Fruit Quality Deterioration Research Articles

Exploring cold quarantine to mango fruit against fruit fly using artificial ripening

Mango quarantine is based mainly on heat treatment, with a possible deterioration of fruit quality. We studied the effects of cold quarantine (19 days storage at 2 °C) on fruit quality of commercial mango cvs. Keitt and Shelly for three consecutive years. Chilling injury (CI) occurs in mango fruit stored at temperatures lower than 12 °C. By reanalysing our previous transcriptome, we found that under sub-optimal temperature storage (5 °C), the fruit increases its ethylene biosynthesis and osmolarity by activating sugar metabolism, thereby probably reducing its freezing point. Similarly, ripe fruit with higher sugar concentration should be more resistant to cold-storage stress. Here, mango fruit was artificially ripened with 150 ppm ethylene. The control group, stored at 2 °C, suffered from severe CI, whereas the combined treatment of artificial ripening, modified atmosphere (fruit were enclosed in perforated bags) and subsequent low-temperature conditioning resulted in a significant reduction in CI to satisfactory levels for consumer acceptance (taste, aroma and texture). The combined treatment reduced lipid peroxidation and maintained flavour, leading to a novel cold-quarantine treatment for mango fruit. Thus, by reversing the supply chain and storing ripe and ready-to-eat fruit, cold quarantine was enabled for mango, and possibly other chilling-susceptible fruits.

SIMULATION OF MASS TRANSFER FROM PEACHES DURING COOL STORE AND ITS EFFECT ON SOME QUALITY PROPERTIES

Peach is a popular product worldwide with its great coloration, high sweetness, alluring flavor and healthy benefit. Increasing of weight loss of fruit product is often observed in different points of a cold room leading to deterioration of fruit quality and safety. The aim of this study was simulation of moisture loss (mass transfer) from Swelling peaches during cold storage (1oC and RH 95±5%) and determines its impact of quality properties (firmness and color). The result showed that, Good agreement between the simulated and experimental results was found for weight loss in cool room. The temperature difference between peaches tested and the cooling air after 24 h was in the range of 1.57 °C and half cooling time ranged from 1.25- 1.55 hour. The higher increasing of weight losses was 7.55 % lead to decreasing of L value by 10.34 % of flesh peaches while a value increased by 91.93% and b value decreased by 11.65 of flesh peaches. the higher increasing of BI was 340.34 and 338.47 occurred after 25 days of cold storage and 7.55% of weight losses of flesh and skin color respectively. The total color change (ΔE) during storage period for peaches was in the range from 1.9 to 9.94 and from 3.52 to 14.21 occurred after 25 days of cold storage and 7.55% of weight losses during cold storage for flesh and skin color respectively. The firmness decline rate was 15 % after 5 days from cold storage period at 1.64 % weight loss, which is less than the firmness decline rate of peaches 52.15 % after 25 day from cold storage and 7.55% of water loss.

Effects of postharvest temperature on apoptosis-related enzyme activity and gene expression in peach fruits (Prunus persica L. cv. Xiahui 8)

Peach fruits are inevitably affected by rapid ripening and senescence after harvest, leading to the relatively quick deterioration of fruit quality. Although previous studies have confirmed that temperature influences fruit ripening and senescence, information regarding apoptosis in stored peach fruits is limited. Moreover, the relationship between apoptosis and ripening and senescence has not been characterized. In this study, peach fruits (Prunus persica L. cv. Xiahui 8) were stored at room temperature (25 °C) or under cold conditions (4 °C) for 8 and 20 days, respectively. The effects of the two temperatures on fruit cell apoptosis as well as the activity of apoptosis-related enzymes and the associated gene expression levels were investigated. Flow cytometry data indicated that the apoptosis of peach fruit cells was delayed more at 4 °C than at room temperature. This observation was supported by an analysis of the activities of apoptosis-related enzymes (i.e., serine protease, lipoxygenase, superoxide dismutase, peroxidase, and catalase). Additionally, serine protease activity, which directly affects apoptosis, exhibited the greatest temperature-induced changes. Moreover, RNA-sequencing and iTRAQ results confirmed that storage temperature affects the expression levels of the genes encoding the abovementioned apoptosis-related enzymes. The observed temperature effects on peach fruit ripening and senescence from the perspective of apoptosis may be relevant for clarifying the molecular mechanism responsible for fruit ripening and senescence and for improving fruit storage techniques.

