Preharvest ultraviolet C (UV-C) irradiation is an innovative approach for increasing the bioactive phytochemical content of strawberries to increase the disease resistance and nutritional value. This study investigated the changes in individual flavonoids in strawberry developed with three different cumulative doses of preharvest UV-C treatment (low, 9.6 kJ m–2; middle, 15 kJ m–2; and high , 29.4 kJ m–2). Significant accumulation (p < 0.05) of phenolics (25–75% increase), namely, cyanidin 3-glucoside, pelargonidin 3-glucoside/rutinoside, glucoside and glucuronide of quercetin and kaempferol, and ellagic acid, was found in the fruit subjected to low and middle supplemental doses of UV-C radiation. The expression of the flavonoid pathway structural genes, i.e., FaCHS1, FaCHI, FaFHT, FaDFR, FaFLS, and FaFGT, was upregulated in the low- and middle-dose groups, while the early stage genes were not affected by the high dose. FaMYB1 was also relatively enhanced in the low- and middle-dose groups, while FaASR was upregulated in only the low-dose group. Hormetic preharvest UV-C dose ranges for enhancing the polyphenol content of strawberries were established for the first time.Keywords: ellagic acid; flavonoids; Fragaria × ananassa; hormetic; MYB proteins; preharvest UV-C; RT-qPCR;

The effects of exogenous nitro oxide (NO) on chilling resistance and the metabolism of polyamine, proline, and γ-aminobutyric acid of bamboo shoots were investigated. Bamboo shoots were dipped in 0.07 mM sodium nitroprusside (SNP) and stored at 1 °C for 56 days. During the storage, the development of chilling injury of SNP treated bamboo shoots was inhibited with decreased accumulation of malonaldehyde and electrical leakage. At the end of storage, the chilling injury incidence of treated bamboo shoots decreased by 37.9% while their malonaldehyde content and electrical leakage were 8.8% and 18.6% lower than that of the control, respectively. Interestingly, the endogenous NO, polyamines, γ-aminobutyric acid, and proline contents of treated bamboo shoot also significantly increased. Consistently, the metabolisms of these nitrogenous compounds were stimulated in treated bamboo shoots, according to their higher (20.2%–49.8%) related enzyme activities, including nitric oxide synthase, arginine decarboxylase, ornithine decarboxylase, glutamate decarboxylase, orn-δ-aminotransferase, and Δ1-pyrroline-5-carboxylate synthetase. The results indicated that the SNP treatment enhanced chilling tolerance of bamboo shoots, which might associate with the activated metabolism of polyamines, γ-aminobutyric acid, and proline. SNP treatment might be an alternative technology to avoid chill injury during cold storage of bamboo shoots.Keywords: bamboo shoot; chilling injury; GABA; nitro oxide; polyamine; proline;

•Marketable yield was not affected by the preharvest UV-C treatments.•Firmness, sugars, acids and volatile compounds were affected differentially by the treatments.•ABA and GA3 were enhanced by low and middle doses while SA was reduced by the high dose.•Attempts were made to established physiological links between quality and phytohormonal changes.Preharvest ultraviolet-C (UV-C) treatment of strawberry is a very new approach, and little information is available on the effect of this treatment on plant growth regulators. In this study, the effect of preharvest UV-C irradiations at three different doses on strawberry yield, fruit quality parameters and endogenous phytohormones was investigated simultaneously. The overall marketable yield of strawberry was not affected by the preharvest UV-C treatments, although more aborted and misshapen fruits were found in UV-C treated groups than in the untreated control. The fruits in the high dose group were firmer and had approximately 20% higher sucrose content and 15% higher ascorbic acid content than the control, while fruits from the middle and low dose groups showed no significant changes in these parameters. The lower abscisic acid (ABA) content found in the fruits in the high UV-C group may be associated with those quality changes. The citric acid content decreased only in the low dose group (reduction of 5.8%), with a concomitant 37% reduction in jasmonic acid (JA) content, compared to the control. The antioxidant status of fruits that received preharvest UV-C treatment was considered enhanced based on their oxygen radical absorbance capacity (ORAC) and malondialdehyde (MDA) content. In terms of aroma, three volatile alcohols differed significantly among the various treatments with obvious activation of alcohol acyltransferase (AAT) activity. The observed synchronous influence on physiological indexes and related phytohormones suggests that preharvest UV-C might affect fruit quality via the action of plant hormones.

