Postharvest maintenance of the shelf life and quality attributes of banana and papaya.

Abstract

Banana and papaya are two commonly grown fruits of the tropical regions of the world. Like most tropical climacteric fruits, these fruits have a short shelf life and deteriorate rapidly after harvest. This becomes more pronounced in tropical areas where cold chain management practices are poor and the ability environmental control is limited. To extend the shelf life with maintained quality of the fruits and to investigate the effect of various postharvest treatments a study was conducted on banana cv. Williams and on papaya cv. Hortus Gold. The treatments included storage in different packaging materials such as micro perforated polypropylene bags (MPB), Micro perforated polypropylene bags with ethylene absorbent (MPB+K), macro perforated polypropylene bags coated with anti mist coating (PP), fruit waxing, gibberellic acid (GA3) and indole butyric acid (IBA) applications. Comparison was made against untreated fruits. Banana fruits were held at 12, 15 and 22°C, while papaya fruit were held at 5.5, 7, 10 and 22°C. Percentage weight loss (PWL), firmness change, visual colour development and respiration rate were evaluated on a weekly basis during the storage period. Selected quality attributes such as total soluble solids (TSS), pH, total chlorophyll, total carotenoids and organic acids for banana and TSS, pH, titratable acid (TA) and sugar:acid ratio for papaya were analyzed at the end of the storage period. PWL, softening, colour development and respiration rate increased significantly (P<O.OO1), irrespective of treatments, as the storage period and temperature were increased. Banana fruits stored at 12°C and papaya fruits at 7°C had an extended shelf life of eight weeks. On the other hand, both fruits stored at higher (22°C) exhibited lower storage life and rapid deterioration. Despite the effect of storage temperatures, MBP, MPB+K, PP and waxing significantly (P<O.OO1) reduced PWL at all storage temperatures for both fruits, especially as compared to control fruits. None of the packaging materials resulted in development of any off-flavour and/or fungal decay, although fruits displayed an increased respiration rate at higher storage temperatures. Similarly, waxing, GA3, PP and MPB significantly (P<O.OO1) reduced fruit softening and colour development as compared to control fruits. As a result fruit shelf life was extended. Waxing and GA3 significantly (P<O.OO1) retarded respiration rate for both fruit types as compared to control fruits. Waxing was the most effective treatment in retarding postharvest physiological changes for both fruits at all storage temperatures. IBA treated banana fruits exhibited significantly (P<O.OO1) reduced PWL and fruit softening as compared to control fruits. Quality analysis after storage for TSS, pH, organic acids, total chlorophyll and total carotenoids for banana, and analysis of TSS, pH, TA and sugar:acid ratio for papaya showed no measurable differences (P<O.05) among treatments. This implies all the treatments, which increased fruit shelf life, also preserved fruit internal quality. It is, therefore, concluded that waxing, GA3, PP, MPB+K and/or IBA and MPB can be alternative approaches to extend fruit shelf life and maintain fruit quality within the context of low infrastructure and poor storage facilities.