Optimization of LED-based phototreatments for enhancing antioxidant potential and marketable traits in microgreens

This study examined the levels of major flavonoids, nutritional components, total secondary metabolite contents, and antioxidant activities in 136 mung bean accessions and statistically analyzed the effect of seed weight difference on each. Vitexin and isovitexin were detected in all the mung bean accessions, with isovitexin being in a higher concentration regardless of seed weight difference. The contents of total protein and total starch were in the ranges of 22.01–28.96 and 32.62–49.03 g/100 g, respectively. Five fatty acids were detected by GC–FID analysis in all mung bean accessions, with linoleic acid being the most dominant (37.96–50.71 g/100 g). Total saponin content (TSC), total phenol content (TPC), DPPH• scavenging activity, ABTS•+ scavenging activity, and ferric reducing antioxidant power (FRAP) showed more than five-fold differences. Analysis of variance supported by multivariate analysis demonstrated that seed weight difference had a significant effect on total starch, all individual fatty acids except for stearic acid and oleic acid, TSC, and all antioxidant activities except for ABTS•+ scavenging activity. On the other hand, vitexin, isovitexin, total protein, total phenol, and total fatty acid contents remained unaffected by seed weight difference. Overall, this study showed the diversity of key flavonoids, nutritional components, total secondary metabolite contents, and antioxidant activities in mung bean genetic materials. Moreover, the study unveiled how seed weight affects the analyzed parameters in mung beans for the first time. These findings could maximize the use of mung beans in food industries and breeding programs as well as lead to more studies in metabolomics and genomics.

Secondary metabolites are produced by plants both during normal growth and under biotic and abiotic stresses. Apart from genetic and environmental factors, the secondary metabolite contents are also influenced by analytical methods. The aims of this study were to obtain suitable solvents and extraction treatments which produced high total flavonoid and phenolic contents as well as antioxidant activity in shiny and dull green mung beans. An extraction of 0.5 g sample with grade 80 mesh in 70% acetone was selected to estimate the contents of total flavonoids and phenolics. A treatment of shaking the sample in 70% acetone (1:10 w/v) for 2 h and followed by 18 h of maceration with twice extractions showed the highest amounts of flavonoid as well as phenolic contents. Total flavonoid and phenolic contents of 14 mung bean cultivars ranged from 1.28 to 2.35 mg CE/g and 3.74 to 6.58 mg GAE/g, respectively. Antioxidant activity represented by percentage of DPPH inhibition varied from 66.8 to 91.5%. A dull green mung bean cultivar Vima 1 had the highest total flavonoid and phenolic contents (2.35 mg CE/g and 6.58 mg GAE/g). Antioxidant activity of Vima 1 cultivar (91.5%) was not different from those of Perkutut (91.5%), Murai (90.1%) and Sriti (88.9%). The small quantity of sample (0.5 g) combined with the simple extraction treatment was effective in quantifying the different contents of total flavonoids and phenolics in mung bean seeds. <br /><br />

