Effects of pre- and post-harvest treatments with hexanal formulations on time to ripening and shelf life of papaya (Carica papaya L.) fruits
Keywords:Hexanal, papaya, pre-harvest, post-harvest
AbstractPapaya (Caria papaya L.) cv. Red lady is used as ripened fresh fruit as well as in the unripe state in many processed products. Therefore, for uses other than fresh fruit consumption, maintenance of fruit in the unripe state is extremely important for viable commercial applications. The application of 2% enhanced freshness formulation (EFF) with hexanal as the main active ingredient, has been shown to delay the onset of ripening in several subtropical fruits. This investigation was done to determine its effect on ripening and senescence in papaya fruits. Trials were conducted using 2% EFF applied as a pre-harvest spray and as a post-harvest dip alone or in combination with the pre-harvest spray. Pre-harvest treatments were applied at two week intervals beginning 30-days before expected harvest maturity. For post-harvest treatments, fruits were completely immersed in the dip solution for ten minutes and allowed to air dry at room temperature before storage. Fruits on trees sprayed pre-harvest with 2% EFF developed first colour stripe approximately 75 days after second spraying while fruits on trees sprayed with the control solution developed first colour stripe 15 days after application of the second spray. This was as expected since the pre-harvest applications were timed to be begin within 30 days of expected harvest. Thus, pre-harvest treatment with 2% EFF resulted in a 60 day delay in the onset of ripening in fruits on treated trees. Fruits were harvested on development of the first colour stripe, indicative of the onset of ripening. Following the delayed onset of ripening, fruits harvested from trees sprayed pre-harvest with 2% EFF ripened to full colour change in 15-18 days during storage at 20-22oC / 90-95% RH. Fruits harvested from trees sprayed with the control solution ripened to full colour change in 8-10 days when stored under the same conditions. At full colour change, fruits from trees treated pre-harvest with 2% EFF had a lower incidence of post-harvest diseases than fruits from control trees. The application of 2% EFF as a pre-harvest treatment and as a postharvest dip can be used to increase the time to onset of ripening of papaya fruit in the field, delay the development of full colour change in fruits after harvest, maintain postharvest quality of fruits during storage at 20-22oC / 90-95% RH and reduce the incidence of post-harvest diseases.