Treatment with exogenous salicylic acid maintains quality, increases bioactive compounds, and enhances the antioxidant capacity of fresh goji (Lycium barbarum L.) fruit during storage

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.

Effect of Different Postharvest Pre-Cooling Treatments on Quality of Water Bamboo Shoots (Zizania latifolia) during Refrigerated Storage

Post-harvest pre-cooling of water bamboo shoots (WBS) [Zizania latifolia] can effectively delay its quality deterioration. Six types of pre-cooling treatments were used to pre-cooling post-harvest WBS, including cold slightly acidic electrolytic water pre-cooling (CSAEW), cold water pre-cooling (CWPC), vacuum pre-cooling (VPC), strong wind pre-cooling (SWPC), refrigerator pre-cooling (RPC), and fluid ice pre-cooling (FIPC). The effects of different pre-cooling treatments on the quality of refrigerated WBS were investigated. The results showed that the FIPC treatment was harmful to the storage quality of WBS, while the other five pre-cooling treatments could extend the shelf life of WBS to some extent. These pre-cooling treatments can inhibit the respiration of WBS, slow down its weight loss and lignification process, and maintain its relatively high levels of nutrient content and antioxidant activity. The CSAEW treatment outperformed other treatments in terms of bactericidal action and microbiological content control for WBS during storage. The protective effect of CSAEW treatment on the storage quality of WBS was relatively the best, and extended the shelf life of WBS by 12 days compared to the control group. This study indicated that the CSAEW pre-cooling treatment offers a new choice for pre-cooling root vegetables.

Salicylic Acid Treatment Ameliorates Postharvest Quality Deterioration in 'France' Prune (Prunus domestica L. 'Ximei') Fruit by Modulating the Antioxidant System

The potential of salicylic acid (SA) in delaying postharvest fruit senescence has been extensively documented; nevertheless, its effect on antioxidant activity and quality of 'France' prune fruit is largely unknown. The study investigated the effects of SA (0.5 mM) on postharvest quality deterioration of 'France' prune fruit. Results indicated that SA impeded the increase in respiration rate and weight loss, and mitigated the decrease of soluble solids content (SSC), titratable acidity (TA) content, firmness, and hue angle. SA sustained the ascorbate-glutathione cycle by inducing the production of ascorbic acid (AsA) and glutathione (GSH) and attenuates flavonoids, total phenols, and anthocyanins degradation by inhibiting polyphenol oxidase (PPO) activity and PdPPO. Moreover, SA significantly improved superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and glutathione reductase (GR) activities and gene expression levels, sustained higher 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging capacity, ferric reducing antioxidant power (FRAP), and hydroxyl radical (·OH) inhibition capacity, and impeded the production of hydrogen peroxide (H2O2) and superoxide anion (O2•-). Overall, SA improved the antioxidant capacity by inducing the synthesis of defense response-related substances and promoting antioxidant enzyme activities to sustain the storage quality of 'France' prune fruit.

Eco-safe hot water dip alleviates antioxidant level and sensory quality of Indian jujube fruits

Indian jujube (Ber) is highly perishable climacteric fruit owing to high decay index limiting its marketability and demands interventions to prolong shelf life. Fungicides are normally used to control rot during postharvest storage, however, residues left necessitate eco-safe alternatives like hot water dipping. Mature, pre-climacteric jujubes were dipped in 45, 50 or 55 °C water for 8, 6 or 4 min, respectively and then stored at 5 °C for periodic quality evaluation. Dipping fruits in 55 °C water resulted in 32.69 and 35.27, 64.21 and 58.57, 30.41 and 30.42, 38.50 and 52.20 % lower weight loss, decay index, malondialdehyde (MDA) and electrolyte leakage, whereas 15.40 and 16.77, 19.51 and 20.48 % greater antioxidant activity and ascorbic acid respectively for Umran and Pakwhite compared to 25 °C water dip. The highest glucose, fructose, malic, citric, and tartaric acids were 23.44 ± 1.04 and 29.9 ± 0.95, 30.68 ± 1.72 and 41.17 ± 2.34 mg/100 g, 138.1 ± 6.45 and 112.97 ± 6.16, 57.49 ± 1.71 and 53.78 ± 1.90, 79.58 ± 5.1 and 65.3 ± 4.83 μg/100 g whereas lower sucrose 12.34 ± 0.94 and 16.33 ± 1.05 mg/100 g were respectively recorded in 55 °C water dipped Umran and Pakwhite fruits. High dip water temperature (55 °C) exhibited better quality with the lowest decay index and weight loss, greater membrane integrity, bioactives content and sensory acceptance scores. Hence, hot water dipping was shown to be an effective residue-free option to extend the marketable period of jujubes to capture distant markets.

