Changes occurring in compositional components of black soybeans maintained at room temperature for different storage periods

Differential responses of B vitamins in black soybean seeds

This study was aimed to determine the contents and the association of B vitamins from seeds of 10 black and one yellow soybean (Glycine max (L.) Merr.) varieties with either green or yellow cotyledon. Thiamine, flavin adenine dinucleotide (FAD), riboflavin and total riboflavin were found highest in 'Chengjakong', while flavin mononucleotide (FMN) was greatest in 'Mirang'. Nicotinic acid and total vitamin B3 were highest in 'Shingi' as a yellow soybean variety but pantothenic acid and pyridoxine contents were greatest in 'Tawon' and 'Mirang', respectively. These content variations of B vitamins directly reflected the wide segregation of soybean varieties on the principal component analysis (PCA) scores plot, indicating that these 4 soybean varieties appeared to be least associated with other soybean varieties based on the different responses of B vitamins. The results of cluster and correlation analyses presented that the cotyledon colour of soybean seed contributed to a variation of B vitamin contents. Overall, the results suggest that a wide range of B vitamin contents would be affected by genotypic factors alongside the difference of cotyledon colour.

Black soybean extract protects against TMT-induced cognitive defects in mice

To find a neuroactive compound with a potent inhibitory effect on acetylcholinesterase (AChE) and in vivo anti-amnesic activity from natural resources, we evaluated anthocyanins and nonanthocyanins from black soybean extract. Nonanthocyanins from black soybean extract were the most potent and dose-dependent AChE inhibitors. Intracellular reactive oxygen species accumulation resulting from H₂O₂ treatment was significantly decreased compared with cells treated with H₂O₂ only. Nonanthocyanins were also neuroprotective against H₂O₂ treated neurotoxicity by 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assay. Finally, nonanthocyanins from black soybean in the preadministration group attenuated trimethyltin (TMT)-induced memory injury in both in vivo tests. AChE, prepared from mice brain tissues, was inhibited by nonanthocyanins from black soybean in a dose-dependent manner. Malondialdehyde generation in the brain homogenates of mice treated with nonanthocyanins from black soybean was decreased. We concluded that nonanthocyanins from black soybean had an efficacious in vitro AChE inhibitory activity, and protected against H₂O₂-induced neurotoxicity. In addition, our findings suggest that nonanthocyanins from black soybean may improve the TMT-induced learning and memory deficit because of AChE inhibition of mice brain tissue. Consequently, these results demonstrate that the nonanthocyanins from black soybean could possess a wide range of beneficial activities for neurodegenerative disorders.

Seed maturity differentially mediates metabolic responses in black soybean

The soybean seed is placed in the middle of the morphological and developmental alterations, such as changes in seed size, weight, and colour, and alteration of the composition and contents of metabolites during maturation. In this study, we used black soybean seeds to investigate the effect of maturity on metabolite levels at different maturity stages. Seeds were sorted into five maturity categories, from M1 to M5, based on seed size and external pigmentation. Maturity stages M1, M3, and M5 are equivalent to R6, R7, and R8 on the soybean reproductive growth stage scale, indicating full seed, beginning maturity, and full maturity, respectively. As seed maturation progressed, the seed size decreased and the water soluble extract changed, indicating that a change of seed pigmentation occurred. At the same time, numerous metabolites responded differentially to seed maturation. The partial least squares (PLS) scores plot indicated that the metabolic alteration during maturation was clearly visible. Furthermore, isoflavones were highly associated with seed maturity on the PLS loading plot while fatty acids, glucose, fructose, and sucrose were less linked with seed maturity, indicating that those metabolites responded less to seed maturation. Overall, the results indicate that each category of metabolites is mediated differentially during maturation in black soybean seeds.

Effects of baking on cyanidin-3-glucoside content and antioxidant properties of black and yellow soybean crackers

Black soybean is a potential functional food ingredient with high anthocyanin content, but the ability to maintain anthocyanin content under dry heat processing has not been reported. This study investigated the effects of soybean seed coat colour and baking time-temperature combinations on the extractable antioxidant properties of a soy cracker food model. Crackers prepared with black soybeans had significantly higher TPC, total isoflavones, and peroxyl, hydroxyl, and ABTS(+) radical scavenging abilities than their yellow counterparts, at all time-temperature combinations. Cyanidin-3-glucoside (C3G) was detected only in black soybean crackers, and all baking treatments significantly decreased C3G. The greatest losses occurred at the low temperature×long time and high temperature×short time, the smallest loss with moderate temperature×short/medium time. The high temperature treatment altered phenolic acid and isoflavone profiles; however, total isoflavones were unaffected. Overall results suggest that moderate baking temperature at minimal time may best preserve anthocyanin and other phenolics in baked black soybean crackers.

Rapid characterisation and comparison of saponin profiles in the seeds of Korean Leguminous species using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) analysis

The present work was reported on investigation of saponin profiles in nine different legume seeds, including soybean, adzuki bean, cowpea, common bean, scarlet runner bean, lentil, chick pea, hyacinth bean, and broad bean using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) technique. A total of twenty saponins were characterised under rapid and simple conditions within 15min by the 80% methanol extracts of all species. Their chemical structures were elucidated as soyasaponin Ab (1), soyasaponin Ba (2), soyasaponin Bb (3), soyasaponin Bc (4), soyasaponin Bd (5), soyasaponin αg (6), soyasaponin βg (7), soyasaponin βa (8), soyasaponin γg (9), soyasaponin γa (10), azukisaponin VI (11), azukisaponin IV (12), azukisaponin II (13), AzII (14), AzIV (15), lablaboside E (16), lablaboside F (17), lablaboside D (18), chikusetusaponin IVa (19), and lablab saponin I (20). The individual and total saponin compositions exhibited remarkable differences in all legume seeds. In particular, soyasaponin βa (8) was detected the predominant composition in soybean, cowpea, and lentil with various concentrations. Interestingly, soybean, adzuki bean, common bean, and scarlet runner bean had high saponin contents, while chick pea and broad bean showed low contents.

Antioxidant and antidiabetic activities of black mung bean (Vigna radiata L.)

Interest in mung bean as a functional food is growing. The objective of this study was to characterize the phenolic compounds, antioxidant activities, and antidiabetic activities of black mung beans. Five black mung beans were selected, and one green mung bean was included for comparison. The free phenolic acid and bound phenolic acid contents ranged from 16.68 to 255.51 μg/g and from 2284.53 to 5363.75 μg/g, respectively, whereas the total anthocyanin contents ranged from 0 to 810.55 μg/g with cyanidin-3-glucoside as the most dominant form, respectively. Among the mung beans tested, black mug bean Xiaoqu 7110 had the highest content of bound phenolic acids and exhibited the strongest antioxidant capacities (1,1-diphenyl-2-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt and oxygen radical absorbance capacity) as compared to the other tested mung beans. Jiheilv 27-3 exhibited higher antidiabetic activities (inhibition of α-glucosidase and advanced glycation end products).