Respiration Rate Of Fruit Research Articles

Search for Expression Marker Genes That Reflect the Physiological Conditions of Blossom End Enlargement Occurrence in Cucumber.

Blossom end enlargement (BEE) is a postharvest deformation that may be related to the influx of photosynthetic assimilates before harvest. To elucidate the mechanism by which BEE occurs, expression marker genes that indicate the physiological condition of BEE-symptomatic fruit are necessary. First, we discovered that preharvest treatment with a synthetic cytokinin, N-(2-Chloro-4-pyridyl)-N'-phenylurea (CPPU), promoted fruit growth and suppressed BEE occurrence. This suggests that excessive assimilate influx is not a main cause of BEE occurrence. Subsequently, the expression levels of seven sugar-starvation marker genes, CsSEF1, AS, CsFDI1, CsPID, CsFUL1, CsETR1, and CsERF1B, were compared among symptomatic and asymptomatic fruits, combined with and without CPPU treatment. Only CsSEF1 showed a higher expression level in asymptomatic fruits than in symptomatic fruits, regardless of CPPU treatment. This was then tested using fruits stored via the modified-atmosphere packaging technique, which resulted in a lower occurrence of BEE, and the asymptomatic fruits showed a higher CsSEF1 expression level than symptomatic fruits, regardless of the packaging method. CsSEF1 codes a CCCH-type zinc finger protein, and an increase in the expression of CsSEF1 was correlated with a decrease in the fruit respiration rate. Thus, CsSEF1 may be usable as a BEE expression marker gene.

The Effect of Preharvest Spraying with Some Nutrients and Anti-Transpiration on the Storage Characteristics of Apple Fruits (Ibrahimi cultivar)

AbstractThe experiment was carried out in one of the refrigerated warehouses in the city of Baqubah, Al-Hadid District, Diyala Governorate, during the 2021 season to study the effect of spraying the treatments (nutrients, anti-transpiration, and the interaction between them) on the characteristics of stored apple fruits (Ibrahimi cultivar). Spraying with nano-calcium carbonate gave the lowest value of total damage of fruit (3.569%), respiration rate (2.636 mg CO2/kg/hour), and total acidity in the fruits (0.214%), it gave the highest hardness rate in the fruits, (1.007 kg/cm2), sugar content in the fruits (12.06%), ascorbic acid content in the fruits (15.93 mg. 100 ml-1), and calcium content in the fruits (895.9 mg/L), while spraying with nano-iron gave the highest rate in the total soluble solids in fruits (14.56%), as for spraying anti-transpiration, spraying of Kaolinite gave the lowest value of total damage of fruit (4.259%), fruit respiration rate (2.559 mg CO2/kg/hour), and total acidity in the fruits (0.222%), it gave the highest total soluble solids in fruits (14.32 %), content of ascorbic acid in the fruits, (14.51mg. 100 ml-1), whereas potassium silicate recorded the highest rate of fruit hardness (1.005 kg/cm2).

New approaches in pear preservation: Putrescine and modified atmosphere packaging applications to maintain fruit quality during cold storage.

Pear (P. communis L.), which is a climacteric fruit species, has a very short storage and shelf life, and significant losses occur due to high metabolic activity and the fruit's respiration rate after harvest. Therefore, preventing or reducing post-harvest quality losses in pear is one of the most basic problems awaiting solution. In this study, we planned for this purpose; the fruits of the Ankara pear cultivar treated with modified atmosphere packaging (MAP), putrescine (1 mM), and MAP + putrescine were stored for 120 days at 1°C and 90 ± 5% relative humidity. The quality analyses and measurements, such as weight loss, decay rate, fruit firmness, soluble solids content (SSC), titratable acidity (TA), total phenolic compounds, antioxidant capacity, organic acids, and specific phenolic compounds, were performed on the 30th, 60th, 90th, and 120th days. Weight loss and decay ratios were lower for putrescine and putrescine + MAP-applied fruit. With these applications, the softening of the fruit was slowed down, and the increasing SSC in the fruit and the decreasing TA rates were lower, and thus the ripening of the fruit was delayed. Changes in individual phenolic content and organic acids were lower in MAP and putrescine-applied fruit. The study revealed that MAP and putrescine applications in pear can be used effectively to maintain fruit quality after harvest.

