Effects of hydrogen water treatment on antioxidant system of litchi fruit during the pericarp browning

Bacillus amyloliquefaciens LY-1 culture broth enhances the storage properties of fresh litchi through acting on ROS metabolism

The impacts of Bacillus amyloliquefaciens LY-1 culture broth (BLCB) on the fruit storage properties and reactive oxygen species (ROS) metabolism of postharvest 'Wuye' litchis were studied. In comparation with control fruit, BLCB-treated litchis showed a lower fruit disease index, a higher rate of commercially acceptable fruit, higher amounts of pericarp pigments (total phenolics, anthocyanin, carotenoid, chlorophyll and flavonoid), higher chromaticity C, a*, b* and L* values but lower hue angle h° of fruit surface. Additionally, BLCB-treated litchis exhibited lower malonaldehyde (MDA) accumulation and superoxide anion radical (O2.-) production rate, higher APX, CAT and SOD activities, higher GSH and AsA amounts, higher reducing power, and higher ability of scavenging DPPH radical. Furthermore, the pericarp browning index and fruit disease index were positively correlated with O2.- production rate. These findings suggested that BLCB treatment increased the storability of postharvest litchi fruit through enhancing scavenging capacity of ROS and inhibiting overaccumulation of ROS.

Transcriptomic analysis of melatonin-mediated drought stress response genes in alfalfa during germination period

BACKGROUND

Drought stress is a predominant abiotic factor contributing to reduced crop yields globally. Therefore, exploring the molecular mechanism of drought control is of great significance to improve drought resistance and ultimately achieve crop yield increase. As a plant endogenous hormone, melatonin plays a key role in the regulation of abiotic stress, but the key genes and metabolic pathways of melatonin mediated drought resistance regulation in alfalfa have not been fully revealed. Based on transcriptomics and physiological index detection, this study aimed to explore the regulatory mechanism of melatonin in alleviating drought stress during alfalfa germination.

RESULTS

The findings revealed that alfalfa seedlings treated with melatonin exhibited higher germination rates, increased shoot length, and greater fresh weight compared to those exposed solely to drought stress. Additionally, there was a reduction in the levels of malondialdehyde (MDA) and superoxide anion (O2-), while the activity and concentration of superoxide dismutase (SOD), peroxidase (POD), and glutathione (GSH) were enhanced to varying extents. To investigate the molecular mechanism underlying melatonin-mediated drought resistance in alfalfa, we performed a transcriptomic analysis on the seedlings. In the drought treatment group, we identified a total of 1,991 differentially expressed genes (DEGs), comprising 778 up-regulated and 1,213 down-regulated genes. Conversely, in the melatonin-treated group, we discovered 2,336 DEGs, including 882 up-regulated and 1,454 down-regulated genes.

CONCLUSIONS

Through the application of GO functional annotation and KEGG pathway enrichment analysis, we discovered that DEGs were predominantly enriched in pathways related to flavonoid and isoflavone biosynthesis, plant hormone biosynthesis and signal transduction, glutathione metabolism, and MAPK signaling, and the ABC transporter signaling. Notably, the DEGs added to the MT group showed greater enrichment in these pathways. This suggests that MT mitigates drought stress by modulating the expression of genes associated with energy supply and antioxidant capacity. These findings hold significant reference value for breeding drought-tolerant alfalfa and other crops.

Research Progress of Hydrogen Rich Water in Preservation of Postharvest Horticultural Products: A Review

The perishable nature of horticultural products and unfavorable factors during storage lead to postharvest losses and shelf life limitations. As an effective hydrogen (H2) supplier, hydrogen-rich water (HRW) is regarded as a new green postharvest preservation strategy of horticultural products. This review presents a complete overview of the application advance of HRW for the preservation of horticultural products, including the potential production mechanisms of hydrogen in plants, the preparation and application methods of HRW, and potential mechanisms of HRW in improving the quality of postharvest horticultural products. The findings show that HRW can maintain the quality and stress tolerance of horticultural products by regulating metabolic pathways and molecular responses, including oxidative defense, energy homeostasis, respiration, cell-wall intergrity, ethylene biosynthesis, related gene expression and phytohormones signaling crosstalk. The information obtained in this review is expected to provide a scientific basis for the application of HRW for the preservation of postharvest horticultural products.

Application trends of hydrogen-generating nanomaterials for the treatment of ROS-related diseases

Reactive oxygen species (ROS) play essential roles in both physiological and pathological processes. Under physiological conditions, appropriate amounts of ROS play an important role in signaling and regulation in cells. However, too much ROS can lead to many health problems, including inflammation, cancer, delayed wound healing, neurodegenerative diseases (such as Parkinson's disease and Alzheimer's disease), and autoimmune diseases, and oxidative stress from excess ROS is also one of the most critical factors in the pathogenesis of cardiovascular and metabolic diseases such as atherosclerosis. Hydrogen gas effectively removes ROS from the body due to its good antioxidant properties, and hydrogen therapy has become a promising gas therapy strategy due to its inherent safety and stability. The combination of nanomaterials can achieve targeted delivery and effective accumulation of hydrogen, and has some ameliorating effects on diseases. Herein, we summarize the use of hydrogen-producing nanomaterials for the treatment of ROS-related diseases and talk about the prospects for the treatment of other ROS-induced disease models, such as acute kidney injury.

External browning mechanism in walnut kernel pellicles under different drying conditions based on the combination of widely-targeted and anthocyanin-targeted metabolomics

There has been limited research on external browning (EB) of walnut. This work discovered 1888 metabolites and 34 anthocyanins in walnut pellicles (WPs) after three drying methods using widely-targeted and anthocyanin-targeted metabolomics. Based on OPLS-DA and correlation analysis, 64 temperature-responsive metabolites (TRMs; 13 anthocyanins and 51 flavonoids) were identified as critical components in relation to EB. Notably, 14 flavonoids exhibited a strong positive correlation (r > 0.9) with the browning index (BI), with upregulation of >60% after browning. Most of the identified anthocyanins were negatively linked with BI because of degradation (>45%), with correlation coefficients ranging from 0.75 to 0.97. Furthermore, anthocyanidin reductase and laccase were the two key enzymes involved in the EB of WPs, with their activities increasing by 10.57-fold and 1.32-fold, respectively, with increasing drying temperature. A metabolic pathway network of the TRM was built to provide insights into the potential mechanisms underlying EB in WPs.

tert-Butylhydroquinone alleviates a postharvest pericarp browning of longan fruit by regulating antioxidant metabolism

Harvested longan fruit is prone to pericarp browning, which restricts preservation quality and shortens fruit shelf life. The antioxidant system can defend against oxidative stress-mediated quality deterioration such as fruit browning. This study aimed to evaluate the effect of tert-butylhydroquinone (TBHQ) on anti-browning ability of longan fruit in association with redox metabolism. The results indicated that the application of 0.02% TBHQ significantly suppressed the progression of pericarp browning. In comparison with control, TBHQ treatment decreased the contents of hydrogen peroxide (H2O2), superoxide radical (O2 -⋅), and malondialdehyde, and retained high levels of ascorbic acid (AsA), glutathione (GSH), total phenolics as well as 1,1-diphenyl-2-picrylhydrazyl scavenging rate. Enhanced enzymatic activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase, and dehydroascorbate reductase (DHAR), but decreased activities of polyphenol oxidase and peroxidase were also observed in TBHQ-treated fruit. Gene expression analysis indicated that redox metabolism-related genes, including DlSOD, DlCAT, DlGR, and DlAPX, were upregulated after TBHQ treatment. Correlation analysis suggested that antioxidants, including AsA, GSH, CAT, APX, SOD, and DHAR, were negatively correlated to reactive oxygen species production and percarp browning. These results suggest that TBHQ is effective in alleviating pericarp browning by increasing antioxidant capacity of longan fruit.

