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Abstract Sweet corn rapidly loses its sweetness, along with other nutrients, once it is harvested, which reduces its economic value. The present study was conducted to elucidate the regulatory mechanisms by which a rapid cooling slurry ice (SI) treatment followed by storage at 0 ± 0.5°C extends the postharvest quality of sweet corn relative to slower direct cooling at 0 ± 0.5°C. In this study, we found that SI treatment can maintain the appearance quality of sweet corn and inhibit grain shrinkage, respiration, and ethylene release. SI treatment delayed the aging of corn by regulating the expression levels of genes and the levels of metabolites. SI treatment also maintains its carbohydrate content, which is mainly related to starch and sucrose metabolism, glycolysis, citric acid cycle, pentose phosphate pathway, and cutin biosynthesis. The results provide a possible target for improving the postharvest quality of sweet corn.

Introduction: Folic acid (FA) is a critical metabolite in all living organisms and an important nutritional component of broccoli. Few studies have been conducted on the impact of an exogenous application of FA on the postharvest physiology of fruits and vegetables during storage. In this regard, the mechanism by which an exogenous application of FA extends the postharvest quality of broccoli is unclear. Objective: This study utilized a multicomponent analysis to investigate how an exogenous application of FA effects the postharvest quality of broccoli. Methods: Broccoli was soaked in 5 mg/L FA for 10 min and the effect of the treatment on the appearance and nutritional quality of broccoli was evaluated. These data were combined with transcriptomic, metabolomic, and DNA methylation data to provide insight into the potential mechanism by which FA delays senescence. Results: The FA treatment inhibited the yellowing of broccoli during storage. CHH methylation was identified as the main type of methylation that occurs in broccoli and the FA treatment was found to inhibit DNA methylation, promote the accumulation of endogenous FA and chlorophyl, and inhibit ethylene biosynthesis in stored broccoli. The FA treatment also prevented the formation of off-odors by inhibiting the degradation of glucosinolate. Conclusions: FA treatment inhibited the loss of nutrients during the storage of broccoli, delayed its yellowing, and inhibited the generation of off-odors. Our study provides deeper insight into the mechanism by which the postharvest application of FA delays postharvest senescence in broccoli and provides the foundation for further studies of postharvest metabolism in broccoli.

Abstract “Golden Hook” beans turn purple to different degrees due to the different compositions and contents of flavonoids during storage. At the same time, quality losses due to softening or pathogen invasion, and the deteriorations of flavor associated with carbohydrate metabolism occur. To reveal the effect of nitric oxide (NO) generated from sodium nitroprusside (SNP) on the postharvest quality of “Golden Hook” beans, we used metabolome, transcriptome, and assay for transposase‐accessible chromatin with high‐throughput sequencing approaches to compare beans at the time of treatment with untreated and SNP‐treated beans stored at 8°C for 12 days. The results showed that NO induced the expression of CERK1, FLS2, JAZ, and MYC2, stimulated the expression of polyphenol oxidase, CAT, and l‐ascorbate oxidase, the accumulation of flavonoids, and the synthesis of lignin in the antioxidant system, improving the ability of beans to resist stress while maintaining the balance of reactive oxygen species. High expressions of F3′H, FLS, INV, SUS, BCAT, and the accumulation of 6‐C‐methylquercetin‐3‐O‐rutinoside were associated with the maintenance of the fresh purplish red appearance of the beans in the SNP‐12d group, without loss of flavor. SNP treatment downregulated the transcription factors blimp‐1, OBP1, COG1, and AT1G6957 associated with bean senescence. These results provide insight into the postharvest quality control of “Golden Hook” beans.

