Physicochemical Properties and Minor Lipid Components of Soybean Germ

Benchmarking Nutraceutical Soybean Composition Relative to Protein and Oil

The aim of this study was to explore relationships between protein, oil, and seed weight with seed nutraceutical composition, focused on total isoflavone (TI) and total tocopherol (TT) contents across genotypic and environmental combinations in soybean. We conducted a synthesis-analysis of peer-reviewed published field studies reporting TI, TT, protein, oil, and seed weight (n = 1,908). The main outcomes from this synthesis-analysis were: (i) relationship of TI-to-protein concentration was positive, though for the upper boundary, TI decreases with increases in protein; (ii) relationship of TT-to-oil concentration was positive, but inconsistent when oil was expressed in mg per seed; and (iii) as seed weight increased, TI accumulation was less than proportional relative to protein concentration and TT decreased more proportional relative to oil concentration. Association between nutraceuticals and protein, oil, and seed weight for soybean reported in the present study can be used as a foundational knowledge for soybean breeding programs interested on predicting and selecting enhanced meal isoflavone and/or oil tocopherol contents.

The characterization of soybean germ oil and the antioxidative activity of its phytosterols

The aim of this study was to characterize the composition of soybean germ and its oil from Northeast (NE-SG) and Shandong Province (SD-SG) of China with a focus on the composition of fatty acids and phytosterols as well as physicochemical properties. The results show that the average contents of water, protein, crude fat, crude fiber and ash of NE-SG and SD-SG were 8.23 ± 0.11%, 40.47 ± 0.10%, 11.65 ± 0.14%, 6.20 ± 0.09% and 4.79 ± 0.14%, respectively. The major fatty acids of the two soybean germ oils were linoleic acid (NE-SGO, 55.45%; SD-SGO, 52.15%), alpha-linolenic acid (NE-SGO, 16.21%; SD-SGO, 18.50%), palmitic acid (NE-SGO, 12.59%; SD-SGO, 11.40%) and oleic acid (NE-SGO, 9.87%; SD-SGO, 10.96%). The soybean germs were rich in phytosterols (NE-SGO, 3168 mg/100 g oil; SD-SGO, 3010 mg/100 g oil) consisting of β-sitosterol, Δ7-stigmastenol, campesterol, stigmastanol, and citrostadienol. The antioxidant ability of soybean germ phytosterols was evaluated using DPPH˙ and OH˙ radical scavenging assays, β-carotene protection assay and a heating oil system. The results demonstrated that soybean germ phytosterols had better antioxidant ability in oil systems than in non-oil systems. The antioxidant ability of these phytosterols was temperature- and time-dependent since it was more effective at lower temperatures (60 °C) with longer times as compared to higher temperatures (120 °C and 180 °C) with shorter times. These results prove that soybean germ phytosterols could be used as antioxidants in preventing lipid oxidation in foods stored at a low temperature for a long time.