Effect of Edible Wax on Postharvest Greening of Potato Tubers during Light Exposure

During retail storage, potato tubers are exposed to light that results in tuber greening. Green tubers are toxic and rejected by consumers. In the present study, the effect of Citrashine® natural wax on the postharvest tuber greening of two potato cultivars (‘Mondial’ and ‘Sifra’) was studied. The tubers were irradiated with white light during a 12-day storage period at ambient temperature. During light exposure, tubers were evaluated for colour, pigmentation, chlorophyll fluorescence and starch granule distribution at 3-day intervals. The results showed that wax-treated tubers had significantly (p < 0.05) less green colour as represented by visual and objective colour parameters (a*, b*, C* and h°), compared to those treated with water (control). The pigmentation of the tubers was significantly influenced by the postharvest Citrashine® natural wax treatment. The total chlorophyll content was significantly lower in wax-treated tubers, while the carotenoid content was significantly higher in wax-treated tubers compared to their contents in control samples. Scanning electron microscopy showed that the starch granule size was normally distributed in wax-treated tubers compared to the untreated ones, which was negatively skewed. In conclusion, Citrashine® natural wax showed the potential to be a postharvest technology for controlling greening defects on potato tubers. The results provide a possible effective strategy for controlling the postharvest greening of potato tubers.