过氧化氢酶催化反应中以靛蓝胭脂红为供氢体的研究

在HAc—NH4Ac缓冲体系中，过氧化氢酶可催化过氧化氢氧化靛蓝胭脂红褪色，过氧化氢浓度在0-0．6μg／ml范围内与△A值成线性，工作曲线的相关系数为0．9976，测定0．4μgH2O2回收率为100．8％，将此体系与葡萄糖氧化酶催化反应联用，测定了人血清中的葡萄糖含量，结果满意。     

Effect of hydrogen peroxide and ozone treatment on improving the malting quality

The effect of hydrogen peroxide (HP) and ozone (O₃) treatment during barley steeping on the quality of malt produced from two barley varieties (GrangeR and AC Metcalfe) by micro-malting was investigated. The two steeping oxidation treatments that was observed to promote barley acrospire growth. Ozone treatment improved the malt enzyme activity of endo-protease, α-amylase, free beta-amylase and total limit dextrinase to differing extents, with GrangeR improving to a greater degree. HP treatment contributed to the increase of α-amylase, β-glucanase and endo-protease. Surprisingly, HP or ozone oxidation during malting resulted in different and novel outcomes for total beta-amylase in GrangeR and AC Metcalfe. In GrangeR, total beta-amylase activity reduced with respect to the control in both treatments. In comparison with AC Metcalfe there was a substantial increase of 78% with HP and 90% O₃ in total beta-amylase activity. Malt quality including wort free amino nitrogen, β-glucan, turbidity and diastatic power was differentially increased by the oxidation induction treatment during steeping in malting. Gene expression analysis indicated that the effects of the steep oxidation treatments on enzyme and malt quality were putatively linked with the up-regulation of certain genes involved in GA synthesis (GA20ox1) and ABA catabolism (ABA8′OH). Barley grain germination assay results also showed that moderate HP induction could improve barley germination tolerance to the ABA effect. Malting including steep oxidation induction was shown to be beneficial to malt quality by improving the resultant wort quality and the efficiency of the beer brewing process. These observations point the way towards improving malt quality and the efficiency of the malting process.     

过氧化氢氧化对甲基苯甲醛制备对甲基苯甲酸研究

[目的]探讨过氧化氢氧化对甲基苯甲醛制备对甲基苯甲酸的工艺条件。[方法]以30%过氧化氢为氧化剂,在碱性条件下氧化对甲基苯甲醛制备对甲基苯甲酸,采用正交试验探讨了对甲基苯甲酸的最佳合成工艺条件,并通过测定熔点、红外光谱表征了目标化合物。[结果]优化的合成条件为:物料摩尔比对甲基苯甲醛∶30%过氧化氢=1∶6,反应温度为40℃;氢氧化钾浓度为60%。该工艺条件下,对甲基苯甲酸产率达到91%以上;重复性试验结果显示,对甲基苯甲酸的平均收率达91.7%。[结论]为对甲基苯甲酸的工业化生产奠定了基础。     

过氧化氢对丹参悬浮细胞生长及次生代谢物积累的影响

以稳定的丹参悬浮细胞为实验材料,研究过氧化氢和过氧化氢与酵母提取物组合对丹参悬浮细胞生长及次生代谢物积累的影响。结果表明,过氧化氢和过氧化氢与酵母提取物的组合均对细胞生长有不同程度的抑制作用;过氧化氢对丹参酚酸和丹参酮的生成均有促进作用,其中10μmol/L过氧化氢处理的细胞中丹参酚酸含量达到最大值94.85 mg/g干重,为对照组的2.43倍;过氧化氢与酵母提取物的组合对丹参次生代谢物的积累作用效果不明显。上述结果表明,过氧化氢是丹参悬浮细胞次生代谢物积累的有效诱导子。     

辣木油的抗氧化稳定性研究

研究温度、光照时间对辣木油抗氧化稳定性的影响,以此选择合理的保存方式。用石油醚浸出法制成辣木油试样,以过氧化值(POV)为试验指标,采用Sehaal烘箱法和室内自然光照射法进行试验,测定不同温度和不同受热、光照时间下的POV值并计算氧化诱导时间。结果表明:不同受热时间下测得的POV值之间的差异性不显著,而不同光照时间的POV值则具有显著性差异,说明辣木油对温度比较稳定,但对光照则相反,光照时间越长抗氧化的稳定性就越差,光照氧化诱导时间仅为3.5 d。提示了辣木油应在20℃左右保存并特别注意避光,在此条件下的货架期可达304 d。      

