Alternative preservation method against Sclerotium tuber rot of Jerusalem artichoke using natural essential oils

Abstract

The Sclerotium tuber rot fungus (Sclerotium rolfsii Sacc.) represents a serious problem for Jerusalem artichoke (JA) tubers during storage periods. The aim of this study was to investigate an alternative preservation method using a natural essential oil to inhibit the fungal growth, increase storability, and keep nutritive value of JA tubers under storage conditions. In vitro antifungal activity was assessed using two essential oils; caraway and spearmint at concentrations of 2, 3, 4 and 5 %. Among the tested treatments, caraway oil at 2 % resulted in complete inhibition of the fungal growth. In the storage experiment, two preservation methods were applied using caraway oil. In the first method, JA tubers were treated with caraway oil at 2 %, kept in perforated polyethylene bags and stored at 4 °C and 90 % relative humidity (RH). In the second method, JA tubers were treated with caraway oil at 2 %, kept between peat moss layers and stored at room temperature (25/10 °C, day /night) and 70 % RH. Comparing with the infected-untreated control, tubers infected with S. rolfsii and treated with caraway oil which kept in peat moss exhibited lower severity of Sclerotium tuber rot, sprouting percentage and weight loss. On the other hand, this treatment led to the highest dry matter and contents of carbohydrates, protein, inulin and total phenols as well as the activity of peroxidase and polyphenol oxidase enzymes. Based on the obtained results we recommend the use of caraway oil and peat moss when storing JA tubers at room temperature due to its eco-safety and saving of the cooling energy.