•The VOC profiles were significantly affected by UV-C treatments in strawberry leaves.•Lipoxygenase and alcohol dehydrogenase activities were increased by UV-C treatments.•The activity of the antioxidant enzymes catalase and peroxidase was inhibited.•Higher JA was found in the high-dose group while lower ABA was found in medium and high dose UV-C treated samples.•UV-C-induced VOC accumulation is apparently related to changes in the antioxidant systems and phytohormone biosynthesis.Recent studies have highlighted the biological and physiological effects of pre-harvest ultraviolet (UV)-C treatment on growing plants. However, little is known about the involvement of volatile organic compounds (VOCs) and their response to this treatment. In this study, strawberry plants were exposed to three different doses of UV-C radiation for seven weeks (a low dose: 9.6 kJ m−2; a medium dose: 15 kJ m−2; and a high-dose: 29.4 kJ m−2). Changes in VOC profiles were investigated and an attempt was made to identify factors that may be involved in the regulation of these alterations. Principle compounds analysis revealed that VOC profiles of UV-C treated samples were significantly altered with 26 VOCs being the major contributors to segregation. Among them, 18 fatty acid–derived VOCs accumulated in plants that received high and medium dose of UV-C treatments with higher lipoxygenase and alcohol dehydrogenase activities. In treated samples, the activity of the antioxidant enzymes catalase and peroxidase was inhibited, resulting in a reduced antioxidant capacity and higher lipid peroxidation. Simultaneously, jasmonic acid level was 74% higher in the high-dose group while abscisic acid content was more than 12% lower in both the medium and high-dose UV-C treated samples. These results indicated that pre-harvest UV-C treatment stimulated the biosynthesis of fatty acid–derived VOCs in strawberry leaf tissue by upregulating the activity of enzymes of the LOX biosynthetic pathway and downregulating antioxidant enzyme activities. It is further suggested that the mechanisms underlying fatty acid-derived VOCs biosynthesis in UV-C treated strawberry leaves are associated with UV-C-induced changes in phytohormone profiles.Download high-res image (193KB)Download full-size image

•Nano-ZnO-based LDPE (NZLDPE)-packaging was applied to the cold storage of peaches.•The chilling tolerance of peaches was improved by NZLDPE-packaging.•NZLDPE-packaging was benefit to rapid formation of low O2 and high CO2 environment.•The activities of pectin-related enzymes were coordinated by NZLDPE-packaging.•NZLDPE-packaging was contributed to pectin metabolism to alleviate chilling injury.The effects of nano-ZnO-based low-density polyethylene (NZLDPE)-packaging on chilling tolerance and pectin metabolism in postharvest “Hujingmilu” peaches were investigated. Peaches packed in low-density polyethylene (LDPE) and NZLDPE were stored at 2 °C for 40 d. Compared with the control, both packages alleviated the development of chilling injury, showed higher fruit firmness with lower browning index, electrolyte leakage, relative viscosity, and decay rate. NZLDPE-packaging performed better than LDPE-packaging because of the rapid formation of low O2 and high CO2. Moreover, NZLDPE-packaging inhibited pectin esterase and enhanced polygalacturonase and β-galactosidase, leading to the promotion of alkali soluble-pectin and water-soluble pectin, and the decrease of chelater-soluble pectin. These effects were of great benefit to the maintaining of cell wall structure and the degradation of calcium-pectate gel, which finally alleviated the chilling injury and therefore maintained good quality during chilling stress.Download high-res image (145KB)Download full-size image