Measurement and evaluation of the effect of vibration on fruits in transit—Review

Mechanical vibration is a prominent cause of produce damage in many postharvest fruit supply chains. Knowledge on the causes, occurrence, and mechanistic relationship of vibration to produce damage is important for systematic development of remedial actions. This review identifies and discusses the critical factors of vibration, their implications for fruit quality, and possible improvements to addressing the issue of fruit quality deterioration. Frequently reported mechanical damage types caused by vibration on fruits are scuffing, fruit rub, and skin bruising. A wide range of factors can significantly affect the vibration intensity and thus resultant mechanical damage. Critical frequencies of vibration in the range of 0 to 10 Hz, attributed to peak energy levels in the power spectrum, cause substantial damage in fruits. Greater vertical acceleration and transmission of vibration to the higher tiers in a stacked column of packages result in increased mechanical damage. Fruit packages stacked in the rear positions of trucks are also affected more by vibration. Produce transported in leaf spring trucks has a higher risk of damage when compared with air‐ride suspension trucks. Additionally increased road roughness, vehicle speed, and duration of exposure to vibration proliferate fruit damage. The effects of different inner packing methods and different package types on mechanical damage are less frequently investigated. More accurate characterization of mechanical damage caused by vibration and shocks and its reproduction by enhanced simulation methods will contribute to optimizing damage prevention mechanisms and further improving the quality of fruits in transit within the postharvest supply chain.

Effect of combined heat and 1-MCP treatment on the quality and antioxidant level of peach fruit during storage

Peach fruit undergo a fast ripening and senescence after harvest, which results in fruit quality deterioration. In this study, a combined treatment with hot water and 1-MCP (HM) was applied to peach fruit to investigate its effect on the quality and antioxidant level during room temperature (RT) storage and low temperature (LT) storage. HM treatment is effective in slowing fruit softening, increasing total soluble solids (TSS) concentration and delaying fruit senescence during RT storage. However, HM treatment has no positive effect on delaying fruit senescence during LT storage, and even decreases fruit sweetness during the late stage of LT storage. Moreover, HM treatment can induce a short-term oxidative stress on the first day of both storages. However, during the late stage of RT storage, HM treatment reduces electrolyte leakage (EL) and suppresses reactive oxygen species (ROS) accumulation by enhancing the antioxidant ability at enzymatic and transcriptional levels in peach fruit. In contrast, HM treatment causes higher EL and ROS level and induces antioxidant activity only at the enzymatic level during the late stage of LT storage. In conclusion, HM treatment is more effective at improving fruit quality and suppressing oxidative stress for fruit at RT, compared with fruit stored at LT.

Label-free visualization of fruit lignification: Raman molecular imaging of loquat lignified cells

BackgroundFlesh lignification, leading to increased fruit firmness, has been reported in several kinds of fruit. Understanding the mechanisms underlying fruit lignification is important to optimize the postharvest storage strategies and reduce the quality deterioration of postharvest fruit. Especially cellular level investigation of lignin deposition in fruits provides novel insight for deciphering the mechanisms underlying fruit lignification. The primary objective of this study was to establish a procedure of using Raman microspectroscopy technique to depict fruit lignification at the cell level.ResultsLignified cells, a special kind of cells contained high lignin content, were found abundantly scattered in red-fleshed ‘Luoyangqing’ loquat. Whereas these special lignified cells were barely detected in ‘Baisha’ loquat flesh. Dominant Raman bands of lignified cells were found primarily attributed to lignin (1664, 1628, 1603, 1467, and 1272 cm−1), cellulose (1383, 1124 and 1098 cm−1) and pectin (852 and 1740 cm−1). The band intensity correlation analysis indicated the peak at 1335 cm−1 assigned to either lignin or cellulose in previous works was related to lignin for the lignified cells. Multi-peaks Gaussian fitting successfully resolved the overlapped fingerprint peaks of lignin in 1550–1700 cm−1 into three independent peaks, which were assigned to different functional groups of lignin. Furthermore, the spatially resolved Raman images of lignified cells were generated, indicating that lignin and cellulose saturated the whole lignified cells, pectin mainly located in the cell corner, and the parenchyma cells contained little lignin. In addition, both phloroglucinol-HCl staining and autofluorescence analysis confirmed the results of lignin distribution of Raman microscopic analysis.ConclusionsA procedure for the simultaneous visualization of the main components of the flesh cells without labeling by high-resolution Raman microspectroscopy has been established. With Raman microscopic imaging technique, we can add a microscopic level to cell compositions, essential for a detailed molecular understanding of loquat lignification. Such method can be further used to chemically monitor the textural changes during the ripening process or postharvest storage of other fruits and vegetables.