Low voltage electrostatic field combined with ice-temperature to improve the quality of litchi during storage

Litchi is popular among consumers due to its delicious taste, however, the extremely short shelf life limits its commercial value. Few studies have been conducted to develop new technologies to extend the shelf life of litchi. Therefore, this study applied a novel technique (low voltage electrostatic field, LVEF) combined with ice-temperature (0 °C) treatment on litchi and evaluated its quality characteristics during storage. The results demonstrated that low voltage electrostatic field with ice-temperature storage (LVEF-IT) decreased malondialdehyde content, relative electrolyte leakage, and polyphenol oxidase and peroxidase activities, successfully delayed the start of peel browning. Additionally, it preserved the fruit pulp's excellent quality, which included high concentrations of soluble solids, ascorbic acid, and soluble protein. These findings imply that LVEF-IT treatment may be a novel technique for extending the storage time of litchi.

Zinc Oxide Nanoparticles Treatment Maintains the Postharvest Quality of Litchi Fruit by Inducing Antioxidant Capacity

Pericarp browning and fruit decay severely reduce the postharvest quality of litchi. Improving the antioxidant capacity of the fruit is an effective way to solve these problems. In our study, the appropriate zinc oxide nanoparticles (ZnO NPs) treatment and its mechanism of action on the storability of litchi was investigated. Litchi fruit was soaked in a 100 mg·L-1 ZnO NPs suspension, water, and 500 mg·L-1 prochloraz for 2 min, respectively. The results showed that the ZnO NPs treatment delayed pericarp browning and decay in litchi fruit and was more effective than prochloraz treatment. The ZnO NPs-treated fruit showed significantly increased contents of total anthocyanin, total phenols, and activities of DPPH scavenging, superoxide dismutase, and glutathione peroxidase, as well as the lowest activities of polyphenol oxidase and laccase. ZnO NPs generated hydrogen peroxide and superoxide anion radicals, which were beneficial in slowing down the decay and inducing antioxidant capacity. However, these reactive oxygen species also consumed catalase, peroxidase, glutathione, and glutathione peroxidase. This means that litchi should be treated with an appropriate concentration of ZnO NPs. We concluded that treatment with a 100 mg·L-1 ZnO NPs suspension could induce antioxidant capacity, which is a promising and effective method to maintain the postharvest quality of litchi.

The role of hydrogen-rich water in delaying the pulp breakdown of litchi fruit during postharvest storage

Previous studies have indicated that hydrogen-rich water (HW) treatment can delay fruit ripening and senescence. However, little is known about the HW-delaying pulp breakdown. In this study, eight physiological characteristics revealed that HW treatment delayed both pericarp browning and pulp breakdown of litchi fruit. To gain a comprehensive understanding of the changes in litchi pulp, a combination of multiple metabolomics and gene expression analyses was conducted, assessing 67 primary metabolites, 103 volatiles, 31 amino acids, and 13 crucial metabolite-related genes. Results showed that HW treatment promoted starch degradation, decelerated cell wall degradation and glycolysis, and maintained the flavor and quality of litchi fruit. Furthermore, HW treatment stimulated the production of volatile alcohols, aldehydes, ketones, olefins, and amino acids, which might play a vital role in HW-delaying pulp breakdown. This study sheds light on the mechanism by which HW delayed pulp breakdown by investigating small molecule metabolites and metabolic pathways.

Hydrogen gas: A new fresh keeping agent of perishable horticultural products

Hydrogen gas (H2), a gaseous signaling molecule, is involved in plant growth and development. This review collates emerging evidence to show that H2 regulates the postharvest senescence of horticultural products through critical biochemical processes, including the improvement of antioxidant systems, the activation of cell wall metabolism, the promotion of energy metabolism, the inhibition of ethylene biosynthesis and the regulation of bacterial communities. Additionally, the interactions between H2 and other signaling molecules are also discussed. This paper presents the current status of H2 research in terms of its biological effects and safety in postharvest products by combining the research results on the molecular mechanisms of biological effects and H2 signaling. The action mechanism of H2 for postharvest preservation is also proposed, and it reflects the complexity and diversity of the pathways involved. Furthermore, a growing body of evidence has found a large number of downstream pathways or targets for the medical effects of H2. Therefore, the scientific and practical aspects of H2 biology are proposed for the postharvest preservation of horticultural products.

Transcriptome analysis reveals that trehalose alleviates chilling injury of peach fruit by regulating ROS signaling pathway and enhancing antioxidant capacity

Peach fruit is prone to chilling injury (CI) during low-temperature storage, resulting in quality deterioration and economic losses. Our previous studies have found that exogenous trehalose treatment can alleviate the CI symptoms of peach by increasing sucrose accumulation. The purpose of this study was to explore the potential molecular mechanism of trehalose treatment in alleviating CI in postharvest peach fruit. Transcriptome analysis showed that trehalose induced gene expression in pathways of plant MAPK signaling, calcium signaling, and reactive oxygen species (ROS) signaling. Furthermore, molecular docking analysis indicated that PpCDPK24 may activate the ROS signaling pathway by phosphorylating PpRBOHE. Besides, PpWRKY40 mediates the activation of PpMAPKKK2-induced ROS signaling pathway by interacting with the PpRBOHE promoter. Accordingly, trehalose treatment significantly enhanced the activities of antioxidant-related enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and gluathione reductase (GR), as well as the transcription levels AsA-GSH cycle related gene, which led to the reduction of H2O2 and malondialdehyde (MDA) content in peach during cold storage. In summary, our results suggest that the potential molecular mechanism of trehalose treatment is to enhance antioxidant capacity by activating CDPK-mediated Ca2 + -ROS signaling pathway and WRKY-mediated MAPK-WRKY-ROS signaling pathway, thereby reducing the CI in peach fruit.

