Effect of postharvest calcium chloride vacuum infiltration on the shelf life and quality of tomato (cv. 'Thilina')

Abstract

Mature turning tomato fruits (cv. ‘Thilina') were treated with four different concentrations of CaCl2 (0%, 2%, 4%, and 6% aqueous solutions) using different modes of application; dipping, vacuum infiltration and pressure infiltration, with a view to improve the shelf life and quality. Fruits vacuum infiltrated at -20 kPa and treated with the four different concentrations of CaCl2 were assessed for pH, total soluble solids (TSS) content, percentage titratable acidity (%TA) and firmness. Total calcium content in the inner and outer pericarp tissues was estimated and the path of calcium infiltration was revealed using black ink. Vacuum infiltration was found to be the most effective treatment with respect to shelf life extension. Also, 6% CaCl2 treatment at -20 kPa was the best in terms of extension of shelf life (by 92%) and in keeping the postharvest quality of tomatoes compared to the untreated fruits kept at 28°C. Fruit firmness significantly increased with CaCl2 application. Delay in fruit colour development, lowering of ethylene production rates and delay in the time taken to reach the ethylene climacteric were observed with increased CaCl2 concentration. Treatment with CaCl2 did not have a considerable effect on fruit pH, TSS or %TA. The amount of total calcium in the inner and outer pericarp regions increased significantly with calcium application. The stem end scar was found to be the main pathway of CaCl2 infiltration in to fruits. Key words: firmness; ethylene; ripening DOI: 10.4038/cjsbs.v39i1.2351 Cey. J. Sci. (Bio. Sci.) 39 (1): 35-44, 2010