Visualization of mitochondrial dynamics in tomato based on green fluorescent protein

This study aimed to visualize the morphological features and dynamic changes of tomato mitochondria to provide a basis for the study of its mitochondrial functions. In this study, transgenic tomatoes expressing mitochondria-localized green fluorescent protein (mitochondria-GFP, Mt-GFP) were obtained by Agrobacterium-mediated genetic transformation. The color, hardness, soluble solids, acidity content, respiration rate, and ethylene production of the transgenic Mt-GFP tomato fruits were determined at the stage of mature green, breaker, and 3, 6, 9 days after breaker, while the wild-type tomato fruits were used as a control. As expected, Mt-GFP recombinant protein did not affect the ripening process, but induced the increased acidity of tomato fruits. The accumulations of Mt-GFP protein in tomato leaves and fruits were successfully verified by Western blotting. The morphological characteristics of mitochondria in flower, leaf and fruit cells as well as the dynamic changes of mitochondria in flower cells were clearly observed and studied under confocal laser microscope. The development of transgenic Mt-GFP tomato plants helps the visualization of tomato mitochondria and provides good research materials for the study of mitochondrial function during tomato development and fruit ripening.

Establishing a maturity prediction model for respiratory fruits via ethylene-regulated physiology: A case investigation of avocado

In addressing the severe waste issue in the Chinese avocado market due to uncontrollable storage temperatures and quality deterioration, this study investigated avocados under three distinct temperature conditions (20, 12, and 4 °C, with 80% ± 5% relative humidity), analyzing fruit respiration rate, ethylene release rate, peel color, flesh hardness, rheological properties, and sensory quality to explore the intrinsic changes during the ripening process. The study revealed significant differences in ripening rates among the different storage temperatures, albeit with relatively consistent physicochemical changes. Among the temperatures investigated, 12 °C was found to be the most suitable condition, effectively delaying fruit ripening, extending the shelf life, and yielding similar sensory quality to that of room temperature ripening. Subsequently, a ripeness prediction model based on respiratory and ethylene data changes was developed using LASSO regression analysis, achieving accuracy rates of 87%, 72%, and 91% at 20, 12, and 4 °C, respectively. This model demonstrates a high degree of fitting and can be used to predict the ripening stage of avocados. The study sets a direction for future data-driven strategies to optimize storage of climacteric fruits, contributing to reducing carbon emissions in the food cold chain and food waste.

Efficient estimation of gas exchange and respiration kinetics in apple using pathlength-resolved GASMAS

Optimization of controlled atmosphere (CA) storage of pome fruit crucially depends on understanding of respiratory gas exchange. Different fruit properties are involved in describing gas transfer and respiration kinetics, which can vary between cultivars, fruit batches and individual fruit. Determination of these properties currently requires a combination of different time-consuming techniques and data analysis procedures. This study introduces a more efficient single method for O2 gas exchange characterization of fruit based on the non-destructive pathlength-resolved GASMAS (gas in scattering media absorption spectroscopy) technique. GASMAS was used to measure the absolute intercellular O2 concentration in fruit of different apple cultivars (Malus x domestica Borkh.) with distinct porosity including 'Jonagold', 'Braeburn', and 'Nicoter'. To resolve the ambiguity between variation in pathlength and O2 concentration inherent to GASMAS, the pathlength travelled through pores cavities was quantified through a second GASMAS measurement at the absorption line of H2O vapour. Dynamic experiments were then performed in which the fruit was subjected to varying external O2 concentrations while measuring the internal O2 response. The observed dynamic profiles of external and internal O2 concentration were fitted with a lumped -respiration model to estimate the effective mass transfer coefficient, maximum respiration rate and Michaelis Menten constant of intact fruit. The model showed a good fit (R2>0.95) with the measured data and reliable estimates for the model parameters. The proposed method provides a novel and more efficient way to estimate the gas exchange properties of fruit that are essential for optimizing CA storage conditions. Future challenges for the proposed method are with applications to other gasses such as CO2 and ethylene.

Changes in the expression of genes encoding xanthophyl acyltransferases during the postharvest ripening of avocado (Persea americana) fruit.