Investigation into Antioxidant Mechanism of Lycium barbarum Extract in Carbendazim-Induced PC12 Cell Injury Model through Transcriptomics and Metabolomics Analyses

Lycium barbarum L., an important functional food in China, has antioxidant and antiaging activity. However, the exact antioxidant activity mechanism of Lycium barbarum extracts (LBE) is not well understood. Therefore, a carbendazim (CBZ)-induced PC12 cell injury model was constructed and vitrificated to study the antioxidant activity of fresh LBE on the basis of extraction parameter optimization via the full factorial design of experiments (DOE) method. The results showed that the pretreatment of PC12 cells with LBE could reduce the reactive oxygen species (ROS) level by 14.6% and inhibited the mitochondrial membrane potential (MMP) decline by 12.0%. Furthermore, the integrated analysis revealed that LBE played an antioxidant role by activating oxidative phosphorylation (OXPHOS) and restoring MMP, maintaining the tricarboxylic acid (TCA) cycle stability, and regulating the GSH metabolic pathway. The results of the present study provide new ideas for the understanding of the antioxidant function of LBE from a global perspective.

Salicylic Acid Spray Delays Sand Pear Fruit Senescence during Room Temperature Shelf Life by Regulating Antioxidant Capacity and Senescence-Related Genes

'Whangkeumbae' (Pyrus pyrifolia) is a variety of sand pear fruit well-known for its smooth surface and good taste. However, the fruit quality is adversely affected by postharvest ethylene production. Therefore, improving postharvest shelf life by regulating fruit senescence is critical to promoting the 'Whangkeumbae' fruit industry. Here, we investigated the effect of salicylic acid (SA) spray on fruit senescence in sand pears during room temperature shelf life. Exogenous SA reduced polyphenol oxidase (PPO) activity and malondialdehyde (MDA) content during room temperature shelf life. Additionally, SA effectively maintained the fruit skin coloration and increased the activity of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). SA treatment inhibited PpPPO1 expression and upregulated PpSOD1, PpAPX6, and PpGST2 expression. Furthermore, SA application downregulated the expression of PpACO2, PpEIN3a, PpNCED1, and PpAOC2, while upregulating PpNPR-1, PpTAR2, and PpCOMT1 during room temperature shelf life. SA treatment also influenced cell wall metabolism and modification genes by inhibiting PpPG1, PpPME2, and PpCEL3 and inducing PpPGIP1 expression. Additionally, SA treatment affected sugar and acid metabolism genes and increased the expression of PpSPS1, PpSUS1, PpSOT1, PpTMT4, PpSWEET15, and PpcyNAD-MDH, but suppressed the expression of PpcyNADP-ME. The Pearson correlation analysis indicated that PPO activity and MDA content were positively correlated with the expression of PpPPO1, PpACO2, PpEIN3a, PpNCED1, PpAOC2, PpPG1, PpPME2, PpCEL3, and PpcyNDA-MDH. Conversely, these factors were negatively associated with the activities of SOD, POD, CAT, and APX, as well as the expression levels of PpSOD1, PpPOD1, PpCAT1, PpAPX6, PpGST2, PpNPR-1, PpTAR2, PpCOMT1, PpPGIP1, PpSPS1, PpSUS1, PpSOT1, PpTMT4, PpSWEET15, and PpcyNAD-MDH. Our results reveal that exogenous SA could delay fruit senescence in sand pear fruit by regulating various biochemical and molecular mechanisms and can be used to effectively extend fruit shelf life during room temperature storage. However, further research is necessary to determine whether the fruits sprayed with SA are suitable for direct human consumption.

