采用HPLC技术快速检测发酵大豆制品中异黄酮的含量

本文介绍了利用高效液相色谱(HPLC)技术快速检测发酵大豆制品中异黄酮含量的方法。在Lichrosper100RP-18(4.6mm×25cm×5μm)色谱柱上,以含有0.1%(v/v)冰醋酸的乙腈和水溶液为流动相进行梯度洗脱,检测波长为254nm,平均回收率达到99%以上。分析结果表明此分析方法灵敏、准确、重现性好。在上述条件下检测发酵大豆制品中异黄酮含量,结果表明发酵大豆制品中异黄酮主要以甙元形式存在。     

大孔树脂分离纯化大豆胚芽中异黄酮的研究

通过柱层析的方法使大豆胚芽中异黄酮的苷元和糖苷得到有效的分离。紫外检测结果显示,大豆胚芽提取液中异黄酮含量为5.35%;HPLC检测结果显示:以AB-8大孔树脂为固定相,乙醇水溶液进行递度洗脱,可使大豆异黄酮的苷元和糖苷得到很好的分离,苷元和糖苷的纯度可达90%以上。     

Antioxidant properties and phenolic,isoflavone, tocopherol and carotenoid composition of Maryland-grown soybean lines with altered fatty acid profiles

One cultivar and five experimental lines of Maryland-grown soybeans with improved fatty acid profiles were investigated for their phytochemical and antioxidant properties. Soybean oils were extracted and analyzed for their fatty acid profiles, tocopherols, and carotenoids. Two of the experimental lines were low in α-linolenic acid and another one was low in both α-linolenic and total saturated fatty acids. The defatted flours were extracted in 50% acetone and 70% ethanol, and estimated for isoflavone compositions, total phenolic contents (TPC), and scavenging capacities against peroxyl (ORAC), hydroxyl (HOSC), and 2,2-diphenyl-1-picryhydrazyl (DPPH) radicals. No difference was observed in tocopherols, carotenoids, TPC, and antioxidant properties between soybeans with reduced α-linolenic and/or saturated fats and the ones with ‘normal’ fatty acid profiles. This study indicates the possibility to produce soybeans with reduced linolenic and/or saturated fat and with desirable levels of health beneficial phytochemicals and antioxidant properties.     

Biotransformation of phenolics (isoflavones,flavanols and phenolic acids) during the fermentation of cheonggukjang by Bacillus pumilus HY1

Changes in β-glycosidase, esterase activities, isoflavone, flavanols and phenolic acid during the fermentation of Korean whole soybean fermented food cheonggukjang by Bacillus pumilus HY1 were investigated. The levels of aglycones, flavanols and gallic acid increased, while the β-glucosidase activity, esterase activity, glycosides content (except for acetylglycosides) and flavanol gallates decreased. Total isoflavone content slightly decreased after 60 h of fermentation, while total flavanol and phenolic acid content increased. The highest levels of daidzein (aglycone type) and acetyldaidzin (glycoside type) were recorded after 48 h of fermentation. The levels of catechin, epicatechin and gallic acid also increased during fermentation. However, total contents of glycosides, malonylglycosides and flavanol gallates decreased by about 80%, 90% and 60% during 60 h of fermentation, respectively. In addition, total phenolic content increased markedly during fermentation, while levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity increased. Hence, it would be beneficial for the food industry if components of cheonggukjang could be separated and developed into functional products.     

Impact of ethanol addition on the solubility of various soybean isoflavones in supercritical carbon dioxide and the effect of glycoside chain in isoflavones

Solubilities of glycoside isoflavones (daidzin, genistin and glycitin) and their aglycons (daidzein, genistein and glycitein) in supercritical carbon dioxide (SCCO₂) were measured. In the SCCO₂-only system, the solubility of glycoside isoflavones was very low. Adding over 0.1 molar fraction of ethanol to SCCO₂ increased the solubility of glycoside isoflavones. The solubility was almost proportional to the third power of the molar fraction of ethanol. Adding ethanol significantly affected the solubility of glycoside isoflavones. In particular, the solubility of daidzin was remarkably increased by ethanol addition. The solubility of six tested isoflavones in SCCO₂ with ethanol was correlated with the second virial coefficient. The solubility depended on seventh power of the molar fraction of ethanol in SCCO₂. This suggested that the addition of ethanol facilitated cluster formation of CO₂ molecules in the supercritical phase, enhancing the solubility of isoflavones. A SCCO₂ and ethanol binary system was especially effective in extracting glycoside isoflavones.     

Optimization of ethanol extraction and further purification of isoflavones from soybean sprout cotyledon

Isoflavones from cotyledons of soybean sprouts were extracted with aqueous ethanol and further concentrated to obtain a product with a high concentration of isoflavone. The ethanol concentration, extraction time and reaction temperature were optimized by using response surface methodology (RSM). Isoflavones in aqueous ethanol were concentrated by a three-step procedure comprised of solid phase extraction (SPE) with Diaion HP-20 and Amberlite-XAD-2 adsorption columns, acid hydrolysis, and liquid–liquid extraction. The maximum amount of isoflavone in aqueous ethanol extracts (11.6 mg/g solid) was obtained when isoflavones in cotyledons (2.18 mg/ g solid) were extracted with 80–90% (v/v) aqueous ethanol above 90 °C for more than 100 min. The isoflavone extracts, obtained by SPE with a Diaion HP-20 column contained 100 mg/g solid. The liquid–liquid extraction (LLE) with ethyl ether further concentrated the extracts up to 229 mg/g solid, retaining 63% of the initial isoflavones.     

大豆萌发过程中异黄酮变化及提升策略

异黄酮在人体内具有丰富的生理活性,被证明在抗氧化及预防乳腺癌、前列腺癌、骨质疏松症和心血管疾病等方面都有积极的作用,因而逐渐受到功能性食品开发的青睐。萌发是改善植物中营养价值的常见手段,而大量研究结果表明,胁迫环境下的萌发能进一步的提升大豆中异黄酮含量、改善其异黄酮组成。因此多种胁迫萌发的条件被用于评估大豆异黄酮含量的提升效果。本文阐述了萌发以及萌发的环境因素对大豆异黄酮含量的影响以及萌发过程中豆芽不同部位中异黄酮含量的变化差异,并重点介绍了多种提升豆芽异黄酮含量的胁迫策略。以期能够为功能性食品的开发提供帮助,并更加全面了解该领域的研究进展。     

从大豆胚芽中提纯活性物质新方法的研究

本文探讨了以水作为介质,对大豆胚芽中的皂甙和异黄酮进行微波和超声波前处理,提取效果和纯溶剂萃取法相比,经正交实验,结果表明经450W功率微波处理30min和400W功率超声波在40篊处理45min,固液比为120,温度为60篊,时间为1h,再经40%的乙醇,浸提2次。异黄酮提取率从1.2%提高到1.74%,皂甙从4.4%提高到5.8%,比溶剂法的提取率分别提高了43%和32%,经聚酰胺柱层析分离纯化,大豆异黄酮和大豆皂甙产品纯度分别达到38%和94%。