Mung bean seeds were germinated, at 30±2OC, in the dark for 0, 6, 12, 18 and 24 h. Crude protein content of germinated mung bean significantly (p˂0.05) increased during germination period. The 24 h-germinated mung bean (24 H-GMB) had the highest protein content but not significantly different compared to that of 18 h-germinated mung bean (18 H-GMB). However, this germination period did not affect the ratio of each amino acid to total amino acids in terms of content. Total phenolic content (TPC) of germinated mung bean significantly increased during germination period (p˂0.05). The 24 H-GMB showed the highest TPC, amounting to 5.78 mg gallic acid g-1 db, the value doubled increased compared to 0 h-germinated mung bean (0 H-GMB), amounting to 2.81 mg gallic acid g-1 db. The 18 H-GMB was chosen as a raw material for protein hydrolysate production and 0 H-GMB was used as the control. These samples were hydrolyzed at 50OC, pH 6.0. Four concentrations of Flavourzyme® (0, 1, 3, and 5% by dried weight of the germinated mung bean) were useds and hydrolysis periods were 0, 1, 2, 3, 4 and 5 h. The results showed that degree of hydrolysis (DH) increased with increasing in both Flavourzyme® concentration and hydrolysis period in both 0 H-GMB and 18 H-GMB. The DH significantly affected the amount of free amino group (FAG) and TPC in all hydrolysate samples obtained from both 0 H-GMB and 18 H-GMB (p˂0.05). Hydrolysis of 0 H-GMB and 18 H-GMB with 5% Flavourzyme® for 5 h gave the highest FAG and TPC compared to other conditions in its group. There was a positive linear correlation between DH and FAG (R2 = 0.920 for 0 H-GMB protein hydrolysate and R2 = 0.997 for 18 H-GMB protein hydrolysate) and between DH and TPC (R2 = 0.971 for 0 H-GMB protein hydrolysate and R2 = 0.962 for 18 H-GMB protein hydrolysate). Antioxidant activities of the protein hydrolysate were measured using chemical methods including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), and metal chelating activity, and using electron spin resonance (ESR) method for DPPH radical scavenging activity, hydroxyl radical scavenging activity and carbon-centered radical scavenging activity. It was found that antioxidant activities of the germinated mung bean protein hydrolysates, measured using both methods, increased when DH increased. This trend was observed in both of the 0 H-GMB protein hydrolysate and 18 H-GMB protein hydrolysate. Higher antioxidant activity was found in the 18 H-GMB protein hydrolysate compared to that obtained from 0 H-GMB protein hydrolysate. Phenolic acid in the freeze dried germinated mung bean hydrolysate was determined by HPLC with an online DPPH radical scavenging activity system. The results showed that antioxidative phenolic acid found in the 0 H-GMB protein hydrolysate and 18 H-GMB protein hydrolysate was gallic acid and certain unidentified compounds. The above results showed that FAG and TPC contribute antioxidant activities of germinated mung bean protein hydrolysates.

Polyphenols play an important role in human nutrition, therefore, how to improve its content with innovative approach is important, and understanding the metabolic pathys is necessary. Mung beans are rich in polyphenols, which made them have physiological functions such as hypoglycemia, antioxidant, and hypotension. However, the content of polyphenols in natural mung bean is relatively low, and it needs to be increased. The methods of increasing polyphenol content in grains and beans by enrichment include physical stress, such as ultrasonic stress, hypoxia stress and ultraviolet radiation, and single exogenous substance stress, such as exogenous amino acids, exogenous sugars. But, the enrichment of polyphenols using exogenous substances in combination with physical stress is less applied. Therefore, this study innovated the use of exogenous γ-aminobutyric acid (GABA) combined with ultrasonic stress to enrich mung bean sprouts polyphenols and enhance their content. The metabolic pathways of the enrichment process were also analyzed to provide a reference for studies related to the enrichment of polyphenols. Mung bean seeds were pretreated with a combination of ultrasound and GABA under different conditions. Single-factor test and response surface methodology were used for optimizing pretreatment conditions of mung bean. Effects of combined pretreatments on the polyphenols content and antioxidant activity of sprouted mung beans were investigated. Additionally, metabolites were identified, and metabolic pathways were analyzed using non-targeted metabolomics techniques. Optimal conditions of mung bean pretreatment were found to be 370 W for ultrasound power, 40 min for ultrasonication time, 10 mmol/L for GABA concentration, and 8 h for the soaking duration. Under these conditions, the predicted polyphenol content was found to be 4.52 mg GAE/g DW. The pretreatment of mung beans with a combination of ultrasound and exogenous GABA resulted in mung bean sprouts with enhanced polyphenol content and antioxidant activity compared to mung beans germinated without pretreatment. A significant increase in the content of six polyphenols [Genistein, (-)-Epigallocatechin, Epicatechin, Nobiletin, Naringenin, Biochanin A] in the pretreated and germinated mung beans was found, and six metabolic pathways (flavonoid biosynthesis, isoflavones biosynthesis, biosynthesis of phenylpropanoids, anthocyanin biosynthesis, biosynthesis of secondary metabolites, and metabolic pathways) were significantly activated. The obtained results suggest that a combination of ultrasound and exogenous GABA treatment can be used to produce mung bean sprouts with enriched polyphenols content and enhanced antioxidant activity.