Abstract N4-acetylcytidine (ac4C) modification of mRNA has been shown to be present in plant RNAs, but its regulatory function in plant remains largely unexplored. In this study, we investigated the differentially expressed mRNAs, lncRNAs and acetylation modifications of mRNAs in tomato fruits from both genotypes. By comparing wild-type (AC) tomato and the ethylene receptor-mutant (Nr) tomato from mature green (MG) to six days after the breaker (Br6) stage, we identified differences in numerous key genes related to fruit ripening and observed the corresponding lncRNAs positively regulated the target genes expression. At the post-transcriptional level, the acetylation level decreased and increased in AC and Nr tomatoes from MG to Br6 stage, respectively. The integrated analysis of RNA-seq and ac4C-seq data revealed the potential positive role of acetylation modification in regulating gene expression. Furthermore, we found differential acetylation modifications of certain transcripts (ACO, ETR, ERF, PG, CesA, β-Gal, GAD, AMY, and SUS) in AC and Nr fruits which may explain the differences in ethylene production, fruit texture, and flavor during their ripening processes. The present study provides new insights into the molecular mechanisms by which acetylation modification differentially regulates the ripening process of wild-type and mutant tomato fruits deficient in ethylene signaling. Graphical Abstract

In order to explore the effect of ozone micro-nano-bubbles (Ozone MNBs) on “green” and the regulative mechanism in soybean sprout, this study took soybean sprout as the experimental material, treated with 4 mg/L Ozone MNBs and stored in white LED condition. Physical quality, synthesizing and decomposing of chlorophyll (enzyme activity and substance) were measured in soybean sprout. Compared with control group, 4 mg/L Ozone MNBs treatment could significantly inhibit the “green”, enhance the activities of chlorophyllase (Chlase), chlorophyll degrading peroxidase (Chl-POX), Mg-dechelatase (MD) and pheophytinase (PPH). And it decreased the levels of precursors in chlorophyll synthesis [δ-aminolevulinic acid (ALA) and Urogen Ⅲ], chlorophyll, chlorophyll a and chlorophyll b. Additionally, it declined the content of ADP, ATP, NADP+ and NADPH in soybean sprout. Thus, 4 mg/L Ozone MNBs treatment affected the substance and enzyme activity of synthesizing and decomposing of chlorophyll, effectively hindered “green” in soybean sprout under white LED.

In order to explore the changes of postharvest quality and antioxidant enzyme activity of different varieties of fresh waxy corn during storage, Jingkenuo 2000, Jingkenuo 768 and Nongkenuo 336 were selected as materials to study the changes of sensory quality, hardness, weight loss rate, color, VC, soluble solids, carbohydrates, malondialdehyde content and antioxidant enzyme activity under 20 ℃ room temperature storage conditions. The results showed that with the extension of storage days, all three varieties showed different degrees of dehydration and shrinkage of grains, favor loss, and decrease of luster and sweetness, with Jingkenuo 768 being the most serious and Jingkenuo 2000 being the least. The hardness, L* value, Vc, soluble solids and soluble sugar content of the all three varieties decreased, while the weight loss rate, b* value, starch and malondialdehyde content increased. The contents of VC, soluble solids and soluble sugar in Nongkenuo 336 decreased the least, while the contents of starch and malondialdehyde increased the least, and the soluble sugar content and peroxidase activity were significantly higher than those of Jingkenuo 2000 and Jingkenuo 768 (P

To investigate the differences in the types and relative contents of refrigerated volatile flavor substances between 'Chitose' and 'Ji Tian No.1' cherry tomatoes, the effect of cold storage at 4 ℃ for 16 d on the flavor quality of cherry tomatoes ('Chitose' and 'Ji Tian No.1') was analyzed by using electronic nose and headspace solid-phase microextraction-gas chromatography. The results showed that electronic nose analysis results displayed, the volatile substances that undergo significant changes before and after refrigeration in two cherry tomatoes were inorganic sulfides, nitrogen oxides, and aromatic substances, a total of 93 volatile substances were detected by HS-SPME-GC-MS technique, including 27 aldehydes, 23 alcohols, 4 esters, 11 ketones, 3 furans, 9 alkanes, 12 olefins and 4 other substances. Compared to 0 d, the relative content of total volatile substances in 'Chitose' and 'Ji Tian No.1' after cold storage decreased by 7.08% and 3.68% respectively. The relative content of the main volatile compounds hexanal and trans-2-hexenal in two cherry tomatoes decreased after refrigeration, the relative content of trans 2-pentenal, heptanal, 1-pentanol, 6-methyl-5-hepten-2-one, and 1-penten-3-one increased after refrigeration. Compared with 'Chitose', 'Ji Tian No.1' could retain higher contents of main volatile substances of cherry tomato such as aldehydes, esters and ketones after cold storage. Therefore, 'Ji Tian No.1' was more suitable for post-harvest storage and transportation and low-temperature refrigeration, which would provide a theoretical basis for high-quality cherry tomato post-harvest storage and transportation technology.

