Application of Ozone against the Larvae of Plodia interpunctella (Hübner) and Its Impacts on the Organoleptic Properties of Walnuts

Abstract

ABSTRACT One of the most important products grown in Iran is walnut (Juglans regia L.), but it can be threatened by storage pests such as insects. Ozonation is an environmentally friendly method for killing pest insects; accordingly, ozone efficacy in the control of a pest species of walnut, Indian meal moth (Plodia interpunctella (Hübner)), was assessed in this research. The selected walnut samples were infested with larvae of Indian meal moth and then subjected to various combinations of ozone concentration (3, 4.5, and 6 ppm) and exposure time (20, 30, 40, and 50 min). After exposure to the treatment combinations, larval mortality rates and changes to the sensory properties (color, taste, smell, crispness, stiffness, and overall acceptability), indicating consumer preference, of the walnuts were evaluated. Our results revealed enhanced mortality rates of P. interpunctella with an increase in both ozone concentration and exposure time: 99% mortality was recorded at the concentration and exposure time of 6 ppm and 50 min, respectively. Sensory assessments of the samples showed that ozone treatments had no significant impacts on the color, taste, crispness, stiffness, and overall acceptability of the product. Also, few changes were recorded for its smell, which could be improved over time after being exposed to the air. We conclude that application of higher ozone concentrations might provide acceptable levels of insect pest control for stored walnuts with no associated reduced trade-off for their quality attributes. HIGHLIGHTS