The metabolism of amino acids, AsA and abscisic acid induced by strigolactone participates in chilling tolerance in postharvest zucchini fruit

Zucchini fruit are notably susceptible to chilling injury when stored at low temperatures. The purpose of this experimental investigation was to assess the influence of strigolactone (ST) (5 μmol L-1) on mitigating chilling injury and the metabolic changes in amino acids, ascorbic acid, and abscisic acid in zucchini fruit stored at 4°C. Research findings demonstrated that ST-treated zucchini fruit displayed a significantly higher tolerance to chilling stress compared to the control group. Postharvest ST treatment led to a decrease in weight loss, accompanied by reduced levels of malondialdehyde and relative ion leakage compared to the untreated group. ST immersion significantly boosted the metabolic pathways associated with proline and arginine, affecting both the enzymatic reactions and gene expressions, thus cumulatively increasing the internal concentrations of these amino acids in zucchini fruit. Zucchini treated with ST exhibited an increased concentration of γ-aminobutyric acid (GABA) as a result of augmented activities and elevated transcriptional levels of glutamate decarboxylase (GAD), GABA transaminase (GAT), and succinate semialdehyde dehydrogenase (SSD). In the ST-treated sample, the elevated enzymatic activities and enhanced gene expressions within the ascorbic acid (AsA) biosynthesis pathway worked together to sustain AsA accumulation. The application of ST resulted in a rise in abscisic acid (ABA) concentration, which correspondingly correlated with the induction of both activities and gene expression levels of crucial enzymes involved in ABA metabolism. Our findings revealed that submerging zucchini fruit in ST could be a highly effective strategy for boosting their chilling tolerance. The alleviation in chilling injury induced by ST may be attributed to the modulation of proline, arginine, GABA, AsA and ABA metabolism.

Effect and Mechanism of L-Arginine against Alternaria Fruit Rot in Postharvest Blueberry Fruit

This study aimed to explore the impact of L-arginine (Arg) on the development of resistance to Alternaria tenuissima (A. tenuissima) in blueberries. The metabolism of reactive oxygen species, pathogenesis-related proteins (PRs), and jasmonic acid (JA) biosynthesis pathways were analyzed, including changes in activity and gene expression of key enzymes. The results indicated that Arg treatment could prevent the development of Alternaria fruit rot in postharvest blueberries. In addition, it was also found to induce a burst of hydrogen peroxide in the blueberries early on during storage, thereby improving their resistance to A. tenuissima. Arg treatment was observed to increase the activity of antioxidant enzymes (peroxidase, catalase, superoxide dismutase, and ascorbate peroxidase) and related gene expression, as well as the total levels of phenolics, flavonoids, and anthocyanin in the blueberries. The activity and gene expression of the PRs (chitinase and β-1,3-glucanase) were elevated in Arg-treated blueberries, boosting their resistance to pathogens. Additionally, a surge in endogenous JA content was detected in Arg-treated blueberries, along with upregulated expression of key genes related the JA biosynthesis pathway (VcLOX1, VcAOS1, VcAOC, VcAOC3, VcOPR1, VcOPR3, VcMYC2, and VcCOI1), thereby further bolstering disease resistance. In conclusion, Arg treatment was determined to be a promising prospective method for controlling Alternaria fruit rot in blueberries.

Hydrogen Fertilization with Hydrogen Nanobubble Water Improves Yield and Quality of Cherry Tomatoes Compared to the Conventional Fertilizers

Although hydrogen gas (H2)-treated soil improves crop biomass, this approach appears difficult for field application due to the flammability of H2 gas. In this report, we investigated whether and how H2 applied in hydrogen nanobubble water (HNW) improves the yield and quality of cherry tomato (Lycopersicon esculentum var. cerasiforme) with and without fertilizers. Two-year-long field trials showed that compared to corresponding controls, HNW without and with fertilizers improved the cherry tomato yield per plant by 39.7% and 26.5% in 2021 (Shanghai), respectively, and by 39.4% and 28.2% in 2023 (Nanjing), respectively. Compared to surface water (SW), HNW increased the soil available nitrogen (N), phosphorus (P), and potassium (K) consumption regardless of fertilizer application, which may be attributed to the increased NPK transport-related genes in roots (LeAMT2, LePT2, LePT5, and SlHKT1,1). Furthermore, HNW-irrigated cherry tomatoes displayed a higher sugar-acid ratio (8.6%) and lycopene content (22.3%) than SW-irrigated plants without fertilizers. Importantly, the beneficial effects of HNW without fertilizers on the yield per plant (9.1%), sugar-acid ratio (31.1%), and volatiles (20.0%) and lycopene contents (54.3%) were stronger than those achieved using fertilizers alone. In short, this study clearly indicated that HNW-supplied H2 not only exhibited a fertilization effect on enhancing the tomato yield, but also improved the fruit's quality with a lower carbon footprint.

Comparative physiological, metabolomic and transcriptomic analyses reveal the mechanisms of differences in pear fruit quality between distinct training systems

BACKGROUND

Canopy architecture is critical in determining the fruit-zone microclimate and, ultimately, in determining an orchard's success in terms of the quality and quantity of the fruit produced. However, few studies have addressed how the canopy environment leads to metabolomic and transcriptomic alterations in fruits. Designing strategies for improving the quality of pear nutritional components relies on uncovering the related regulatory mechanisms.

RESULTS

We performed an in-depth investigation of the impact of canopy architecture from physiological, metabolomic and transcriptomic perspectives by comparing pear fruits grown in a traditional freestanding system (SP) or a flat-type trellis system (DP). Physiological studies revealed relatively greater fruit sizes, soluble solid contents and titratable acidities in pear fruits from DP systems with open canopies. Nontargeted metabolite profiling was used to characterize fruits at the initial ripening stage. Significant differences in fruit metabolites, including carbohydrates, nucleic acids, alkaloids, glycerophospholipids, sterol lipids, and prenol lipids, were observed between the two groups. Transcriptomic analysis indicated that a series of organic substance catabolic processes (e.g., the glycerol-3-phosphate catabolic process, pectin catabolic process and glucan catabolic process) were overrepresented in fruits of the DP system. Moreover, integrative analysis of the metabolome and transcriptome at the pathway level showed that DP pear fruits may respond to the canopy microenvironment by upregulating phenylpropanoid biosynthesis pathway genes such as PpPOD. Transient assays revealed that the contents of malic acid and citric acid were lower in the pear flesh of PpPOD RNAi plants, which was associated with regulating the expression of organic acid metabolism-related genes.

CONCLUSIONS

Our results provide fundamental evidence that at the physiological and molecular levels, open-canopy architecture contributes to improving pear fruit quality and is correlated with increased levels of carbohydrates and lipid-like molecules. This study may lead to the development of rational culture practices for enhancing the nutritional traits of pear fruits.