In this study, the effects of storage at 4 ℃ for 0, 30 and 60 d on the phenolic content and browning key enzyme activities of fresh-cut yam during shelf life were investigated using 'Changshan fine hair yam' vegetable yam and 'Henan Wenxian' iron stick yam as test materials. The results showed that the browning index of both fresh-cut yams increased with the extension of shelf life, but with the extension of storage period, the browning index of vegetable yam was lower, while the browning index of iron stick yam was higher. At the 8th day of shelf period, the browning index of fresh-cut vegetable yam stored for 30 d was only 4.6% lower than that stored for 60 days, with no significant difference, while the browning index of fresh-cut iron stick yam for the same period was 8.4% lower than that stored for 60 days, and the difference was significant (P

Key Clinical Message Our purpose is to clearly diagnose the tongue and back tuberculosis ulcer through detailed medical history collection combined with examination, so as to provide certain experience for the diagnosis and treatment of oral tuberculosis.

Tomato is one of the most important vegetable crops in the world and is a model plant used to study the ripening of climacteric fleshy fruit. During the ripening process of tomato fruit, flavor and aroma metabolites, color, texture and plant hormones undergo significant changes. However, low temperatures delayed the ripening process of tomato fruit, inhibiting flavor compounds and ethylene production. Metabolomics and transcriptomics analyses of tomato fruit stored under low temperature (LT, 5 °C) and room temperature (RT, 25 °C) were carried out to investigate the effects of storage temperature on the physiological changes in tomato fruit after harvest. The results of transcriptomics changes revealed that the differentially expressed genes (DEGs) involved in tomato fruit ripening, including several kinds of transcription factors (TFs) (TCP, WRKY, MYB and bZIP), enzymes involved in cell wall metabolism [beta-galactosidase (β-GAL), pectinesterase (PE) and pectate lyase (PL), cellulose and cellulose synthase (CESA)], enzymes associated with fruit flavor and aroma [acetyltransferase (AT), malic enzyme (ME), lipoxygenase(LOX), aldehyde dehydrogenase (ALDH), alcohol dehydrogenase (ADH) and hexokinase (HK)], genes associated with heat stress protein 70 and genes involved in the production of plant hormones such as Ethylene responsive factor 1 (ERF1), Auxin/indoleacetic acids protein (AUX/IAA), gibberellin regulated protein. Based on the above results, we constructed a regulatory network model of the effects of different temperatures during the fruit ripening process. According to the analysis of the metabolomics results, it was found that the contents of many metabolites in tomato fruit were greatly affected by storage temperature, including, organic acids (L-tartaric acid, a-hydroxyisobutyric acid and 4-acetamidobutyric acid), sugars (melezitose, beta-D-lactose, D-sedoheptulose 7-phosphate, 2-deoxyribose 1-phosphate and raffinose) and phenols (coniferin, curcumin and feruloylputrescine). This study revealed the effects of storage temperature on postharvest tomato fruit and provided a basis for further understanding of the molecular biology and biochemistry of fruit ripening.

