Cold-stored Fruit Research Articles

N-α-Lauroyl-L-arginine ethyl ester hydrochloride combined with hot water treatment alleviates chilling injury of postharvest cucumber fruit

Postharvest cucumber fruit is prone to chilling injury (CI) under cold stress, leading to severe quality deterioration. In this study, the effects of N-α-Lauroyl-l-arginine ethyl ester hydrochloride (LAE), hot water (HW), and LAE combined with HW treatments on CI in cucumber fruit stored at 4 ± 1 ℃ were investigated. The response surface methodology (RSM) confirmed that the LAE concentration of 1.00 g L−1, HW temperature of 44 ℃, and immersion time of 10 min were the optimal condition for cucumber fruit preservation during cold storage. Further analysis revealed that LAE, HW, and LAE combined with HW treatments, all significantly mitigated chilling injury symptoms in cucumber fruit in comparison with the control, but the application of LAE combined with HW was the most effective method for enhancing cold tolerance in cucumber fruit. Moreover, LAE combined with HW treatment could reduce reactive oxygen species (ROS) accumulation, and enhance superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) activities in cold-stored cucumber fruit. Meanwhile, the activities of arginine decarboxylase (ADC), ornithine decarboxylase (ODC), Δ1-pyrroline-5-carboxylate synthetase (P5CS), ornithine δ-aminotransferase (OAT), and glutamate decarboxylase (GAD) were also increased by LAE combined with HW treatment, while the activities of proline dehydrogenase (PDH) and γ-aminobutyric acid transaminase (GABA-T) were decreased by LAE combined with HW treatment, which contributed to maintaining higher polyamines, proline, and GABA contents. These findings suggested that LAE combined with HW treatment can reduce chilling injury in cucumber fruit via enhancing antioxidant enzymes activities, PA, proline, and GABA contents to maintain ROS homeostasis during cold storage.

Hydrogen sulfide alleviates chilling injury by modulating respiration and energy metabolisms in cold-stored peach fruit

The respiration and energy metabolisms of refrigerated peach fruit and their relationship to chilling injury (CI) treated with hydrogen sulfide (H2S) were investigated. Results showed that H2S treatment reduced the activities of hexokinase (HK), phosphor-glucose isomerase (PGI), phosphofructokinase (PFK) and pyruvate kinase (PK), and the contents of glucose, pyruvate and nicotinamide adenine dinucleotide (hydrogen) (NAD(H)) in the Embden-Meyerhof-Parnas (EMP) and tricarboxylic acid (TCA)-cycle compared to control and hypotaurine (HT, H2S scavenger) treatment, resulting in a lower respiration rate. Meanwhile, H2S treatment increased the activities of NADK, glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) and NADP(H) contents in the pentose phosphate pathway (PPP), while HT showed the opposite results. Moreover, H2S treatment induced the higher activities of adenosine triphosphatases (ATPases), succinic dehydrogenase (SDH) and cytochrome C oxidase (CCO) along with enhanced levels of ATP and energy charge, whereas HT suppressed energy generation, which increased cell membrane permeability and malondialdehyde content. Therefore, results suggested that H2S could maintain the integrity of the membrane structure by inhibiting the respiration and substance consumption in EMP pathway, increasing the proportion of PPP and energy supply to alleviate CI in peaches.

Alginate-Based Zinc Oxide Nanoparticles Coating Extends Storage Life and Maintains Quality Parameters of Mango Fruits “cv. Kiett”