•Chilling injury was alleviated by NO treatment in postharvest banana fruit.•NO treatment promoted accumulation of PAs, GABA and proline.•NO treatment enhanced ADC, ODC, DAO and PAO activities.•NO treatment enhanced GAD activities, while inhibited GABA-T activities.•Accumulation of PAs, GABA and proline contribute to chilling tolerance.Effect of exogenous nitric oxide (NO) on polyamines (PAs) catabolism, γ-aminobutyric acid (GABA) shunt, proline accumulation and chilling injury of banana fruit under cold storage was investigated. Banana fruit treated with NO sustained lower chilling injury index than the control. Notably elevated nitric oxide synthetase activity and endogenous NO level were observed in NO-treated banana fruit. PAs contents in treated fruit were significantly higher than control fruit, due to the elevated activities of arginine decarboxylase and ornithine decarboxylase. NO treatment increased the activities of diamine oxidase, polyamine oxidase and glutamate decarboxylase, while reduced GABA transaminase activity to lower levels compared with control fruit, which resulted the accumulation of GABA. Besides, NO treatment upregulated proline content and significantly enhanced the ornithine aminotransferase activity. These results indicated that the chilling tolerance induced by NO treatment might be ascribed to the enhanced catabolism of PAs, GABA and proline.

•The development of chilling injury in banana fruit was inhibited by 0.5 mM H2S.•H2S treatment inhibited ethylene production.•H2S treatment inhibited chilling injury with the maintenance of high energy status.•H2S treatment enhanced the activities of H+-ATPase, Ca2+-ATPase, CCO and SDH.In this study, the effect of hydrogen sulfide (H2S) on energy metabolism in postharvest banana fruit under chilling stress was investigated. Banana fruit, fumigated with optimal concentration (0.5 mM) of aqueous sodium hydrosulfide (NaHS) solution for 24 h, were initially stored at 7 °C for 14 d and 20 °C for another 6 d. H2S treated banana fruit showed both higher value of firmness and Hue angle, as well as lower value of electrolyte leakage, malondialdehyde (MDA) content and ethylene production. These indicated slower development of chilling injury compared with the control. Decrease in adenosine triphosphate (ATP) and energy charge was not noticeable in H2S treated banana fruit. Moreover, the activity of H+-ATPase, Ca2+-ATPase, cytochrome C oxidase (CCO) and succinate dehydrogenase (SDH), associated with energy metabolism, were significantly enhanced by H2S treatment. Therefore, it can be deduced that H2S can potentially alleviate chilling development in banana fruit by increasing enzymes activities, involved in energy metabolism, to maintain energy charge.

The role of sucrose as a signal molecule in plants was in debate for a long time, until recently, it gradually becomes more prominently accepted. Sucrose plays roles in a vast array of developmental processes in plants, however, its function in fruit ripening has not been well elucidated. In this study, the influence of exogenous sucrose treatment (500 mM) on postharvest tomato fruit ripening was investigated. It was found that, in comparison with mannitol treatment (500 mM, set as control), sucrose accelerated the ripening process with higher levels of respiration rate and ethylene production during the storage. Sucrose treatment up-regulated its biosynthetic genes, whilst stimulated expressions of genes encoding degradation related enzymes in the fruits. However, higher sucrose content was observed in sucrose-treated fruits only in the first few days. In addition, sucrose application had minor effect on the contents of its degrading products, glucose and fructose. Moreover, exogenous sucrose treatment up-regulated expressions of ethylene biosynthetic genes, and promoted ethylene signal transduction via influencing critical genes of the signaling pathway in different patterns. These results indicate that sucrose stimulates tomato fruit ripening may through mediating its own metabolism, which facilitates nutrients fluxes and metabolic signaling molecules activation, and also by enhancing ethylene biosynthesis and signal transduction.