Comparative metabolomics and transcriptomic profiling reveal the mechanism of fruit quality deterioration and the resistance of citrus fruit against Penicillium digitatum

Decay, caused by Penicillium infection, is one of the main problems during postharvest storage in citrus fruit. A deeper understanding of the mechanism of fruit quality deterioration and the fruit's defense responses may lead us to develop rational approaches for disease control. To identify the metabolic and regulatory mechanisms of citrus against Penicillium digitatum, Powell orange (Citrus sinensis) fruit pulps were collected after 40 h and 60 h infected with P. digitatum for RNA-Seq analysis complemented with metabolic profiling of polar metabolites and volatile emissions. Results demonstrated that several primary metabolites and volatile organic compounds (VOCs) were significantly regulated in response to P. digitatum infection. The contents of sugars (e.g. glucose and sucrose), organic acids (e.g. citric acid, malic acid, and oxalic acid), vitamin C and D-limonene were decreased, while others such as ethanol and a-terpineol were in outstanding increases, resulting in fruit quality deterioration. Rhamnose, inositol, serine, threonine and γ-aminobutyric acid (GABA) also accumulated, thereby enhancing the resistance to P. digitatum infection. RNA-Seq data revealed a series of significantly enriched pathways. P. digitatum infection induced G-protein and RLK signal pathways and enhanced the transcription of stress-related genes including peroxidase and NBS-LRR. Furthermore, P. digitatum infection triggered a defense response via both the jasmonic acid and ethylene pathways, and increased the transcript abundance of several transcription factors such as ERFs, WRKYs, and MYB. Phenylpropanoids pathways were also activated at the transcriptomic level. In summary, our results unravel the significantly regulated metabolites and biological pathways, which provide new insights into the mechanism of fruit quality deterioration and the induction of resistance against P. digitatum in Powell fruit.

Effect of generally regarded as safe (Gras) chemical treatments on the quality of litchi during storage

Pericarp browning of litchi is the most important problem which takes place rapidly after harvest and reduces the commercial acceptability and shelf-life of fruit. To study the combine effect of Generally Regarded as Safe (GRAS) chemicals on the litchi fruits, the combinational treatments with sodium hypochlorite (0.2%) + KMS (0.5%), sodium hypochlorite (0.2%) + KMS (0.6%), sodium hypochlorite (0.2%) + sodium chlorite (0.05%), and sodium hypochlorite (0.2%) + sodium chlorite (0.06%) by the immersion method were given to Shahi litchi fruits. The treated fruits were packed in punnets and stored at 2oC and 90–95% relative humidity. In general, all treatments significantly reduced pericarp browning. The most remarkable effect was obtained with sodium hypochlorite (0.2%) in combination with KMS (0.5%) followed by sodium chlorite (0.05%), which was effective in delaying anthocyanin degradation, polyphenol oxidase activity and weight loss as well as retaining higher amounts of total soluble solids, titratable acidity and phenolic content in fruits. The combinational treatment of sodium hypochlorite and KMS (0.5%) was able to extend shelf life up to 25 days and could be used as cost-effective alternative method to reduce pericarp browning and fruit quality deterioration of litchi during low temperature storage.

Effect of Small Paper Bag Coverage at Young Fruit Stage on the Reduction of Fruit Damage Incidence and Quality Deterioration during ‘Hwasan’ Pear Cultivar

Effect of Small Paper Bag Coverage at Young Fruit Stage on the Reduction of Fruit Damage Incidence and Quality Deterioration during ‘Hwasan’ Pear Cultivar

Elucidating the Mechanisms of the Tomato ovate Mutation in Regulating Fruit Quality Using Proteomics Analysis.