Modulation of carotenoid biosynthesis in maize (Zea mays L.) seedlings by exogenous abscisic acid and salicylic acid under low temperature

KEY MESSAGE

Abscisic acid could regulate structural genes in the carotenoid biosynthesis pathway and alleviate the decrease of carotenoids in maize seedlings under low-temperature stress. Low temperature often hampers the development of maize seedlings and hinders the accumulation of carotenoids, which are functional against chilling stress for plants and providing health benefits for human. To explore effective approaches in reducing chilling stress and enhancing the potential nutritional values of maize seedlings, exogenous plant hormones abscisic acid (ABA) and salicylic acid (SA) that may affect carotenoid biosynthesis were applied on low-temperature-stressed maize seedlings. Results showed that low temperature significantly reduced the carotenoid levels in maize seedlings, only preserving 62.8% in comparison to the control. The applied ABA probably interacted with the ABA-responsive cis-acting elements (ABREs) in the promoter regions of PSY3, ZDS and CHYB and activated their expressions. Consequently, the total carotenoid concentration was apparently increased to 1121 ± 47 ng·g-1 fresh weight (FW), indicating the stress alleviation by ABA. The application of SA did not yield positive results in alleviating chilling stress in maize seedlings. However, neoxanthin content could be notably boosted to 52.12 ± 0.45 ng·g-1 FW by SA, offering a biofortification strategy for specific nutritional enhancement. Structural gene PSY1 demonstrated positive correlations with β-carotene and zeaxanthin (r = 0.93 and 0.89), while CRTISO was correlated with total carotenoids (r = 0.92), indicating their critical roles in carotenoid accumulation. The present study exhibited the effectiveness of ABA to mitigate chilling stress and improve the potential nutritional values in low-temperature-stressed maize seedlings, thereby promoting the production of plant-based food sources.

Metabolic Profiling and Molecular Mechanisms Underlying Melatonin-Induced Secondary Metabolism of Postharvest Goji Berry (Lycium barbarum L.)

Postharvest decay of goji berries, mainly caused by Alternaria alternata, results in significant economic losses. To investigate the effects of melatonin (MLT) on resistance to Alternaria rot in goji berries, the fruits were immersed in the MLT solutions with varying concentrations (0, 25, 50, and 75 μmol L-1) and then inoculated with A. alternata. The results showed that the fruits treated with 50 μmol L-1 MLT exhibited the lowest disease incidence and least lesion diameter. Meanwhile, endogenous MLT in the fruits treated with 50 μmol L-1 MLT showed higher levels than in the control fruits during storage at 4 ± 0.5 °C. Further, the enzymatic activities and expressions of genes encoding peroxidase, phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4-coumarate-CoA ligase, chalcone synthase, chalcone isomerase, and cinnamyl alcohol dehydrogenase were induced in the treated fruit during storage. UPLC-ESI-MS/MS revealed that secondary metabolites in the fruits on day 0, in order of highest to lowest levels, were rutin, p-coumaric acid, chlorogenic acid, ferulic acid, caffeic acid, naringenin, quercetin, kaempferol, and protocatechuic acid. MLT-treated fruits exhibited higher levels of secondary metabolites than the control. In conclusion, MLT treatment contributed to controlling the postharvest decay of goji fruit during storage by boosting endogenous MLT levels, thus activating the antioxidant system and secondary metabolism.

Exogenous melatonin activates the antioxidant system and maintains postharvest organoleptic quality in Hami melon (Cucumis. melo var. inodorus Jacq.)

Hami melon is prone to postharvest perishing. Melatonin is a signaling molecule involved in a variety of physiological processes in fruit, and it improves fruit quality. We hypothesized that melatonin treatment would improve the storage quality of Hami melon by altering its respiration and reactive oxygen species (Graphical abstract). Our results indicated that optimal melatonin treatment (0.5 mmol L-1) effectively slowed the softening, weight loss, and respiratory rate of the Hami melon fruit. Furthermore, melatonin markedly improved the antioxidant capacity of the fruit and protected it from oxidative damage by decreasing its contents of superoxide anions, hydrogen peroxide, and malondialdehyde. Melatonin significantly enhanced the activities of superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase. The total phenol, total flavonoids, and ascorbic acid contents were maintained by melatonin treatment. This treatment also repressed the activities of lipase, lipoxygenase, and phospholipase D, which are related to lipid metabolism. Thus, exogenous melatonin can maintain postharvest organoleptic quality of Hami melon fruit by increasing its antioxidant activity and inhibiting reactive oxygen species production.