•Octacosanol (OC) from sugarcane rind were identified by GC–MS.•Non-isothermal DSC was used to evaluate the oxidative stability of OC.•Water, metallic ions and fatty acid accelerate the oxidation of OC.•Oxidation reactions of OC in different temperature level were different.•OC and its oxidation products were identified by GC-FID after DSC test.The chemical composition and selected physical parameters of crude 1-octacosanol (1-OC) extracted from sugarcane rind have been determined. GC–MS results exhibited that 1-OC sample was primarily composed of 1-OC (45.17%), 1-docosene (12.04%), 1-triacontanol (0.23%), 1-heneicosanol (0.33%), 1-tetracosanal (0.28%), campesterol (4.5%), stigmasterol (9.12%) and β-sitosterol (8.23%). The linoleic acid had important effects on physical and chemical properties of 1-OC sample, as it notably changed the melting point and the onset oxidation temperature To of 1-OC sample from 83.75 ± 0.35 °C to 63.25 ± 0.35 °C and 245.64 ± 2.04 °C to 160.03 ± 0.01 °C, respectively. It was also proved that the oxidation reactions were significantly different at different temperature levels. 1-OC was stable up to 245.64 ± 2.04 °C. However, when the temperature continued to rise, 1-OC and its oxidation products started to be oxidized. Therefore, attention should be paid to the quality of 1-OC during the preparation of food and to minimize the undesirable breakdown products.

•A method based on direct saponification followed by HPLC analysis was developed.•Acid hydrolysis was used to determine the composition of ASGs and SGs.•Among different parts of sugarcane, tips had the greatest amount of phytosterols.•Glycosylated sterols are found as an important group of sterols in sugarcane.•Red-rind sugarcane contained more β-sitosterol than green-rind sugarcane.A simple method based on direct saponification followed by RP-HPLC analysis was developed for quantification of free and conjugated sterols in sugarcane. Acid hydrolysis prior to alkaline saponification was used to determined acylated steryl glycoside and steryl glycoside in sugarcane. The applicability and generality of this method were improved with intensive investigation. Compared to traditional solvent extraction method, this method was more time saving and appropriate for characterization of sterol fractions in sugarcane. This method was successfully applied for determination of free and conjugated sterols in different sugarcane samples. The results exhibited that stigmasterol (varied from 883.3 ± 23.5 to 1823.9 ± 24.5 μg/g dry weigh) and β-sitosterol (varied from 117.6 ± 19.9 to 801.4 ± 33.5 μg/g dry weight) were major phytosterols in the sugarcane sample, and their glycosylated forms accounted for almost 87.0% of stigmasterol and 87.5% of β-sitosterol in sugarcane, respectively. In addition, among other parts of sugarcane, tips contained the greatest amount of phytosterols.

A novel nano-SiO2 modified low density polyethylene (NSLDPE) packaging was prepared by blending LDPE with nano-SiO2 in this study. Its effect on the quality of Pacific white shrimp Penaeus vannamei during 8-day storage at (4 ± 1) °C and compared NSLDPE with existing LDPE were investigated. The effect of NSLDPE packaging on the shrimp was compared with normal LDPE by analyzing the microbiological and physicochemical indices. Results showed that shrimp packaged in NSLDPE packaging possessed higher sensory evaluation score and stronger water holding capacity. NSLDPE packaging inhibited the polyphenoloxidase activity and melanosis occurrence and reduced the contents of thiobarbituric acid reactive substances, total volatile base nitrogen and K value by 25.48, 8.09, and 22.22 % at the end of storage when compared with LDPE packaging, respectively. Additionally, NSLDPE packed shrimps remained the commercial acceptability for 8 days, while the total viable counts of control reached to a limiting level for shrimp processing (1 × 106 CFU g−1) after 6 days. NSLDPE packaging delayed the deterioration by improved gas barrier, inhibited endoenzyme activity, antimicrobial effect, and extended the shelf life of shrimp by nearly 33 %. Therefore, NSLDPE packaging should be recommended as a promising alternative method to maintain the quality of Pacific white shrimp.