Critical assessment of the delivery methods of chemical and natural postharvest preservatives for fruits and vegetables: a review

Through a comprehensive review on preservative delivery methods in fruits and vegetables preservation, it becomes evident that majority of existing studies concentrate on the development and mechanisms of preservatives. However, a notable gap lies in comparative analysis of different delivery methods, despite the direct impact of delivery methods on preservation outcomes. Additionally, emerging delivery techniques have displayed promising potential in enhancing delivery efficiency and likewise preservation effectiveness.

Enhancement of Growth and Secondary Metabolites by the Combined Treatment of Trace Elements and Hydrogen Water in Wheat Sprouts

This study aimed to evaluate the response of Triticum aestivum to hydrogen water (HW) and trace elements treated with HW. A pot experiment was conducted to assess the growth indices, secondary metabolites, and antioxidant levels. The response surface methodology (RSM) approach was used to ascertain the concentrations and significant interaction between treatments. The outcomes demonstrated that the combined treatment of Se acid and Mo oxide exhibited a notable positive effect on the growth and secondary metabolites, when treated with HW as compared to distilled water (DW). Notably, the interaction between these two treatments is significant, and the higher response was observed at the optimal concentration of 0.000005% for Se acid and 0.06% for Mo oxide. Additionally, an in vitro experiment revealed that the mixture treatment inhibits the accumulation of lipids in HepG2 hepatocytes cells. Moreover, metabolic analysis revealed that upregulated metabolites are linked to the inhibition of lipid accumulation. In addition, the analysis emphasizes that the continued benefits of higher plants as a renewable supply for chemicals compounds, especially therapeutic agents, are being expanded and amplified by these state-of-the-art technologies.

Selenium application during fruit development can effectively inhibit browning of fresh-cut apples by enhancing antioxidant capacity and suppressing polyphenol oxidase activity

Browning is a crucial factor affecting the quality of fresh-cut apples. A safe, simple, and effective method to inhibit browning is urgently needed in fresh-cut apple production. We carried out this study to explore the effect mechanism of exogenous selenium (Se) fertilizer on fresh-cut apple browning. During the development of apples, 0.75 kg/plant Se fertilizer was exerted on the 'Fuji' apple tree at the critical stage of the young fruit stage (late May), early fruit expansion stage (late June), and fruit expansion stage (late July), an equal amount of Se-free organic fertilizer was used as control. Polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities, phenolic and malondialdehyde (MDA) content, antioxidant enzymes activity, and DPPH free radical scavenging rate of the apple at different development stages were investigated. The highest Se accumulation efficiency was observed in apple fruit one month after applying Se fertilizer, which was 41.1%. Se-rich apples exhibited a more remarkable ability to resist browning than control after fresh-cut. The anti-browning effect of the fertilization group (M7) was the best, the PPO activity decreased to 0.5 × 103 U kg-1, and the browning index was 28.6. The total Se content (TSC) of 331.4 μg kg-1 DW and organic Se content (OSC) of 292.0 μg kg-1 DW were the highest in the apple samples, reached the classification standard of Se content in Se-rich food. The correlation analysis found that fresh-cut apple browning was closely related to antioxidant capacity and PPO activity. The stronger the antioxidant capacity of fresh-cut apples treated with Se fertilizer, the lower their browning degree. Therefore, exogenous Se can alleviate fresh-cut apples browning by improving antioxidant capacity and reducing PPO activity. Se-rich apples could increase the Se content of the human essential trace element and inhibit the browning of fresh-cut apples, which would become a new, safe and effective way to solve the fresh-cut apples browning.

Browning inhibition in fresh-cut Chinese water chestnut under high pressure CO2 treatment: Regulation of reactive oxygen species and membrane lipid metabolism

Fresh-cut Chinese water chestnut (CWC) was treated with high pressure CO₂ (HPCD) to inhibit the browning reactions, and the underlying mechanism was investigated in this study. Results showed that HPCD at 2 MPa pressure significantly inhibited lipoxygenase activity and enhanced superoxide dismutase activity, leading to decreased malondialdehyde and H₂O₂ contents in surface tissue. Moreover, HPCD could reduce total phenols/flavonoids content of surface tissue. Compare with control, homoeriodictyol, hesperetin, and isorhamnetin contents of 2 MPa HPCD-treated samples on day 10 were reduced by 95.72%, 94.31%, and 94.02%, respectively. Furthermore, HPCD treatment enhanced antioxidant enzyme activities, and improved the O₂^- scavenging ability and reducing power of inner tissue. In conclusion, by regulating ROS and membrane lipid metabolism, HPCD treatment with appropriate pressure could retard the biosynthesis of flavonoids and enzymatic oxidation of phenolic compounds in surface tissue, and enhance antioxidant activity of inner tissue, thereby, delaying the quality deterioration of fresh-cut CWC.

Storability and Linear Regression Models of Pericarp Browning and Decay in Fifty Litchi (Litchi chinensis Sonn.) Cultivars at Room Temperature Storage

The primary cause for the limited shelf life of litchi fruit is rapid pericarp browning and decay. This study aims to evaluate the storability of 50 litchi varieties and establish a linear regression model for pericarp browning and decay based on 11 postharvest physical and chemical indices after 9 days of storage at room temperature. The results indicated that the average value of the browning index and decay rate significantly increased to 3.29% and 63.84% of 50 litchi varieties at day 9, respectively. Different litchi varieties showed different variations in appearance indicators, quality indicators, and physiological indicators. Furthermore, principal component analysis and cluster analysis revealed that Liu Li 2 Hao exhibited the highest resistance to storage, whereas Dong Long Mi Li, Jiao Pan Li, E Dan Li 2 Hao, and Ren Shan Li were not resistant. Stepwise multiple regression analysis further demonstrated that the factors were highly correlated with the decay index, with a partial correlation coefficient of 0.437 between the effective index and the decay index. Therefore, pericarp thickness, relative conductivity, pericarp laccase activity, and total soluble solids were significant indicators for the comprehensive evaluation of litchi browning and decay, and relative conductivity was the significant determinant causing fruit browning. These findings provide a new perspective on the sustainable development of the litchi industry.

Hydrogen-rich water alleviates chilling injury-induced lignification of kiwifruit by inhibiting peroxidase activity and improving antioxidant system

BACKGROUND

Kiwifruit is prone to chilling stress and displays chilling injury (CI) such as lignification; however, the underlying physicochemical mechanism remains largely unknown. Here, the changes in levels of quality attributes, lignin biosynthesis, antioxidant system and sugars were compared in kiwifruit between control and hydrogen-rich water (HRW) treatments during cold storage for 90 days at 0 °C.

RESULTS

The results reveal that HRW is an effective measure for CI alleviation, as indicated by the decrease in lignification level with repressed peroxidase activity but enhanced polyphenol oxidase activity. The amelioration of membrane peroxidation was suggested by the repressed levels of H₂ O₂ and malondialdehyde. They were accompanied by the improvement of antioxidant system, which is supported by the enhancement of sugars including fructose and glucose.

