紫玉米花青素的浸提技术研究

首先通过选择试验选择乙酸作为最佳提取剂,然后按照4因素3水平正交L9(34)试验设计对浸提剂浓度、浸提温度、浸提时间及不同物料配比对紫玉米花青素提取率的影响进行了研究[1-2],确定其最佳提取条件为:pH2.5乙酸溶液作浸提剂、在60℃的温度条件下加热60min、物料配比在1∶15,其二次提取得率可达80.1%。     

紫肉甘薯中花青素在不同环境条件下稳定性的研究

研究了紫肉甘薯中的红色素———花色苷在不同环境条件下的稳定性。结果表明 :该色素在 pH 3以下较稳定 ,耐光性和耐热性好 ,色素粗提物中的糖、酸、多酚类物质等可能与色素发生辅色效应而使稳定性大大提高     

乌洋芋色素抑菌活性与清除DPPH·能力研究

对乌洋芋色素抑菌活性与清除DPPH·能力的研究结果表明，乌洋芋色素对枯草芽胞杆菌、金黄色葡萄球菌、都柏林沙门氏菌和大肠杆菌有一定的抑制作用，最低抑菌浓度分别为41.75、25.05、25.05和300.58mg/L；对DPPH·具有较好的清除作用，半清除浓度（EC50）为20.842mg/L。     

Structure-texture relationships of fresh pastes prepared from different yam (Dioscorea spp.) varieties

Yam (Dioscorea spp.) presents an important tropical food crop rich in starch. In West Africa, yam is traditionally prepared by pounding of cooked yam to obtain a dough-like paste known as pounded yam or ‘foutou’. The present investigation deals with structure-texture relationships of yam pastes as influenced by yam varieties. In general, the firmness of yam pastes prepared from D. cayenensis-rotundata was higher than that from D. alata. Difference in firmness was found to be related to the extent of cell disintegration, which was more pronounced for D. alata as assessed by light microscopy. Pronounced textural changes were measured during ageing of yam pastes, which is a consequence of the reorganization (retrogradation) of the amylose fraction. Post-harvest storage of yam tubers resulted in increased firmness and decreased adhesion properties in the pastes, but no significant influence of the storage treatment with gibberellic acid, which reduces storage losses, was detected. It is concluded that the texture of yam pastes is largely determined by the integrity of cells and the properties of the continuous starch phase.     

浅淡宜兴紫砂花货塑器艺术造型

简要分析了宜兴紫砂花货塑器艺术造型的特点,概述了紫砂陶手工成型的制作方法及其精加工过程。     

Diosgenin quantification,characterisation and chemical composition in a tuber collection of Dioscorea spp. in the state of Jalisco,Mexico

Dioscorea spp. tubers are known commonly as camote de cerro to the state of Jalisco, México. Besides its use as food, it contains diosgenin, a raw material used widely for synthesising steroid hormones. The purpose of the present research was to determine diosgenin contents by gas chromatography‐mass spectrometry (GC‐MS), as well as physical and chemical characteristics of sixty Dioscorea spp. accessions cultivated in mesh shade coming from eleven localities in the state of Jalisco. Extraction protocol for diosgenin was maceration combined with ethanol 80%. Significant statistical differences for diosgenin content were found between accessions, finding levels between 0.02 and 0.16 mg kg^?1 in dry basis. Length, weight tuber, proportion pulp/skin, percentage of pulp and percentage of skin showed significant differences. Chemical composition based in fresh weight presented in moisture percentage a range of 71.93–83.26%, crude protein 1.42–1.74%, ashes 0.80–1.16%, lipid 0.13–0.17%, crude fibre 3.80–4.02% and total carbohydrates 13.97–25.44%. Results show that tubers from Jalisco can be an important source of nutrients for consumers.     

新安画家程门及其浅绛彩瓷绘的艺术成就

新安画家程门，以他为首创建的浅绛彩瓷绘，开创了瓷绘工艺与高雅的中国画艺术全面结合的先河，并孕育了一大批徽州籍的制瓷名家，将新安画风直接带入瓷画之中，为徽学研究提供了难得的新史料，极大地丰富了博大精深的徽州文化。     

Phenolic profiles of Andean purple corn (Zea mays L.)

Qualitative and quantitative high performance liquid chromatography with diode array detection (HPLC-DAD) was performed to characterize the presence of phenolic compounds in Andean purple corn. Phenolic compounds were analyzed by separating them in two main fractions: a water fraction (WF) and an ethyl acetate fraction (EAF). The WF rich in anthocyanins revealed the presence of cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside. The respective acylated anthocyanin glucoside forms of these compounds were also detected following alkaline hydrolysis. The EAF was composed of phenolic acids such as p-coumaric, vanillic acid, protocatechuic acid, flavonoids such quercetin derivatives and a hesperitin derivative. Alkaline and acid hydrolysis of the EAF revealed the presence of p-coumaric and ferulic acid as main components in four bound hydroxycinnamic acid forms present in the ethyl acetate fraction.     

Browning in processed yams: peroxidase or polyphenol oxidase?

Polyphenol oxidase and peroxidase were purified from white yam (Dioscorea rotundata) using DEAE‐cellulose ionexchange chromatography. Thermoinactivation curves for polyphenol oxidase showed monophasic kinetics, while those for peroxidase were biphasic. Urea partially stabilised peroxidase against irreversible thermoinactivation, but did not do so in the case of polyphenol oxidase. Only peroxidase was capable of regenerating activity after thermoinactivation. The results showed that thermoinactivation of peroxidase was mainly due to conformational changes, while that of polyphenol oxidase was probably due to covalent damage. Peroxidase reactivation might play an important role in the browning of processed yam. © 2002 Society of Chemical Industry