响应曲面法优化野蔷薇根多糖脱色工艺

[目的]优化野蔷薇根多糖的过氧化氢(H2O2)法脱色工艺条件,为野蔷薇根多糖的脱色纯化提供技术支持.[方法]以野蔷薇根为试验材料,以多糖脱色率和保留率为考察指标,利用响应曲面法对H2O2法脱色野蔷薇根多糖的工艺条件进行优化.[结果]通过响应曲面法建立野蔷薇根多糖脱色的回归模型为:Y=94.84+3.08A+1.83B+0.88C+0.17AB+0.23AC-0.055BC-3.17A2-1.31B2-0.87C2(Y为多糖脱色率,A为H2O2体积分数、B为溶液pH、C为脱色时间),该模型拟合度较好.H2O2法脱色野蔷薇根多糖的最佳工艺条件为:H2O2体积分数35.0%、溶液pH 9.00、脱色时间4.5 h,在此条件下多糖脱色率和保留率分别为95.48%和75.17%,脱色率与理论值96.55%的相对误差为1.11%.H2O2体积分数、溶液pH和脱色时间3个因素对野蔷薇根多糖脱色效果均有极显著影响(P<0.01).[结论]H2O2脱色法具有操作简便、脱色效果明显、成本低等优点,可对野蔷薇根多糖进行有效脱色.     

干旱胁迫下不同浓度Ca2+对苜蓿根系活力、脯氨酸含量和过氧化物酶活性的影响

文章采用盆栽试验,用5,10,20,30,50mmol·L-1CaCl2溶液对苜蓿种子浸泡16h,研究干旱胁迫下,Ca2+对苜蓿抗旱性的影响。结果表明,CaCl2浸种后可以提高苜蓿的叶片含水量,降低细胞膜透性,提高苜蓿的根系活力,增加脯氨酸的积累量,提高过氧化物酶的活性,用5￣20mmo·lL-1CaCl2处理时,能够减轻干旱胁迫对植株的伤害,提高根系的吸水和叶片保水能力,进而提高苜蓿的抗旱性。     

Prediction of chemical composition and peroxide value in unground pet foods by near‐infrared spectroscopy

The massive development of the pet food industry in recent years has lead to the formulation of hundreds of canine and feline complete extruded foods with the objective of meeting both the needs of the animals and numerous demands from pet owners. In the meantime, highly variable raw material compositions and the industry's new production techniques oblige manufacturers to monitor all phases of the extrusion process closely in order to ensure the targeted composition and quality of the products. This study aimed at evaluating the potential of infrared technology (visible and near‐infrared spectrophotometer; 570–1842 nm) in predicting the chemical composition and peroxide value (PV) of unground commercial extruded dog foods. Six hundred and forty‐nine commercial extruded dog foods were collected. For each product, an unground aliquot was analysed by infrared instrument while a second aliquot was sent to a laboratory for proximate analysis and PV quantification. The wide range of extruded dog food typologies included in the study was responsible for the wide variability observed within each nutritional trait, especially crude fibre and ash. The mean value of the 208 pet foods sampled for PV quantification was 17.49 mEq O₂/kg fat (min 2.2 and max 94.10 mEq O₂/kg fat). The coefficients of determination in cross‐validation of NIRS prediction models were 0.77, 0.97, 0.83, 0.86, 0.78 and 0.94 for moisture, crude protein, crude fat, crude fibre, ash and nitrogen‐free extract (NFE) respectively. PV prediction was less precise, as demonstrated by the coefficient of determination in cross‐validation (0.66). The results demonstrated the potential of NIRS in predicting chemical composition in unground samples, with lower accuracy for moisture and ash, while PV prediction models suggest use for screening purposes only.     

市售鲜鸡蛋杂菌污染调查及涂膜法保鲜研究

随机抽检市售鲜鸡蛋每个蛋壳表所污染的杂菌，总数达１４２３．１万个．０．５％～１．０％过氧乙酸液对污染鸡蛋壳表杂菌的抑菌圈半径细菌为５．５～８．６ｍｍ，真菌为７．２～９．３ｍｍ．市售鲜鸡蛋贮存３个月期间每隔１５ｄ递减的鲜鸡蛋失重率平均值，聚乙烯醇涂膜法为１．４９％，不涂膜的对照为２．３６％，用聚乙烯醇涂膜法贮存保鲜的市售鲜鸡蛋，在自然气温为６．５～２３．６℃及空气相对湿度为４１．２％～９１％等自然温湿度条件下贮存的累计蛋黄完好率，贮存４５ｄ者为８６．７％，而不涂膜的对照为６４．３％；贮存９０ｄ者为６７．５％，而不涂膜的对照仅为４０％．每千个鸡蛋所用的聚乙烯醇成本为１．７０元（当时的市售价格）．     

不同密度水稻抽穗后生理特性的研究

稀植栽培的水稻,抽穗后田间表现为中下部光强明显增加,光合作用时间延长,硝酸还原酶和过氧化物酶活性降低,蛋白质含量增加50%以上,叶片衰老延缓,籽粒干物质积累加速,千粒重提高。