CONCLUSION

In conclusion, HRW can enhance chilling tolerance, as suggested by the alleviation of lignification through inhibiting peroxidase activity and elevating the antioxidant system to attenuate membrane peroxidation. © 2022 Society of Chemical Industry.

Postharvest melatonin treatment enhanced antioxidant activity and promoted GABA biosynthesis in yellow-flesh peach

The effects of postharvest melatonin treatment on antioxidant activity and γ-aminobutyric acid (GABA) biosynthesis in yellow-flesh peach fruit stored at 4 °C and 90% RH for 28 d were explored. Results showed that melatonin treatment was effective in maintaining firmness, total soluble solids content and color in peach fruit. Melatonin treatment significantly reduced H₂O₂ and MDA contents, enhanced high level of non-enzymatic antioxidant system (ABTS∙⁺ scavenging capacity), and increased the activity or content of antioxidant enzymes including CAT, POD, SOD and APX. Melatonin treatment increased the contents of total soluble protein and glutamate, while reducing total free amino acid content. Moreover, melatonin treatment up-regulated the expression of GABA biosynthesis genes (PpGAD1 and PpGAD4) and suppressed the expression of GABA degradation gene (PpGABA-T), resulting in the accumulation of endogenous GABA. These findings indicated that melatonin treatment exerted positive effects on improving antioxidant activity and promoting GABA biosynthesis in yellow-flesh peach fruit.

Hydrogen Gas Improves the Postharvest Quality of Lanzhou Lily (Lilium davidii var. unicolor) Bulbs

Hydrogen gas (H₂) is an important molecular messenger in animal and plant cells and is involved in various aspects of plant processes, including root organogenesis induction, stress tolerance and postharvest senescence. This study investigated the effect of H₂ fumigation on the quality of Lanzhou lily scales. The results indicated the H₂ remarkably declined the color variation and browning degree in Lanzhou lily scales by suppressing the activity of phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO). Moreover, H₂ significantly alleviated the degradation of soluble proteins and soluble sugars in Lanzhou lily scales during postharvest storage, mitigating the decline in nutritional quality. This alleviating effect of H₂ might be achieved by increasing the endogenous H₂ concentration. Collectively, our data provide new insights into the postharvest quality reduction of Lanzhou lily scales mitigated by H₂ fumigation.

Multiple metabolomics comparatively investigated the pulp breakdown of four dragon fruit cultivars during postharvest storage

Pulp breakdown is the main reason for the reduction of fruit quality. However, there are relatively few studies on small molecule metabolites based on the pulp breakdown of dragon fruit. In this study, four dragon fruit cultivars were comparatively analyzed during pulp breakdown. According to five firmness-related and six quality-related indicators, the pulp breakdown rates from low to high were 'Baiyulong (WP, with white pulp)', 'Dahong (RP, with red pulp)', 'Hongshuijing (CRP, with red pulp)' and 'Baishuijing (CWP, with white pulp)'. Five secondary metabolites showed cultivar-specific accumulation, and the increase of their contents during postharvest storage might be related to delaying pulp breakdown. After multiple metabolomics analysis, a total of 186 metabolites were identified, among which 14 primary metabolites, 23 volatiles, 2 hydrolyzed amino acids and 12 free amino acids were considered as key metabolites. The contents of hydrocarbons in WP and RP were much higher than that in CWP and CRP, which was negatively correlated with pulp breakdown. White pulp were rich in amino acids, while red pulp had more soluble sugars, aldehydes and terpenes. The contents of 13 key metabolites increased during pulp breakdown in all four cultivars, mainly including amino acids and alkanes. The contents and changes of those key metabolites might directly or indirectly respond to the pulp quality and resistance of dragon fruit.

Maintenance of postharvest storability and overall quality of 'Jinshayou' pummelo fruit by salicylic acid treatment

INTRODUCTION

The loss of postharvest storability of pummelo fruit reduces its commodity value for long run. To maintain its storability, the effects of postharvest dipping treatment by salicylic acid (SA) with different concentrations (0, 0.1, 0.2, or 0.3%) were investigated on pummelo fruit (Citrus maxima Merr. cv. Jinshayou) during the room temperature storage at 20 ± 2°C for 90 d.

RESULTS AND DISCUSSION

Among all treatments, pre-storage SA treatment at 0.3% demonstrated the most significant ability to reduce fruit decay incidence, decrease weight loss, delay peel color-turned process, and inhibit the declines in total soluble solids (TSS) as well as titratable acid (TA) content. The increases in electrolyte leakage, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) content of the 0.3% SA-treated pummelo fruit were reduced compared to the control (dipped in distilled water). Pummelo fruit treated with 0.3% SA exhibited the most outstanding ability to excess reactive oxygen species (ROS) accumulation, as evidenced by promoted the increases in glutathione (GSH), total phenolics and flavonoids contents, delayed the AsA decline, and enhanced the activities of antioxidant enzymes and their encoding genes expression.

CONCLUSION

Pre-storage treatment dipped with SA, particularly at 0.3%, can be used as a useful and safe preservation method to maintain higher postharvest storability and better overall quality of 'Jinshayou' pummelo fruit, and thus delaying postharvest senescence and extend the storage life up to 90 d at room temperature.

A Genome-Wide View of the Transcriptome Dynamics of Fresh-Cut Potato Tubers

Fresh fruits and vegetable products are easily perishable during postharvest handling due to enzymatic browning reactions. This phenomenon has contributed to a significant loss of food. To reveal the physiological changes in fresh-cut potato tubers at the molecular level, a transcriptome analysis of potato tubers after cutting was carried out. A total of 10,872, 10,449, and 11,880 differentially expressed genes (DEGs) were identified at 4 h, 12 h and 24 h after cutting, respectively. More than 87.5% of these DEGs were classified into the categories of biological process (BP) and molecular function (MF) based on Gene Ontology (GO) analysis. There was a difference in the response to cutting at different stages after the cutting of potato tubers. The genes related to the phenol and fatty biosynthesis pathways, which are responsible for enzymatic browning and wound healing in potato tubers, were significantly enriched at 0-24 h after cutting. Most genes related to the enzymatic browning of potato tubers were up-regulated in response to cut-wounding. Plant hormone biosynthesis, signal molecular biosynthesis and transduction-related genes, such as gibberelin (GA), cytokinin (CK), ethylene (ET), auxin (IAA), jasmonic acid (JA), salicylic (SA), and Respiratory burst oxidase (Rboh) significantly changed at the early stage after cutting. In addition, the transcription factors involved in the wound response were the most abundant at the early stage after cutting. The transcription factor with the greatest response to injury was MYB, followed by AP2-EREBP, C3H and WRKY. This study revealed the physiological changes at the molecular level of fresh-cut potato tubers after cutting. This information is needed for developing a better approach to enhancing the postharvest shelf life of fresh processed potato and the breeding of potato plants that are resistant to enzymatic browning.