Evaluating Food Additives Based on Organic and Inorganic Salts as Antifungal Agents against Monilinia fructigena and Maintaining Postharvest Quality of Apple Fruit

A set of commonly used food additives was evaluated for their antifungal activity against the brown rot disease of fruits caused by the fungal pathogen Monilinia fructigena, which is one of the most economically important agents, causing important damage to pome fruits, such as pears and apples. The radial mycelial growth of the fungal pathogen was assessed in PDA amended with different concentrations (0.5, 2, 2.5, and 5%) of each additive. The results underlined that most of the additives displayed a significant inhibition of mycelial growth, with the extent of inhibition varying depending on the specific additive and concentration used. Five food additives showed high inhibition rates (above 88%), of which sodium bicarbonate, sodium carbonate, copper sulphate, and sodium hydroxide were the most effective, whereas ammonium carbonate, magnesium chlorite, and citric acid were the least effective. Interestingly, the coatings containing sodium bicarbonate, copper sulphate, and ammonium bicarbonate significantly reduced the incidence of brown rot disease in apples, but other additives were not effective, such as ammonium carbonate and magnesium sulphate. The anhydrous sodium sulphate used at a concentration of 2%, was found to be one of the least effective additives, with a reduction rate of 20%. Subsequently, food additives showing good growth inhibition rates and reduction in disease severity were then tested in semi-commercial trials at temperatures of 4 °C and 22 °C. The results indicated that these additives demonstrate effectiveness in controlling M. fructigena at specific concentrations, and lower temperatures (4 °C) can improve the efficiency of the control measures. In addition, the selected food additives exhibited significant antimicrobial activity against M. fructigena, suggesting their application as a promising alternative for managing brown rot disease in apple fruits.

Comparative Analysis of Polyphenols in Lycium barbarum Fruits Using UPLC-IM-QTOF-MS

Variety, geographical origin, and harvest season are important factors affecting the accumulation of polyphenols in Lycium barbarum. In this study, the effects of these factors on the polyphenolic components of this species were analyzed using ultra-performance liquid chromatography ion mobility quadrupole time-of-flight mass spectrometry. Moreover, the in vitro antioxidant activities of fruit extracts from this species were evaluated. The total polyphenolic contents of L. barbarum fruits from Jinghe County in Xinjiang and Zhongning County in Ningxia were 5.52-11.72 and 7.06-9.37 mg (gallic acid equivalent)/g dry weight, while the total flavonoid contents of L. barbarum fruits from these regions were 12.52-30.29 and 12.67-20.77 mg (rutin equivalent)/g dry weight, respectively. Overall, 39 types of polyphenols were identified in the fruit extracts, including 26 flavonoids, 10 phenolic acids, and three tannins. Of these, 11 polyphenols were quantitatively analyzed, which revealed rutin to be the most dominant polyphenolic component in fruits from Jinghe and Zhongning. There were significant differences (p < 0.05) in the polyphenolic contents and antioxidant activities of L. barbarum fruit extracts, depending on the geographical origin, variety, and harvest season. The antioxidant activity of this species was found to be significantly positively correlated with the polyphenolic contents. This study provided scientific guidance for comprehensive applications of polyphenols from different varieties of L. barbarum from separate geographical origins.

Low temperature reduces potato wound formation by inhibiting phenylpropanoid metabolism and fatty acid biosynthesis

INTRODUCTION

Potato tubers have the healing capacity to prevent surface water transpiration and pathogen invasion after mechanical damage. Previous research has shown the inability to form healing periderm in potatoes under low temperatures, but the potential mechanism is still unclear.