The effect of nitric oxide (NO) on chlorophyll degradation and antioxidant response in banana fruits after cold storage was investigated. Pre-climacteric green banana fruit treated with NO donor sodium nitroprusside of 0.05 mM was stored at 7 °C for 15 days and then ripened at 22 °C for 6 days. Chilling injury (CI) index, color, chlorophyll, total phenolics, activities of chlorophyllase, Mg-dechelatase, catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD), phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) of the banana peel, together with firmness, titratable acidity (TA) and total soluble sugar (TSS) of the banana pulp were analyzed in this research. NO treatment improved chilling tolerance of banana fruits as shown by the reduced CI index. The retarded color change of the peel and higher firmness, TA and TSS content of the pulp showed that ripening process of NO-treated banana fruit was delayed by 2 days. The activities of chlorophyllase and Mg-dechelatase were significantly inhibited by NO, resulting in the retention of chlorophyll content. Further investigation showed that activities of CAT, APX and POD were enhanced in NO-treated banana fruits. Compared to control fruits, NO treatment significantly promoted PAL activity and inhibited PPO activity, and thus led to higher levels of total phenolics content. Results suggested that NO could enhance both enzymatic and non-enzymatic antioxidant system, and thus retarded chlorophyll degradation of banana fruits. Due to its effect on inhibition of chlorophyll degradation enzyme activities and promotion of the antioxidant defense system, NO is suggested as a potential approach to preserve chlorophyll content and maintain fruit quality of banana fruits after cold storage.

Bamboo shoots are highly nutritious but difficult to preserve even under low temperature since they are sensitive to chilling. In the present research, bamboo shoots were exposed to UV-C light (4.1 kJ/m2) prior to 56 days storage at 1 °C to evaluate the potential of UV-C treatment on alleviating chilling injury (CI) of bamboo shoots under cold storage. CI incidence and physiological and biochemical characteristics associated with CI were determined during storage. The results showed that UV-C treatment apparently inhibited the development of CI and resulted lower EI and MDA content than that of the control. Further investigation demonstrated that UV-C treatment increased activities of CAT, APX, GR and DPPH scavenging activity of bamboo shoots, which greatly contribute to alleviating CI. The increases in both O2− production rate and H2O2 content of UV-C-treated bamboo shoots were significantly delayed, PAL activity was increased which contributed to enhancing accumulation of TP, and endogenous proline synthesis was promoted, which resulted from the increased activity of P5CS and decreased PDH activity. The results above suggest that the improved antioxidative defense system and enhanced proline accumulation is the underlying mechanism that UV-C treatment enhanced chilling tolerance in bamboo shoots.

•High TTC was detected in sugarcane.•Phytosterols of different parts of sugarcane were identified by HPLC.•Sugarcane rind contained highest TFC and TPC.•Positive relationship between TFC, TPC and antioxidant activity was found.Antioxidant capacities and phytochemicals such as phenolics, flavonoids, triterpenoids, phytosterols of four parts of two sugarcane cultivars have been characterised. The total triterpenoid content (TTC), total phenolic content (TPC), total flavonoid content (TFC) and total sterol content (TSC) were different among parts and cultivars of sugarcane. The node of both cultivars contained the highest TTC (2096.02 and 1779.66 mg ursolic acid/100 g DW for green-rind and red-rind sugarcane, respectively). However, the highest TPC, TFC and TSC were found in the rind. Green-rind sugarcane cultivars contained higher TSC than the red-rind sugarcane cultivars in most parts, while opposite trend were found in TPC and TFC. Stigmasterol and β-sitosterol were found as two main phytosterols. Furthermore, TPC and TFC revealed good correlations with DPPH and FRAP. As cultivars and parts could affect phytochemical content, present result may provide a theoretical basis for further exploitation of the health beneficial resources of sugarcane.

