Physicochemical evaluation of Ambul banana treated with composite coatings of plant extracts to minimize the postharvest loss.

Abstract

Ambul banana is one of the most available and highest-selling fruits in Sri Lanka with a massive postharvest loss. In this research, edible coatings were formulated by combining three plant extracts namely, Aloe vera, Neolitsea cassia, and alginate extracted from Sargassum crassifolium, with glycerol as the plasticizer and treated on green commercially matured bananas aiming to minimize physicochemical changes during postharvest storage and extend the shelf life at ambient storage (29-32 ºC and 70-75% RH). Bananas coated with high proportions of alginate and Neolitsea cassia (25% each) showed significantly lower weight loss (25.10±0.63%) after 21 days of storage than the uncoated banana control (39.40±0.93 %) showing good moisture barrier properties of the coating. An interaction effect between optimum coatings and the change of color of the banana with storage time was identified, where the L* of the control banana increased significantly by week four (56.34±14.40). Deterioration of the brightness of the color of treated banana hands was comparatively lower, reporting a least L* value of 42.52±06.08. The a* of banana with storage was positively high in the control (7.76±1.98) since the fruits turned brownish in colour due to overripe, while negative values were reported for the treated bananas due to low chlorophyll degradation. Similarly, the yellowness of the control banana also improved (47.16±6.32) by week four, whereas the b* values for the treated ones increased and yet were significantly lower than the control. With ripening, the control banana showed a considerable decrease in pH than the treated, and changes in titratable acidity (TA) content of the control and coated samples during the storage period too were statistically significant where the control showed the highest TA (0.41±0.02 %). The total soluble solids (TSS) content of both coated and control bananas increased throughout the storage period. The control sample reached a maximum TSS of 22.56±0.04 % after a 21-day storage. Overall, coating formulated with a high proportion of all plant extracts (2:2:2:2) showed the most promising results and extended the postharvest life of Ambul banana in ambient storage for 26 days, in comparison to 14 days of control banana samples.