Avocado fruit is rich in xanthophylls, which have been related to positive effects on human health. Xanthophyl acetyltransferases (XATs) are enzymes catalyzing the esterification of carboxylic acids to the hydroxyl group of the xanthophyll molecule. This esterification is thought to increase the lipophilic nature of the xanthophyll and its stability in a lipophilic environment. Studies on XATs in fruits are very scarce, and no studies had been carried out in avocado fruit during postharvest. The objective of this work was to investigate the changes in the expression of genes encoding XAT, during avocado fruit ripening. Avocado fruits were obtained from a local market and stored at 15 °C for 8 days. The fruit respiration rate, ethylene production, and fruit peel's color space parameters (L*, a*, b*) were measured during storage. Fruit mesocarp samples were taken after 1, 3, 5, and 7 days of storage and frozen with liquid nitrogen. Total RNA was extracted from fruit mesocarp, and the quantification of the two genes designated as COGE_ID: 936743791 and COGE_ID: 936800185 encoding XATs was performed with real-time quantitative reverse transcription polymerase chain reaction using actin as a reference gene. The presence of a climacteric peak and large changes in color were recorded during postharvest. The two genes studied showed a large expression after 3 days of fruit storage. We conclude that during the last stages of ripening in avocado fruit there was an active esterification of xanthophylls with carboxylic acids, which suggests the presence of esterified xanthophylls in the fruit mesocarp. © 2024 Society of Chemical Industry.

Effects of Delayed Precooling on the Postharvest Quality and Anthracnose Incidence of “Irwin” Mangoes

Mangoes are typical climacteric tropical fruits with accelerated metabolism, degradation, and senescence after harvest due to the accumulation of field heat. Thus, removing field heat as soon as possible after harvest is essential. In addition, a severe postharvest disease of mango, anthracnose, has been reported to be caused by Colletotrichum gloeosporioides, thus decreasing the shelf life and limiting mango export. This study was performed to investigate the effect of delayed precooling on the quality and incidence of anthracnose during storage of Irwin mango at different operational times after the harvest. Therefore, in this study, Irwin was precooled for 30 min at 3, 6, 12, and 24 h postharvest and immediately stored in a cold room at 5°C. The appearance, anthracnose incidence, respiration rate, ethylene production, firmness, total soluble solids (TSS), titratable acidity (TA), and fruit overripening rate were monitored throughout the shelf life. Early precooling was found to delay anthracnose incidence during the shelf life. Furthermore, the fruit respiration rate during the shelf life was negatively correlated with the precooling delay. The respiration rate of fruits precooled for 3 h after harvest was 8.08 mg CO2 kg–1 h–1 and retained a good appearance throughout the shelf life. Their ripening, reduced firmness, and TA were significantly delayed compared with those of fruits with longer precooling delays, which had a firmness of 19 N, TA of 0.29%, and TSS of 12.6°Brix after 30 d of storage at 5°C, while subsequent warming to 20°C for 3 d, the rate of overripening was significantly lower in fruits with precooling delays of 3 and 6 h than in fruits with a precooling delay of 24 h. Thus, precooling mangoes within 3–6 h of harvest will reduce their respiration rate, delay ripening, decrease anthracnose incidence, preserve quality, and prolong storage life.

Effect of exogenous essential oil treatments on the storage behaviour of apricot fruit harvested at different altitudes

ABSTRACT Due to the short shelf life of fresh apricots, special postharvest preservation techniques and practices are necessary to avoid significant economic losses. The purpose of the current study is to bring to light an approach that can be used to extend the storage life of apricot fruits treated with essential oils (EOs) (peppermint, thyme and carob EO) and examine the effects of two altitudes (1000 m and 1200 m) on the organic acid levels and respiration rate of apricot fruit during long-term storage. The results show that growing apricots at high altitudes increases the level of organic acids in the fruit, improving its quality and extending its postharvest life. Additionally, treating apricots with EOs postharvest slows down the respiration rate, reducing the consumption of organic acids during storage compared to the untreated fruit. The organic acid content was significantly higher in ‘Kabaaşi’ than in ‘Hacihaliloğlu’, and fruit harvested at 1200 m had significantly higher levels of organic acid than the fruit harvested at 1000 m. During storage, the highest organic acid content and the lowest respiration rate were observed in the fruit of both cultivars treated with peppermint, carob, and thyme oil, as compared to control fruit, respectively. To summarize, the use of EOs as postharvest treatment for apricot is recommended for maintaining the quality of the fruit during extended storage.