The effect of exogenous nitric oxide (NO) on chilling injury to banana fruit was investigated. Banana fruit was treated with NO donor sodium nitroprusside of 0.05 mM at 20 °C for 10 min and then stored at 7 °C for up to 20 days. Banana fruit treated with NO sustained a lower chilling injury index and higher firmness and kept lower electrolyte leakage and malondialdehyde content than the control. Further investigation showed that NO treatment enhanced activities of guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase compared to the control. It also maintained higher ascorbic acid, reduced glutathione content, and total antioxidant capacity but reduced hydrogen peroxide and superoxide anion to lower levels compared to control fruit during storage. NO treatment significantly enhanced the accumulation of total phenolics and proline, which resulted from the increased activities of phenylalanine ammonia-lyase and Δ1-pyrroline-5-carboxylate synthetase and decreased proline dehydrogenase activity. We proposed that the enhanced chilling tolerance induced by NO treatment may result from the reduction of oxidative stress and proline accumulation.

The effects of salicylic acid (SA) treatment on chilling injury, disease incidence, electrolyte leakage (EL), flesh browning index, malondialdehyde (MDA) and total phenolic content, phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activities, and polyamine (PA) content of bamboo shoot, during storage at 1 °C for 50 days, were examined. Chilling injury and disease incidence, EL, MDA content of control shoot increased progressively. Chilling injury promoted PAL, PPO and POD activities, which are associated with shoot total phenolic content and flesh browning index increase. Chilling injury was significantly positively correlated with putrescine (Put) or spermidine (Spd) contents. Suppression of chilling injury by SA treatment was associated with reducing EL, MDA and total phenolic content, retarding activities of PAL, PPO and POD, and promoting PA accumulation. The present findings suggest that SA treatment could be used commercially to control chilling injury in bamboo shoot during cold storage.Highlights► Bamboo shoots are chilling sensitive at low temperature. ► Phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activities increased during cold storage. ► Chilling injury was suppressed by salicylic acid (SA) treatment. ► PAL, PPO and POD activities were retarded by SA treatment. ► SA treatment reduced browning index and total phenolic content, and promoted polyamine accumulation.

In order to evaluate the effects of heat treatment on the quality of postharvest bamboo shoots, the firmness, disease incidence, respiration and ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities, lignin and cellulose contents, and the activities of phenylalanine ammonia-lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD) were examined during storage at 20 °C after heat treatment at 45 °C for 5 h. Heat treatment inhibited disease incidence and respiration, retarded ethylene production, and decreased ACS and ACO activities in bamboo shoots. Furthermore, heat treatment significantly delayed the rise in the activities of PAL, CAD and POD, which were associated with the inhibition of the synthesis of lignin and the delayed tissue lignification. These findings suggest that heat treatment could be a potential tool to delay lignification and decrease disease incidence in bamboo shoots during storage at 20 °C.Highlights► Heat treatment decreased ACS and ACO activities in bamboo shoots and delayed the rise in PAL, CAD and POD activities. ► Heat treatment slowed the synthesis of lignin and cellulose in bamboo shoots. ► Heat treatment delayed tissue lignification in bamboo shoots.

Fresh bamboo (Phyllostachys praecox f. prevernalis.) shoots were harvested, and the changes of firmness, electrical conductivity (EC), respiration rate, ethylene production, total sugars (TS), reducing sugars (RS), lignin and cellulose content and the activity of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase POD were investigated during storage at 2 or 20°C for 30 or 12 days, respectively. EC increased quickly, with a more rapid rate at higher temperature, but it increased sharply after 24 days at 2°C. Respiration rate increased slowly at 20°C, while at low temperature (2°C) respiration rate and ethylene production significantly decreased. There was a quickly decrease in TS content at 20°C. Shoot firmness, lignin and cellulose increased and accelerated by higher storage temperature during storage at 2 or 20°C. Shoots firmness showed a positive correlation with accumulation of lignin and cellulose in the flesh. Among the enzymes associated with lignin synthesis, PAL and CAD activity showed a persistent rise over the whole 12 days, while POD activity increased rapidly within 6 days during storage at 20°C, followed by a slowly decrease. Accumulation of lignin in flesh tissue was also positively correlated to activity of PAL, CAD and POD. Our results suggest that the increase in firmness of bamboo shoots during storage is a consequence of tissue lignification, a process associated with increases in PAL, CAD and POD activity.