The ovate mutation has frequently been used to study changes in fruit shape but not fruit quality. A deterioration in fruit quality associated with the ovate mutation was discovered in this study. To elucidate how ovate influences the quality of fruit, we performed a proteomics analysis of the fruits of the ovate mutant (LA3543) and wild-type ("Ailsa Craig", LA2838A) using tandem mass tag analysis. The results indicated that the ovate mutation significantly influences fruit quality in a number of ways, including by reducing the expression of 1-aminocyclopropane-1-carboxylic acid oxidase 3 (ACO3) in ethylene biosynthesis, improving firmness by reducing the amount of pectinesterase and polygalacturonase, reducing sugar accumulation by downregulating the abundance of mannan endo-1,4-β-mannosidase 4, β-galactosidase, and β-amylase, and reducing the malic acid content by downregulating the accumulation of malic enzymes and malate synthase. These findings could inform future improvements in fruit quality.

EFFECT OF MODIFIED ATMOSPHERE PACKAGING (MAP) AND POSTHARVEST TREATMENTS ON QUALITY OF LITCHI FRUITS DURING STORAGE

In this article, effect of modified atmosphere packaging (MAP) and different postharvest treatments on quality of litchi (Litchi chinensis Sonn.) fruit was investigated. Quality indexes of litchi during cold storage at 4 ± 1 oC were measured in terms of decay, total soluble solids, titratable acidity, color, anthocyanin content and incidence of microbiological infection. These indexes were determined at harvest and 7, 14, 21, 28 and 35 days after storage. The results suggested that after 35 days of storage, the pericarp browning and fruit quality deterioration can be improved compared to the control by dipping fruit is hot water at 47 oC in 7 min., followed by oxalic acid solution (pH = 3 in 6 min.) and finally packed in MAP bag (LDPE, thickness of 30 µm incorporated 3-5 % silica additive) and stored at 4 ± 10C and relative humidity of 90 %.

The Effects of Postharvest Hot Water and Fungicide Treatments on Guignardia citricarpa Growth and the Development of Citrus Black Spot Symptoms on ‘Valencia’ Orange Fruit

Citrus black spot (CBS), caused by Guignardia citricarpa, is a fungal disease that was first described in Australia in the 1890s and has since been discovered in Southwest Florida in 2010. The current study evaluated the effects of hot water treatments on mycelial growth of G. citricarpa in vitro and also evaluated postharvest hot-water dips and fungicide treatments on CBS development on ‘Valencia’ oranges. In vitro exposure to 56 °C for 120 seconds, 59 °C for 60 seconds, or 62 °C for 30 seconds suppressed mycelial growth of all three G. citricarpa isolates by >30%. These treatments did not significantly reduce disease incidence or severity of CBS lesion development on whole ‘Valencia’ oranges from CBS-infected trees when the fruit already had visible CBS symptoms before treatment. On asymptomatic fruit, while the treatments did not significantly reduce the incidence of CBS lesion development, fruit dipped in 56 °C water for 120 seconds significantly reduced disease severity after 2 weeks of storage compared with the control. None of the treatments caused peel scalding or fruit quality deterioration. Postharvest application of azoxystrobin, imazalil, or thiabendazole significantly reduced CBS disease severity on fruit that were asymptomatic at harvest, but did not affect disease incidence. These fungicides were not effective on fruit harvested later in the season (April), possibly because most lesion expression had already occurred before harvest, with little left to develop after harvest. On fruit showing CBS symptoms at harvest, postharvest fungicide treatments did not significantly affect disease incidence or severity after storage. Heating the fungicide solutions did not significantly improve fungicide effectiveness. These results demonstrated that fungicide azoxystrobin, imazalil, or thiabendazole could reduce CBS severity, but not incidence, on orange fruit that are still asymptomatic at harvest.

Sap volatile components in relation to susceptibility of anthracnose and Aspergillus rot of mangoes (Mangifera indica L.)