METHODS

To explore the effects and mechanisms of low-temperature potato healing, wounded potatoes were stored at low temperature (4°C) and room temperature (22°C), respectively.

RESULTS

In this study, compared with 22°C healing, low temperature reduced the content of hydrogen peroxide, and the down-regulation of StAMY23 inhibited the conversion of starch to sugar, alleviated the degradation of starch, and reduced the content of soluble sugars and sucrose. Meanwhile, inhibition of phenylalanine metabolism by suppression of StPAL1 and St4CL expression reduced lignin accumulation. Low temperature also down-regulated the expression of StKCS6, StFAOH, StGPAT5, and StPrx, causing the lower deposition amount of suberin in wounds of potato tubers.

DISCUSSION

The above results suggested that low temperature led to less wound tissue deposition at the wound surfaces via suppressing phenylpropanoid metabolism and fatty acid biosynthesis in potato tubers.

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.

Quality of Goji Berry Fruit (Lycium barbarum L.) Stored at Different Temperatures

Goji berries are widely known for their outstanding nutritional and medicinal properties; they are usually found in the market as dried fruit or as juice because the fruit has a short shelf-life, and little information is available about its postharvest behavior at low temperatures. This study aimed to determine the storage performance of goji berry fruit by evaluating physicochemical, and sensorial attributes during storage at three different temperatures (0, 5, and 7 °C) for 12 days in a range that has not been extensively studied before. In addition, fruit respiration and ethylene production rates were also measured at the three temperatures. Fruit stored at 0 °C showed the lowest respiration rate and ethylene production (5.8 mg CO2 kg-1h-1 and 0.7 µg C2H4 kg-1h-1, respectively); however, at this temperature, the incidence and severity of pitting and electrolytic leakage were the highest. In contrast, 5 °C was found to be the best storage temperature for goji berry fruit; the fruit appeared fresh and healthy, had the highest scores during sensory analysis with an acceptable general impression, and had the lowest amount of damage attributable to chilling injury, with 17.1% fruit presenting with shriveling, 12.5% pitting, 6.7% mold, and 35% electrolytic leakage on day 9 of storage. Storage of goji berries at 7 °C resulted in the lowest marketability and the highest incidence of decay. Significant differences were also found in the phytochemical attributes, vitamin C content, soluble solid content (SSC), titratable acidity (TA), SSC/TA ratio, total polyphenol content, 2,2-diphenylpicrylhydrazy (DPPH), and anthocyanin content. This study revealed that a storage temperature of 5 °C for 9 days is recommended to maintain the quality of fresh goji berry. Thus, broadening the existing knowledge of the postharvest behavior of fresh goji berries; our results can help improve the commercial life of goji berries and ensure high-quality attributes throughout distribution.

Abscisic acid alleviates chilling injury in cold-stored peach fruit by regulating ethylene and hydrogen peroxide metabolism

Peach (Prunus persica (L.) Batsch) is susceptible to chilling injury under improper low-temperature storage (2°C-5°C). Previous research has shown that abscisic acid (ABA) alleviates chilling injury in fruits and vegetables, but the potential mechanism is still unclear. To explore its effectiveness and potential mechanism in alleviating chilling injury during cold storage, exogenous ABA was applied to peach fruit by immersion in 100 μmol L-1 solutions for 10 min. In our experiment, ABA alleviated chilling injury by reducing hydrogen peroxide (H2O2) content and ethylene production. In addition, ABA inhibited the expression of the ethylene synthesis-related genes PpACO1 and PpEIN2. At the same time, ABA activated the antioxidant enzymatic pathway and the ascorbate-glutathione (AsA-GSH) cycle, the transcript abundance encoding genes related to antioxidant enzyme activities also changed correspondingly. The results suggested that ABA alleviated chilling injury by scavenging excessive H2O2 by promoting antioxidant enzymes and the AsA-GSH pathway.