Effect of Foliar Calcium Fertilization on Fruit Quality, Cell Wall Enzyme Activity and Expression of Key Genes in Chinese Cherry

ABSTRACT Chinese cherries are early flowering and early fruiting, with both edible and ornamental values. This study aims to explore the effects of pre-harvest spraying with different concentrations of CaCl2, amino acid calcium, and sugar alcohol calcium on the quality of Chinese cherry and the expression of genes related to cell wall softening. The goal is to identify suitable calcium-based agents for pre-harvest spraying on Chinese cherry. The results of the study demonstrated that all three exogenous calcium treatments significantly increased the mineral content compared to the control group. Moreover, these treatments also led to a significant increase in various fruit quality parameters such as hundred fruit weight, firmness, soluble solid, soluble sugar, titratable, vitamin C, soluble protein, β-Carotene content and superoxide dismutase, peroxidase activities. Additionally, they were found to effectively reduce rot rate, polyphenol oxidase activity, malondialdehyde content and relative conductivity. The activity of pectin methylesterase, polygalacturonase, cellulase and β-galactose was reduced by amino acid calcium and sugar alcohol calcium. All three types of exogenous calcium down-regulated the expression of PME and ChCaBP1. Additionally, amino acid calcium and sugar alcohol calcium decreased the expression of PG, Cx, and BGal. Exogenous calcium reduces the size of stomata in the fruit epidermis, leading to a decrease in both fruit respiration rate and transpiration. Of the three calcium preparations, amino acid calcium and sugar alcohol calcium were more effective than CaCl2, with 0.12 g·L−1sugar alcohol calcium and 0.06 g·L−1 amino acid calcium being the most effective.

Modelling the respiration rate of dabai fruit (Canarium odontophyllum Miq.) stored in different packaging films

Dabai (Canarium odontophyllum Miq.) is a highly nutritious fruit that has a huge potential to be marketed both locally and globally. However, the lack of promotion leads to an oversupply during peak season, thus reducing its market price. Proper handling and packaging are therefore necessary to maintain the quality and extend the shelf life of dabai. In the present work, nylon film with an oxygen transmission rate (OTR) of 55 cc/m2/day and water vapour transmission rate (WVTR) of 334 g/m2/day; polyethylene terephthalate (PET) film with an OTR of 90 cc/m2/day and WVTR of 35 g/m2/day; and low-density polyethylene (LDPE) film with an OTR of 8000 cc/m2/day and WVTR of 200 g/m2/day were used to pack dabai and stored at 5°C for 14 d. All films had a dimension of 200 × 300 mm, and a thickness of 0.01 μm. It was found that dabai maintained its hue angle (h°) values within the dark purple region (299.73° to 338.64°) and its lightness (L*) values throughout storage. However, the colour intensity (chroma) significantly changed (p < 0.05) between different films throughout storage (p < 0.05). The control sample had the most significant decrease in firmness and weight (p < 0.05) between day 0 and 14, followed by the samples stored in PET, LDPE, and nylon. Whereas the samples in LDPE demonstrated the lowest respiration rate as compared to nylon and PET. The uncompetitive Michaelis-Menten equation model was used to model the respiration rate of dabai. Results showed that all films obtained good fit (R2 of near to 1). Additionally, the mean relative percentage (E%) was less than 10%, thus indicating that the data were suitable for real-time application.

Contactless estimation of apple fruit respiration rate using machine learning models based on laser speckle imaging

This article presents the application of the laser speckle imaging method, a nondestructive and contactless method monitoring the gas exchange rate of intact apples. Red and infrared lasers in a typical setup for laser speckle imaging were used. A new parameter, speckle pattern relaxation time, has been proposed to evaluate speckle dynamics. Machine learning methods were used to develop a set of predictive models calibrated and validated against the respiration rate of two apple fruit cultivars measured with the flush system. The model with the highest performance used three variables: the speckle pattern relaxation time (τRED or τIR), fruit mass, and categorical variables describing apple varieties. This model provided satisfactorily low values of mean absolute prediction errors of 6.04%. Data from laser light scattering measurements combined with modern machine learning algorithms provided a nondestructive and fast method for estimating the apple fruit respiration rate. The developed solution has the potential for a wide range of industrial applications, especially in fruit storage, where the fruit respiration rate indicates optimal storage conditions.

