Managing Postharvest Storage Issues in ‘Shiranui’ Mandarin

Abstract

‘Shiranui’ is a mandarin (Citrus reticulata var. austera) that is highly treasured for its unique and delicious flavor, and obtains premium prices in the marketplace. Although flavorful, ‘Shiranui’ tends to develop off-flavor during storage. In this study we examined the use of different storage wax (SW) and pack wax (PW) combinations to determine whether flavor in ‘Shiranui’ can be improved after storage by adjusting wax coating protocols. In the initial test, either SW or no wax was applied after harvest, and each was followed by an application of SW or one of two types of PW after 1 day, 3 weeks, or 7 weeks of storage and then held 1 week at either 7 or 20 °C. Results indicate that the initial wax was not an important factor but the use of SW instead of either type of PW as the final coating led to greater internal oxygen levels in the fruit and less off-flavor formation. The lessening of off-flavor by SW was significant only after 20 °C of storage, when off-flavor was greatest. Greater weight loss accompanied the use of SW as the final coating. In a second test, SW with greater solids concentrations (5%, 10%, and 15%) were evaluated to attempt to reduce weight loss, but this led to greater development of off-flavor and loss in acceptability than observed when using SW with 1% solids in test 1. ‘Shiranui’ is prone to developing off-flavor in storage, but this may be mitigated, at least in part, by using SW as the final wax rather than PW.