小麦多酚氧化酶(PPO)活性的基因型、环境及其互作效应的分析

选用16个有代表性的小麦品种(系)，分别在山东8个地区进行小麦多酚氧化酶(PPO)活性的基因型与环境效应分析。结果表明，在随机效应中，小麦籽粒PPO活性的品种与试点互作效应最为显著。在对面团白度性状进行选择时，既要选择多酚氧化酶(PPO)活性低的品种，又要注意选择在PPO积累低的地区种植，以实现优质品种的优质生产。     

漆酶及其应用

漆酶是一种含铜多酚氧化酶,具有催化氧化酚型底物的能力.漆酶在很多领域得到了广泛的应用.本文主要从纸浆的生物漂白、生物制浆、去除氯酚类化合物的毒性等几个方面进行了介绍.     

桑黄子实体多糖、黄酮和多酚含量与抗氧化活性相关性

探讨子实体抗氧化的物质基础。通过提取和萃取得到7种组分:水提物(WE)、醇提物(AE)、粗多糖(CP)、醇沉上清干物(RL)和二氯甲烷(MCE)、乙酸乙酯(EAE)、正丁醇(n BE)萃取物,采用FRAP值法测定体外抗氧化能力,分光光度法测定多糖、黄酮和多酚含量。结果表明:抗氧化活性物存在于醇提物中,抗氧化活性和多酚、黄酮含量有关,并呈线性正相关(R2为0.9977和0.9950),多糖在抗氧化中所起作用小,酚类、黄酮类为其主要抗氧化活性物质。      

H2O2对家蝇蛹内部几种酶活性的影响

目的研究外源H2O2对家蝇蛹内与抗性相关的几种酶活性的影响。方法通过H2O2诱导,测定家蝇蛹内过氧化氢酶（CAT）、过氧化物酶（POD）、抗坏血酸过氧化物酶（AsA-POD）以及多酚氧化酶（PPO）的活性变化。结果H2O2处理后蛹内CAT和AsA-POD的活性变化规律与处理前差别不大;POD活性在H2O2处理后12h内出现活性高峰,约为对照组的2.5倍,此后稍高于对照组,最后基本与对照组持平;PPO活性在处理后12h内与对照组相当,此后活性骤然升高,处理后24h达到对照组的2.13倍,然后变化速度减慢,但一直维持在对照组的1.3倍左右,48h后活性开始下降。结论H2O2对CAT和AsA-POD的活性影响较小,对POD和PPO的活性有一定的影响。     

鸭梨多酚氧化酶的特性及抑制剂研究

以邻苯二酚为底物，采用分光光度法在420nm处测定鸭梨多酚氧化酶（PPO）的活性，研究了不同底物、温度、pH值和底物浓度对其活性的影响，并建立了酶促褐变反应动力学方程，探讨了柠檬酸、EDTA、亚硫酸氢钠和抗坏血酸四种抑制剂对鸭梨酶促褐变的抑制效果。结果表明，鸭梨多酚氧化酶的最适底物为邻苯二酚，最适温度为30℃，最适pH为6．6；酶促褐变反应动力学符合米氏方程所描述的单底物酶促反应动力学，以邻苯二酚为底物的动力学参数Km=0．333mol／L，Vmax=0．089U／min。相应的动力学方程为v=0．089[S]／（0．333＋[S]；四种物质对该酶均表现出不同的抑制作用，抑制效果为：抗坏血酸〉EDTA〉柠檬酸〉亚硫酸氢钠。     