In this study, we describe the synthesis of zinc oxide nanoparticles (ZnO NPs) and evaluate the impact of alginate-based ZnO NPs (Alg–ZnO NPs) on microbiological activity, storage behavior, and physico-chemical properties of ‘Kiett’ mango fruit. The fruits were coated with alginate and Alg–ZnO NPs and then stored at 13 °C; uncoated mango fruits were used as controls. ZnO NPs were synthesized and characterized, confirming the formation of spherically shaped particles with sizes ranging from 12 to 15.1 nm and a zeta potential equal to 31 mV. Alg–ZnO NPs exhibited the same inhibition capacities against the growth of E. coli and S. aureus bacteria. The cold-stored fruits showed an increase in weight loss, respiration rate, total soluble solids (TSS), total sugars, and total carotenoids over the storage period. However, this increase was comparatively less significant in coated fruits than in uncoated ones. Alg–ZnO NP treatment maintained better fruit quality, controlled the decay incidence, and increased the shelf life of the mango fruits. Firmness and titratable acidity (TA) significantly decreased during storage, but this decrease was reduced in coated fruits. We conclude that Alg–ZnO NP treatment could be a promising safe alternative for maintaining fruit quality, extending the storage period, and increasing the shelf life of mango fruits ‘cv. Kiett’.

1-Methylcyclopropene delays degradation of peel greenness but induces internal physiological disorders in cold-stored fruit of interspecific pears

The green-skinned interspecific ‘Greensis’ pear cultivar is a promising pear cultivar due to its crispness, juiciness, and strong resistance to scab disease. Postharvest storability and metabolic activity can be maintained by treating cold-stored pears with 1 μL L−1 of 1-methylcyclopropene (1-MCP) for 16 hr at 22 °C. After 1-MCP treatment, the ‘Greensis’ pears were stored at 0.5 °C for up to 6 months, after which they were transferred at 22 °C for 7 days of shelf life. 1-MCP treatment had no visible effects on physiological responses, such as fruit weight loss, firmness, titratable acidity, and soluble solids content. However, metabolic profile analyses indicated that the 1-MCP-treated fruit had lower levels of amino acids and soluble carbohydrates (except for sucrose) than the control fruit. The incidence of cortex browning and cavities was much higher in 1-MCP-treated fruit than in untreated fruit. Similarly, the chroma values of the peel and cortex tissues were higher in 1-MCP-treated fruit than in untreated fruit. Moreover, the total chlorophyll and chlorophyll a contents were more preserved in 1-MCP-treated fruit than in untreated pears. Overall, 1-MCP treatment increased sucrose, chlorophyll a, and total chlorophyll contents, thus delaying chlorophyll degradation during storage. These results suggested that 1-MCP treatment delayed the skin color degradation of interspecific ‘Greensis’ pears during storage and prevented changes in the profiles of major metabolites. Nevertheless, the incidence and severity of cortex browning and cavities were highly increased in 1-MCP-treated fruit during storage.

Elevated level of chilling tolerance in cucumber fruit was obtained by β-aminobutyric acid via the regulation of antioxidative response and metabolism of energy, proline and unsaturated fatty acid

• BABA treatment enhances the chilling tolerance in cucumber fruit. • BABA application improved the antioxidant capacity of harvested cucumber fruit. • BABA-treated fruit exhibited higher level of energy status. • BABA promoted proline accumulation and maintained higher level of UFA contents. This experimental study was conducted to investigate the effects of β-aminobutyric acid (BABA) on chilling injury in cold-stored cucumber fruit. Results showed that BABA decreased the development of chilling injury in cucumber fruit. BABA-treated fruit exhibited elevated antioxidant ability, indicated by high activities of superoxide dismutase (SOD) and catalase (CAT) and low levels of hydrogen peroxide and superoxide anion. BABA treatment maintained a high level of energy status by promoting the activities and genes expression of H + -ATPase, Ca 2+ -ATPase, succinate dehydrogenase (SDH) and cytochrome C oxidase (CCO). Increased enzymes activities and genes expression of Δ 1 -pyrroline-5-carboxylate synthase (PCS) and ornithine-δ-aminotransferase (OAT) and depressed enzyme activity and gene expression of proline dehydrogenase (PDH) in BABA-treated cucumber collectively promoted the accumulation of proline. Furthermore, BABA treatment delayed the decreasing trend of unsaturated fatty acid content in cucumber. Thus, BABA is effective in enhancing chilling tolerance in cucumber fruit possibly by improving the antioxidant ability and adjusting the metabolism of energy, proline and unsaturated fatty acids.

