Effect of Pectin Coatings Containing Trans-cinnamaldehyde on the Postharvest Quality of Rambutan

Abstract

Rambutan (Nephelium lappaceum L.) (Sapinadeae) fruit, a nutritional staple in Hawaii, exhibits desiccation and physiological browning soon after harvest, and methods to prolong shelf life may be commercially advantageous. In this study, freshly harvested fruit were treated with pectin coatings with or without trans-cinnamaldehyde (TCIN) and stored at 10 °C or 20 °C (room temperature) to evaluate postharvest quality attributes. Control fruit were treated with deionized water only. To find the best formulation of the coatings, three concentrations of TCIN were incorporated into a pectin solution to get 0.05% TCIN, 0.1% TCIN, and 0.2% TCIN coatings. At 0, 2, 4, and 6 days postharvest, fruit stored at 20 °C were evaluated for weight loss, firmness, pericarp browning, sugar, acid, and taste. The results showed that the 0.1% TCIN coating exhibited significantly lower weight loss than both control and the 0.2% TCIN coating through the entire storage time at 20 °C. The 0.1% TCIN coating–treated fruit were significantly firmer than control after 4 days of storage at 20 °C. The 0.1% TCIN coating also significantly reduced the pericarp browning over the control. Therefore, we selected 0.1% TCIN coating for fruit storage at 10 °C for up to 15 days. At 10 °C, the control fruit showed significantly higher pericarp browning than all TCIN-containing coated fruit. The 0.1% TCIN-treated fruit showed a significantly higher overall quality value than control fruit. The results indicate that the 0.1% TCIN coating may extend the commercial shelf life of rambutans and other perishable fruits. By extending shelf life, this coating can reduce postharvest losses and facilitate expanded fruit exports in Hawaii.