Several physiological changes occur during fruit storage, which include the regulation of genes, metabolisms and transcription factors. In this study, we compared ‘JF308’ (a normal tomato cultivar) and ‘YS006’ (a storable tomato cultivar) to determine the difference in accumulated metabolites, gene expression, and accessible chromatin regions through metabolome, transcriptome, and ATAC-seq analysis. A total of 1006 metabolites were identified in two cultivars. During storage time, sugars, alcohols and flavonoids were found to be more abundant in ‘YS006’ compared to ‘JF308’ on day 7, 14, and 21, respectively. Differentially expressed genes, which involved in starch and sucrose biosynthesis were observed higher in ‘YS006’. ‘YS006’ had lower expression levels of CesA (cellulose synthase), PL (pectate lyase), EXPA (expansin) and XTH (xyglucan endoglutransglucosylase/hydrolase) than ‘JF308’. The results showed that phenylpropanoid pathway, carbohydrate metabolism and cell wall metabolism play important roles in prolonging the shelf life of tomato (Solanum lycopersicum) fruit. The ATAC-seq analysis revealed that the most significantly up-regulated transcription factors during storage were TCP 2,3,4,5, and 24 in ‘YS006’ compared to ‘JF308’ on day 21. This information on the molecular regulatory mechanisms and metabolic pathways of post-harvest quality changes in tomato fruit provides a theoretical foundation for slowing post-harvest decay and loss, and has theoretical importance and application value in breeding for longer shelf life cultivars.

Tomato is one of the most widely cultivated horticultural plants in the world, while the key volatile compounds of tomato fruits generally derive from fatty acid, carotenoid, phenylalanine, and branched-chain amino acid pathways. As an important endogenous signal molecule, methyl salicylate (MeSA) plays a crucial role in the fruit ripening process of plant. Recently, it has been demonstrated that MeSA can maintain the flavor quality of full ripe tomatoes after cold-storage preservation. However, few research teams attempted to investigate the effects of MeSA plus low temperature treatment on the different volatile biosynthetic pathways of tomatoes previously. Therefore, in this study, the effects of methyl salicylate pre-treatment (0.05 mM MeSA, 24 h) on the volatile profile and flavor-related key gene expressions of tomato fruits stored at 10°C were evaluated for the first time. Our results showed that the loss of volatile compounds in low temperature-treated tomato fruits could be effectively alleviated by MeSA pre-treatment. Although MeSA had no remarkable effect on the formation of carotenoid pathway- and branched-chain amino acid pathway-related volatiles in tomatoes subjected to low temperature, the content of fatty acid pathway-related volatiles (including cis-3-hexenal, hexanal, and trans-2-hexenal) in full red fruits of 10°C MeSA group was remarkably higher than that of 10°C control group. Furthermore, MeSA pre-treatment significantly up-regulated the expression of LOXC or LOXD gene in low temperature-treated fruits at breaker or full red stage, respectively. In conclusion, pre-treatment with MeSA might avoid the loss of aromatic compounds in tomato fruits stored at low temperature by activating the fatty acid pathway.

Tomato fruit are sensitive to chilling injury (CI) during cold storage. Several factors have been discovered to be involved in chilling injury of tomato fruit. Plant hormones play an important regulatory role, however, the relationship between chilling injury and N6-methyladenosine (m6A) methylation of transcripts in plant hormone pathways has not been reported yet. In order to clarify the complex regulatory mechanism of m6A methylation on chilling injury in tomato fruit, Nanopore direct RNA sequencing was employed. A large number of enzymes and transcription factors were found to be involved in the regulation process of fruit chilling injury, which were associated with plant hormone, such as 1-aminocyclopropane 1-carboxylate synthase (ACS), aspartate aminotransferase (AST), auxin response factor (ARF2), ethylene response factor 2 (ERF2), gibberellin 20-oxidase-3 (GA20ox) and jasmonic acid (JA). By conjoint analysis of the differential expression transcripts related to chilling injury and m6A methylation differential expression transcripts 41 differential expression transcripts were identified involved in chilling injury including 1-aminocyclopropane-1-carboxylate oxidase (ACO) and pectinesterase (PE) were down-regulated and heat shock cognate 70 kD protein 2 (cpHSC70), HSP70-binding protein (HspBP) and salicylic acid-binding protein 2 (SABP2) were up-regulated. Our results will provide a deeper understanding for chilling injury regulatory mechanism and post-harvest cold storage of tomato fruit.