ABSTRACTSap burn injury and postharvest diseases are major causes of mango fruit quality deterioration, resulting in considerable postharvest losses in many countries. Susceptibility of selected cultivars of mango in Sri Lanka to sap burn injury and the incidence of anthracnose and Aspergillus rot of mango were examined in this study. Volatile components of non-aqueous (oil) phase were investigated using GC-MS, and artificial inoculation studies were carried out to assess disease resistance with Colletotrichum queesnlandicum (KC 820802) and Aspergillus niger (KC 820801). It was observed that the popular ‘Karuthakolumban’ and ‘Willard’ mangoes with high sap flow at harvest and high sap burn incidence were more susceptible to sap burn injury compared with ‘Chembaddan’ and ‘Ambalavi’ mangoes. Cultivar variations in susceptibility to Aspergillus rot of mangoes are reported for the first time in this study, where ‘Willard’ mangoes were more resistant to Aspergillus rot than other cultivars. The sap exudates of ‘Ambalavi’ and ‘Karuthakolumban’ mangoes were observed to contain the preformed antifungal compounds 5-pentadecyl resorcinol and 5-(Heptadeca-8,11- dienyl) benzene1,3-diol, with variety ‘Ambalavi’ showing a high resorcinol level. These cultivars were found to be resistant to anthracnose disease. These results suggest that presence of sap volatiles is cultivar dependent and could be used to identify cultivars resistant to postharvest diseases and sap burn.

Responses of Young 'Fuyu' Persimmon Trees to Summer Fertilization Rate and Leaf-fruit Ratio

Small-sized persimmons produced by high crop load are better accepted in the export markets. However, maintaining high crop load frequently results in weakness of tree vigor, deterioration of fruit quality, and increase of the risks for alternate bearing. This experiment was conducted to determine the combined effects of fertilization rate and leaf-fruit (L/F) ratio on container-grown 3-year-old ‘Fuyu’ persimmon trees. Application of 3.6-g N, 2.1-g P₂O 5 , 2.7-g K₂O, 2.7-g CaO, and 0.6-g MgO was for the control fertilization rate (CF) and that of a 3-fold CF was for the high fertilization rate (HF). Commercial fertilizers were surface-applied to a container on July 6, July 17, and August 10 in three equal aliquots. Single tree for each fertilization rate was assigned for 12 L/F ratios (5, 6.3, 7.7, 9, 10.4, 13, 15.5, 18, 21, 24, 27, and 33) mostly by fruit thinning or rarely by defoliation on July 1. HF did not affect the yield, weight and soluble solids of the fruits but decreased skin color. As L/F ratio increased, yield decreased but average weight, skin color, and soluble solids of fruits increased. With HF, N and K concentrations in leaves, fruits, and shoots increased to some extent but soluble sugars in dormant shoots decreased. Many shoots were cold-injured with low L/F ratio especially at the HF. HF did not increase number of flower buds the next spring either on a shoot or on a tree basis but increased shoot length, compared with the CF. Increasing L/F ratio markedly increased number of flower buds and shoot growth the following year at both fertilization rates. Therefore, an appropriate combination of fertilization rate and L/F ratio should be necessary to maintain stable fruit production and tree vigor at high crop load.

Leaf Potential Productivity at Different Canopy Levels in Densely-planted and Intermediately-thinned Apple Orchards

Most apple orchards in the apple production districts in China were densely planted with vigorous rootstocks during the 1980s. These orchards have suffered micro-environmental deterioration and loss of fruit quality because of the closed canopy. Modification of the densely-planted orchards is a priority in current apple production. Intermediate thinning is a basic technique used to transform densely-planted apple orchards in China. Our goal was to provide theoretical basis for studying the effect of thinning on the efficiency of photosynthetically active radiation (PAR), fruit quality, and yield. We measured leaf area, solar radiation, and leaf air exchange at different tree canopy levels and by fitting relevant photosynthetic models, vertical distribution characteristics of leaf photosynthetic potentials and PAR were analyzed in various levels within canopies in densely-planted and intermediately-thinned orchards. Intermediate thinning significantly improved the radiant environment inside the canopies. PAR distribution within the canopies in the intermediately-thinned orchard was better distributed than in the densely-planted orchards. The invalid space under 30.0% of relative photosynthetically active radiation (PARr) was nearly zero in the intermediately-thinned orchard; but minimum PARr was 17.0% and the space under 0.30 of the relative height of the canopy was invalid for photosynthesis in the densely-planted orchard. The leaf photosynthetic efficiency in the intermediately-thinned orchard was improved. Photosynthetic rates (Pn) at the middle and bottom levels of the canopy, respectively, were increased by 7.80% and 10.20% in the intermediately-thinned orchard. Leaf development, which influences photosynthetic potential, was closely related to the surrounding micro-environment, especially light. Leaf photosynthetic potentials were correlated with leaf nitrogen content (Nl) and specific leaf weight (Ml) at various levels of canopies. Compared with the densely-planted orchard, the photosynthetic capacity parameters, such as maximum carboxylation rate (CEmax) and maximum electron transfer rate (Jmax), significantly increased in the intermediately-thinned orchard. Leaf photosynthetic potentials mainly depended on Nl and Nl was closely related to PARr. Leaf photosynthetic potentials and PARr can be assessed using spatial distribution patterns of relative leaf nitrogen content (Nlr).

