Walnut green husk extract enhances the effect of chlorine dioxide on kernel quality and antioxidant properties of fresh-eating walnuts during their shelf life

Fresh-eating walnuts are perishable and become mildewed during shelf life, limiting their sales span. The effects of chlorine dioxide (ClO2) alone and its combination with walnut green husk extract (WGHE) on shelf stored fresh walnuts were investigated to develop a pollution-free preservative for the produce. The initial development of mildew incidence was delayed by both treatments under 25 °C, whereas, WGHE + ClO2 acted more effectively than ClO2 under 5 °C. The WGHE + ClO2 treatment presented superior effects on improving moisture, soluble sugar and total phenol content, alleviating loss of oil and unsaturated fatty acid and delaying peroxide value increase of walnut kernels at both temperatures. Both treatments inhibited the activities of three lipolytic enzymes and two oxidases at 25 °C and 5 °C, WGHE + ClO2 acted more effectively at 5 °C. The results guide the combined application of WGHE with ClO2 on shelf preservation of fresh walnut.