Incorporation of hydrogen into the packaging atmosphere protects the nutritional, textural and sensorial freshness notes of strawberries and extends shelf life

Strawberries are known for their high perishability and short shelf life. The effects of incorporating hydrogen gas into sealed packaging on the quality and shelf life of strawberries were evaluated. Fruits were packaged under reducing atmosphere [RAP1 (5% CO 2 , 4% H 2 , 91% N 2 ) and RAP2 (10% CO 2 , 4% H 2 , 86% N 2 )], modified atmosphere [MAP1 (5% CO 2 , 95% N 2 ) and MAP2 (10% CO 2 , 90% N 2 )], and control, followed by 12 weeks storage at 4 °C. At the end of storage, RAPs exhibited higher total soluble solids (TSS), firmness, L* and a*, phenolic and anthocyanin contents, and antioxidant activity followed by MAPs when compared with control. RAP2 was more potent in protecting the freshness indices than RAP1, and MAP2 outperformed MAP1, with the best protection characteristic attributed to RAP2. RAP technique extended the shelf life by 3-5 times the control, and 1.5-3.0 times the MAP. RAP should be recommended as a green and healthy preservation technique for the long storage of fresh fruits.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05427-y.

The class III peroxidase gene family is involved in ascorbic acid induced delay of internal browning in pineapple

Excessive production of reactive oxygen species (ROS) leads to potential toxicity in an organism. Class III peroxidases (PRXs) play an important role in maintaining ROS homeostasis in plants. Internal browning (IB) limits industrial development of pineapple, which is the third most important fruit trade in the world. IB is mainly caused by ROS, and the mechanism underlying IB is still unknown from the perspective of ROS. Here, we soaked pineapples in ascorbic acid after harvest and before storage to decrease excessive ROS and polyphenol oxidase (PPO) activity, ultimately restraining the spread and deterioration of IB. Using phylogenetic analysis; we identified 78 pineapple PRX genes (AcPRXs) and divided them into five subgroups. Gene structure analysis indicated that the exon numbers ranged from 2 to 14, and conserved motif analysis verified that all of the AcPRXs identified here have standard peroxidase domains. Analysis of duplication events suggested that tandem and segmental duplication events may have played equal and important roles in expanding the AcPRX family. Comprehensive transcriptomic analysis uncovered that AcPRXs may play an important role in negatively regulating the occurrence of IB. In summary, we found that ROS scavenging delayed IB occurrence. The results of characterized AcPRX family revealed that AcPRXs family responded to growth and development, and negatively regulated to IB occurrence in storage stage. This research provides potential target genes for future in-depth analysis of the molecular mechanisms underlying IB and contributes to develop IB-resistant pineapple varieties.

Preharvest application of hydrogen nanobubble water enhances strawberry flavor and consumer preferences

The improvement of fruit flavor is a challenge for producers and breeders. This study investigated the effects and mechanisms of preharvest hydrogen nanobubble water (HNW) application on the flavor of cultivated strawberry (Fragaria × ananassa 'Benihoppe'). Compared with surface water, HNW enhanced the volatile profiles, sugar-acid ratio, and sensory attributes (e.g., aroma, flavor, and overall liking) with/without fertilizer application. Meanwhile, flavor components such as esters (e.g., ethyl hexanoate), acids (e.g., hexanoic acid), and soluble sugars (including glucose, fructose, and sucrose) significantly contributed to increased strawberry flavor achieved with HNW. Importantly, HNW may alleviate the negative effects of fertilizers on strawberry fruit aroma. Further study elucidated that the aroma-related genes (including FaLOX, FaADH, FaAAT, FaQR, FaOMT, and FaNES1) were involved in the accumulation of specific volatiles after HNW treatment. This study provided evidence that the practical application of H₂ can improve horticultural product quality at a lower carbon cost.

Melatonin-mediated postharvest quality and antioxidant properties of fresh fruits: A comprehensive meta-analysis

At postharvest, fruits have a short shelf life. Recently, there has been much literature on the effects of melatonin on the postharvest quality of horticultural crops. However, reports of various findings comprise mixed claims and product-specific conclusions. Therefore, a meta-analysis systematically dissects the comprehensive effect on several fruits. In this meta-analysis, standard mean difference (SMD) was adopted using a random-effect model. The study used 36 articles and isolated 24 indicator parameters of postharvest quality and antioxidant properties based on the inclusion criteria. As exhibited in the forest plot, melatonin reduced chilling injury, weight loss, respiration rate, and ethylene content (SMD -0.90, 95% CI [-1.14, -0.65]; I²  = 81%; p < .00001). Similarly, the application of melatonin significantly suppressed electrolyte leakage, malondialdehyde (MDA), hydrogen peroxide, superoxide anion, lipoxygenase, and polyphenol oxidase (SMD -0.89, 95% CI [-1.09, -0.69]; I²  = 70%; p < .00001). In addition, exogenous melatonin application induced endogenous melatonin content, phenolic content, and flavonoid and anthocyanin contents (SMD 1.15, 95% CI [0.91, 1.39]; I²  = 71%; p = .01). Moreover, melatonin treatment enhanced antioxidant activities (catalase, superoxide dismutase, peroxidase, ascorbate peroxidase, and phenylalanine ammonia-lyse) (SMD 1.37, 95% CI [1.03, 1.71]; I²  = 86%; p < .00001). Thus, in the whole study, the overall effect was significantly high in treated fruit (p < .0001), and the overall heterogeneity was above (I² ) > 70%. In addition, the funnel plot showed symmetry in the most selected studies. To sum up, the result gives a further understanding of melatonin's capabilities in reducing postharvest losses and maintaining the quality of fresh fruits.

The role of hydrogen water in delaying ripening of banana fruit during postharvest storage

Experiments were conducted to identify the role of hydrogen water (HW) in banana fruit ripening. Banana fruit soaked with 0.8 ppm HW showed longer ripening than control fruit. HW treatment significantly reduced ethylene production and respiratory rate, and inhibited the expressions of ethylene synthesis- and signaling-related genes. Similarly, HW treatment inhibited the down-regulation of chlorophylls binding proteins and delayed the increase of chromaticity a*, b* and L* in banana peel. Furthermore, HW-treated peel exhibited lower expressions of cell wall degradation-related genes and higher levels of fruit firmness, pectin, hemicellulose and lignin. In addition, HW-treated pulp exhibited higher levels of starch, lower level of total soluble solids (TSS) and lower expression of flavor-related genes. Microstructural observation further confirmed that HW treatment delayed the degradations of starch and cell walls. Those results indicated that HW treatment delayed banana ripening via the role of ethylene in relation to degreening, flavor and softening.