Banana ERF transcription factor MaERF110 is involved in ethylene-induced chilling tolerance by regulating ROS accumulation

Banana fruit is susceptive to chilling injury (CI), resulting in quality deterioration. Although ethylene treatment alleviates banana CI symptom, the underlying mechanism remains largely unknown. Here, as compared with control banana fruit, ethrel (an ethylene-releasing compound) treatment maintained lower levels of CI index and relative electrolytic leakage, lower contents of malondialdehyde (MDA) and reactive oxygen species (ROS) in cold-stored fruit and inhibited the expressions of ROS-synthesis genes, including MaRbohB, MaRbohE, and MaRbohJ. A potential upstream regulator of MaRbohE was identified by Yeast one-hybrid assay and named as MaERF110. Ethrel repressed MaERF110 expression during cold storage, and MaERF110 protein was localized in the nucleus with transcriptional activation activity. Gel mobility shift assay and dual-luciferase reporter assay displayed that MaERF110 bound to GCC-box in the promoters of MaRbohB, MaRbohE, and MaRbohJ and activated their expressions. Thus, the results expand our understandings of ethylene-improved chilling tolerance in banana fruit during cold storage.

Limiting the production of virulence factors as a mechanism of action for the control of Penicillium expansum by the Antarctic antagonistic yeast Debaryomyces hansenii F9D

Fungal decay, predominantly caused by Penicillium expansum, is the main cause of apple postharvest losses. To overcome this problem, synthetic fungicides are applied to fruit before storage. Public concern about this practice has raised interest in developing alternative biocontrol strategies for postharvest diseases. Debaryomyces hansenii F9D, a psychrotrophic Antarctic yeast, has been previously selected as a promising biocontrol agent due to its ability to reduce blue mold incidence in apples and pears. Previous in vitro studies indicated that the biocontrol mechanism of this yeast does not involve the production of antifungal metabolites or other inhibitory or competitive interactions with the pathogen. In this work, we conducted further studies in order to understand the interaction between Penicillium expansum and D. hansenii F9D within apple wounds. The growth of both microorganisms in apple wounds during cold storage was followed over time by q-PCR and viable cell counts. Scanning electron microscopy observations of co-inoculated and control wounds (inoculated only with the yeast or with the pathogen) were conducted to evaluate if the pathogen conidia could germinate in presence of the yeast and to determine the colonization patterns of P. expansum and the biocontrol yeast. Our results indicate that Debaryomyces hansenii F9D is able to prevent cold stored apples' wounds rot by inhibiting the virulence factors produced by the pathogen without impeding its growth. These findings provide circumstantial evidence for a new biocontrol mechanism associated with the prevention of fungal decay in apples by biocontrol yeasts during cold storage of fruit.

Antifungal activity of chitosan and its combination with the yeast Debaryomyces hansenii F9D for the control of Penicillium expansum in apples and pears stored at low temperatures

Penicillium expansum is an important pathogen of cold-stored fruit, currently controlled by chemical fungicides. In this work chitosan combined with the biocontrol yeast Debaryomyces hansenii F9D was tested as a safer alternative for its control on cold-stored apples and pears. When medium molecular weight chitosan was applied on fruit a reduction of rot incidence of 62% and 53% was achieved in apples and pears. respectively. When chitosan was combined with the yeast, disease reduction was 76% and 90%. The combination of biological control with chitosan appears as a feasible strategy for the control of phytopathogenic fungi.