Shelf life of cocktail tomato extended with chitosan, chia mucilage and levan

Tomato is among the most important parts of the human diet globally. However, due to its short shelf life, the produce faces the non-desired huge postharvest losses that can be ascribed to high ethylene emission, high respiration rate, and weight loss. Conventional approaches used to enhance the shelf life of cocktail tomatoes come with certain disadvantages such as chilling injury and investment cost. This study aimed to investigate the effects of bio-based coatings on the shelf life of cocktail tomatoes. The breaker stage tomato fruit were treated with chitosan (CS), chitosan+levan (CS-LVN), chitosan+mucilage (CS-MCLG), and chitosan+ mucilage+levan (CS-MCLG-LVN) edible coatings. Control (CTL) fruit received no treatment. Tomatoes were kept in cold storage (CST) for 30 days (d) at 10 °C temperature and 90–95% relative humidity (RH). At every removal, the fruit was kept for an additional 3 d at 20 °C and 60 ± 5% RH to determine the shelf life (SL) performance. Edible coating treatments minimized the weight loss, ethylene emission, respiration rate, and amount of unmarketable fruit and slowed down the synthesis of lycopene. The minimum weight losses and amount of unmarketable fruit were determined in the CS-MCLG-LVN coating treatment. CS-MCLG-LVN and CS-MCLG-treated fruit had the lowest ethylene emission and respiration rates. CS coating treatment manifested the highest L* value and malic acid content while the maximum total phenolic and total flavonoid contents were in CS-LVN. It can be concluded that CS-LVN, CS-MCLG, and CS-MCLG-LVN edible coatings maintained the postharvest quality of tomatoes for 30 d.

Chilling injury control in pomegranate fruit with compostable stretchable skin film

The use of stretch films as a second skin over fruits is a common technological solution to prevent their deterioration during postharvest storage. However, these films pose an environmental problem, and the management of this waste is a challenge. To address this issue, a new biodegradable polymer composed of a blend of butylene adipate-co-terephthalate and polylactic acid (PBAT-PLA) called Nature Fresh® has been developed to produce stretch films suitable for post-harvest use without environmental concerns. Pomegranate is a fruit that is highly sensitive to Chilling Injury (CI) at temperatures below 5 °C. To evaluate the suitability of Nature Fresh® film for pomegranate packaging, two cultivars with different sensitivity to CI, 'Bigful' and 'Mollar de Elche', were wrapped with the film and stored for 56 days at 2 °C plus 2 days at 20 °C. Control groups included fruits without film and fruits wrapped with stretch film made of linear low-density polyethylene (LLDPE), which is commonly used in post-harvest storage. Pomegranates packed in PBAT-PLA and LLDPE films showed similar evolution in the appearance of internal and external husk CI, respiration rate, ion leakage, total polyphenol, and anthocyanin content, these parameters being lower than in control fruit. However, due to differences in water vapor and gas permeability between the two films, weight loss and firmness reduction were significantly higher in pomegranates wrapped in PBAT-PLA compared to LLDPE, but this did not impact any detrimental effect on overall appearance. Internal CI was significantly (P < 0.001) positively correlated with fruit respiration rate, ion leakage, weight loss, total polyphenol, and anthocyanin content; while it was negatively correlated with fruit firmness, skin and aril color, soluble solids, acidity, and maturity index. In summary, the use of PBAT-PLA film presents a feasible substitution to LLDPE on maintaining the quality of pomegranates during post-harvest storage, while also aligning with worldwide initiatives aimed at decreasing plastic waste.

Respiratory and energy metabolisms participate in the disease occurrence of fresh Chinese olive caused by Pestalotiopsis microspora

Pestalotiopsis microspora (P. microspore) is the primary pathogen causing postharvest rot and spoilage in Chinese olive (Canarium album L.). This study investigated P. microspore-induced disease development in postharvest Chinese olives in relation to respiratory and energy metabolism. Results suggested that P. microspore-inoculated Chinese olives had higher fruit disease index, fruit disease diameter, and fruit respiration rate, but a lower energy charge. Furthermore, P. microspore-inoculated Chinese olives displayed higher respiratory metabolism-related enzymes (RMREs) activities, higher levels of NAD(H), and lower levels of NADP(H). Additionally, P. microspore-inoculated Chinese olives had lower ATPase activities, as well as lower ATP and ADP contents but higher AMP content. These findings suggest that P. microspore infection exacerbates disease development in postharvest Chinese olives by increasing respiration metabolism and causing energy deficiency.

