The kiwifruit was introduced to the world market from New Zealand in 1950s. The export of fresh fruit led to rapid expansion (Barboni et al., 2010). Production is almost exclusively of the cultivar Hayward because of its longer storage life and its larger fruit size (Franco et al., 2006). The increasing market demand for this fruit has challenged postharvest and food technologists to develop procedures to lengthen storage life (Piga et al., 2003).
With attention to the risk of improper use of chemicals in postharvest technology and consumer's demand for healthy products, study on application of postharvest treatments such as heat treatment is necessary (Shafiee et al., 2010). Heat treatments have already been used to control postharvest decay and to improve the storage quality in intact fruits as a result of changes it induces in physiological and physicochemical characteristics and post-processing quality (Beirão-da-Costa et al., 2006). Heat treatments also inhibited ripening, softening, and improved postharvest quality. This was observed in the case of whole fruit with apples (Klein and Lurie, 1990), strawberries (Civello et al., 1997), citrus fruit (Porat et al., 2000), and mangoes (Benitez et al., 2006). The mechanism by which a heat treatment causes changes in fruit ripening such as inhibition of ethylene synthesis and cell wall degrading enzymes may be the result of changes in gene expression and protein synthesis. During a high-temperature treatment, the mRNA of fruit-ripening genes decreases and those of heat shock proteins accumulates (Lurie, 1998).
Ca plays a significant role in maintaining quality in a number of different fruits (Hopkirk et al., 1990). Pre- and postharvest Ca application has been demonstrated to produce beneficial effects on whole fruit quality, decreasing the incidence of physiological disorders (Serrano et al., 2004) and delaying softening (Antunes et al., 2004). Ca is directly involved in strengthening plant cell walls through its ability to crosslink with carboxyl groups of polyuronide chains of pectins found in the middle lamella (Lara et al., 2004). Furthermore, Ca ions help in the stabilization of cell membranes (Picchioni et al., 1995) and affecting cellular turgor pressure (Mignani et al., 1995).
Temperature can have an effect on Ca uptake. A combination of heat treatment followed by Ca dip has also been applied for the primary purpose of controlling postharvest pests and/or diseases and has been found to have satisfactory results in maintaining or improving the texture of several products. In this sense, Ca application, combined or not with heat treatments, maintained firmness in a wide variety of fruit and vegetables including lettuce (Roura et al., 2008).
According to our review, there is no report on postharvest application of Ca and hot water on qualitative parameters of kiwifruit during cold storage. The overall aim of this research was to evaluate the effect of hot water combined with Ca solution treatments to maintain qualitative characteristics of kiwifruit during cold storage.
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Benitez, M., Acedo, A. Jr, Jitareerat, P. & Kanlavanarat, S. 2006 Mango fruit softening response to postharvest heat treatment. IV International Conference on Managing Quality in Chains—The Integrated View on Fruits and Vegetables Quality 712. p. 811–816
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Djioua, T., Charles, F., Lopez-Lauri, F., Filgueiras, H., Coudret, A., Ducamp-Collin, M.N. & Sallanon, H. 2009 Improving the storage of minimally processed mangoes (Mangifera indica L.) by hot water treatments Postharvest Biol. Technol. 52 221 226
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Rico, D., Martin-Diana, A.B., Frias, J.M., Barat, J., Henehan, G. & Barry-Ryan, C. 2007 Improvement in texture using calcium lactate and heat-shock treatments for stored ready-to-eat carrots J. Food Eng. 79 1196 1206
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