Melatonin alleviates chilling injury and maintains postharvest quality by enhancing antioxidant capacity and inhibiting cell wall degradation in cold-stored eggplant fruit

Melatonin improves the chilling tolerance and quality of postharvest fruit. In this study, we investigated the effect of melatonin on postharvest quality in cold-stored eggplant fruit for 30 d at 5 °C. Melatonin at 100 μmol L−1 was notably effective in decreasing chilling injury (CI) incidence, CI index, weight loss, and in delaying the decrease of lightness, thereby maintaining better postharvest quality of the fruit. Exogenous melatonin inhibited increases in hydrogen peroxide (H2O2), malondialdehyde (MDA), and relative electro-conductivity in the pericarp and pulp, while maintaining higher levels of superoxide dismutase (SOD), catalase (CAT), total polyamines, anthocyanins, and melatonin, as well as the expressions of SOD, CAT1/2, and other genes involved in polyamine biosynthesis (ADC, ODC), melatonin biosynthesis (TDC1, T5H, SNAT1, ASMT, COMT), anthocyanin biosynthesis (PAL, CHS1, CHI, F3H, F3′H, DFR, ANS, 3GT), and cold regulation (COR1, CBF, ZAT2/6/12), thereby conferring the higher chilling tolerance. Melatonin delayed fruit softening and senescence by inhibiting the activities and gene expressions of cell wall degradation enzymes (PME, PG, Cel) and expressions of senescence-associated genes (IAA17, SAG12, SEN4). Overall, these results indicate that melatonin alleviates chilling injury and maintains postharvest quality by enhancing antioxidant capacity and inhibiting cell wall degradation in cold-stored eggplant fruit, which provides a theoretical foundation for extending fruit shelf-life of eggplant during cold storage.

On-Tree Fruit Bagging and Cold Storage Maintain the Postharvest Quality of Mango Fruit

The present study investigates the influence of on-tree fruit bagging on the quality and shelf life of mango (Mangifera indica L. cv. ‘Samar Bahisht Chaunsa’) during cold storage (12 °C ± 1; 85–90% RH) for 0, 10 and 20 days (d) and subsequent shelf storage under ambient conditions (25 °C ± 1; 60–65% RH). Fruits were covered with brown paper bags at the marble stage and then harvested at commercial maturity. Results showed that 0 d and 10 d cold-stored fruits, irrespective of bagging treatments, retained eatable quality and shelf-life up to 7 d and 5 d during ambient storage, respectively. However, bagged fruits had better postharvest performance compared with non-bagged fruits by exhibiting slower weight loss, higher fruit firmness, more total soluble solids, vitamin C and total phenolic content and higher activities of catalase and superoxide dismutase during cold storage and ambient shelf storage. On the other hand, 20 d cold-stored fruits, both bagged and non-bagged, were decayed when kept under ambient conditions. It is proposed that mango fruit bagging could be a potential cultural practice to preserve postharvest quality up to 10 d of cold storage, followed by 5 d under ambient conditions.

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.

Hormone profiling and heat-induced tolerance to cold stress in citrus fruit

The involvement of jasmonic acid (JA), different JA-related metabolites, salicylic acid (SA), indole-3-acetic acid (IAA) and abscisic acid (ABA) in the heat-induced cross-adaptation to chilling has been investigated in citrus fruit. The effects of heating ‘Fortune’ mandarins at 37 ºC, and storing them at a chilling temperature (2 ºC) after being exposed, or not, to a heat-conditioning treatment (3 d at 37 ºC) on the levels of these signalling molecules were examined. Jasmonate metabolism activation at 37 ºC was followed by that of SA, and then by a rise in IAA and a drop in ABA. Storage at 2 ºC transiently increased the contents of IAA, of the JA precursor, cis-(+)− 12-oxo-phytodienoic acid (OPDA), and of the JA-derivatives jasmonoyl-isoleucine (JAIle) and methyl jasmonate (MeJA), and decreased ABA in the non-conditioned fruit. The results also indicated that fruit were protected from developing chilling symptoms by virtue of the heat-conditioning treatment having higher JAIle levels than the non-conditioned fruit for very long cold storage periods, while the heat-induced rises in SA, OPDA and MeJA noted in the cold-stored fruit were transient.