Improving ‘Nanguo’ pear fungal disease and storability by chitosan coating combined with diepoxy-poly (ethylene glycol)

A protective coating can aid in reducing mechanical harm to food during harvesting, handling, and transportation, resulting in fewer bruises, wounds, and other injuries, thereby improving the overall quality of the produce. In this study, coatings with 1% (w/v) chitosan (CS) and 0.6% (w/v) diepoxy-polyethylene glycol (PEG) were prepared by the co-blending method. According to the findings, increasing the PEG concentration enhanced the moisture content, water vapor permeability, and contact angle properties. In addition, when viewed by scanning electron microscopy (SEM), the morphology of the films containing more PEG appeared rougher and denser. In addition, at room temperature, the freshness of ‘Nanguo’ pears and the antifungal efficacy of the coating against Penicillium italicum (P. italicum) and Botrytis cinerea (B. cinerea) were evaluated. According to the findings, the weight loss or total soluble solids of pears coated with CS or PEG did not differ significantly during storage. The fruit respiration rate and ascorbic acid (AA) and malondialdehyde (MDA) contents were maintained after coating CS insertion with PEG. The CS-PEG composite coating successfully inhibits the growth of P. italicum and B. cinerea (P. italicum > B. cinerea), according to an in vitro antifungal activity assay that was improved by adding PEG. According to principal component analysis (PCA) results, the CS-PEG coating significantly impacts pear sensory evaluation and firmness. At room temperature, the shelf life of pears with a CS-PEG coat has been extended from 15 days to 25 days.

Exogenous nitric oxide inhibits the respiratory metabolism of postharvest wax apple fruit and its role in the delayed cottony softening

This study investigated the impacts of nitric oxide (NO) fumigation on the respiratory metabolism of postharvest wax apple fruit and its impact on fruit cottony softening. NO treatment inhibited the respiration rate of wax apple fruit and delayed the development of cottony softening; NO treatment suppressed the activities of hexokinase, phosphohexose isomerase (PGI), pyruvate dehydrogenase, and succinate dehydrogenase (SDH) in fruit pulp, but improved the activities of pyruvate kinase and citrate synthase (CS), and maintained the contents of glucose and pyruvic acid, indicating a reduction in the EMP-TCA pathway. Moreover, the NADH content and the activities of SDH and cytochrome C oxidase (CCO) were decreased with NO treatment, while the NADH/NAD ratio increased, suggesting that the electron transport chain complexes of wax apple fruit were reduced. Besides, NO treatment enhanced the activity of NADK in wax apple fruit, which lowered the levels of NAD and NADH but increased levels of NADP and NADPH, indicating an increase in pentose phosphate pathway. Additionally, CATPCA and heatmap analysis show that the PGI, CS, SDH, and CCO played a crucial role in NO-inhibited respiration. Collectively, these findings indicate that NO treatment suppressed the respiratory metabolism of postharvest wax apple fruit via regulating respiratory pathways, which reduces fruit senescence and delays cottony softening.

Dynamics of ethanol and its metabolites in fruit: The impact of the temperature and fruit species