Incorporation of 1-methylcyclopropene and salicylic acid improves quality and shelf life of winter jujube (Zizyphus jujuba Mill. cv. Dongzao) through regulating reactive oxygen species metabolism

Winter jujube fruit is susceptible to aging, peel reddening, dehydration, shrinkage, and tissue softening during shelf life after it is removed from the cold storage conditions. In this study, the effects of 1-methylcyclopropene (1-MCP) and salicylic acid (SA) on the quality of winter jujube fruit during shelf life were investigated by measuring physiological indexes and the activities of antioxidant enzymes and enzymes related to reactive oxygen species (ROS) metabolism of winter jujube fruit. The results showed that 1-MCP treatment and SA treatment suppressed weight loss, respiratory rate, malondialdehyde (MDA) content, H₂O₂ content, and O2-· production rate, but improved firmness, color difference (ΔE), soluble solid content (SSC), titratable acidity (TA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), phenylalanine ammonia-lyase (PAL) activities, ascorbic acid content, glutathione content, total phenolic content, and total flavonoid content in comparison with the control. Particularly, the combined treatment of 1-MCP and SA (1-MCP+SA treatment) showed the maximum efficacy compared to the 1-MCP treatment and SA treatment alone. 1-MCP+SA treatment exhibited the best preservation effect, followed by SA treatment and 1-MCP treatment. Thus, the combined treatment of 1-MCP and SA is an effective approach to maintain the postharvest quality of winter jujube fruit and extend the shelf life.

Poly(allylamine)-copper(II) coordination complex grafted on core@shell upconversion nanoparticles for ultrafast and sensitive determination of the phytohormone salicylic acid in plant extracts

Salicylic acid (SA) is a phenolic phytohormone with critical roles in plant growth regulation and resistance to biotic and abiotic stress. Since low SA concentrations can modulate many plant biochemical responses, innovative analytical tools are required to deeply understand its activity and to control its exogenous application in modern agricultural systems. Herein, a NIR-activated composite based on NaYF₄:Yb,Er@NaYF₄ core@shell upconversion nanoparticles decorated with the poly(allylamine)-Cu(II) complex [UCNPs-PAAm-Cu(II)] was developed to sensitively determine the SA molecule in plant-derived samples. Accordingly, the PAAm-Cu(II) complex grafted on the UCNPs induces a strategic charge transfer band which triggers a quenching process through a resonance energy transfer (RET) mechanism. Such process is gradually deactivated upon the addition of SA and the consequent formation of the SA-Cu(II) complex, allowing a luminescence recovery in the 1-800 nM linear range. This mechanism is promoted by the strong stability of the SA-Cu(II) complex (log β_2-SA/Cu = 19.01) which is over twelve orders of magnitude stronger than the PAAm-Cu²⁺ counterpart. Furthermore, the equilibrium and kinetic studies on the involved mononuclear Cu²⁺ complexes formation permitted instantaneous analytical responses and excellent selectivity against other representative phytohormones and metallic cations. The reliability of this method was demonstrated by determining the SA content of some edible fruits and vegetables comprising apple, lemon, kiwi, tomato, and cucumber, whose concentrations ranged from 0.30 to 2.99 μg g^-1, with percent recoveries between 94.6 to 102.3%. Thereby, the reported nanocomplex can help to understand the SA activity in plants with significant applications in crop yield improvement and food quality assessment.

Hydrogen sulfide treatment increases the antioxidant capacity of fresh Lingwu Long Jujube (Ziziphus jujuba cv. Mill) fruit during storage

Hydrogen sulfide (H₂S) has been identified as an important gaseous signal molecule in plants. Here, we investigated the effects of H₂S on postharvest senescence and antioxidant metabolism of Lingwu Long Jujube (Ziziphus jujuba cv. Mill) fruits (LLJF). Fumigation of Jujube fruits with H₂S released from 0.4 mm NaHS could significantly prolong the postharvest shelf life of jujube fruits, reduce the decay rate of fruit, the weight loss of fruit, and inhibit the fruit loss, hardness, color, soluble solids, and titratable acidity. Compared with the control group, exogenous H₂S fumigation significantly decreased the loss of chlorophyll, carotenoids, soluble protein, ascorbic acid, phenols, and flavonoids in jujube fruits during post-harvest storage. At the same time, H₂S could significantly delay the accumulation of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and superoxide anion (O₂^∙−) and promote catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) activity, and inhibit polyphenol oxidase (PPO) activity. To summarize, H₂S can effectively alleviate postharvest senescence and decay of jujube fruits by regulating the ROS accumulation and antioxidant enzymes, and prolong the storage period of postharvest.