Precooling and Cold Storage Methods for Fruits and Vegetables in Sub-Saharan Africa—A Review

Fruits and vegetables, known for their large nutrient potential, are more susceptible to high postharvest loss than other crops. Factors such as perishability, poor post-production handling and storage and processing infrastructures, increase the magnitude of food losses. The postharvest loss of fruits and vegetables in Sub-Saharan Africa ranges from 30% to 50%. One key strategy to overcome such losses is through cold chain integration in value chains. However, most developing countries currently lack the basic infrastructure and management skills needed to support the development of integrated cold chains, particularly in rural areas, where up to 60% of overall food losses occur on the farm and in ‘first-mile’ distribution. Storage of highly perishable produce in a controlled environment with respect to temperature and relative humidity leads to quality and quantity preservation. This contributes to increases in food and nutrition security, household incomes and environmental protection. This review addresses the need for adopting and strengthening measures for the precooling and cold storage of fruits and vegetables to improve their value chains. A range of precooling and cold storage methods, their suitability, energy demands and the constraints on storage and distribution are discussed and recommendations are made on how to improve their accessibility for small-scale farmers in rural communities.

Lipid peroxidation and lipid-soluble antioxidants as quality control markers in cold-stored fruit for establishing commercial acceptability in Bacon avocados

Avocados are prone to chilling injury disorders when stored at low temperatures. Although most studies have been performed in the worldwide distributed ‘Hass’ variety, other less exploited commercial varieties such as ‘Bacon’ might be more cold-tolerant. Aiming at evaluating how cold storage influences chilling injury, the extent of lipid peroxidation and the contents of lipophilic antioxidants were measured in ‘Bacon’ avocados. Harvested fruit were divided into two groups: one stored for 6 weeks at 4 °C and sampled at various time intervals for 42 days, and the other maintained at low temperatures for 3 and 6 weeks and then exposed to room temperature for 5 days until ripened. Long-term cold storage negatively influenced tocochromanols and carotenoids composition in unripen fruit, decreasing progressively both vitamin E and plastochromanol-8 contents, and most particularly carotenoids; yet chilling injury was prevented during cold storage for 6 weeks. When these fruits were ripened at room temperature, chilling injury increased 20% in the peel but only 5% in the mesocarp (edible part). Enhanced chilling injury in the mesocarp was associated with a 2.3-fold increase in lipid hydroperoxides (a primary lipid peroxidation product) and a 2.5-fold increase in plastochromanol-8 content, while contents of other tocochromanols, carotenoids and malondialdehyde (a secondary product of lipid peroxidation) kept unaltered. Interestingly, medium-term cold storage (3 weeks at 4 °C) did not lead to chilling injury in ripe fruit, therefore cold storage for 3 weeks is considered optimal to prevent large antioxidant vitamin degradation and maintain fruit quality in ripen avocados. In conclusion, despite the high cold tolerance shown by ‘Bacon’ avocados, fruit showed a strong depletion (60%) in carotenoids content after 6 weeks of storage at 4 °C, negatively affecting their commercial acceptability. Aside from evaluating visual chilling injury symptoms, evaluation of lipid peroxidation markers and contents of lipid-soluble antioxidants are deemed to be essential to establish commercial acceptability in cold-stored fruit.

Cross-Cultural Differences between Italian and UK Consumer Preferences for 'Big Top' Nectarines in Relation to Cold Storage.

Nectarines are perishable fruits grown in Southern Europe, valued for their sensorial properties. Chilling is used in the supply chain for Northern European consumers, while Southern European consumers can access fresh, locally grown fruit or cold-stored supermarket fruit. Cold storage and fruit ripening affect texture and flavour. Here a consumer survey and hedonic testing compared the appreciation of nectarines (cv. Big Top) in Italy and at two UK sites (n = 359). Fruit was at the commercial harvest stage, or stored at 1 °C or 5 °C for seven days, then sampled after two days’ (Italy and one UK site) or four days’ (second UK site) ambient recovery. In the consumer survey, the most important factors involved in purchase decision were ripeness, texture, colour, taste and price. Named varieties were more important to Italian than UK respondents, whilst ripeness, price, taste, blemishes, aroma, and ‘best before date’ were more important in the UK. In sensory analyses, fruits at the commercial harvest stage were preferred to those stored at 1 °C. Preference for the 5 °C stored peaches depended on recovery time. Distinct clusters of peach sensorial attributes were positively or negatively linked to hedonic rating. Factors important in purchase decisions did not affect hedonic rating in the tasting.

