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Dark malts used in the production of brewing wort affect the ethanol fermentation process, the phenolic content, antioxidant capacity and the physiology of yeast cells. An innovative element of this research is the combination of investigating the effect of beer wort color modulated by the use of dark specialty malts on the course and effects of fermentation and the characteristics of post-fermentation yeast biomass of brewer’s strains with different characteristics. Dark and pale beer were obtained. The beers had different ethanol contents (4.51–5.79% v/v), resulting from real (62.29–80.36%) and apparent (75.37–98.26%) attenuation levels. Metabolic and morphological differences were demonstrated in the brewer’s yeast strains used. S. cerevisiae var. diastaticus was distinguished by its ability to ferment dextrin, resulting in the highest ethanol content in beers. The total phenolic content in beer depends on the color of the wort and the yeast strain used (244.48–547.56 mg of gallic acid/L). Dark beers show higher ferric ion reduction ability (FRAP) and antioxidant capacity (ABTS•+) than pale beers fermented with the same yeast strains. Through biomass analysis, differences in yeast cell physiology depending on yeast strain and beer wort color were also revealed. 相似文献
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Dr. Gopal Sirasani Liuchuan Tong Prof. Emily P. Balskus 《Angewandte Chemie (International ed. in English)》2014,53(30):7785-7788
Organic chemists and metabolic engineers use orthogonal technologies to construct essential small molecules such as pharmaceuticals and commodity chemicals. While chemists have leveraged the unique capabilities of biological catalysts for small‐molecule production, metabolic engineers have not likewise integrated reactions from organic synthesis with the metabolism of living organisms. Reported herein is a method for alkene hydrogenation which utilizes a palladium catalyst and hydrogen gas generated directly by a living microorganism. This biocompatible transformation, which requires both catalyst and microbe, and can be used on a preparative scale, represents a new strategy for chemical synthesis that combines organic chemistry and metabolic engineering. 相似文献
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Izabela Podgrska-Kryszczuk Ewa Solarska Monika Kordowska-Wiater 《Molecules (Basel, Switzerland)》2022,27(5)
Mycotoxins, toxic secondary metabolites produced by fungi, are important contaminants in food and agricultural industries around the world. These toxins have a multidirectional toxic effect on living organisms, causing damage to the kidneys and liver, and disrupting the functions of the digestive tract and the immune system. In recent years, much attention has been paid to the biological control of pathogens and the mycotoxins they produce. In this study, selected yeasts were used to reduce the occurrence of deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEA) produced by Fusarium culmorum, F. graminearum, and F. poae on wheat grain and bread. In a laboratory experiment, an effective reduction in the content of DON, NIV, and ZEA was observed in bread prepared by baking with the addition of an inoculum of the test yeast, ranging from 16.4% to 33.4%, 18.5% to 36.2% and 14.3% to 35.4%, respectively. These results indicate that the selected yeast isolates can be used in practice as efficient mycotoxin decontamination agents in the food industry. 相似文献
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Terpenoid Biosynthesis Off the Beaten Track: Unconventional Cyclases and Their Impact on Biomimetic Synthesis 下载免费PDF全文
Martin Baunach Jakob Franke Prof. Dr. Christian Hertweck 《Angewandte Chemie (International ed. in English)》2015,54(9):2604-2626
Terpene and terpenoid cyclizations are counted among the most complex chemical reactions occurring in nature and contribute crucially to the tremendous structural diversity of this largest family of natural products. Many studies were conducted at the chemical, genetic, and biochemical levels to gain mechanistic insights into these intriguing reactions that are catalyzed by terpene and terpenoid cyclases. A myriad of these enzymes have been characterized. Classical textbook knowledge divides terpene/terpenoid cyclases into two major classes according to their structure and reaction mechanism. However, recent discoveries of novel types of terpenoid cyclases illustrate that nature’s enzymatic repertoire is far more diverse than initially thought. This Review outlines novel terpenoid cyclases that are out of the ordinary. 相似文献