The effect of 100% oxygen (O2)-modified atmosphere packaging (MAP) on the quality improvement of fresh-cut broccoli stored at 4 °C for 15 days was investigated in this study. The results indicated that, compared to the control group conditions, 100% O2 MAP treatment effectively maintained broccoli sensory evaluation scores, green color, and texture; reduced respiration and chlorophyll degradation; and reduced total bacterial count (TBC), malondialdehyde (MDA) levels, electrolyte leakage (EL), hydrogen peroxide (H2O2), and superoxide (O2−) contents. Furthermore, 100% O2 MAP led to a smaller loss of nutrients and increased antioxidant capacity. In conclusion, the use of 100% O2 MAP is an effective approach for maintaining high-quality fresh-cut broccoli during refrigerated storage at 4 °C.

Foodborne illnesses present a major threat to public health and are frequently attributed to foodborne pathogens present on fresh produce. Some opportunistic pathogens of broccoli are also responsible for causing head rot. Three different light treatments, UV-C, red LED (50 μml/m2/s), and UV-C + LED were used to treat broccoli prior to or during storage. Following the light treatments, microorganisms present in eluates obtained from the surface of broccoli heads were characterized using a metagenomic approach. Metagenomic DNA libraries were subjected to high-throughput sequencing on an Illumina Hiseq platform. Results indicated that the combined treatment of LED red light and UV-C provided the best sensory preservation of broccoli, followed by LED red light and then UV-C. The bacterial communities in the eluates obtained from the surface of broccoli heads in all three light treatments were primarily represented at the phylum level by Proteobacteria and Firmicutes, while fungal communities were primarily represented by Ascomycota and Basidiomycota. Further analysis indicated that the all three light treatments reduced the presence of foodborne pathogens and bacterial taxa responsible for broccoli spoilage. While UV-C had a significant inhibitory effect on Botrytis cinerea, the light treatments increased the relative abundance of Pseudomonas fluorescens. Results indicate that a metagenomic approach can be used to detect pathogenic bacteria and fungi on fresh vegetables and assess the impact of management practices, such as light treatments, designed to maintain postharvest quality, on the composition of the microbiome present on the surface of harvested produce.

The effect of palmitic acid (PA) on stem browning was investigated in freshly harvested mini-Chinese cabbage (Brassica pekinensis). Results indicated that concentrations of PA ranging from 0.03 g L−1 to 0.05 g L−1 inhibited stem browning and decreased the rate of respiration, electrolyte leakage, and weight loss, as well as the level of malondialdehyde (MDA) in freshly harvested mini-Chinese cabbage stored at 25 °C for 5 d. The PA treatment enhanced the activity of antioxidant enzymes (ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), 4-coumarate:CoA ligase (4CL) and phenylalamine ammonia lyase (PAL)), and inhibited the activity of polyphenol oxidase (PPO). The PA treatment also increased the level of several phenolics (chlorogenic acid, gallic acid, catechin, p-coumaric acid, ferulic acid, p-hydroxybenzoic acid, and cinnamic acid) and flavonoids (quercetin, luteolin, kaempferol, and isorhamnetin). In summary, results indicate that treatment of mini-Chinese cabbage with PA represents an effective method for delaying stem browning and maintaining the physiological quality of freshly harvested mini-Chinese cabbage due to the ability of PA to enhance antioxidant enzyme activity and the level of phenolics and flavonoids during 5 d.

