2963 Research Article Received: 14 May 2015 Revised: 12 September 2015 Accepted article published: 16 September 2015 Published online in Wiley Online Library: 20 October 2015 (wileyonlinelibrary.com) DOI 10.1002/jsfa.7462 Eﬀect of calcium chloride treatments on calcium content, anthracnose severity and antioxidant activity in papaya fruit during ambient storage Babak Madani, a* Amin Mirshekari b and Elhadi Yahia c Abstract BACKGROUND: There have been no reports on the eﬀects of preharvest calcium application on anthracnose disease severity, antioxidant activity and cellular changes during ambient storage of papaya, and therefore the objective of this study was to investigate these eﬀects. RESULTS: Higher calcium concentrations (1.5 and 2% w/v) increased calcium concentration in the peel and pulp tissues, maintained ﬁrmness, and reduced anthracnose incidence and severity. While leakage of calcium-treated fruit was lower for 1.5 and 2% calcium treatments compared to the control, microscopic results conﬁrmed that pulp cell wall thickness was higher after 6 days in storage, for the 2% calcium treatment compared to the control. Calcium-treated fruit also had higher total antioxidant activity and total phenolic compounds during storage. CONCLUSION: Calcium chloride, especially at higher concentrations, is eﬀective in maintaining papaya fruit quality during ambient storage. © 2015 Society of Chemical Industry Keywords: Carica papaya; postharvest; anthracnose; ambient storage; quality INTRODUCTION Papaya (Carica papaya L.) is a large perennial plant with rapid growth. 1 It is an important fruit in the Malaysian economy, rank- ing third after durian and banana. The Eksotika II cultivar is a high yielding F 1 hybrid with good quality that was released by the Malaysian Agricultural Research and Development Institute (MARDI). This cultivar has gained popularity in the local and export market; 2 however, postharvest pathogens result in signif- icant losses in some years. 3 Anthracnose, caused by Colletotrichum gloeosporioides Penz, is one of the most important pathogens of papaya. With increased interest in non-fungicidal management approaches, researchers are looking for new ways to maintain disease-free fruit in the postharvest milieu. 4 Calcium is a key plant nutrient with signiﬁcant functions, includ- ing reducing fruit softening and senescence. 5 While calcium deﬁ- ciency has been involved in several disorders in some fruit, such as bitter pit in apples, cork spot in pears, and blossom end rot in tomatos, 6 there are few reports related to the eﬀects of calcium on tropical fruit infections by C. gloeosporioides. For example, calcium can increase anthracnose resistance in dragon fruit. 7 A wide range of structural changes including cell wall thickness, enhanced cell membrane permeability and intercellular spaces are important indications of fruit ripening. 8,9 About 60% of the total calcium in plants is related to the cell wall fraction. The cell wall is made of cellulose microﬁbrils placed in a gel-like matrix composed of diﬀerent non-cellulosic glycoproteins and polysaccharides. 10 Calcium, as an intermolecular binding agent, helps stabilise the middle lamella’s pectin–protein complexes and increase cell turgor pressure. 11,12 Calcium can also stabilise cell membrane by bridging carboxylate and phosphate groups of phospholipids and proteins leading to a delay in membrane protein and phospholipid catabolic processes, and to a reduction of ion leakage during fruit storage. 5 The accessibility of minerals during plant growth has a strong inﬂuence on concentrations of phenolic acids and overall antioxidant properties of fruit and vegetables. 13,14 There are a few reports about the role of calcium in anthracnose disease, and they are mostly related to its eﬀect during cold storage. 15 Madani et al. 15 reported that calcium content of papaya fruit signiﬁcantly increased by spraying the fruit with 2.0% calcium. They have also reported that the increase of fruit calcium content by calcium sprays at 1.5 and 2.0% (w/v) signiﬁcantly reduced ∗ Correspondence to: Babak Madani, University Putra Malaysia, Crop Science, Serdang, Selangor, Malaysia. E-mail: babakmadani2010@gmail.com a University Putra Malaysia, Crop Science, Serdang, Selangor, Malaysia b Department of Agronomy and Plant Breeding, Faculty of Agriculture, University of Yasouj, Yasouj, Iran c University of Queretaro, Facultad de Ciencias Naturals, Avenida de las Ciencias s/n Juriquilla, Queretaro, Queretaro, Mexico J Sci Food Agric 2016; 96: 2963–2968 www.soci.org © 2015 Society of Chemical Industry