Characterization of the brown pigment in sautéed onion by metal-chelating Sepharose 6B column chromatography and microbial decolorization

The brown pigment in sautéed onion was characterized by a microbiological procedure (involving microbial decolorization) and a chemical procedure (involving metal-chelating chromatography with a Sepharose 6B column). The suitability of the chemical procedure as a method for classifying brown pigments was also examined.The pigment from sautéed onion was about 40% decolorized by Coriolus versicolor IFO 30340, as were the model pigments caramel and model melanoidin (MM). The phenol-type model pigments (PTMP) were approximately 40-60% decolorized by Paecilomyces canadensis NC-1, but the sautéed-onion pigment, the MM and the caramel were merely 5% decolorized by it. The pigment from sautéed onion was separated into two components by Cu²⁺, Fe²⁺, or Zn²⁺-chelating chromatography, as were caramel and MM; the PTMP was not separated into multiple components by either Cu²⁺ or Fe²⁺-chelating chromatography. The results from both methods indicate that the pigment from sautéed onion is similar to MM and caramel but not the phenol-type pigment.     

鸡肉味风味基料中蛋白黑素的初步分析

利用鸡骨架酶解液为原料,通过美拉德反应制备鸡肉味风味基料。通过大小排阻高压液相色谱对鸡肉味风味基料中的蛋白黑素进行分子质量(Mw)分析,发现其大小约为11561.1D;对使用0.2mol/L和0.5mol/L NaCl溶液洗脱出的蛋白黑素进行傅里叶变换红外光谱分析,鉴定出部分C－H、C＝O以及C－N等吸收峰,说明蛋白黑素是一类复杂的有机化合物,可能由氨基酸复合物聚合、交联和美拉德反应的早期阶段的糖降解产物形成的,具体结构仍需深入研究。     

黑酱油类黑素的提取、光谱性质及功能

从黑酱油中提取类黑素并对其光谱性质和功能进行研究。结果表明：经有机溶剂沉淀及脱盐处理,冷冻干燥获得类黑素粗制品,得率为22.8g/100mL;经Sephadex G-50凝胶层析除去小分子物质,得到分子质量分布在3000～55000u的类黑素纯品。紫外和红外光谱扫描结果显示类黑素粗品是美拉德反应和酶促褐变的产物。类黑素粗制品对DPPH自由基的清除率最高达89.0%,对羟自由基的清除能力达89.5%,对亚硝胺合成的抑制率可达80.0%。提示酱油类黑素粗制品可以作为功能性固体酱油被开发,类黑色素纯品可开发成为功能性食用色素。     

美拉德反应产物对肠道微生物影响的研究进展

美拉德(Maillard)反应是食品加工、贮藏及烹饪过程中普遍存在的重要反应。Maillard反应会导致蛋白质或氨基酸的胃肠消化性下降,进而增加其进入大肠被肠道微生物发酵利用的可能性。本文主要综述Maillard反应产物对肠道微生物生长及其发酵代谢产物形成等影响的研究进展,旨在为研究Maillard反应产物、肠道微生物与健康的关系提供参考。     

Vc对简单模拟美拉德反应体系的影响

为了更加接近实际食品体系,研究还原糖相似物对简单美拉德反应体系的影响,文中以葡萄糖/半胱氨酸为模拟体系,考察了在甘氨酸存在情况下,Vc对该体系残余葡萄糖、半胱氨酸、甘氨酸和Vc的浓度,体系褐色物质和pH值,以及感官质量评定结果的影响。结果表明:随着添加Vc含量的增加,葡萄糖残余含量逐渐增大,半胱氨酸残余含量先增大后减小,甘氨酸残余含量先减小后趋于平衡,残余Vc的含量逐渐增大,体系420 nm吸光值先(褐色物质)增大后减小,pH值逐渐减小,体系硫的刺激性气味先上升后稳定,肉味逐渐下降,而烘烤味则变化不大,并且在Vc添加含量为0.05 mol/L时体系的感官评定分数最高。     

山西老陈醋类黑精的分离及其抑菌活性

为探究老陈醋类黑精的抑菌作用,采用超滤和尺寸排阻色谱法将山西老陈醋冻干粉（Shanxi aged vinegarextract,SAVE）分离成不同分子质量的水提物和类黑精部分,采用NaCl解离法将醋类黑精解离为类黑精骨架和小分子复合物两部分,用比浊法测定各组分对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌的抑菌活性。结果表明：SAVE中的类黑精具有显著的抑菌活力（P＜0.05）,类黑精对SAVE的抑菌性发挥了主要作用;类黑精中分子质量在3～5 kD的组分抑菌活力最强,其对3 种受试菌的最低抑菌浓度（minimal inhibitory concentration,MIC）均为5 mg/mL;类黑精组成中的小分子复合物比类黑精骨架部分具有更强的抑菌活性。     

中国传统食醋营养健康物质组成研究进展

中国传统食醋有着悠久的酿造历史,不仅风味独特,而且含有丰富的营养健康成分,具有抗氧化、降血脂、降血糖等多种保健功效。该文对我国传统食醋中的有机酸、氨基酸、多酚、川芎嗪、类黑精等主要营养健康物质及其研究进展进行综述,有利于进一步加深对我国传统食醋的科学理解,同时也对保障人民营养健康,提升我国传统食醋国际影响力等具有重要的意义。     

Application of mesoporous magnetic nanosorbent developed from macadamia nut shell residues for the removal of recalcitrant melanoidin and its fractions

ABSTRACT

A novel mesoporous magnetic nanosorbent developed from macadamia nut shell residues was applied as an adsorbent for the removal of dissolved organic carbon (DOC) associated with melanoidin and its fractions in a batch system. The most favored molecular fraction of the melanoidin for adsorption onto the nanosorbent was 1–5 kDa with adsorption capacity of 10.26 mg DOC g^?1 achieving 68.4% removal efficiency. The sorption behaviors were all well fitted to a pseudo-second-order kinetic model and Langmuir isotherm. Optimum operating conditions needed for the maximum uptake of 14.7 mg DOC g^?1 were found to be pH of 6.3, temperature of 41.7°C at the dosage of the magnetic nanosorbent of 877.7 ppm.     

A METHOD FOR ESTIMATING TOTAL POLYPHENOLS IN BEER

A procedure is described whereby polyphenols in beer are extracted under acid and alkaline conditions. These fractions are analysed to obtain the net amount of polyphenols and these are in turn used as standards for calibration in developing a colorimetric method for the determination of total polyphenols in beer.     

曲霉型豆豉类黑精的提取与精制

本文研究了用水浸提和树脂精制曲霉型豆豉类黑精。实验结果表明：水浸提法粗提曲霉型豆豉类黑精的最佳工艺参数为：料液比为1：15，提取时间为8h，提取级数为二级；大孔树脂精制曲霉型豆豉类黑精的最佳工艺条件为：吸附流速为1．5mL／min；在室温和解吸流速为1．5mL／min的条件下，以60％乙醇作为解吸剂时洗脱效果最好。