Packaging with hydrogen gas modified atmosphere can extend chicken egg storage

BACKGROUND

Although hydrogen gas (H₂ ) has been widely used in industry and gradually used in medicine, it is less applied to agriculture, especially in modified atmosphere packing (MAP).

RESULTS

During chicken egg storage, H₂ MAP not only slowed down or delayed the reduction in antioxidant capacities, but also alleviated the deterioration of egg quality. The extent of micro-cracks in the eggshell was also negatively influenced by H₂ , which might result in eggs being less vulnerable to microbes. The earlier results demonstrated that the H₂ MAP-extended shelf life of chicken eggs might be caused by the responses of eggshell and re-establishment of redox homeostasis. According to the data collected from different provinces of China, cost-economics analysis further suggested that the increase in the extra cost caused by H₂ was trivial compared with the original price of eggs.

CONCLUSION

Together, H₂ MAP can prolong the shelf life of chicken eggs with the prospect of wider application. © 2021 Society of Chemical Industry.

Physiological response of soybean leaves to uniconazole under waterlogging stress at R1 stage

Waterlogging is a major limiting factor in global crop production and seriously endangers growth and yield improvement in low-lying, rainfed regions. Soybean is an important economic crop affected by waterlogging stress. The current study investigates the effects of waterlogging stress on the leaf physiology and yield of two soybean varieties (Kenfeng 14, waterlogging-tolerant and Kenfeng 16, waterlogging-sensitive) and the mitigation effect of uniconazole (S3307) in promoting growth and productivity under waterlogging conditions. The results showed that waterlogging stress increased antioxidant enzyme activity and decreased the contents of non-enzymatic antioxidants such as AsA and GSH. Furthermore, the content of MDA and H2O2 increased significantly, indicating oxidative stress and O2-· production rate also improved, and the increase in the waterlogging-sensitive variety Kenfeng 16 was greater than that of the waterlogging-tolerant variety Kenfeng 14. Spraying S3307, however, increased the activities of antioxidants such as SOD, POD, CAT, and APX. GR, MDHAR, and DHAR increased the content of non-enzymatic antioxidants, effectively inhibited the increase of MDA, H2O2 content, and O2-· production rate, and alleviated the loss of yield factors caused by waterlogging stress. The waterlogging-tolerant variety Kenfeng 14 recovered better than the waterlogging-sensitive variety Kenfeng 16. In summary, S3307 ameliorated the effects of waterlogging stress on the physiological characteristics of soybean leaves and improved yield as a result of improved antioxidant defense mechanisms that impeded lipid peroxidation. Thus, S3307 could decelerate the damages caused by waterlogging stress to some extent.

The Applications of Molecular Hydrogen in Horticulture

Improvements in the growth, yield, and quality of horticultural crops require the development of simply integrated, cost-efficient, and eco-friendly solutions. Hydrogen gas (H2) has been observed to have fertilization effects on soils by influencing rhizospheric microorganisms, resulting in improvements in crop yield and quality. Ample studies have shown that H2 has positive effects on horticultural crops, such as promoting root development, enhancing tolerance against abiotic and biotic stress, prolonging storage life, and improving postharvest quality of fruits, vegetables and cut flowers. In this review, we aim to evaluate the feasibility of molecular hydrogen application in horticulture and the strategies for its application, including H2 delivery methods, treatment timing, and the concentration of H2 applied. The discussion will be accompanied by outlining the effects of H2 and the likely mechanisms of its efficacy. In short, the application of H2 may provide novel opportunities for simple and cost efficient improvements of horticultural production in terms of increased yield and product quality but with low carbon dioxide emissions.

Antibiotic Effects of Volatiles Produced by Bacillus tequilensis XK29 against the Black Spot Disease Caused by Ceratocystis fimbriata in Postharvest Sweet Potato

Black spot disease caused by Ceratocystis fimbriata is destructive to the production, transportation, and storage of sweet potato. The antifungal effects of Bacillus tequilensis XK29 against C. fimbriata through volatile organic compounds (VOCs) were evaluated in this study. The activated carbon assay proved that XK29 could exert antibiotic effects through volatiles. By optimizing the wheat seed weight, inoculation method, concentration, volume, and time, the antifungal activity of XK29 was significantly improved. XK29 fumigation inhibited spore formation and germination and changed the cell morphology of C. fimbriata. During the storage of sweet potato tuber roots, XK29 effectively controlled black spot disease and reduced the weight loss and malondialdehyde content. Metabolomic analysis revealed that 21 volatile compounds were released from XK29. Isovaleric acid, isobutyric acid, and 2-methylbutanoic acid effectively inhibited the growth of C. fimbriata. These results indicate that B. tequilensis XK29 has a good potential to be developed as a microbial fumigation agent.

Highly sensitive non-enzymatic hydrogen peroxide monitoring platform based on nanoporous gold via a modified solid-phase reaction method

In this work, nanoporous gold (NPG) fabricated using a modified solid-phase reaction method was developed as an electrocatalyst for the nonenzymatic detection of hydrogen peroxide (H2O2). The NPG morphology and structure were characterized by scanning electron microscopy and high-resolution transmission electron microscopy. The fabricated NPG exhibited a nanoporous framework with numerous structural defects. The NPG-based amperometric H2O2 sensor had a good selectivity, reproducibility, and low detection limit (0.3 μM) under near physiological conditions (pH = 7.4). The sensitivities of this sensor over concentration ranges of 0.002-5 mM and 5-37.5 mM were 159 and 64 μA mM-1 cm-2, respectively. These results indicate that the developed NPG is a promising material for the electrochemical sensing of H2O2.

Maintenance of Postharvest Quality and Reactive Oxygen Species Homeostasis of Pitaya Fruit by Essential Oil p-Anisaldehyde Treatment

The performance of p-Anisaldehyde (PAA) for preserving pitaya fruit quality and the underpinning regulatory mechanism were investigated in this study. Results showed that PAA treatment significantly reduced fruit decay, weight loss and loss of firmness, and maintained higher content of total soluble solids, betacyanins, betaxanthins, total phenolics and flavonoids in postharvest pitaya fruits. Compared with control, the increase in hydrogen peroxide (H₂O₂) content and superoxide anion (O₂^•−) production was inhibited in fruit treated with PAA. Meanwhile, PAA significantly improved the activity of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Moreover, PAA-treated pitaya fruit maintained higher ascorbic acid (AsA) and reduced-glutathione (GSH) content but lower dehydroascorbate (DHA) and oxidized glutathione (GSSG) content, thus sustaining higher ratio of AsA/DHA and GSH/GSSG. In addition, activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydrogenation ascorbic acid reductase (DHAR), as well as the expression of HpSOD, HpPOD, HpCAT, HpAPX, HpGR, HpDHAR and HpMDHAR, were enhanced after PAA treatment. The findings suggest that postharvest application of PAA may be a reliable method to control postharvest decay and preserve quality of harvested pitaya fruit by enhancing the antioxidant potential of the AsA-GSH cycle and activating an antioxidant defense system to alleviate reactive oxygen species (ROS) accumulation.