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阴极溶出伏安法测定硒酵母中微量硒 总被引:2,自引:1,他引:2
建立了用阴极溶出法测定硒酵母中硒含量的分析方法。硒酵母样品用H2 SO4 -HClO4 -Na2 Mo4 消解液消解 ,用浓HCl加热还原Se (Ⅵ )为Se (Ⅳ ) ;三电极包括汞膜电极 (工作电极 ) ,Ag -AgCl (参比电极 ) ,Pt电极 (辅助电极 ) ,优化条件为 :支持电解质为 3mol LHCl,预电解电位为 -2 0 0mV ,富集时间为 1 5 0s ,峰电位在 -0 4 4V。测定Se (Ⅳ )的标准曲线线性范围为 1 0~ 80 μg/L。测定硒酵母中的硒的结果为 8 1 0× 1 0 -3 ,与分光光度法测定结果相比 ,相对误差为7 2 %。 相似文献
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对盐碱法提取酵母核酸进行了研究。结果表明,最佳提取条件为提取温度85℃,提取pH为7.5,NaCl的含量为6.5%,提取时间180 min,对酵母核酸的平均提取率达到5.70%。 相似文献
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气相色谱-质谱法测定富硒酵母中的硒蛋氨酸 总被引:6,自引:0,他引:6
建立了气相色谱-质谱(GC-MS)测定富硒酵母中硒蛋氨酸含量的方法。比较了3种从样品中提取硒蛋氨酸方法的效果。样品在三羟甲基氨基甲烷(Tris)缓冲液中酶解24 h后,以丁醇及三氟乙酸酐为衍生化试剂对硒蛋氨酸进行衍生化,采用选择离子模式对衍生物进行GC-MS测定。硒蛋氨酸的回收率为98.5%~103.7%,相对标准偏差为0.9%~2.4%,检出限为0.5 mg/L(S/N=3)。对实际样品进行测定,得到样品中硒蛋氨酸的含量结果。该法简便快速,准确可靠,灵敏度高。 相似文献
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微量元素硒治疗肝病138例的探讨 总被引:3,自引:0,他引:3
汪俊之 《广东微量元素科学》2003,10(6):32-33
用西维尔(硒酵母片)治疗了肝病138例,对其疗效进行了观察和探讨。结果表明,硒对各种肝炎、肝肿大者疗效显著;对已患肝癌或肝硬化者疗效不明显。 相似文献
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In this paper, the separation and determination of the sweetener aspartame by ion chromatography coupled with electrochemical amperometric detection is reported. Sodium saccharin, acesulfame-K and aspartame were separated using 27.5 mmol/l NaOH isocratic elution on a Dionex IonPac AS4A-SC separation column. Aspartame can be determined by integrated amperometric detection without interference from the other two sweeteners. The method can be applied to the determination of aspartame in powered tabletop, fruit juice and carbonated beverage samples, and the results obtained by integrated amperometry were in agreement with those obtained using a UV detection method. A method for determining analytes with an NH2 group by ion chromatography with integrated amperometry was developed. 相似文献
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The interaction of metal complex with RNA has been studied by isothermal titration calorimetry (ITC) for the first time. ITC experiments show that complex [Ru(phen)2MPIP]^2 {phen= 1,10-phenanthroline, MP[P-2-(4-methylphenyl)imidazo[4,5-f]-1, 10-phenanthroline} interacts with yeast tRNA in terms of a model for a singleset of identical sites through intercalation, which is consistent with our previous observation obtained from spectroscopic methods, and this binding process was driven by a moderately favorable enthalpy decrease in combination with a moderately favorable entropy increase, suggesting that ITC is an effective method for deep studying the interactions of metal complexes with RNA. 相似文献
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Baker's Yeast Mediated Reduction of Optically Active Diketone 总被引:1,自引:0,他引:1
Xiao Lei GAO Gang ZHOU Yu Kun GUAN Wei Dong LI Yu Lin LI* National Laboratory of Applied Organic Chemistry Institute of Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2001,(4)
Baker's yeast (BY) mediated reduction of synthetic substrate is a useful method for preparing chiral intermediate in synthesis chemistry1,2, because it is readily available and inexpensive. The selectivity is generally predicted by Prelog rule3, that is, a hydride is transferred to the re face of the prochiral ketone.The baker's yeast mediated reduction of bicyclic diketones was previously reported by several groups4-6, but to our knowledge, no application of this reduction to sesquiter-pene-… 相似文献
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采用连续浸提、氢化物发生一原子荧光法测定研究了富硒酵母中硒的赋存形态。结果表明,富硒酵母中不同形态的硒所占比例从高到低顺序为:碱溶态,水溶态,盐溶态,醇溶态,残渣态;酵母硒中有机态硒达78%以上,主要以碱溶态形式存在。 相似文献
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稀土元素对铬酵母中铬含量影响的研究 总被引:3,自引:0,他引:3
研究了稀土化合物在铬酵母制备过程中对总铬和有机铬含量的影响作用。镧、铈、镨、钕等轻稀土化合物均能明显提高铬酵母中总铬和有机铬的含量 ,其中镧化合物对铬酵母中总铬和有机铬含量的提高作用最显著 ,总铬含量可达到 70 8.33μg·g- 1 ,有机铬含量可达到 6 39.0μg·g- 1 ,是未加稀土铬酵母样品的近 3倍 ;添加钕化合物的铬酵母中有机铬占总铬的比例最高 ,可达到 97.5 %。通过紫外光谱分析 ,发现有机铬在 2 6 0nm处有特征吸收峰 ,通过红外光谱分析 ,发现有机铬在 478cm- 1 处有特征吸收峰 ,而加稀土化合物的铬酵母样品在此两处的吸收峰值均高于未加稀土的铬酵母样品 相似文献