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 (Actinidia deliciosa cv. Hayward). Whole fruits were treated with hot water for 5, 10, and 15 minutes at 47 °C, therefore dipped in CaCl2 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 CaCl2 maintained chromatic parameters for kiwifruits compared with control and hot water or CaCl2 treatments solely. In addition, the levels of total phenolic compounds remained significantly higher for hot water combined with CaCl2-treated fruit as compared with control or untreated fruits. According to the results, hot water treatments had a significant firming effect, whereas CaCl2 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.
Shirin Shahkoomahally and Asghar Ramezanian
Sara Atrash, Asghar Ramezanian, Majid Rahemi, Reza Mostofizadeh Ghalamfarsa, and Elhadi Yahia
Penicillium digitatum is one of the most important causes of postharvest decay of Mexican lime fruit. The first stage of this study dealt with examining the effect of savory (Satureja hortensis) essential oil on P. digitatum mycelial growth in vitro. Savory essential oil (SEO) applied at concentrations of 0, 200, 400, 600, 800, 1000, and 1200 μL·L−1 to potato dextrose agar (PDA) medium. The results revealed that the application of SEO at concentrations of 1000 and 1200 μL·L−1 completely prevented the growth of P. digitatum. Gas chromatography–mass spectrometry results indicated that the dominant components of SEO were carvacrol (55.67%) and γ-terpinene (31.98%). In the second phase of the experiment, in vivo assays were conducted to evaluate the efficiency of SEO (800 and 1000 μL·L−1), hot water (40 and 50 °C), and gum arabic coating (2.5% and 5%) in restricting the fungi activity on Mexican lime fruit. The Mexican lime fruit were immersed in the aqueous solutions of SEO and gum arabic or in the hot water for 5 minutes, and then stored at 8 °C for 30 days. Savory essential oil at the concentration of 800 μL·L−1 proved to be the most effective treatment in conserving bioactive compounds of the fruits such as total phenols. This treatment also optimally maintained antioxidant activity and suppressed the activity of polyphenol oxidase (PPO) in the fruit peel. Moreover, hot water at 40 °C caused the least physicochemical changes and the highest appearance quality during storage.