褐藻酸寡糖诱导下大豆营养成分的变化

【目的】探索褐藻酸寡糖诱导大豆抗毒素生成和积累过程中,特别是当大豆抗毒素累积量达到最大时,大豆的异黄酮类化合物、氨基酸、寡糖、脂肪酸等营养成分的变化,为大豆的充分开发和利用提供科学依据。【方法】采用4%(w/v)的褐藻酸寡糖溶液作为诱导剂对大豆进行诱导。分别提取不同培养时间(0—6d)下大豆中的异黄酮化合物、氨基酸、寡糖、脂肪酸等营养成分;利用高效液相色谱(HPLC)、全自动氨基酸分析仪、气相色谱(GC)等方法检测各培养时间下大豆营养成分的含量。【结果】经褐藻酸寡糖诱导后,大豆中的异黄酮化合物、氨基酸、寡糖、脂肪酸等含量均发生了变化。异黄酮类化合物中,大豆抗毒素的累积量在培养第5天时达到最高,由诱导前的0.01 mg·g-1升高至1.72 mg·g-1,第5天时香豆雌酚含量由开始时的15.74μg·g-1升高至664.8μg·g-1,染料木素含量由开始时的1.58μg·g-1升高至24.03μg·g-1,大豆苷元则由培养开始时的54.56μg·g-1降低至19.02μg·g-1。诱导组大豆中的总氨基酸含量由开始时的39.38%升高至43.45%,且苏氨酸、亮氨酸等必需氨基酸含量也有所升高,非诱导组大豆中的氨基酸含量也有一定程度的提高,但含量总体低于诱导组大豆。诱导组大豆中蔗糖含量由培养开始时的53.72 mg·g-1减少至21.5 mg·g-1,棉籽糖和水苏糖分别在培养第3天和第4天即被完全消耗;非诱导组大豆中蔗糖含量由培养开始时的53.72mg·g-1减少至23.09 mg·g-1,且仍有少量的棉籽糖和水苏糖被检出。诱导组大豆中的脂肪酸总含量由培养开始时的14.27%降低至14.01%,但其中亚油酸的含量和比例有所增加。【结论】褐藻酸寡糖在诱导大豆获得最高大豆抗毒素含量时,增加了大豆中异黄酮类化合物含量,提高了大豆蛋白质的营养价值,消除了大豆中的胀气因子,并且在一定程度上提高了大豆的油脂品质。

Changes in Nutritional Properties of Soybeans Induced by Alginate Oligosaccharides

【Objective】 The aim of this study was to explore the nutritional composition (isoflavonoids, amino acids, oligosaccharides and fatty acids) changes in soybean seeds induced by alginate oligosaccharide and provide a scientific basis for further utilization of soybean resource. 【Method】 Soybean seeds were induced by 4% (w/v) alginate oligosaccharides as elicitor. Isoflavones, amino acids, oligosaccharides and fatty acids were extracted from the induced and non-induced soybean seeds during different incubation times (1 d to 6 d). Contents of these compositions during different incubation times were detected and analyzed by HPLC, automatic amino acid analyzer or GC. 【Result】 Isoflavones, amino acids, oligosaccharides and fatty acids in induced soybeans changed dramatically. During the incubation period, glyceollins content was observed to have increased steadily from day 1 to day 5 having concentration of 0.01 mg·g^-1 DW at 1 d and 1.72 mg·g^-1 DW was recorded at 5 d. Highest accumulations were recorded for coumestrol (664.8 μg·g^-1 DW) and genistein (24.02 μg·g^-1 DW) at 5 d. While, daidzein decreased from 54.56 μg·g^-1 DW to 19.02 μg·g^-1 DW, respectively. Nutritional composition changes recorded during the five days were as follow: total amino acids content in induced soybeans seeds increased from 39.38% to 43.45% during the incubation period, contents of threonine and leucine were observed to have increased. Amino acids content recorded in the non-induced soybean seeds during analysis also showed nutritional changes, but the changes were generally lower than the changes observed in the induced soybean seeds. The content of sucrose in induced soybean seeds decreased from 53.72 mg·g^-1 DW to 21.5 mg·g^-1 DW, raffinose decreased totally at 3 d, while stachyose decreased at 4 d. In non-induced soybean seeds, sucrose decreased from 53.72 mg·g^-1 DW at 1 d to 23.09 mg·g^-1 DW, little amount of raffinose and stachyose were also detected. The total fatty acids content in the induced soybean seeds decreased from 14.27% to 14.01% during analysis, while the proportion of linoleic acid increased. 【Conclusion】 During the period of glyceollins accumulation in soybeans which were induced by oligosaccharides, the production of isoflavones in soybeans increased, the nutritional value of soybean protein was enhanced, flatulence factor in soybeans was eliminated, the property of soy oil was promoted. All of these changes were of great importance to the fully utilization of soybean resource.