The effects of 1-methylcyclopropene (1-MCP) and ethylene on quality and lignification of postharvest bamboo shoot (Phyllostachys praecox f. prevernalis.) were examined during storage at 20 °C. Disease incidence and respiration rate of control bamboo shoot increased, while total sugar (TS) content decreased quickly. Reducing sugar (RS) content and ethylene production increased at first and then decreased quickly. Increased shoot firmness after harvest was positively correlated with higher lignin and cellulose contents. Accumulation of lignin in flesh tissue was also positively correlated with activities of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD). Ethylene treatment enhanced firmness, respiration rate and ethylene production increase, promoted TS decrease, but retarded disease incidence. 1-MCP treatment resulted in lower firmness, higher disease incidence and TS content, inhibited respiration rate and ethylene production, delayed the activities of PAL, CAD and POD, and retarded lignin and cellulose accumulation. The present findings show that ethylene is involved in bamboo shoot lignification, and suggest that 1-MCP could be used commercially to control this important postharvest physiological disorder in bamboo shoot.

•UV-C radiation maintained quality of minimally processed lily bulb effectively.•UV-C radiation decreased browning by suppressing PPO and POD activities.•UV-C radiation increased PAL activity, phenolic content and antioxidant activity.•UV-C radiation inhibited starch degradation.The effects of 4.5 kJ m−2 UV-C radiation on the quality of minimally processed lily bulb, such as browning, growth of microorganism, total phenolic content, starch, total soluble sugar, reducing sugar content, the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), α-amylase, β-amylase, starch phosphorylase and the antioxidant activity were studied. Results showed that UV-C treatment inhibited browning index and microbial growth by approximately 37% and 32% respectively. Compared with the control, PPO and POD activities of UV-C treated minimally processed lily bulb were reduced by about 26% and 18% respectively, while total phenolic content was increased by 13%. UV-C treatment down-regulated the activities of α-amylase, β-amylase and starch phosphorylase, which resulted in higher content of starch, total soluble sugar content and lower content of reducing sugar. The antioxidant activity and PAL activity were higher than the control during storage. These results indicated UV-C treatment could effectively maintain quality of minimally processed lily bulb stored at 4 ± 1 °C. Therefore, UV-C radiation might be an effective and safe alternative technology for minimally processed lily bulb.Download high-res image (100KB)Download full-size image

•The yellowing of broccoli florets was inhibited by 0.8 mM H2S.•H2S treatment increased the endogenous H2S by activating synthesis-related enzymes.•H2S treatment maintained high level of ATP and energy charge.•The enzymes involved in energy metabolic pathways were activated by H2S.The effects of H2S on yellowing and energy metabolism of broccoli florets treated with hydrogen sulfide (H2S) or DL-propargylglycine (PAG) were investigated after four days of storage at 20 °C. Our study showed that H2S treatment enhanced endogenous H2S content by 28.19% and 49.78% in comparison to the control and PAG-treated group respectively. This result might be related to the increase of l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) activities. Meanwhile, H2S treatment can maintain chlorophyll content at 0.329 g kg−1, whereas the control at 0.298 g kg−1 and PAG-treated group at 0.275 g kg−1. This led to an alleviation of the yellowing in broccoli florets. In addition, high endogenous H2S content also activated the key enzymes, involved in energy metabolism, including ATPases, cytochrome C oxidase (CCO), succinate dehydrogenase (SDH), glucokinase, fructokinase, glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). As a result, significantly higher energy charge was observed in H2S-treated group (p < 0.05). These results suggest that H2S can effectively inhibit the yellowing and maintain high energy charge, therefore prolong the shelf life of postharvest broccoli.Download high-res image (154KB)Download full-size image

