Effect of guar gum coatings containing essential oils on shelf life and nutritional quality of green-unripe mangoes during low temperature storage

This study investigated the effect of treatment of guar gum coating coupled with essential oils. Harvested unripe green mangoes (UGM) were preserved using edible coatings containing essential oils of Nigella sativa, Coriandrum sativum, Foeniculum vulgare and Laurus nobilis derived using two different solvents (methanol and ethanol) and stored at refrigeration temperature (10 °C, 80-85% relative humidity). Physiological and biochemical parameters that assess the quality of fruits were determined. Microbiological analysis was also performed at the start and end of shelf life. Generally, it was observed that ethanolic essential oils supplemented coatings conferred a greater retention of fruit quality as compared to both controls. Bacterial counts were significantly reduced in fruits that were coated with ethanolic essential oil edible coatings. Secondly, the coatings supplemented with ethanolic and methanolic essential oils extended shelf life up to 24 days whereas treated and untreated control decayed after 10 and 6 days respectively (P < 0.05). These results suggested the application of these edible coatings for preservation of unripe green mangoes during cold storage.