Tomato fruit is susceptible to chilling injury (CI) when stored at low temperatures, limiting its storage potential, and resulting in economic loss if inappropriate temperatures are used. Brassinolide (BR) is a plant growth regulator that is known to decrease the susceptibility of fruit to CI. In this study, transcriptome, metabolome, and proteome analysis revealed the regulation mechanism of BR treatment in alleviating tomato fruit CI. The results showed that the differentially expressed metabolites mainly included amino acids, organic acids, carbohydrates, and lipids. Differentially expressed genes (DEGs) were involved in plant cold stress response (HSFA3, SHSP, and TPR), fruit redox process (POD, PAL, and LOX), related to the fruit texture (CESA, β-Gal, and PAE), plant hormone signal transduction (ACS3, ARF, and ERF,), transcription factors (TCP, bHLH, GATA). Moreover, differentially expressed proteins were associated with fruit texture (CESA, PE, PL, and CHI), plant oxidation processes (LOX, GPX, CAT, and POD), plant cold stress response (HSF, HSP20, HSP70, and HSP90B), plant hormone signal transduction (BSK1 and JAR1) and transcription factors (WRKY and MYB). Our study showed that BR alleviates CI symptoms of tomato fruit by regulating LOX in the α-linolenic acid metabolism pathway, enhancing jasmonic acid-CoA (JA-CoA) synthesis, inhibiting cell wall and membrane lipid damage. The results provided a theoretical basis for further study on the CI mechanism of tomato fruit.

Sag is an important indicator of the operational health of a transmission line, and its timely measurement is of great significance to maintain the stability and reliability of power systems. However, traditional contact measurements may be affected by the electromagnetic interference of conductors. In contrast, measurement methods without direct electrical contact with the subject provide greater portability and flexibility. This paper presents a study of a transmission line sag measurement and simulation based on non-contact electric field sensing. The finite element method was used to analyze the conductor distribution, establish the coupling relationships among the electric field, transmission line, and measurement point, propose a sag inverse calculation model, and assess the impact of the transmission line parameter on the curved drooping measurement. Simultaneously, sag measurement schemes for single-round and dual-circuit lines were designed for multi-conductive lines, and measurement array studies were conducted. The vertical component of the electric field in space measured by the array was obtained, which could be used to perform conductor sag measurement simply and efficiently. The proposed method will facilitate the monitoring of the overhead transmission line status, which is conducive to the effective operation of the entire system.

Alkannin (ALK) has anti-inflammatory and anti-tumour activities. We tried to probe the underlying functions of ALK in oral squamous carcinoma (OSCC) cells growth, migration and invasion. OSCC cells viability was investigated after treatment with ALK. Then, BrdU, flow cytometry, Western blot and Transwell assays were executed to appraise proliferation, apoptosis, migration and invasion in OSCC cells with ALK stimulation. The biological functions of miR-9 were explored after miR-9 mimic/inhibitor transfection. The relevance of RECK and miR-9 was predicated by dual luciferase activity assay. JAK1/STAT3 and PI3K/AKT pathways were estimated by Western blot. Tumour formation in vivo was executed by xenograft tumours assay. We found that ALK restrained cell proliferation, facilitated apoptosis, repressed migration and invasion also interdicted JAK1/STAT3 and PI3K/AKT pathways in CAL-27 and SCC-9 cells. miR-9 expression was upgraded in OSCC tissues but decreased in OSCC cells along with ALK administration; meanwhile, overexpressed miR-9 inverted the influences of ALK in OSCC cells growth, migration and invasion. RECK was predicated as a novel target gene of miR-9, and overexpressed RECK hindered JAK1/STAT3 and PI3K/AKT pathways in OSCC cells. ALK prohibited tumour formation in vivo. In conclusion, ALK restrained OSCC cells growth, migration and invasion via adjusting miR-9/RECK axis.HighlightsALK restrains cell growth, migration and invasion in OSCC cells;miR-9 is enhanced in OSCC tissues but is repressed by ALK in OSCC cells;miR-9 inverts the repressive effect of ALK on CAL-27 and SCC-9 cells;RECK is a novel target of miR-9;ALK or RECK hinders JAK1/STAT3 and PI3K/AKT pathways in CAL-27 and SCC-9 cells;ALK prohibits tumour formation in vivo.

