目的:以甘肃省靖远县枸杞为原料,研究枸杞多糖(Lycium barbarum polysaccharides,LBP)的提取工艺,并对其单糖组成进行分析.方法:采用响应面法,考察时间、液料比和温度对LBP提取产率的影响,从而优化提取工艺.利用柱前衍生化高效液相色谱(high performance liquid chromatography,HPLC)法,对LBP的单糖组成进行测定.结果:LBP的最佳提取工艺为:时间3.9 h,液料比36.6:1,温度93.2℃,此时产率为4.28％.柱前衍生HPLC法测定结果表明,LBP由甘露糖、鼠李糖、半乳糖醛酸、葡萄糖、半乳糖和阿拉伯糖6种单糖组成,其含量比例为4.98:2.93:8.38:22.44:25.38:35.89.结论:LBP提取的最佳工艺稳定可行,可为其生产提供理论依据;使用柱前衍生化HPLC法测定LBP单糖组成操作简便、准确度及重复性好,可作为LBP的质量控制方法.

研究不同取代度羧甲基酵母葡聚糖(CMG)体外抗氧化活性,并优化具优体外抗氧化活性的羧甲基酵母菌葡聚糖(CMG)的制备工艺.通过清除羟基自由基和ABTS+·和螯合Fe2+试验来考察取代度对羧甲基酵母葡聚糖(CMG)体外抗氧化活性的影响;在单因素试验的基础上,采用响应面分析中的Box-BehnknDesign建立数学模型确定取代度为0.8羧甲基酵母葡聚糖(CMG)的制备工艺.结果表明:结合体外抗氧化活性和实际生产情况,决定优化取代度为0.8的羧甲基酵母葡聚糖(CMG);取代度为0.8CMG制备工艺为氢氧化钠和葡聚糖的质量比3.2,氯乙酸和氢氧化钠的质量比1.5,羧甲基化时间2.0h,碱化时间1.5h.使用此工艺制备出取代度为0.784的CMG.

利用80 MeV/u能量的12C6+重离子束辐照处理面包酵母(Saccharomyces cerevisiae),经过发酵培养筛选,获得了9株高产β-葡聚糖的突变菌株,其中突变菌株YH-11的β-葡聚糖产量高达1.4833mg/mL,比出发菌株YS-00 β-葡聚糖产量高73％.不同培养基条件碳源、氮源及金属离子浓度的改变对酵母菌β-葡聚糖产出能力影响的发酵实验表明,最佳培养条件是2％葡萄糖、1％牛肉膏,以及0.1％的KH2PO4和Mg2SO4,在此实验条件下,突变菌株YH-11的β-葡聚糖产量高达1.4833 mg/mL,较出发菌株YS-00产量提高了1.73倍.实验证明,重离子辐照技术是一种高效的微生物诱变育种手段,在未来的微生物发酵工业应用中具有广阔发展前景.

综合讨论了世界范围内食源性疾病的发展及食品辐照技术的应用现状,综述了国内外辐照技术控制生鲜食品病原菌的研究进展,并对辐照食品的安全性和受照剂量问题进行了探讨.未来的研究,将继续积累生鲜食品中对电离辐射敏感的病原菌数据,重点探索影响辐照的因素和机理,从辐照组合处理方法入手,建立和完善各种食品辐照的剂量、工艺程序和操作规范.

试验旨在研究甜高粱饲料青贮过程中窖池温度变化对复合微生物菌剂青贮饲料品质的影响.在甜高粱渣中接种3种复合微生物菌剂,研究窖池的高、中、低层温度变化及温度对青贮饲料品质的影响.结果表明:窖池昼夜温差为5℃,有显著差异(P＜0.05);稳定发酵时窖池高、中、低层平均温度分别为37.85℃、36.60℃、35.44℃,有显著差异(P＜0.05);在窖池中层,青贮饲料粗蛋白质含量为5.09％,明显高于窖池高、低层饲料粗蛋白质含量(3.71％、3.76％)(P＜0.05);窖池中层青贮饲料乳酸含量比窖池高、低层乳酸含量分别提高了12.92％、1O.18％(P＜0.05),中层青贮饲料丙酸含量比窖池高、低层分别提高了38.07％、29.68％(P＜0.05);窖池温度变化对青贮饲料pH值、乙酸含量的影响没有显著性差异(P＞0.05).窖池中层温度有利于青贮复合微生物菌剂提高甜高粱青贮饲料品质.

A mutant bread yeast strain with high protein content of 55% was gained by use of 12C6+ ions.The MINITAB 16.0 software,Plackett-Burman experimental design and response surface methodology were applied to optimize the culture medium for the irradiated yeast.The most important three factors which influenced the culture results were identified as glucose,magnesium sulphate and yeast extract.The path of the steepest ascent was undertaken to approach the optimal region of the three significant factors.Box-Behnken design and response surface methodology were used for the regression analysis.Finally,the optimal fermentation conditions were identified as glucose 11.03 g/L,yeast extract 6.53 g/L and magnesium sulphate 5.59 g/L by the regression analysis.It was found that the biomass of the bread yeasts reached 4.84 g/L and increased by 15% compared to original conditions.

The DNA of organism can be damaged by the direct and indirect effect of heavy ion irradiation included the chain interruption of DNA,the insertion and missing of base and oxidative damage.The lesions of DNA are detrimental to organism,since they will impact replication,transcription and protein synthesis immediately.At the same time,they also are the significant cause leading to mutation.Therefore,the system of DNA damage repair is distinctly important to organism.In Saccharomyces cerevisiaes,which is used as model organism for the research eukaryotes,these damage are repaired by the pathways of HHR,MMR and BER which have been studied broadly and emerged numerous achievement continually.In particular,both relevant pathways and protein are always a hot research area.In this paper,the recent findings on the approach of DNA damages repair in S.cerevisiae are reviewed.

Five mutants with high ability of producing alcohol were selected out by using TTC as an indicator after irradiation of the alcohol yeast with 100 MeV/u carbon ions.The fermentation experiment in sweet sorghum juice showed that the alcohol production ability of mutant T4 strain increased 18.6% compared to the control strain.The residual sugar content in the juice was decreased too.After that,the optimum fermentation conditions of the T4 strain in sweet sorghum juice were investigated.The results showed that the optimum temperature and pH value for fermentation were 30 ℃ and 4.5,respectively.The verification experiment was fermented in a 10 l bio-reactor and the obtained data indicated that the fermentative rate and the ability of producing alcohol in T4 strain was higher than that in the control strain under the same fermentation condition.

As a substitute for food supplies, sweet sorghum juice with high grade has demonstrated outstanding advantage in fermentation. To obtain the optimized fermentation conditions, the growth, the bio-mass of bread yeast cultured in sweet sorghum juice and total residual sugar were investigated in the paper. The fermentation was performed and optimized in a 10—100 l bio-reactor. The results show that the application of sweet sorghum juice in bread yeast production is very potential.