‘Qingnai’ plum fruit were treated with 0, 250, 500 or 1000 nL L−1 of 1-methylcyclopropene (1-MCP) for 6 h and stored at 20 °C. The fruit firmness, peel color, chlorophyll content, titratable acidity (TA), respiration rate and ethylene production, chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities were monitored during postharvest ripening of ‘Qingnai’ plums. ‘Qingnai’ plums without 1-MCP treatment soften very rapidly at room temperature after harvest, showing a continuing decrease in hue angle, chlorophyll content, TA and increase in chlorophyllase, PME and PG activities during postharvest storage. In contrast, the 1-MCP-treated fruits showed reduced ethylene production and respiration rate and delayed softening, which was associated with the reduction in the activity of PME and PG. The 1-MCP treatment also significantly inhibited the chlorophyllase activity and peel color development in ‘Qingnai’ plums during postharvest ripening at 20 °C. These results suggest that 1-MCP treatment may be useful for maintaining the fruit quality and extending the postharvest shelf-life of ‘Qingnai’ plums.

•ABA accelerated strawberry fruit ripening while UV-C radiation inhibited it.•ABA enhanced activities of anthocyanin biosynthetic enzymes.•Effects of UV-C on anthocyanin biosynthetic enzymes activities were transient.•UV-C radiation combined with ABA resulted in specific responses.Effects of 1 mM abscisic acid (ABA) and 4.1 kJ/m2 UV-C radiation on quality, antioxidant capacity, anthocyanin contents, and anthocyanin biosynthetic enzyme activities of large green strawberry fruit stored at 20 °C were evaluated. Results showed that ABA promoted color formation, firmness decrease, soluble solids content and anthocyanin accumulation while UV-C inhibited these processes. Activities of phenylalanine ammonia-lyase, tyrosine ammonia-lyase and p-coumarate ligase were immediately upregulated by approximately 50% with UV-C radiation but were inhibited, including dihydroflavonol 4-reductase especially on day 3 or 4. UV-C radiation had little effect on activity of cinnamate 4-hydroxylase (C4H). ABA enhanced activities of anthocyanin biosynthetic enzymes except C4H. These data indicated that the stimulatory effect of ABA on strawberry anthocyanin accumulation was related to enhancement of biosynthetic enzyme activities, while the effects of UV-C were more transient. In addition, it appeared that C4H was not a rate-limiting enzyme in the strawberry anthocyanin biosynthesis pathway.

•4.1 kJ/m2 UV-C delayed tomato fruits ripening induced by wound.•UV-C delayed and lowered climacteric peaks of ethylene production in wounded fruit.•UV-C retarded PME and PG activities and inhibited protopectin degradation in wounded fruit.•UV-C delayed lycopene accumulation and chlorophyll degradation in wounded fruit.Tomato fruits were dropped from 1.5 m to simulate wound, treated with 4.1 kJ/m2 ultraviolet-C (UV-C) radiation, stored at 20 °C for 12 d. During storage, firmness, color, ethylene production, respiration rate, lycopene, chlorophyll, protopectin, water soluble pectin (WSP), pectin methyl esterase (PME) and polygalacturonase (PG) activities of the tomato fruits were analyzed. UV-C delayed the decrease of firmness and hue angle in wounded tomato fruits. Lycopene accumulation and chlorophyll degradation were retarded by UV-C. Wound advanced the climacteric ethylene production and respiration rate peaks, while a delay up to 4 d in UV-C treated fruits was found. UV-C significantly postponed protopectin degradation and WSP accumulation, which were associated with the delay of PME and PG activities and contributed to the firmness maintenance. These results indicated that UV-C could maintain quality and delay wounded tomato fruits ripening.Download high-res image (140KB)Download full-size image