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。     

Effects of dietary daidzein supplementation of pregnant sows on carcass and meat quality and skeletal muscle cellularity of the progeny

The effects of dietary daidzein during late gestation on maternal performance, neonatal body composition, carcass and meat quality at market weight, and skeletal muscle cellularity were studied. Multiparous sows received a soybean-free diet (n=8, control) or the same diet supplemented with 1mg daidzein/kg body weight (n=7) daily from d 85 of gestation to parturition. Litter size, litter weight, and birth weight remained unaffected by daidzein feeding. In newborn piglets from litters >15, the proportions of muscle tissue and skin tended to be decreased (P=0.09) or increased (P=0.03), respectively, after gestational daidzein feeding. The body fat percentage was higher in response to maternal daidzein (P=0.04). Postnatal growth and carcass composition at 180d of age were not affected, however, maternal daidzein supplementation led to increases in longissimus muscle pH(45) (P=0.02) and pH(end) (P=0.11) in pigs from large litters. The proportion of fast-twitch glycolytic fibres in semitendinosus muscle was increased (P=0.06) by maternal daidzein feeding. The results suggest that supplemental daidzein in the maternal diet during late gestation marginally affects meat quality and skeletal muscle cellularity of the progeny.     

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%。     

Determination of optimal acid hydrolysis time of soybean isoflavones using drying oven and microwave assisted methods

The aim of the present research was to determine an optimal acid hydrolysis condition using drying oven and microwave assisted methods to estimate isoflavone contents by RP-HPLC in soybean. All isoflavone glucosides were completely converted to their aglycones at 120 min for drying oven and 50 min for microwave. Optimal extraction time of the highest isoflavone aglycone content after acid hydrolysis was achieved in 3 h. These results indicated that the optimised hydrolysis and extraction conditions of isoflavones in soybean were: soybean (1 g) hydrolysed by 10 ml of 1 N HCl at 100 °C for 50 min using microwave assisted acid hydrolysis method, and then 15 ml of EtOH was added to the mixture which leaved alone for 3 h at room temperature for complete extraction. Thus, microwave is an easy, consumed less time, and reliable acid hydrolysis method to estimate soybean isoflavones in comparison with drying oven method.     

Changes in some components of soymilk during fermentation with the basidiomycete Ganoderma lucidum

Soymilk was fermented with the basidiomycete Ganoderma lucidum WZ02 and the changes in the contents of polysaccharide, sugars, crude protein, B-vitamins, free amino acids and isoflavones were analyzed. Polysaccharide and crude protein were increased by the fermentation of G. lucidum while most free amino acids were reduced. The flatulence factor (e.g. stachyose and raffinose) was significantly decreased and stachyose was not detected after 72 h of fermentation. The contents of thiamin, riboflavin, and niacin were increased during the fermentation. Most of isoflavone glycosides were converted to aglycones and the contents of daidzein and genistein were increased by the fermentation of G. lucidum. The results suggested that fermentation by G. lucidum could improve the acceptability and health properties of soymilk.     

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.     

Production of 8-Hydroxygenistein through Biotransformation by Using Aspergillus oryzae

8-Hydroxygenistein is one of the orthohydroxygenisteins, which are derivatives of genistein. Although 8-hydroxygenistein is generally produced through the biotransformation of soya isoflavones by using specific microorganisms, the yield of produced 8-hydroxygenistein is low. In this study, we optimized the cultivation medium for 8-hydroxygenistein production. The results of the central composite design indicated that the optimal nutrient concentrations were 35 g/L of glucose, 22 g/L of malt extract, and 4.75 g/L of soya peptone. The maximum product concentration of 8-hydroxygenistein obtained was 77.76 mg/L. Based on literature review, this concentration of 8-hydroxygenistein is the highest yet reported. The effects of operating conditions on the concentration of 8-hydroxygenistein were also determined using a fermenter. After investigating the effects of the agitation speed and aeration rate, a final product concentration of 83.01 mg/L was obtained. Thus, large-scale biotransformation of genistein to 8-hydroxygenistein can be performed using Aspergillus oryzae.     

紫外分光光度法测定非发酵性豆制品中异黄酮含量

干燥的非发酵性豆制品粉末在索氏抽提器中用乙醚脱脂5h后用80％的甲醇溶液以25:1的液固比热回流5h,冷却过滤,所得溶液在波长254nm条件下用紫外-可见光分光光度法测定其总异黄酮含量。此方法得出标准曲线的相关系数为r=0.9979。本方法的回收率平均为98％,相对标准偏差2.3％。该方法简单、干扰少、线性好、使用的试剂毒性小且廉价易得。     

The potentials of Bacillus licheniformis strains for inhibition of B. cereus growth and reduction of biogenic amines in cheonggukjang (Korean fermented unsalted soybean paste)

The aim of this study was to control Bacillus cereus growth and biogenic amines formation by using a starter in cheonggukjang fermentation. We used the four selected B. licheniformis strains for cheonggukjang fermentation and investigated whether the strains are effective in reducing both B. cereus level and biogenic amines content. We confirmed that the selected strains are able to reduce B. cereus level to below l log CFU/g after cheonggukjang fermentation from the initial level of 3–4 log CFU/g (artificial contamination). Tryptamine, β-phenylethylamine, putrescine, cadaverine, tyramine, spermidine, and spermine were detected whereas histamine, serotonin, noradrenaline, and dopamine were not detected in the cheonggukjang samples. Most of biogenic amines contents were lower than those of previous studies, indicating that the strains produced the low level of biogenic amines in cheonggukjang fermentation. The acceptable levels of amino-type nitrogen, free amino acids, and isoflavones were contained in the cheonggukjang samples. These results demonstrate that the selected strains are not only effective for reduction of both B. cereus contamination and biogenic amines but also suitable for preparation of cheonggukjang with good quality.     

Introduction and nutritional evaluation of germinated soy germ

Germinated soy germ (GSG) were developed and evaluated for their nutritional value. Separated soy germ was germinated at room temperature for 24 h under running water. As germination progressed, the protein and fibre content of GSG increased slightly, while the lipid and carbon to nitrogen (C/N) ratio decreased; free amino acids including GABA increased considerably while free sugars decreased. Linoleic and linolenic acid were the most abundant unsaturated fatty acids in soy germ, and slight changes were observed in GSG. The tocopherol and isoflavone contents showed a rapid increase of 32.4% and 27.9%, respectively, during germination. The abundance of GABA, isoflavones and tocopherols demonstrates the high nutritional value of GSG and suggests that GSG can be utilised as a reasonable and effective source of healthy foods.