Optimization of Microwave Pre-Cooked Conditions for Gelatinization of Adzuki Bean

Pre-cooked adzuki beans (Vigna angularis), which looks like dried adzuki bean, is easily cooked and preserved. This study aimed to optimize the microwave pre-cooked conditions on adzuki beans by applying the response surface methodology. The results showed that soaking time has a significant effect on the gelatinization degree of adzuki beans according to microwave time. The most suitable gelatinization and the sensory scores were obtained with a soaking time of 7.8 h, a microwave power of 830 W, and microwave time of 92 s. The pre-cooked treatment had no significant effect (p > 0.05) on the protein, free amino acid, fat and starch content of adzuki bean products. The results of SEM and polarized light microscopy showed that the surface and center of starch were damaged after microwave treatment. XRD showed that microwave pre-cooking did not change the crystal structure of starch and maintained the original order of type A structure while reducing the relative starch crystallinity. FT-IR showed that the pre-cooked treatment did not produce new structure in adzuki bean starch, but the ratio of 1047/1022 cm−1 was slightly decreased, indicating that the starch crystallization area decreased relative to the amorphous area and the relative crystallinity decreased. The results of FTIR were consistent with X-ray diffraction results. Therefore, microwaves improved the gelatinization of adzuki beans and made the pre-cooked adzuki beans more suitable.

iTRAQ based protein profile analysis revealed key proteins involved in regulation of drought-tolerance during seed germination in Adzuki bean

Adzuki bean is an important legume crop due to its high-quality protein, fiber, vitamins, minerals as well as rich bioactive substances. However, it is vulnerable to drought at the germination stage. However, little information is available about the genetic control of drought tolerance during seed germination in adzuki bean. In this study, some differential expression proteins (DEPs) were identified during seed germination between the drought-tolerant variety 17235 and drought-sensitive variety 17033 in adzuki bean using iTRAQ method. A total of 2834 proteins were identified in the germinating seeds of these two adzuki beans. Compared with the variety 17033, 87 and 80 DEPs were increased and decreased accumulation in variety 17235 under drought, respectively. Meanwhile, in the control group, a few DEPs, including 9 up-regulated and 21 down-regulated proteins, were detected in variety 17235, respectively. GO, KEGG, and PPI analysis revealed that the DEPs related to carbohydrate metabolism and energy production were significantly increased in response to drought stresses. To validate the proteomic function, the ectopic overexpression of V-ATPase in tobacco was performed and the result showed that V-ATPase upregulation could enhance the drought tolerance of tobacco. The results provide valuable insights into genetic response to drought stress in adzuki bean, and the DEPs could be applied to develop biomarkers related to drought tolerant in adzuki bean breeding projects.

Exogenous ABA foliar spray treatment alleviates flooding stress in adzuki bean (Vigna angularis) during the seedling stage

Abscisic acid (ABA) plays an important role in regulating activities of antioxidant enzymes, hormone levels, accumulation of reactive oxygen species under stress. To understand the effects of exogenous ABA treatment on flooding tolerance at seedling stage in adzuki bean (Vigna angularis), the water-sensitive (WS) variety ‘Tianjinhong’ (TJH) and the water-tolerant (WT) variety ‘Longxiaodou 4’ (LXD 4) were foliar sprayed exogenous ABA with 20 μM, followed by flooding stress for 5 days under pot conditions. Our results revealed that under flooding stress at seedling stage, the contents of H2O2 and MDA, proline and soluble protein in adzuki bean leaves significantly increased, the contents of ABA, IAA and SA significantly increased, and the activities of SOD, POD and CAT also significantly increased. Flooding treatment for 5 days resulted in a significant decrease in single pot yield of LXD 4 by 8.40% and TJH by 9.91%. Foliar spray of 20 μM exogenous ABA could resist flooding stress, considerably increased the contents of proline and soluble protein, significantly decreased the contents of H2O2 and MDA, significantly increased the activities of SOD and POD, increased the contents of ABA and SA, and significantly inhibited the increase of IAA content in adzuki bean leaves. Spraying exogenous ABA significantly increased the yield of ‘LXD’ 4 by 6.95% after 4 days of flooding treatment, and ‘TJH’ by 4.46%. To sum up, there were significant differences in physiological stress among different varieties of adzuki bean under flooding stress, and spraying exogenous ABA could effectively alleviate the effects of flooding stress on physiology and yield of adzuki bean. The results of this study provided a theoretical basis for further studying the physiological mechanism of adzuki bean resisting flooding stress at seedling stage and improving the yield of adzuki bean under flooding stress. Thus, foliar spraying exogenous ABA effectively improved submergence tolerance by enhancing the activity of protective enzymes and osmoregulation. These results provided novel insights and were expected to aid in the development of more effective stress resistance cultivation methods in adzuki bean production.