Defense Responses of Salicylic Acid in Mango Fruit Against Postharvest Anthracnose, Caused by Colletotrichum gloeosporioides and its Possible Mechanism

AbstractThe effects and mechanisms of salicylic acid (SA) on defense response to Colletotrichum gloeosporioides from mango fruits were investigated by in vitro and in vivo test. In vitro experiment results showed that SA significantly reduced mycelial growth of C. gloeosporioides in a concentration‐dependent manner. SA effectively controlled anthracnose decay on inoculated mango fruit, as well as natural infection. Disease incidence and lesion diameter in SA‐treated fruit were significantly lower than those of the control fruit. SA treatment increased the activities of chitinase, β‐1,3‐glucanase, phenylalanine ammonia‐lyase and polyphenoloxidase, and the content of total phenolic compounds and lignin in mango fruit. Moreover, SA treatment effectively maintained fruit firmness by suppressing conversion of insoluble protopectin into water soluble pectin. And correlation analysis showed there is a higher negative correlation between fruit firmness and disease incidence. These findings suggest that the effect of SA on postharvest diseases was attributed to its direct antimicrobial activity and the elicitation of resistant responses, as well maintaining the firmness in mango fruit. Therefore, SA treatment is a promising measure for controlling postharvest anthracnose rot in mango.Practical ApplicationsInduction of fruit resistance against pathogenic infection with biological or chemical elicitors has been thought to be a promising approach for controlling of postharvest diseases and reducing the use of synthetic fungicides. Anthracnose, caused by Colletotrichum gloeosporioides is the predominant postharvest disease in mango production that causes severe postharvest losses and fruit quality deterioration. SA is a natural plant substance involved in plant defense responses to biotic stresses. The present results from in vitro and in vivo experiment suggested that SA treatment could effectively inhibit mycelial growth of C. gloeosporioides, enhance resistance of mango fruit against the pathogen and reduce anthracnose rot, as well maintain fruit firmness. Hence, SA can be applied in mango storage and preservation.

Salicylic acid influences biochemical characteristics of harvested tomato (Solanum lycopersicon L.) during ripening

Biochemical characteristics of tomato were studied with dip treatment of different concentration of salicylic acid (SA). Green mature fruits of tomato (Solanum lycopersicon L.) cultivars Pusa Rohini and Pusa Gaurav were dipped in solutions of salicylic acid (SA), viz., 0.5, 0.75 and 1.0 mM and control (double distilled water) at 20 °C for 15 min. The content of carotenoid, lycopene, ascorbic acid, total phenolics, total soluble solids, total sugar, titrable acidity, free amino acid and γ-amino butyric acid were recorded at 5, 10, 15 and 22 days after treatments in Pusa Rohini and 5, 12, 17 and 24 days after treatments in Pusa Gaurav. It was observed that the 0.75 mM SA dip treatment delayed the biosynthesis of these biochemicals that led to increase in the keeping quality of fruits with respect to control. Moreover, decline in total soluble solids and total sugar at early stages of ripening with 0.75 mM SA treatment delayed the ripening and deterioration of fruit quality.

Metabolite and transcriptomic analysis reveals metabolic and regulatory features associated with Powell orange pulp deterioration during room temperature and cold storage