A Gas-Permeation Controllable Packaging Membrane with Porous Microspheres as Gas "Switches" for Efficient Preservation of Litchi

Food wastage represented by the deterioration of perishable food like fruits and vegetables is a serious global problem with tremendous ethical, financial, and environmental costs. The atmosphere (CO₂ and O₂) has a crucial role in food storage and can regulate physiological food metabolism and microbial growth. Modified atmosphere packaging (MAP) is a promising method used to extend shelf life and preserve the quality of perishable food; yet, its use depends on the specific gas permeability and selectivity of polymer membranes to generate an atmosphere desirable for storage. In this study, we established and validated a new plant leaf-mimetic shellac-based MAP membrane embedded with chitosan porous microspheres loaded with antimicrobial tannic acid (TA-CPM) as gas "switches" for regulating O₂ and CO₂ permeability and CO₂/O₂ selectivity. The effects of different amounts of TA-CPM added into the hybrid membranes were examined for litchi preservation at room temperature. Our results showed that this hybrid TA-CPM/shellac packaging membrane could regulate the internal CO₂ and O₂ concentrations and the CO₂/O₂ ratio within the packages containing litchis by adjusting the addition amount of TA-CPM. The 0.05% TA-CPM/shellac and 0.10% TA-CPM/shellac packages, especially 0.05% TA-CPM/shellac, generated a more desirable CO₂ and O₂ atmosphere for litchi preservation compared with controls, which was reflected by the delaying of browning and rotting, maintaining of the natural color of the litchi pericarp, preservation of pulp quality, inhibition of polyphenol oxidase and guaiacol peroxidase activities, and reduction of oxidative cell damage in litchis. The results suggested that 0.05% TA-CPM/shellac and 0.10% TA-CPM/shellac packaging membranes, especially 0.05% TA-CPM/shellac, could generate an ideal atmosphere for litchi storage at room temperature, demonstrating that this permeation-controlled hybrid membrane has great potential in food preservation and other applications requiring a modified atmosphere.

Novel alternative for controlling enzymatic browning: Catalase and its application in fresh-cut potatoes

Surface browning is a vital phenomenon that adversely reduces the quality of fresh-cut potatoes. Although many anti-browning methods have been explored, it is unclear whether exogenous catalase (CAT) treatment influences the enzymatic browning. Our results showed that 0.05% CAT immersion for 5 min alleviated browning during cold storage (4°C, 8 days), which was accompanied by a higher lightness and lower redness; additionally, lower H₂ O₂ and O₂ ·- contents were found. The activities of CAT, ascorbate peroxidase, and glutathione peroxidase and the scavenging efficiency of 2,2-diphenyl-1-picrylhydrazyl were also increased. Moreover, CAT treatment inhibited the activities of polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase and reduced phenol accumulation. Treatment with 0.1% hydrogen peroxide (H₂ O₂ ) achieved the opposite results. This is the first report of CAT application reducing fresh-cut potato browning, providing a safe treatment alternative for enzymatic discoloration and preliminarily revealing the underlying mechanism with insight into antioxidant regulation. PRACTICAL APPLICATION: This research is helpful for fresh-cut potato producers because a novel, safe, easy-to-carry out anti-browning solution was proposed. Dipping in 0.05% catalase solution for 5 min revealed color improvement in the quality of fresh-cut potato slices. The mechanism may rely on enhancing antioxidant ability (ascorbate peroxidase, and glutathione peroxidase, and 2,2-diphenyl-1-picrylhydrazyl scavenging), reducing reactive oxygen species (H₂ O₂ , O₂ ·-, malondialdehyde) and controlling enzymatic browning reaction factors (polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase, and phenol accumulation). This method shows promise for better meeting the requirements and demands of consumers for fresh quality products.

Molecular Hydrogen Maintains the Storage Quality of Chinese Chive through Improving Antioxidant Capacity

Chinese chive usually becomes decayed after a short storage time, which was closely observed with the redox imbalance. To cope with this practical problem, in this report, molecular hydrogen (H₂) was used to evaluate its influence in maintaining storage quality of Chinese chive, and the changes in antioxidant capacity were also analyzed. Chives were treated with 1%, 2%, or 3% H₂, and with air as the control, and then were stored at 4 ± 1 °C. We observed that, compared with other treatment groups, the application of 3% H₂ could significantly prolong the shelf life of Chinese chive, which was also confirmed by the obvious mitigation of decreased decay index, the loss ratio of weight, and the reduction in soluble protein content. Meanwhile, the decreasing tendency in total phenolic, flavonoid, and vitamin C contents was obviously impaired or slowed down by H₂. Results of antioxidant capacity revealed that the accumulation of reactive oxygen species (ROS) and hydrogen peroxide (H₂O₂) was differentially alleviated, which positively matched with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and the improved activities of antioxidant enzymes, including superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Above results clearly suggest that postharvest molecular hydrogen application might be a potential useful approach to improve the storage quality of Chinese chive, which is partially achieved through the alleviation of oxidative damage happening during the storage periods. These findings also provide potential theoretical and practical significance for transportation and consumption of perishable vegetables.

Physiological Changes of Bamboo (Fargesia yunnanensis) Shoots During Storage and the Related Cold Storage Mechanisms

The mechanisms for physiological senescence in bamboo shoots after harvest remain unclear. This study investigated physiological changes in Fargesia yunnanensis shoots during storage at different temperatures. The relationship between morphological and physiological changes in bamboo shoots during storage was also analyzed. The results show that cold storage can reduce weight loss, browning, respiration rates, and sugar degradation in bamboo shoots; decrease related enzymatic activities; and inhibit the increase in lignin and cellulose content. The quality of bamboo shoots declines more during the first 3d after harvesting than it does during subsequent periods. The increase in the degree of lignification and fibrosis is the main reason for senescence and for the decline in quality of bamboo shoots after harvest. The bamboo shoots under RT conditions began browning during the third 3d of storage, with a browning rate of 688gkg^-1 even in the upper parts; the increase in shoot browning degrees significantly decreased the quality. Low temperatures had better inhibitory effects on browning than they did on lignification and fibrosis. Nonstructural carbohydrates in bamboo shoots are degraded and flow into sheath and shoot respiration, phenols, and shoot fibrosis and lignification at room temperature, but only flow into sheath respiration, shoot fibrosis, and lignification at cold temperature. Soluble protein and free amino acids are primarily distributed into shoot and sheath respiration and into phenols at room temperature, but that process is well inhibited at cold temperature. Bamboo shoots, once removed from cold storage, should be consumed rapidly because enzyme activity recovers quickly. This research provides new theoretical information on the preservation of bamboo shoots.