Hydrogen sulfide-induced chilling resistance in peach fruit is performed via sustaining the homeostasis of ROS and RNS

Hydrogen sulfide (H2S) application impacts on endogenous H2S, reactive oxygen species (ROS), and reactive nitrogen species (RNS) in cold-stored peach fruit were investigated. 20 μL L−1 H2S (NaHS as the donor) efficiently retarded the quality deterioration arising from chilling injury (CI), triggering endogenous H2S production, while enhancing antioxidant systems and ROS generation (NADPH oxidative enzyme). H2S promoted nitric oxide (NO) correlated with the S-nitrosoglutathione reductase (GSNOR)-mediated GSNO reduction, while suppressing the peroxynitrite anion content. As the pivotal coenzyme of ROS and RNS, nicotinamide adenine dinucleotide phosphate (NADPH) levels were elevated by H2S during late-stage storage via the tricarboxylic acid cycle, where reduced NADP-isocitrate dehydrogenase (NADP-ICDH) activity and gene expression. Structural analysis of peach NADP-ICDH (UniProtKB M5WXP5) deduced that Cys79 and Tyr396 are the likeliest targets for S-nitrosylation and nitration, respectively. These results indicate that H2S counteracts the disorders of ROS and RNS to ameliorate CI of peach fruit.

From Glaciers to Refrigerators: the Population Genomics and Biocontrol Potential of the Black Yeast Aureobasidium subglaciale.

ABSTRACTApples are affected by numerous fungi known as storage rots, which cause significant losses before and after harvest. Concerns about increasing antimicrobial resistance, bans on various fungicides, and changing consumer preferences are motivating the search for safer means to prevent fruit rot. The use of antagonistic microbes has been shown to be an efficient and environmentally friendly alternative to conventional phytopharmaceuticals. Here, we investigate the potential of Aureobasidium subglaciale for postharvest rot control. We tested the antagonistic activity of 9 strains of A. subglaciale and 7 closely related strains against relevant phytopathogenic fungi under conditions simulating low-temperature storage: Botrytis cinerea, Penicillium expansum, and Colletotrichum acutatum. We also investigated a selection of phenotypic traits of all strains and sequenced their whole genomes. The tested strains significantly reduced postharvest rot of apples at low temperatures caused by B. cinerea, C. acutatum (over 60%), and P. expansum (about 40%). Several phenotypic traits were observed that may contribute to this biocontrol capacity: growth at low temperatures, tolerance to high temperatures and elevated solute concentrations, and strong production of several extracellular enzymes and siderophores. Population genomics revealed that 7 of the 15 strains originally identified as A. subglaciale most likely belong to other, possibly undescribed species of the same genus. In addition, the population structure and linkage disequilibrium of the species suggest that A. subglaciale is strictly clonal and therefore particularly well suited for use in biocontrol. Overall, these data suggest substantial biological control potential for A. subglaciale, which represents another promising biological agent for disease control in fresh fruit.IMPORTANCE After harvest, fruits are often stored at low temperatures to prolong their life. However, despite the low temperatures, much of the fruit is lost to rot caused by a variety of fungi, resulting in major economic losses and food safety risks. An increasingly important environmentally friendly alternative to conventional methods of mitigating the effects of plant diseases is the use of microorganisms that act similarly to probiotics—occupying the available space, producing antimicrobial compounds, and consuming the nutrients needed by the rot-causing species. To find a new microorganism for biological control that is particularly suitable for cold storage of fruit, we tested different isolates of the cold-loving yeast Aureobasidium subglaciale and studied their phenotypic characteristics and genomes. We demonstrated that A. subglaciale can significantly reduce rotting of apples caused by three rot-causing molds at low temperatures and thus has great potential for preventing fruit rot during cold storage.