The Complementarity of Amino Acids in Cooked Pulse/Cereal Blends and Effects on DIAAS

The aim was to study the complementary effect between cereals and pulses on protein quality. The values for the digestible indispensable amino acid score (DIAAS) in cooked cereals and pulses, given alone, and blends of cooked cereals and pulses, were determined. True ileal digestibility (TID) values of amino acids for adult humans were obtained. It is difficult to determine ileal amino acid digestibility in humans directly, and for this reason, the growing pig is often used to obtain such values, as a preferred animal model. Seven growing pigs fitted with a T-cannula at the terminal ileum were allotted to a 7 × 6 incomplete Latin square with seven semi-synthetic diets (cooked mung bean, adzuki bean, millet, adlay, mung bean + millet, adzuki bean + adlay, and an N-free diet) and six 7-day periods. The mean TID values for crude protein differed significantly (p < 0.05), with millet having the highest digestibility (89.4%) and the adzuki bean/adlay mixture having the lowest (79.5%). For lysine, adzuki bean had the highest TID (90%) and millet had the lowest (70%). For the mean of all the amino acids, there was a significant (p < 0.05) effect of diet, with the TID ranging from 72.4% for the adzuki bean/adlay mixture to 89.9% for the adzuki beans. For the older child, adolescent, and adult, the DIAAS (%) was 93 for mung beans, 78 for adzuki beans, 22 for millet, 16 for adlay, and 66 for mung beans + millet, and 51 for adzuki beans + adlay. For mung beans, valine was first-limiting, and the SAA for adzuki beans, while lysine was first-limiting for the other foods. Chinese traditional diets, containing both cereals and pulses, are complementary for most, but not all of the indispensable amino acids.

Adzuki Bean Alleviates Obesity and Insulin Resistance Induced by a High-Fat Diet and Modulates Gut Microbiota in Mice

Adzuki bean consumption has many health benefits, but its effects on obesity and regulating gut microbiota imbalances induced by a high-fat diet (HFD) have not been thoroughly studied. Mice were fed a low-fat diet, a HFD, and a HFD supplemented with 15% adzuki bean (HFD-AB) for 12 weeks. Adzuki bean supplementation significantly reduced obesity, lipid accumulation, and serum lipid and lipopolysaccharide (LPS) levels induced by HFD. It also mitigated liver function damage and hepatic steatosis. In particular, adzuki bean supplementation improved glucose homeostasis by increasing insulin sensitivity. In addition, it significantly reversed HFD-induced gut microbiota imbalances. Adzuki bean significantly reduced the ratio of Firmicutes/Bacteroidetes (F/B); enriched the occurrence of Bifidobacterium, Prevotellaceae, Ruminococcus_1, norank_f_Muribaculaceae, Alloprevotella, Muribaculum, Turicibacter, Lachnospiraceae_NK4A136_group, and Lachnoclostridium; and returned HFD-dependent taxa (Desulfovibrionaceae, Bilophila, Ruminiclostridium_9, Blautia, and Ruminiclostridium) back to normal status. PICRUSt2 analysis showed that the changes in gut microbiota induced by adzuki bean supplementation may be associated with the metabolism of carbohydrates, lipids, sulfur, and cysteine and methionine; and LPS biosynthesis; and valine, leucine, and isoleucine degradation.

iTRAQ Based Protein Profile Analysis Revealed Key Proteins Involved in Regulation of Drought-Tolerance During Seed Germination in Adzuki Bean

Adzuki bean is famous as its high-quality protein, fiber, vitamins, minerals as well as rich bioactive substances. However, it is vulnerable to drought at the germination stage. Up to date, little information is available about the genetic controls of drought tolerance during seed germination in adzuki bean. In this study, differential expression proteins（DEPs）were identified based on iTRAQ technology during seed germination between the drought-tolerant variety 17235 and drought-sensitive variety 17033 in adzuki bean. A total of 2834 proteins were identified in the two adzuki bean in the germinating seeds. Eighty-seven and eighty DEPs were increased and decreased accumulation in variety 17235 compared to 17033 under drought, respectively. Meanwhile, 132/205 and 144/123 DEPs were up- or down-regulated in 17235 and 17033 under drought compared to the control, respectively. GO, KEGG, and PPI analysis revealed that the proteins related to carbohydrate metabolism and energy production showed abundantly increase in response to drought stresses. Ectopic overexpression of one candidate encoding V-ATPase in tobacco enhanced the drought tolerance of plants. The results provide valuable insights into adzuki bean response to drought stress, and the DEPs might be applied to develop drought tolerant adzuki bean in breeding programs.