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

Abstract

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.

Keywords: Keitt; anti-ethylene; coating; edible film; fruit; melatonin; storage.

Figure 1

Tragacanth (TRG) film viscosity changes in response to different shear rates.

Figure 2

Images of fruit surface showing (a) uncoated healthy surface and (b) healthy surface coated with 1% TRG.

Figure 3

Effect of postharvest melatonin (MT) and tragacanth (TRG) treatments on the decay percentage (a), general appearance (b), L value (c), and b value (d) of Keitt mango fruits stored at 12 °C for 32 days. Vertical bars reflect the standard error of the means, with different letters indicating significant variance (p ≤ 0.05) across means, as determined by Duncan’s multiple range test.

Figure 4

Effect of postharvest melatonin (MT) and tragacanth (TRG) treatments on the visual appearance of Keitt mango fruits stored at 12 °C for 32 days.

Figure 5

Effect of postharvest melatonin (MT) and tragacanth (TRG) treatments on the weight loss (a), flesh firmness (b), respiration rate (c), and ethylene production (d) of Keitt mango fruits kept at 12 °C for 32 days. Vertical bars reflect the standard error of the means, with different letters indicating significant variance (p ≤ 0.05) across means, as determined by Duncan’s multiple range test.

Figure 6

Effect of postharvest melatonin (MT) and tragacanth (TRG) treatments on the TSS (a) and TSS/TA (b) of Keitt fruit kept at 12 °C for 32 days. Vertical bars reflect the standard error of the means, with different letters indicating significant variance (p ≤ 0.05) across means, as determined by Duncan’s multiple range test.

Figure 7

Effect of postharvest melatonin (MT) and tragacanth (TRG) treatments on the total phenolic content (a), pectin methylesterase (PME) activity (b), polyphenol oxidase (PPO) activity (c), and peroxidase (POD) activity (d) of Keitt mango fruits stored at 12 °C for 32 days. Vertical bars reflect the standard error of the means, with different letters indicating significant variance (p ≤ 0.05) across means, as determined by Duncan’s multiple range test.

Figure 8

Correlation matrix among several quality attributes of Keitt mango fruits stored at 12 °C for 32 days in response to melatonin (MT) and tragacanth gum (TRG) treatments. Asterisks (* or **) denote statistically significant difference at p ≤ 0.05 or 0.01, respectively, in the Pearson correlation analysis, which was performed with three replicates (n = 3).