Review of phase change materials as an environmental approach for postharvest fruit and vegetable cold storage

Today, almost half of the cultivated products are lost before they even reach the consumption stage. Data show that one-third of food never reaches the end consumer. It is known that 50% of these losses are caused by technical errors related to control and temperature management. Reducing post-harvest losses will play an important role in the sustainable feeding of the world's population in the future. From this point of view, preventing or at least minimizing the loss of fresh fruits and vegetables has become an important issue. Cold storage with petroleum fuels and electrical energy is costly and causes environmental pollution. Recently, phase change material (PCM), which is a clean, environmentally friendly and renewable energy source, is an interesting material in this field. PCM s are capable of storing the ambient heat as latent heat energy and returning the latent heat energy they have stored during temperature rises and falls to the environment. With a PCM with the right phase change temperature range, it can provide maximum energy savings and an economical storage system by working as low and high temperature barriers, as well as an environmentally friendly cooling that reduces carbon emissions. This study is a compilation research examining the storage with thermal energy storage, which is a new generation, energy-saving environmentally friendly method, which includes PCMs that can be preferred for cold storage of fruits and vegetables after harvest.

Effect of cold water and cold electrolyzed functional water treatments on the postharvest quality of cold stored jujube fruit ( Ziziphus jujuba Mill. “Hupingzao”)

This study evaluated the effect of cold electrolyzed functional water (CEFW) treatment on the quality of cold-stored Hupingzao jujube fruit. In the study, the fruit firmness, total soluble solids (TSS), titratable acid (TA), TSS/TA ratio, color development, weight loss, respiration rate, vitamin C content, malondialdehyde (MDA) content were evaluated. In addition to this, the polyphenoloxidase (PPO), superoxide dismutase (SOD), and peroxidase (POD) activities were assessed. The results indicated that CEFW treatment inhibited the decline in firmness, weight loss, vitamin C content, and fruit brightness. On the 100th day, CEFW treatment reduced the fruit TSS/TA to 119.74, respiration rate to 32.91 CO2 mg kg−1 h−1, peel color reddening index a*/b* to 0.53, and PPO activity to 3.97 U min−1 g−1. The MDA content of CEFW-treated fruit was 1.31 μmol g−1, which was significantly lower than the control group; the activity of SOD and POD in CEFW-treated fruit was 35.49 U g−1 and 2.31 U min−1 g−1, respectively, which were significantly higher than the control group. In conclusion, cold water and CEFW treatments could delay the senescence of postharvest jujube fruit and maintain the fruit quality during cold storage, and CEFW treatment had better effect. Novelty impact statement The quality of Hupingzao jujube was declined during cold storage. The reddening of the jujube fruit peel was alleviated after cold water and cold electrolyzed functional water treatments, and the fruit quality was maintained. And the cold electrolyzed functional water treatment had better effect.

Amelioration of chilling injury and enhancement of quality maintenance in cold-stored guava fruit by melatonin treatment.

The influence of melatonin treatment on the quality and chilling injury of guavas during storage at 4±1°C were evaluated. Compared with control group, fruit of guava cv. Xiguahong exposed to various concentrations (50, 100, 150, and 200μmol/L) of melatonin showed a significantly lower fruit respiration rate, weight loss, cell membrane permeability, and chilling injury index, but a higher commercially acceptable fruit rate, higher peel L*, h° value, and chlorophyll content. Melatonin treatment also delayed the decreases of fruit firmness, sucrose, total soluble sugar, vitamin C, titratable acidity, and total soluble solids. These data indicate that melatonin treatment could increase chilling tolerance and retain quality of cold-stored guavas. Among various concentrations of melatonin treatment, 100μmol/L melatonin-treated guavas showed the preferable quality properties and lowest chilling injury index. Thus, melatonin may be a novel method of postharvest handling to enhance cold resistance and extend storage-life of cold-stored guava fruit.