The objective of the present work is to optimize fermentation conditions for a set of three legume-based synbiotic beverages made from green mung and red kidney beans, namely GMB (100% mung bean); RKB (100% kidney bean); and KB (7:3, kidney bean: mung bean) to attain desirable quality attributes. Face-centered composite design (FCCD) was applied using fermentation time and temperature as independent variables. The responses, namely, pH, protein digestibility (PD), and total viable count (TVC) of probiotic Lacticaseibacillus casei ATCC 335, were optimized using response surface methodology (RSM) followed by numerical optimization. The optimization was based on maximizing the desirability, which connected the responses and importance. The experimental and predicted values were similar, and the model was valid for all beverages with R2 >0.9. The optimized condition suggested that fermentation at 20°C for 18h in the case of KB and GMB and 21h for RKB would lead to desired pH (6.0-6.5), maximum PD (>60%), and highest TVC (>8 log CFU/ml). A significant reduction in antinutritional factors (ANFs), namely, tannin (20-44%), saponin (43-52%), and phytate (43-46%) from an initial value of around 0.30, 0.40, and 0.50mg/L respectively, for all the beverages at optimized fermentation conditions was observed. Similarly, a slight loss of<3.5% in total phenol content (TPC) was seen. Additionally, good proteolytic and antibacterial activity was observed, with KB being the best. Hence, all developed legume-based synbiotic beverages exhibit desirable goals when subjected to optimized fermentation conditions and enhanced functionality. PRACTICAL APPLICATION: When subjected to optimized fermentation conditions, the developed synbiotic legume-based beverages can be used as a potential functional food in the nondairy beverage industry with added health benefits and new tasting flavors.

Effects of slice thickness of quince (Cydonia oblonga Miller) , microwave incident power and air drying temperature on antioxidant activity and total phenolic content of quince were investigated during drying in microwave and air drying. Optimum conditions were found to be: i) for microwave drying, 285 W and 4.14 mm thick (maximum antioxidant activity) and 285 W and 6.85 mm thick (maximum total phenolic content), and ii) for air drying, 75 ºC and 1.2 mm thick (both maximum antioxidant activity and total phenolic content). Drying conditions were optimized by using the response surface methodology. 13 experiments were carried out considering incident microwave powers from 285 to 795 W, air temperature from 46 to 74 ºC and slice thickness from 1.2 to 6.8 mm.

ABSTRACT. The present study evaluated the optimum conditions of ultrasound-assisted extraction (UAE) and Soxhlet extraction (SE) of antioxidant capacities and total phenolics from fresh Moringa oleifera leaves, using the response surface methodology. Spectrophotometric method with Folin–Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagents was used to determine the total phenolic content (TPC) and the antioxidant activity (AA), respectively. The four models obtained showed the non-linear and quadratic dependences of both measured responses (TPC and AA) which were influenced significantly by all control variables including the acetone solvent (70%, v/v) to solid (SS) ratio, extraction time, and extraction temperature of both extraction methods. Furthermore, at the same extraction temperature, the extraction efficacy of UAE was better than SE as significantly shorter extraction time, less extraction solvent, but higher bio-active content was experienced. The optimal UAE conditions included a SS ratio of 31:1 (mL/g), extraction time of 26 min, and extraction temperature of 59 oC, resulting in the maximum TPC (34.36 mg GAE/g dry weight, DW) and AA (491.9 µmol TE/g DW) in the extracts. In addition, the models proposed were considered to be accurate and reliable for predicting the TPC and AA of fresh M. oleifera leaf extract. The research findings also imply potential applications for ultra-sonication extraction to produce the extracts from fresh M. oleifera leaves for pharmaceutical industry as well as food technology.&#x0D; &#x0D; KEY WORDS: Antioxidant activity, Herbal plant, Model, Polyphenols, RSM&#x0D; &#x0D; Bull. Chem. Soc. Ethiop. 2022, 36(2), 261-275. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v36i2.2

Effects of different intensities of far-red and green light on the growth and photosynthetic characteristics of melon seedlings

