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
Highlights
Tomato (Lycopersicon esculentum, Mill) is one of the most widely consumed vegetables in the world
Vacuum infiltration under -30 kPa with 6% CaCl2 gave the longest shelf life, it resulted in oozing out of juice from the stem end scar which led to the growth of fungi at the red-ripe stage of tomato fruits
The technique of vacuum infiltration has been reported to be effective in raising the calcium content in fruits like mango (Tirmazi and Wills, 1981; Shorter and Joyce, 1998), avocado (Tingwa and Young, 1974), tomato (Wills et al, 1977, Wills and Tirmazi, 1979) and pears (Wills et al, 1982)
Summary
Tomato (Lycopersicon esculentum, Mill) is one of the most widely consumed vegetables in the world. Postharvest handling is as critical as production practices due to their delicate nature. Postharvest losses may take place at any stage in the handling system from harvesting through storage and marketing to final delivery to the consumer. Due to its climacteric nature, tomato is highly perishable especially in tropical and subtropical areas. 30-50% of the produce is lost after harvest because of inadequate handling and preservation (Inaba and Crandall, 1986). In the present study the effect of different modes of CaCl2 application at different concentrations was examined for a local tomato variety ‘Thilina’ harvested at commercial maturity. The postharvest quality of fruits treated with CaCl2 was evaluated under normal tropical storage conditions. The likely pathways of calcium were studied using a watersoluble dye
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