Assessing the Role of Gaseous Chlorine Dioxide in Modulating the Postharvest Ripening of Keitt Mangoes through the Induction of Ethylene Biosynthesis.

Consumer acceptance of Keitt mangoes (Mangifera indica L.) is significantly affected by their slow postharvest ripening. This work used gaseous chlorine dioxide (ClO2(g)) to prepare the ready-to-eat Keitt mango and explored the potential mechanisms for the mango ripening. Harvested mangoes were treated with 20 mg·L-1 of ClO2(g) or ethephon for 3 h (25 °C) and left in a climatic chamber with a temperature of 25 ± 1 °C and a relative humidity of 85 ± 5% for 4 d. The results showed that ClO2(g) treatment significantly promoted the orange coloration of mango flesh compared to the untreated control group. Moreover, ClO2(g) treatment significantly elevated the total soluble solids, total soluble sugar, and total carotenoids content of mangoes, whereas the firmness and titratable acidity were reduced. ClO2(g)-treated mangoes reached the edible window on day 2, as did mangoes treated with ethephon at the same concentration, except that the sweetness was prominent. The residual ClO2 level of the mangoes was <0.3 mg/kg during the whole storage time, which is a safe level for fruit. In addition, ClO2(g) significantly advanced the onset of ethylene peaks by 0.5 days and increased its production between days 0.5 and 2 compared to the control group. Consistently, the genes involved in ethylene biosynthesis including miACS6, miACO1, and miACO were upregulated. In sum, ClO2(g) can be a potential technique to reduce the time for harvested mango to reach the edible window, and it functions in modulating postharvest ripening by inducing ethylene biosynthesis.

Harnessing the metabolic modulatory and antioxidant power of 1-(3-Phenyl-Propyl) cyclopropane and melatonin in maintaining mango fruit quality and prolongation storage life.

BACKGROUND: The aim of this study was to compare and investigate the effects of 1-(3-phenyl-propyl) cyclopropene (PPCP) and melatonin (MT) as anti-ethylene agents on postharvest senescence, quality, chilling tolerance, and antioxidant metabolism in the mango fruit cv. "Keitt". The study involved exposing the fruit to 20 µL L- 1 PPCP or 200 µM MT, in addition to a control group of untreated fruit, before storing them at 5 ± 1 °C for 28 d. The findings revealed that the treatments with PPCP and MT were effective in reducing chilling injury and preserving fruit quality when compared to the control group. RESULTS: The use of 20 µL L- 1 PPCP was an effective treatment in terms of mitigating chilling injury and preserving fruit quality for 28 d. This was attributed to the decrease in metabolic activity, specifically the respiration rate and the production of ethylene, which led to the maintenance of fruit firmness and bioactive compounds, energy metabolism, and antioxidant activity, such as ascorbic acid, total flavonoids, trolox equivalent antioxidant capacity, dehydroascorbate reductase, glutathione reductase activity, ATP, and ATPase activity. The study also found that the MT treatment at 200 µM was effective in reducing chilling injury and weight loss and improving membrane stability. Additionally, it led to a decrease in malondialdehyde content and electrolyte leakage, and the maintenance of fruit quality in terms of firmness, peel and pulp colour values for mango peel and pulp total carotenoid content, as well as phenylalanine ammonia lyase and tyrosine ammonia lyase activity. These findings indicate that PPCP and MT have the potential to be efficient treatments in maintaining mango quality and minimizing post-harvest losses. CONCLUSION: The utilisation of treatments with 20 µL L- 1 of PPCP or 200 µM MT was found to effectively preserve the postharvest quality parameters, in terms of bioactive compounds, energy metabolism, and antioxidant activity, of mangoes cv. "Keitt" that were stored at 5 ± 1 °C for 28 d.

Synergistic Effects of Tragacanth and Anti-ethylene Treatments on Postharvest Quality Maintenance of Mango (Mangifera indica L.).

Mango (Mangifera indica L.) is one of the most popular tropical fruits grown in Egypt and several other countries, making it a potential export commodity. Excessive deterioration after harvest requires various treatments to maintain fruit quality. We evaluated the treatments effects of melatonin (MT) as an anti-ethylene agent and tragacanth gum (TRG) as an edible coating individually and together (MT-TRG) before storing mangoes at 12 °C for 32 days under 85-90% relative humidity. Compared with control, all treatments were significantly effective in preserving fruit quality. Fruits treated with MT-TRG showed significantly lower decay values, respiration rates, ethylene production, and weight loss than untreated fruits. MT-TRG treatment significantly enhanced fruit quality, thereby maintaining fruit appearance, flesh color, firmness, total soluble solids and phenolic contents, and pectin methyl esterase, polyphenol oxidase, and peroxidase activities during the storage period. We propose 200 µM MT + 1% TRG as a safe postharvest treatment to reduce the deterioration of mangoes and maintain fruit quality.

Characterization of the major aroma-active compounds in Keitt mango juice: Comparison among fresh, pasteurization and high hydrostatic pressure processing juices.

The commercial mango cultivar Keitt lacks a theoretical foundation for aroma control during processing. To discriminate the aroma-active compounds in fresh mango juice, odor activity value (OAV) and detection frequency analysis (DFA) were used collaboratively. A total of 12 components were identified as major aroma-active compounds, among which 2,4-dimethylstyrene was firstly confirmed as an aroma compound in mango. The changes of aromatic compounds during pasteurization and high hydrostatic pressure (HHP) sterilization were further studied. Quantitative descriptive analysis (QDA) was applied to validate the sensory differences. Principal component analysis (PCA) based on aroma compound variation coincided with the overall note. QDA demonstrated that fresh mango juice was the most accepted, followed by HHP and pasteurized juices. The finding might be well correlated with the differences in 6 odor notes. This work would help to better understand and control the critical aroma determinants for mango juice processing.