The objectives of this study were to: i) determine the effect of temperature on the ethanol vaporization rate, ii) determine the effect of temperature on the uptake rate of fruit species and cultivars, iii) understand the relationship between the temperature that ethanol is applied, ethylene metabolism, and respiration rate of fruit, and iv) evaluate the interaction between temperature that fruit are submitted to ethanol treatment on the metabolites produced by them as a response to ethanol treatment. The ethanol vaporization rate was performed in an empty container experiment at 2, 10, and 20 °C. Four experiments were conducted to identify the ethanol uptake rate in ‘Maxi Gala’ and ‘Cripps Pink’ apples, ‘BRS Isis’ table grapes, and ‘Rojo Brillante’ persimmons at 2, 10, and 20 °C. The metabolites produced by the fruit as a response to the ethanol treatment were determined using HS-SPME-GC/MS analysis. Our findings showed that the ethanol vaporization rate increases exponentially with the temperature and has a linear relationship with time. Moreover, the temperature and fruit species/cultivar affected the ethanol uptake rate, with the highest uptake rate at 20 °C. Furthermore, ethanol vapor uptake rate was positively correlated to respiration rate when all fruit species/cultivars were evaluated together, showing that fruit metabolism affects ethanol uptake rate. The temperature impacted the metabolite produced by fruit from ethanol application, evidencing the possibility of managing the volatile compounds produced from ethanol based on the ethanol treatment temperature. The fruit species has a decisive impact if ethanol is esterified or transformed to acetaldehyde, being predominantly esterified in apples and grapes, and converted to acetaldehyde in persimmons. Ethanol vapor treatment reduced the ethylene metabolism in apples at 20 °C, although ethanol increased ethylene in persimmons at 2 °C. Moreover, the respiration rate was generally unaffected or reduced in ethanol-treated fruit compared to untreated fruit of the same species/cultivar.

Impact of Ozonated Water on Brown Rot Development and Storage Potential of Nectarine and Plum

ABSTRACT Postharvest fruit rot is one of the most serious diseases of fleshy stone fruits such as nectarine and plum. The efficacy of ozonated water sprayed in different doses in a packing line [low dose, 1.5 ppm ozone (Ο3) for 100 sec; medium dose, 3.0 ppm Ο3 for 100 sec; high dose, 1.5 ppm Ο3 for 400 sec] in controlling the brown rot (Monilinia fructicola) development was studied in the nectarine cultivar ‘Τasty Free’ and the plum cultivar ‘Angelino.’ Changes in flesh firmness, ripening index, ethylene and respiration rate, and peel color during storage (0℃ for 3 weeks) and shelf-life (20℃ for 4 days) were used as ‘indicator’ quality parameter responses in storage and shelf-life. The most efficient dose of O3 in controlling the Monilinia infection was the highest applied, followed by the middle O3 dose. The efficacy of O3 treatments was higher when a lower Monilinia spore concentration was applied. The O3 doses applied did not cause any visible symptoms of O3 toxicity, yet they caused an acceleration in the fruit ripening process, suggested mainly by an increase in the fruit respiration rate in both nectarine and plum, and an increase in the ripening index and darker peel coloration only in plums. In conclusion, spraying with ozonated water is an eco-friendly and efficient sanitizing agent, but in fleshy commodities such as nectarine and plum may diminish their postharvest performance.

Methyl salicylate pretreatment maintains quality and antioxidant capacity of fresh-cut pitaya fruit by modulating phenylpropanoid metabolism and antioxidant system

The effect of 0.1 mmol L−1 methyl salicylate (MeSA) pretreatment on quality properties of fresh-cut pitaya fruit and their relationships with phenylpropanoid metabolism and antioxidant system were studied. Results revealed that MeSA pretreatment efficiently inhibited flesh browning, respiration rate, ethylene production, electrical conductivity (EC) and malondialdehyde (MDA) content of fresh-cut pitaya fruit compared with the control. Moreover, the contents of total phenolics and flavonoids, antioxidant system, and the major phenolic acids (protocatechuic acid, chlorogenic acid and gallic acid) and flavonoid compounds (phloridin, kaempferol, rutin and epicatechin) were overall higher in MeSA-pretreated group than those in the control. Meanwhile, the gene expressions and activities of key enzymes (phenylalanine ammonia lyase (PAL), 4-coumarate-CoA ligase (4CL), cinnamic acid 4-hydroxylase (C4H)) closely related with phenolic biosynthesis were induced by MeSA, while polyphenoloxidase (PPO) and peroxidase (POD), key enzymes closely related to phenolic oxidation, were suppressed at lower activities in MeSA-pretreated group. In addition, MeSA pretreatment stimulated higher superoxide anion (O2·−) generation rate and hydrogen peroxide (H2O2) content at the beginning of storage but led to lower levels of them afterwards. As for the antioxidant enzymes system and ascorbate-glutathione (AsA-GSH) cycle, superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) activities were all increased, while the losses of AsA and GSH were alleviated due to the application of MeSA. These results demonstrated that MeSA pretreatment maintained quality of fresh-cut pitaya fruit through modulating phenylpropanoid metabolism and antioxidant system.