, even produce autolysis. When there are more than 5% of the beer in beer yeast autolysis, produces obvious beer yeast flavour, bitterness and astringency, and associated with other aspects of the quality problems. Yeast autolyzed yeast is aging death, in the actual production can't completely prevent yeast autolysis, can only control the limits of yeast autolysis. The following talk about death and environmental factors on the yeast autolysis. The wort extract oxygen and cultivate certain cases, the effect of the temperature of the wort of beer yeast nutrients metabolism is very important. Alpha in the wort Amino nitrogen, fermentable sugar, PH value, the inorganic ions and auxin nutrients such as unreasonable, poor nutrition can lead to yeast, slow metabolism, yeast aging, leading to the possibility of death and autolysis of yeast. Such as wort cold coagulation precipitation is not complete, into yeast fermentation necessarily hinder reproduction, metabolism, reduce the activity of the yeast, the yeast cell aging, death, and autolysis. 25 mg/L, but not more than 2 mg/L. If zinc ion content, such as alcohol dehydrogenase intracellular enzyme activity decreased obviously, cause yeast breeding, fermentation at a slower pace slow; If zinc ion concentration is too high, can promote the growth of yeast metabolism, but easy to aging, yeast autolysis. The copper ion content of wort was above 0. LPPM, easily induced yeast, inhibit the activity of enzyme. Tin lead ions and bivalent ions, heavy metal ions, such as ion of hexavalent chromium has toxicity to the yeast, deprive beer yeast activity. Wort iron ions content is higher than 1. 0 mg/L. Also can make yeast premature aging, increase the probability of death and autolysis. Nitrite ion of the yeast cells with a strong toxicity, lose beer yeast activity. Fluorine ion and nitrate ions could also change the yeast genetic, inhibit the growth of yeast fermentation and silicon oxide ion combined with proteins to form silicon body cloudy, during fermentation form micelles, adsorption on the surface of yeast, reduce the yeast metabolism ability. Lack of effective phosphorus content in the wort beer yeast during whole process of life will be adversely affected. Dissolved oxygen (do) when the lack of dissolved oxygen in wort and beer yeast proliferation rate fell, the new robust beer yeast decrease, easy cause yeast cell death of aging. In han sunni cans or storage tank preserve beer yeast yeast, the yeast contact with oxygen, may exacerbate yeast and cell death. Fermentation conditions of fermentation medium and high or low temperature, reduction temperature, step up too late. Will promote the degradation of beer yeast, increase mortality. After the fermentation, diacetyl reduction, should be timely discharge cone at the bottom of the pot of beer yeast, if you don't net emissions, cooling at the bottom of the difficulties, temperature rise, easy cause death, yeast autolysis. Yeast mud without washing, In traditional fermentation) Directly for conical tank do other type of yeast, must take part of aging, death, yeast, increases the chances of autolysis. Under the condition of low temperature, temperature can occur in a yeast autolysis, is just a cell (at a slow pace. As temperatures rise, beer yeast autolysis. Increase fermentation temperature, can make the yeast metabolism faster, shortening the fermentation time, but is easy to cause the increase of harmful by-products generation, but also accelerate the aging of beer yeast. Conical tank, yeast improper storage tank design, namely the bottom without cooling system or insulation device, the deposition in the bottom of the beer yeast is higher than the upper 3 ~ 6 ℃ temperature, increase the mortality rate of the yeast. Pressure effects can sealing pressure is too high, some yeast cells die. Recycling, add yeast, differential pressure change is too big, will cause the burst of yeast cell wall, adding yeast mortality. Yeast addition amount reproduce cans or high filled with cans of yeast in fermentation tank, More than 28. 00 x 106 / ml) , the alpha a amino nitrogen in wort rapidly assimilated, will cause the growth of yeast breeding algebra is relatively small, the new yeast concentration is too low, lack of nutrition, late yeast is dead. If autolyzed yeast inoculation use, will cause a vicious circle. Miscellaneous bacterium in the fermented liquid of wild yeast and bacterial leaching are inevitably hurt beer yeast, showed a higher mortality rate. High concentrations of adding hop hop extract yeast activity will also be affected. When adding enzymes enzyme preparation in the fermented liquid yeast using algebra is unfavorable and exorbitant, because enzyme preparation can promote the dissolution of yeast cells, leading to increased mortality. So using enzyme preparation must be discreet, with accurate amount, adding time is reasonable, the quality of enzyme preparation. Can secrete a variety of beer yeast autolysis enzyme, the optimum PH of these autolytic enzyme is 6 ~ 8. Fermented liquid PH too high or too low, is not conducive to normal growth, and yeast fermentation. Flush time reproduce cans, conical tank, storage tank with chlorine dioxide and hydrogen peroxide sterilization after rinse time is too short, Within 15 minutes) Chloride ion concentration at more than 100 mg/l, can make the beer yeast premature aging, so, after the sterilization time should be more than 40 minutes, wash with water. The company's web site: tranogroup. com