Conventional techniques for phenolics extraction from pomegranate (Punica granatum) peel (PP) have several insufficiencies like longer time duration, bioactive degradation, excess use of harmful chemicals and solvents. In the present study, we established the synergistic use of two non-conventional extraction strategies i.e., enzyme-assisted extraction (EAE) using a cellulolytic enzyme preparation (Viscozyme) followed by microwave-assisted extraction (MAE) for efficient recovery of phenolics from PP. This optimized method was individually compared with EAE, MAE, and conventional solvent extraction (CSE) methods for recovering PP phenolics with maximum antioxidant activity (AOA). Extracts were analyzed for AOA using ferric reducing antioxidant power (FRAP) and cupric reducing AOA (CUPRAC) methods. Response surface methodology (RSM), was used as an optimization tool to achieve maximum yield of phenolics and with highest AOA at power 443.5W, time 131.0min, and solvent-to-solid ratio 23.6:1. The predicted values for maximum phenolics and AOA obtained through RSM were 305mg GAE/g, 1788μmol TE/g (FRAP) and 2641μmol TE/g (CUPRAC), respectively. Phenolic contents of only 94.6, 165.46, and 197.6mg GAE/g were achieved through CSE, EAE and MAE, respectively. Here we substantiate the auxiliary role of Viscozyme and microwave treatment in achieving high phenolic content and AOA from PPs. Phenolic rich extracts are known to act as multi-target ligands that inhibit various enzymes involved in diseases like Alzheimer's, Parkinson's, and diabetes mellitus. The extract can be commercially exploited for the development of functional foods, supplements, and natural preservatives.

This study aimed to optimize minimal thermal treatment conditions for sour cherry juice using response surface methodology. The effects of ultrasound power (UP; 54, 35, 14 W), ultrasound time (UT; 8, 5, 3 min), ohmic electrical field strength (OE; 40, 30, 20 V/cm) and ohmic time (OT; 8, 5, 3 min) on total phenolic content (TPC), antioxidant activity (AA), color values (L*, a*, b*, ), total monomeric anthocyanin content (TMAC), polymeric color (PC), color density (CD), polymeric color ratio (PC%), total mesophilic aerobic bacteria (TMAB) and yeast‐mold count (YM) were investigated. UP significantly affected TPC, L*, a*, b*, and , while OE affected TPC, TMAC, PC, PC%, and TYC. UT affected TPC, L*, AA, CD, PC and PC%, and OT level affected TPC and b* values. The optimum points were determined by considering maximum TPC as 28.7564, maximum AA as 6.7714, maximum TMAC as 4.9616, maximum L* as 21.3839, maximum a* as 5.5396, maximum b* as 3.4260, maximum color density as 27.1412, minimum polymeric color as 17.3148, minimum PC% as 4.9253, minimum TYC as 1.9251 and minimum TMBC as 2.3301. The optimum levels were found to be 54 W, 8 min, 27.06 V/cm and 8 min. Improvements in TPC, TMAC and AA were determined after ultrasound‐ohmic combination thermal treatment. Although ohmic (OH) has the effect of maintaining juice quality, its effectiveness is impacted by the electrochemical properties of food. By using ultrasound, the electrical conductivity values of juices were increased; thus, ultrasound improved the electrochemical properties of sour cherry juice. Further studies are needed to evaluate the effects of ultrasound‐ohmic combination for juice processing on a large scale.

Steam explosion (SE), as a physicochemical pretreatment process, has the dual effect of high temperature and high pressure. In this study, SE was applied to pretreat mung beans to increase phenolic extraction and their antioxidant activity. It can make the material loose and porous, which is beneficial to the release of phenolic compounds from mung beans. Insoluble‐bound phenolics (IBPs) were the dominating fraction, followed by glycosidic phenolics (GPs) and esterified phenolics (EPs), and free phenolics (FPs) were the lowest in mung beans. After SE, the maximum contents of FPs, EPs, GPs, IBPs, and total phenolics were detected at 0.75 MPa for 30 s, which were 1.47‐, 1.87‐, 1.73‐, 1.48‐, and 1.58‐fold compared with the untreated samples, respectively. On the whole, the effect of SE on phenolics in mung beans first increased and then decreased. SE increased the contents of protocatechuic acid, p‐coumaric acid, ferulic acid, catechin, and epicatechin; but there was a decrease in caffeic acid. Compared with the untreated samples, the antioxidant activity of FPs, GPAs, EPs, and IBPs was also improved by SE. The relationship between the phenolic content and antioxidant activity was very high with coefficients of 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐ sulfonic acid) > 2,2′‐diphenyl‐1‐picrylhydrazyl > ferric reducing antioxidant power. In conclusion, an appropriate SE can lead to a more efficient extraction of phenolics and improvement of antioxidant activity in mung beans.

