Hot Water Combined with Calcium Treatment Improves Physical and Physicochemical Attributes of Kiwifruit (Actinidia deliciosa cv. Hayward) during Storage

Abstract

<jats:p>Kiwifruit has a short storage life and encounters severe disorders during maintenance mainly as a result of its climacteric behavior. The role of calcium and heat treatment in delaying degenerative processes during storage has been revealed. This study investigated the effects of hot water combined with calcium (Ca) dips on the quality of kiwifruit (<jats:italic>Actinidia deliciosa</jats:italic> cv. Hayward). Whole fruits were treated with hot water for 5, 10, and 15 minutes at 47 °C, therefore dipped in CaCl<jats:sub>2</jats:sub> solution (2% w/v) and stored at 0 °C for up to 120 days. During storage, fruit were sampled at 0, 30, 60, 90, and 120 days for postharvest quality evaluation. Postharvest evaluations included chromatic parameters (L*, a*, b*, hue, and chroma), firmness, and physiological parameters [phenolic content and polyphenol oxidase (PPO)]. Heating combined with Ca dips significantly reduced PPO activity. The results showed that mild heat treatments in combination with CaCl<jats:sub>2</jats:sub> maintained chromatic parameters for kiwifruits compared with control and hot water or CaCl<jats:sub>2</jats:sub> treatments solely. In addition, the levels of total phenolic compounds remained significantly higher for hot water combined with CaCl<jats:sub>2</jats:sub>-treated fruit as compared with control or untreated fruits. According to the results, hot water treatments had a significant firming effect, whereas CaCl<jats:sub>2</jats:sub> dips solely had less effect on chromatic parameters. However, the influence of hot water treatments was dependent on application time with (treatment that showed significant results) showing significant improved kiwifruit postharvest qualities. Overall, with this simple and non-contaminant technology, after long-term storage, quality of kiwifruit could be even greater than in recently harvested fruits.</jats:p>

Bioactive compounds and antioxidant activity of papaya inoculated withColletotrichum gloeosporioidesas affected by hot water-calcium chloride

“…On the other hand, Mahmud, Eryani‐Raqeeb, Omar, Zaki, and Abdul‐Rahman () found that the immersion of papayas in calcium chloride affected the skin yellowness and delayed the ripening process. Similar results were obtained for whole and fresh‐cut papaya (Ayón‐Reyna et al, ; Ayón‐Reyna, López‐Valenzuela et al, ; ), kiwifruit (Shahkoomahally & Ramezanian, ), mango (Dessalegn, Ayalew, & Woldetsadik, ), and fresh‐cut apple (Aguayo, Requejo‐Jackman, Stanley, & Woolf, ), where hot water combined with calcium maintained for longer time the initial color of fruit. Comparing with the parameters measured in papaya of the control treatment, HW‐Ca treatment delayed the ripening process, maintained the firmness and color, and decreased the decay rate.…”

“…This mechanism can explain the best effects on this parameter of both HW and HW‐Ca treatments. It has been reported that HW treatment decreases the expression of enzymes involved in cell wall degradation and ethylene synthesis (e.g., polygalacturonase, pectinmetilesterase, and 1‐aminocyclopropane‐1‐carboxylate (ACC) synthase and ACC oxidase), contributing also with firmness retention (Shahkoomahally & Ramezanian, ; Sharma, Singh, & Pal, ). Moreover, heat treatment increases the solubility of calcium in water and the membrane permeability allowing a better diffusion of calcium ions into the fruit and vegetable cells (Aguayo, Escalona, & Artés, ).…”

“…In this sense, some reports have demonstrated that some fruits are negatively affected by heat treatment, as it happened with apple (Li, Li, Wang, Jiang, & Ban, ) and papaya (Chávez‐Sánchez, Carrillo‐López, Vega‐García, & Yahia, ), which show carotenoid isomerization and loss of redness and yellowness. As above discussed, heat treatment decreases the protein synthesis, including the clorophyllase, affecting the metabolism of pigments associated with the fruit color (Shahkoomahally & Ramezanian, ). On the other hand, Mahmud, Eryani‐Raqeeb, Omar, Zaki, and Abdul‐Rahman () found that the immersion of papayas in calcium chloride affected the skin yellowness and delayed the ripening process.…”

“…In addition, other studies have shown that hot water treatment increased the expression of enzymes involved in the biosynthesis of phenolic compounds (Spadoni, Guidarelli, Sanzani, Ippolito, & Mari, ; Yuan et al, ). Shahkoomahally and Ramezanian () reported HW‐Ca treated kiwifruit showed higher total phenolics content and lower polyphenol oxidase activity (PPO), enzyme involved in polyphenol oxidation into quinones. The authors suggested that the maintenance of cellular integrity conferred by calcium diminished the possible contact of the enzyme with its substrate, resulting in higher phenolics content; also, PPO activity decreases at temperatures higher than 40°C.…”

“…In this sense, hot water immersion and calcium treatments have been successfully applied in papaya fruits to decrease the development of diseases and to maintain the postharvest quality (Chávez-Sánchez, Carrillo-López, Vega-García, & Yahia, 2013;Li, Li, Wang, Jiang, & Ban, 2013;Madani, Mirshekari, & Yahia, 2016;Mahmud, Eryani-Raqeeb, Omar, Zaki, & Abdul-Rahman, 2008). Additionally, the combined treatment of hot water and calcium applied on fruits has resulted better than any individual treatment to maintain the postharvest quality and to reduce storage disorders (Shahkoomahally & Ramezanian, 2015;Sharma, Singh, & Pal, 2013). In this regard, our previous results showed that the hot water immersion treatment combined with calcium chloride delays the anthracnose development in papaya inoculated with Colletotrichum gloeosporioides during 20 days of storage at 12°C (Ayón-Reyna, López-Valenzuela et al, 2017;) and induces changes in bioactive compounds of whole and fresh-cut papaya (Ayón-Reyna et al, 2015;;Ayón-Reyna, López-Valenzuela et al, 2017;).…”