Prolonging storage time of baby ginger by using a sand-based storage medium and essential oil treatment.

Abstract

Wilt and rot occur readily during storage of baby ginger because of its tender skin and high moisture content (MC). A storage medium, which consisted of sand, 20% water, and 3.75% super absorbent polymers delayed weight loss and loss of firmness at 12 °C and 90% relative humidity. Microorganisms were isolated and purified from decayed rhizomes; among these, 3 fungi were identified as pathogens. The results of 18S rDNA sequence analysis showed that these fungi belonged to Penicillium, Fusarium, and Mortierella genera. The use of essential oil for controlling these pathogens was then investigated in vitro. Essential oils extracted from Cinnamomum zeylanicum (cinnamon) and Thymus vulgaris (thyme) completely inhibited the growth of all of the above pathogens at a concentration of 2000 ppm. Cinnamon oil showed higher antifungal activity in the drug sensitivity test with minimal fungicidal concentration (<500 ppm against all pathogens). In the in vivo test, cinnamon fumigation at a concentration of 500 ppm reduced infection rates of Penicillium, Fusarium, and Mortierella by 50.3%, 54.3%, and 60.7%, respectively. We recommended cinnamon oil fumigation combined with medium storage at 12 °C as an integrated approach to baby ginger storage.