With the development of facility agriculture, low-light stress is a prominent problem and a popular research topic currently. In this study, transcriptome analysis was used to analyze the genes in the fruit peel of photosensitive and nonphotosensitive eggplant and to explore the mechanism of changes in fruit color, texture, hormone content, aroma, and taste of these two different types of eggplant. We identified 51, 65, 66, and 66 genes involved in synthesizing anthocyanins, texture, hormone content, and aroma and flavor, respectively, in the two different types of eggplant based on the variation in gene expression trends in the fruit peel. These results provide a basis for further analysis of the molecular mechanism underlying the regulatory processes in eggplant fruits under low-light stress.

This study examines ultraviolet-C (UV-C) treatment supplementation as a means of inhibiting the senescence of pepino fruit after harvest. Pepino fruits were subjected to 1.5 kJ/m2 UV-C treatments and then packed and stored at 10 °C for 28 d. Results showed that 1.5 kJ/m2 UV-C treatment had the greatest ability to maintain firmness, and reduced the level of respiration and ethylene production. Further analysis indicated that the 1.5 kJ/m2 UV-C treatment maintained the content of total soluble solids (TSS), chlorophyll, vitamin C, flavonoids, and total phenolics. Lower levels of malondialdehyde (MDA) and higher levels of antioxidant enzyme activity were found in UV-C treated fruit during storage. An electronic nose (E-nose) and headspace-gas chromatography-mass spectrometry (HS-GC-MS) was used to determine volatile compounds. Results revealed that the UV-C treatment may promote the synthesis of a large number of alcohols and esters by maintaining the overall level of acids, aldehydes, and esters in fruits. This may contribute to the maintenance of the flavor of harvested fruits. In conclusion, 1.5 kJ/m2 UV-C treatment was demonstrated to be an effective treatment for the maintenance of the sensory, nutritional, and flavor parameters of pepino fruit.

The interactive effects of six maturity stages and refrigerated storage (chilling)/blanching (heating) treatments on the volatile profiles of ripe tomatoes were studied. A total of 42 volatiles were identified, of which 19 compounds had odor activity values equal to or greater than 1. Of those, “green” and “leafy” aroma volatiles were most abundant. Chilling and heating treatments both suppressed overall volatile production, with chilling having the greater impact, regardless of harvest maturity. However, fruit harvested at the turning stage had the least volatile suppression by chilling and heating treatments in comparison with fruit harvested earlier or later, mostly in the fatty acid- and phenylalanine-derived volatiles. Volatiles derived from amino acids were promoted by heat treatment for fruit harvested at all maturities, and those derived from carotenoid and phenylalanine pathways and harvested at advanced harvest maturities were stimulated by chilling treatment. Volatile production is generally believed to be improved by delayed harvest, with vine-ripe being optimum. However, opposite results were observed possibly because the later-harvested fruit had longer exposure to open-field weather stress. The best harvest maturity recommendation is the turning stage where fruit developed abundant volatiles and were least impacted by chilling and heating treatments.

Low-intensity (10 μmol m−2 s−1) white LED (light-emitting diode) light effectively delayed senescence and maintained the quality of postharvest pakchoi during storage at 20 °C. To investigate the mechanism of LED treatment in maintaining the quality of pakchoi, metabolite profiles reported previously were complemented by transcriptomic profiling to provide greater information. A total of 7761 differentially expressed genes (DEGs) were identified in response to the LED irradiation of pak-choi during postharvest storage. Several pathways were markedly induced by LED irradiation, with photosynthesis being the most notable. More specifically, porphyrin and chlorophyll metabolism and glucosinolate biosynthesis were significantly induced by LED irradiation, which is consistent with metabolomics reported previously. Additionally, chlorophyllide a, chlorophyll, as well as total glucosinolate content was positively induced by LED irradiation. Overall, LED irradiation delayed the senescence of postharvest pak-choi mainly by activating photosynthesis, inducting glucosinolate biosynthesis, and inhibiting the down-regulation of porphyrin and chlorophyll metabolism pathways. The present study provides new insights into the effect and the underlying mechanism of LED irradiation on delaying the senescence of pak-choi. LED irradiation represents a useful approach for extending the shelf life of pak-choi.