燕麦膳食纤维的制备工艺及物理特性研究

本文研究了以燕麦麸皮为原料制取燕麦膳食纤维,确定简单经济的的工艺路线,并着重分析了燕麦膳食纤维的物理特性。     

Effect of cooking on the antioxidant properties of coloured peppers

Pepper (Capsicum annum L.) has long been recognized as an excellent source of antioxidants, being rich in ascorbic acid and other phytochemicals. This study was conducted to investigate the effect of different cooking methods on the antioxidant properties of coloured peppers. Six varieties of peppers were subjected to different cooking methods, such as microwave heating, stir-frying and boiling in water, for 5 min individually. The cooked and raw peppers were analyzed for radical-scavenging activity (RSA) and total polyphenol content (TP) using 1,1-diphenyl-2-picrylhydrazyl–high-pressure liquid chromatography (DPPH)–HPLC and Folin-Ciocalteu methods, respectively. The samples were also evaluated for ascorbic acid content (AsA) by HPLC. Total carotenoid content was determined spectrophotometrically. Results suggest that there is no significant (P > 0.05) difference in RSA, TP, AsA and total carotenoid contents between the cooked and raw peppers when processed for 5 min. However, the cooked peppers show marked differences (P < 0.05) in the RSA, TP and AsA when cooked for 5 min in boiling water with further reduction observed after boiling for 30 min. This may be due to the leaching of antioxidant compounds from the pepper into the cooking water during the prolonged exposure to water and heat. Therefore, it is vital to use less water and cooking time and also to consume the water used for boiling so as to obtain the optimum benefits of bioactive compounds present in peppers. It is concluded that microwave heating and stir-frying without using water are more suitable cooking methods for pepper, to ensure the maximum retention of antioxidant molecules.     

燕麦粉蛋白的理化性质研究

采用扫描电子显微镜(SEM)观察燕麦粉蛋白的结构特点,垂直电泳仪测定其分子量的分布范围,AR1000型动态流变仪分析其凝胶特性,结果表明:燕麦蛋白是包裹着燕麦淀粉的胶状物质,结构紧密;燕麦粉蛋白分子量分布在14.4～66.2kD之间,分子量大小在35.0～45.0kD之间和20.0～28.5kD之间蛋白含量较大;在pH5时,起泡性最差,泡沫稳定性最好,乳化性最差,乳化稳定性最好;燕麦蛋白在第一步升温过程中,贮能模量G1随着温度的增加先降低后增加,在62.1℃时的G1最小为48.11Pa,在90.8℃时G1最大为369Pa;损耗模量G11和G1的变化趋势基本相同,在62,1℃时的G11最小为38.66Pa,在93.7℃时G"最大为106.9Pa:在20～28℃之间tan(delta)＞1,黏性大于弹性,28～100℃之间tan(delta)＜1,黏性小于弹性.在冷却降温过程中,G1随着温度的降低在100～48℃之间缓慢增加,48～20℃之间急剧增加,燕麦蛋白的耐热性为844.1Pa,凝胶强度为9194Pa.     

桉叶多酚提取物体内外抗氧化活性评价

桉叶资源丰富且生物活性高,但少有研究对桉叶多酚提取物进行系统的抗氧化活性评价.本实验旨在研究纯化后桉叶多酚提取物体内外抗氧化活性.以化学法、RAW264.7巨噬细胞模型、秀丽隐杆线虫(以下简称线虫)模型为评价方法,以自由基清除率、抗氧化酶活力及线虫寿命等为指标,评价桉叶多酚提取物的抗氧化能力.结果 表明,桉叶多酚提取物...     

Biochemical composition and storage of Jamaican yams (Dioscorea sp)

Dioscorea yam tubers of 11 cultivars from five common species grown in Jamaica were analysed for the following: protein content, total phenolics, vitamin C, total lipids, fatty acid composition and activity of the polyphenol oxidase enzyme. The results show that the yams grown in Jamaica are of good nutritional value with considerable amounts of protein, vitamin C, low lipids with only one cultivar ‘renta yam’ (D alata) possessing high levels of phenolic compounds. The fatty acids present in the total lipid extracts show that yam tubers generally possess high levels of saturated fatty acids mainly palmitic acid. However, the species D alata (cv white yam) and the species D trifida (cv yampie) have high levels of the unsaturated fatty acid, linolenic. All the polyphenol oxidases from the 11 cultivars show activities towards the diphenol substrates, catechol and DL-DOPA (DL-3,4-dihydroxyphenylalanine). However, no oxidation was observed with L-tyrosine, a monophenol substrate. All cultivars studied were found to have different lengths of dormancy which varied with storage conditions. When the harvested tubers were washed, sunned and stored at 20?C in a dark cupboard, it was possible to extend their lengths of dormancy by a further 11 weeks.