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H₂S treatment could significantly prolong the postharvest shelf life of jujube fruits.

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H₂S could significantly delay the accumulation of MDA, H₂O₂ and O₂^∙− during storage of jujube fruits.

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H₂S treatment promote CAT, SOD, APX, POD activity, and inhibit PPO activity during storage of jujube fruits.

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Provides a new method for storage of post-harvest jujube fruits.

NMR-based metabolomics of dried berries in comparison with dietary supplements

Consumption of dried berries is increasing worldwide due to their health benefits. This popularity has introduced berry-based supplements as an easier way to take in berry nutrients. The chemical composition of six dried berries (blueberry, cranberry, goji berry, golden berry, maqui berry, and raspberry) were compared to their berry-based supplements by metabolomics using nuclear magnetic resonance spectroscopy (NMR). Thirty-three metabolites were identified and 23 were quantified. Chemometric analysis of berries revealed that goji berry showed the highest content of amino and organic acids, while cranberry and golden berry showed a high carbohydrate content. Fatty acids were predominant in blueberry, golden berry, maqui berry, and raspberry. Additionally, an exploratory analysis of phenolic compounds in berry extracts were conducted. phenolic compounds in berry extracts could be correlated with their antioxidant activity. Additionally, derived supplements did not show similarities with their respective berry, suggesting the minimal addition of dried berry in their formulation. Thus, non-declared additives have highlighted the importance of food safety investigation.

Yield, Fruit Quality, and Storability of 'Canino' Apricot in Response to Aminoethoxyvinylglycine, Salicylic Acid, and Chitosan

Ethylene plays a pivotal role in the climacteric fruit ripening and senescence process. The effect of three ethylene inhibitors on the yield, quality, and storability of ‘Canino’ apricot fruit was studied. Foliar sprays of distilled water (control), aminoethoxyvinylglycine (AVG) (150 and 100 mg·L⁻¹), salicylic acid (SA) (4 and 2 mM), and chitosan (2.5% and 1.5%) were applied 30 and 15 days before harvest. Results indicated that the high concentrations of AVG and SA recorded the lowest percentage of preharvest fruit drop and, hence, the highest yield. Trees receiving either concentration of AVG showed the highest fruit firmness. High concentrations of all three ethylene inhibitors reduced fruit weight loss, total carotenoids, and soluble solid content (SSC), but increased total acidity (TA) during cold storage (2 °C). A high score of overall taste acceptability was observed with a higher concentration of SA, which was also recorded the lowest fruit malondialdehyde content (MDA) at harvest and during storage. The highest concentrations of SA and chitosan recorded no decay for 28 days of storage. Gene expression analysis reflected higher expression of PaACS1 gene with the highest concentrations of ethylene inhibitors, suggesting that SA (4 mM) is recommended for optimal yield, quality, and storability of ‘Canino’ apricot fruit grown under Egyptian conditions.

Chemical Composition, Crystal Morphology, and Key Gene Expression of the Cuticular Waxes of Goji (Lycium barbarum L.) Berries

The cuticular wax of fruit is closely related to quality, storability, and pathogen susceptibility after harvest. However, little is known about the cuticular wax of goji berry (Lycium barbarum L.) cultivars. In the present study, the chemical composition, crystal structures, and expression levels of associated genes of the cuticular wax of six goji cultivars were investigated. We detected 70 epicuticular wax compounds in six goji cultivars. Among them, fatty acids, alkanes, and primary alcohols were the major components of the cuticular wax of goji berries, which were related to the formation of irregular lamellar crystal structures. The terpenoid compounds in the cuticular wax of goji berries were highly resistant to Alternaria rot. Moreover, the CER1, CER6, LACS1, MAH1, LTP4, ABC11, MYB96, and WIN1 genes in goji berries might be closely related to wax synthesis. These results provide valuable information for breeding and screening goji cultivars suitable for postharvest storage.