Fruit senescence is an inevitable developmental process that involves dynamic alterations in many metabolic and regulatory pathways. In this study, GC–MS and RNA-Seq were employed to characterize the metabolite and transcriptomic profiles during postharvest storage under room temperature (RT) and low temperature (LT) in Powell (Citrus sinensis) fruits. Results showed that RT-storage up-regulated genes involved in primary metabolism including sucrose metabolism, glycolysis, gluconeogenesis, fermentation and GABA shunt pathways, resulting in declines of sucrose and organic acids such as malate, citrate and α-ketoglutaric acid, and accumulations of hexoses and GABA. Furthermore, calcium-sensor proteins were strongly induced including CMLs, CBL-CIPKs and CPKs, indicating the potential roles of calcium signaling during postharvest storage under RT. RT-storage enhanced ABA and ethylene signaling pathways via up-regulation of PYLs, ABI5 and ERFs, which revealed hormone regulatory networks on fruit senescence. In addition, the induced RPLs, NAC and WRKY transcription factors and MAP kinases provided a comprehensive view on the fruit senescence regulation. During LT storage, the levels of metabolites and catabolism related genes were substantially maintained, and auxin signal was modulated by upregulation of TIR1 and downregulation of Aux/IAAs. In summary, RT storage accelerates calcium, ABA and ethylene signals, which could positively regulate fruit senescence and result in induced primary metabolism and fruit quality deterioration. LT storage might accelerate the auxin signal, thus delaying senescence and maintaining fruit quality.

Reducing postharvest pericarp browning and preserving health promoting compounds of litchi fruit by combination treatment of salicylic acid and chitosan

Litchi (Litchi chinensis Sonn.) is one of the important fruit crops of the subtropical region. The fruit is highly perishable in nature and losses its commercial value within 1–2 days after harvest due to pericarp browning and deterioration in fruit quality. In the present study, effect of postharvest treatment with salicylic acid (0.5mM and 1.0mM) and chitosan (2%) on reducing pericarp browning and preserving functional and sensory quality of litchi fruit was investigated. Physiologically mature litchi fruits (cv. Purbi) were treated with salicylic acid (0.5mM and 1.0mM) and chitosan (2%) alone or in combination by dipping method for 5min. Following treatments, fruits were air-dried and stored at 4°C for 6 days. The results showed that among the applied treatments, salicylic acid (1.0mM) in combination with chitosan (2%) was highly effective in reducing pericarp browning, weight loss, decay loss and maintaining higher anthocyanins, phenolics, flavonoids, ascorbic acid and antioxidant capacity than control fruits. This treatment showed 1.4-fold lower pericarp browning, 1.6-fold lower weight loss and 6.7-fold lower decay loss than control. It also maintained 88% higher anthocyanin, 47% higher total phenolics, 29% higher total flavonoids and 35% higher total antioxidant capacity than control fruits. It also delayed increase in total soluble solids content in litchi fruit during storage. There was no significant effect of treatments on titratable acidity during storage but ascorbic acid content was maintained higher in treated fruits. Thus, combination treatment of 1.0mM salicylic acid and 2% chitosan can be used to reduce pericarp browning and preserving quality of litchi fruit during postharvest storage.

Effects of 1-Methylcyclopropene and Chitosan on the Fruit Shelf-Life and Qualities of Two Different Ripening Stages of ‘Cavendish’ Banana

Our previous research with chitosan leads us to conclude that 2.5% chitosan can be promptly used as a fruit coating. However, to be used as a fruit coating for climacteric fruits, the effect of ethylene trapped under chitosan coating on ripening needs to be blocked. 1- methylcyclopropene (1-MCP) is known as an anti-ethylene and it can be applied in combination with chitosan. This research which was conducted during September-October 2013 was aimed at studying the effects of 1-MCP and its combination with 2.5% chitosan in prolonging fruit shelf-life and maintaining fruit qualities of two different ripening stages of ‘Cavendish’ banana. A completely randomized design of two factors was used. The first factor was 1-MCP gassing (control and 1-MCP), and the second one was chitosan (control and 2.5% chitosan). 1-MCP gas was developed by diluting 0.5 g 1-MCP powder into 30 ml of water. The results showed that the fruits of early and late stages responded differently to treatments of chitosan, 1-MCP, and their combination. (1) At early stage, the chitosan-coated fruit showed slow color development and fruit quality deterioration, whereas at late stage, the chitosan-coating accelerated ripening by a quick decrease of fruit firmness, decrease of soluble solid content and increase of acidity. (2) In general, 1-MCP lengthened shelf-life of banana fruits by slowing fruit quality deterioration, and its effect was accentuated when applied in combination with chitosan. (3) The effect of combined application of chitosan and 1-MCP was best if it was applied at fruit yellowing stage (stage V), because at early stage (stage III) the combined application resulted in imperfect fruit color development.