Effect of Germination and Illumination on Melatonin and Its Metabolites, Phenolic Content, and Antioxidant Activity in Mung Bean Sprouts

Untargeted metabolomics combined with vitro antioxidant to comprehensively evaluate the effect of sodium sulfite immersion on the holistic quality of mung bean sprouts

Mung bean sprouts are widely consumed as a seasonal fresh vegetable, renowned for their affordability and richness in antioxidants and bioactive compounds. This study employed ultra-high-performance liquid chromatogram-Q-Exactive HF mass spectrometry (UHPLC-QE-MS) and multivariate statistical analysis to comprehensively evaluate the chemical profile of mung bean sprouts following sulfite immersion. The findings revealed a significant alteration in the overall chemical composition of mung bean sprouts following sodium sulfite immersion. Eleven components, including four sulfur-containing compounds, were identified as characteristic markers distinguishing between non-immersed and sodium sulfite-immersed mung bean sprouts. Esterification and addition reactions were inferred to occur during sodium sulfite immersion, leading to the transformation of flavonoid and saponin sulfates. Commercial samples analysis indicated that sulfur-containing compounds were detectable in 9 of 11 commercial mung bean sprouts. Meanwhile, when sodium sulfite concentration exceeded 3.00 mg/mL and immersion time exceeded 360 min, the contents of total polyphenol and flavonoid were significantly reduced and the antioxidant activity was adversely influenced.

Enhancing the stability of mung bean-based milk: Insights from protein characteristics and raw material selection

Plant-based milk (PBM) alternatives are gaining popularity worldwide as the change of consumers' nutritional habits and health attitudes. Mung beans, recognized for their nutritional value, have gained attention as potential ingredients for PBM. Nevertheless, mung bean-based milk (MBM) faces instability issues common to other plant-based milks. This study investigated the factors influencing MBM stability focusing on raw materials. We selected 6 out of 20 varieties based on their MBM centrifugation sedimentation rates, representing both stable and unstable MBM. Stable MBM exhibited distinct advantages, including reduced separation rate, smaller particle size, lower viscosity, fewer protein aggregates, higher soluble protein content, and increased consumer acceptance. Major nutritional components such as protein, starch, and lipids were not significant different between stable and unstable MBM varieties. The pivotal distinction may lay in the protein properties and composition. Stable MBM varieties exhibited significantly improved protein solubility and emulsion stability, along with elevated concentrations of legume-like acidic subunits, basic 7S proteins, and 28 kDa and 26 kDa vicilin-like subunits. The increasement of these proteins likely contributed to the improvement in protein characteristics that affect MBM stability. These findings offer valuable insights for raw material selection and guidance for future mung bean breeding to enhance mung bean milk production.

Spatial Lipidomics Reveals Lipid Changes in the Cotyledon and Plumule of Mung Bean Seeds during Germination

Seed germination is a vital process in plant development involving dynamic biochemical transformations such as lipid metabolism. However, the spatial distribution and dynamic changes of lipids in different seed compartments during germination are poorly understood. In this study, we employed liquid chromatography/mass spectrometry (LC/MS)-based lipidomics and MALDI mass spectrometry imaging (MSI) to investigate lipid changes occurring in the cotyledon and plumule of mung bean seeds during germination. Lipidomic data revealed that the germination process reduced the levels of many glycerolipids (e.g., triglyceride) and phosphatidylglycerols (e.g., phosphatidylcholine) while increased the levels of lysophospholipids (e.g., lysophosphatidylcholine) in both the cotyledon and plumule. Sphingolipids (e.g., sphingomyelin) displayed altered levels solely in the plumule. Sterol levels increased in the cotyledon but decreased in the plumule. Further imaging results revealed that MALDI-MSI could serve as a supplement and validate LC-MS data. These findings enhance our understanding of the metabolic processes underlying seedling development, with potential implications for crop improvement and seed quality control.

The Effect of Light and Dark Treatment on the Production of Rosmarinic Acid and Biological Activities in Perilla frutescens Microgreens

This study aimed to investigate the effect of light [a long-day photoperiod (16 h light/8 h dark cycle)] and dark treatment on the production of rosmarinic acid in P. frutescens microgreens and to determine its antioxidant and antibacterial activities. Microgreens of P. frutescens were grown under light and dark conditions and harvested after 10, 15, 20, and 25 days of each treatment. Although dry weight values of microgreens gradually increased from 10 to 25 days of both treatments, the microgreens grown under light treatment possessed slightly higher levels of dry weight than those grown in the dark. Rosmarinic acid and total phenolic content (TPC) were also analyzed using high-performance liquid chromatography (HPLC) and Folin-Ciocalteu assay. The accumulation patterns of rosmarinic acid and TPC gradually increased and decreased, respectively, in P. frutescens microgreens grown in continuous darkness. The highest accumulation was observed in microgreens grown for 20 days. However, rosmarinic acid and TPC values were not significantly different in microgreens grown under light conditions. According to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition assay, the extracts of P. frutescens microgreens were confirmed to be strong antioxidants, and their ability to scavenge DPPH radicals was positively correlated with the total phenolic content in the microgreens after 10, 15, 20, and 25 days of both treatments. Considering the relatively higher values of dry weight, rosmarinic acid, TPC, and DPPH assay, P. frutescens microgreens after 20 days of darkness and 20 days of light treatment, respectively, were selected for screening antibacterial activity using nine pathogens. Both microgreen extracts showed strong antibacterial activity against pathogens. In particular, the extracts of microgreens grown for 20 days under light treatment showed higher antimicrobial effects. Therefore, the light treatments for 20 days, as well as the darkness treatment for 20 days, were the best conditions for P. frutescens microgreen production because of their high levels of dry weight, phenolics, and biological activities.

Polyphenol and Tryptophan Contents of Purple Corn (Zea mays L.) Variety KND and Butterfly Pea (Clitoria ternatea) Aqueous Extracts: Insights into Phytochemical Profiles with Antioxidant Activities and PCA Analysis

Plants are a rich source of phytochemical compounds with antioxidant activity. Several studies have revealed that the consumption of plant polyphenols reduces the risk of diseases. Purple corn (Zea mays L. variety KND) and butterfly pea (Clitoria ternatea; CT) were selected to be investigated as alternative natural polyphenol sources to increase the value of these plants. Phytochemical profiles and antioxidant activities of KND cob, silk, husk and CT extracts alone and in combination were investigated in this study. The results revealed that purple corn cob (C) extract had the highest tryptophan, melatonin, total anthocyanin (TAC) and delphinidin content, while the purple corn silk (S) extract showed the highest total phenolic content (TPC) and antioxidant activities. Serotonin was found only in purple corn husk (H) extract and C extract. High contents of tryptophan and sinapic acid were found in CT extract. Principal component analysis (PCA) revealed that strong antioxidant activities were strongly correlated with protocatechuic acid and p-hydroxybenzoic acid contents, moderate antioxidant activities were strongly correlated with melatonin, and low antioxidant activities were strongly correlated with sinapic acid content. Therefore, the purple corn variety KND waste cobs, silk and husks are a potentially rich source of health-promoting phytochemical compounds.