Prunella vulgaris, a medicinal plant with antioxidant capacity, was investigated for its response to varying intensities of far-red light and nutrient levels. Plantlets were cultured for 30 d under low far-red light (LFR) or high far-red light (HFR) conditions and different nutrient levels (full, half, and quarter). HFR reduced leaf and branch number, dry weight, and accumulation of chlorophylls (Chl) and carotenoids (Car), while increasing plant height. Lower nutrient levels increased plant height and leaf number, but decreased branch number, Chl, and Car. HFR significantly increased total phenolic content (TPC), rutin, and rosmarinic acid levels, while total flavonoid content decreased. As nutrient levels decreased, TPC and rosmarinic acid declined. HFR induced significant DPPH scavenging activity, while reducing power increased with higher far-red light and nutrient levels. The ferrous ion chelating effect under LFR reduced with lower nutrient levels. There were strong correlations among TPC, rosmarinic acid, DPPH scavenging activity, and reducing power. In conclusion, HFR inhibited plantlet growth but enhanced secondary metabolite accumulation and antioxidant capacity. Different nutrient levels stimulated diverse growth responses, while elevated nutrient levels promoted secondary metabolite production. This study demonstrated the responses of growth, secondary metabolite accumulation, and antioxidant activity in the in vitro cultured P. vulgaris to supplemental far-red light and various nutrient levels.

Does Processing have a Considerable Effect on the Nutritional and Functional Properties of Mung Bean (Vigna Radiata)?

Pressurized liquid extraction (PLE) is a green extraction technique that can enhance extraction rates of bioactive compounds. PLE was used to extract antioxidants and polyphenols from industrially generated apple pomace at two different temperature ranges: 160 to 193 degrees C and 75 to 125 degrees C. Antioxidant activity (DPPH radical scavenging test), total phenol content and three individual polyphenol groups were determined. Response surface methodology was used to optimize the five response values. Maximum antioxidant activity was obtained at a temperature of 200 degrees C, but unwanted compounds such as hydroxymethylfurfural were formed. Therefore a lower temperature range between 75 and 125 degrees C is recommended. Using this temperature range, a maximum antioxidant activity was determined at 60% ethanol and 102 degrees C. By using PLE the antioxidant activity was increased 2.4 times in comparison to traditional solid-liquid extraction, and the technique may be a promising alternative to conventional techniques for extracting antioxidants.

Light availability is a key environmental factor regulating nitrogen assimilation, carbon metabolism, and nutritional quality in leafy vegetables grown in controlled environments. However, how practical lighting regimes used in plant factories with artificial lighting (PFALs) influence the coordination between nitrogen assimilation and central carbon metabolism across different lettuce cultivar types remains insufficiently understood. This study investigated how moderate differences in photosynthetic photon flux density (PPFD) influence nitrogen metabolism and metabolic coordination in hydroponically cultivated lettuce. Two cultivars representing contrasting morphological types, iceberg lettuce (‘Celebration’) and leaf lettuce (‘Sunny’), were grown under LED light intensities of 150 and 200 µmol·m−2·s−1. Nitrate, nitrite, and ammonium concentrations were measured together with the activities of nitrate reductase (NRA) and nitrite reductase (NiRA), as well as ascorbic acid content. Metabolomic profiling was additionally performed to characterize broader metabolic responses. Higher light intensity enhanced nitrate reduction capacity in both cultivars, but the resulting patterns of nitrogen accumulation were strongly genotype-dependent. The leaf lettuce cultivar ‘Sunny’ exhibited increased NRA and reduced nitrate accumulation under higher light intensity, whereas the iceberg lettuce cultivar ‘Celebration’ accumulated more nitrate under the same conditions. Ammonium responses further suggested differences in downstream nitrogen assimilation processes. Elevated light intensity also increased ascorbic acid levels in both cultivars. Metabolomic analysis revealed contrasting cultivar-specific shifts in central carbon metabolism, particularly involving soluble sugars and tricarboxylic acid cycle intermediates, indicating differential coordination between carbon metabolism and nitrogen utilization. Overall, these findings demonstrate that moderate changes in light intensity within the practical PFAL cultivation range can significantly influence the integration of carbon and nitrogen metabolism in lettuce. Importantly, cultivar-specific physiological traits determine how these metabolic responses translate into nitrate accumulation and nutritional quality in controlled-environment production systems.