Gaseous ozone and plant extract-based edible coatings as postharvest treatments for 'Hass' avocado (Persea americana Mill.) fruit

There is a high global demand for reducing the use of chemicals on fruit due to the residue levels which results in serious health concerns. Furthermore, naturally produced plant products and gases are gaining significant interest to consumers as alternative postharvest treatments of fruit. Edible coatings and ozone have been known to have potential in enhancing fruit quality during postharvest fruit storages since they do not pose any health problems after consumptions. However, there is no literature regarding the use of edible coating under cold ozonized storage in the postharvest quality of avocado fruit. This research was conducted to evaluate the combined effects of plant-based edible coatings and gaseous ozone in maintaining postharvest quality of avocado (Persea americana Mill.) fruit. Hass fruit were treated with moringa 2% in carboxymethyl cellulose (CMC, 1%) and Rosemary 2% in CMC 1% and the fruit was thereafter exposed to two levels of ozone (with and without ozone) in a cold storage chamber with air delivery of 5.5°C for 21 days. Fruit mass loss, firmness and color were measured on 7-day intervals from day 0, 7, 14, 21 and 28. The results revealed significant differences between coated and uncoated fruit under ozone and no ozone storage conditions. Coated avocados significantly reduced mass loss (1.61±0.18%) compared to control (3.12±0.09), retained higher firmness (61.1±1.2 N) than the control (53.9±1.2 N), and slowed down the rate of color change. These findings demonstrated that edible coatings of moringa and rosemary extracts in CMC plus ozonized cold storage prolong shelf-life and maintain overall quality avocados during postharvest life, therefore it is advisable that they are researched further as potential substitutes of chemical treatments in current use.