Chitosan and graphene oxide-based biodegradable packaging for maintaining postharvest quality of mango

Abstract

Mango is a highly appreciated tropical fruit with high respiration rate and ethylene production, which makes it highly perishable after harvest and limits fruit long-distance marketing. Thus, postharvest technologies are essential to reduce metabolic activity and extend postharvest life of mangoes shipped to distant markets. Modified atmosphere is one of the most used technologies for fruit conservation, generally applied through the use of synthetic petroleum-based bags. Despite their effectiveness, these synthetic packaging are non-biodegradable and slow to decompose, causing several impacts on environmental ecosystems and on human health. Chitosan is a natural, renewable and biodegradable polymer that has been extensively studied in fruit postharvest conservation, including mangoes. Despite its several advantages, the use of chitosan is limited by its hydrophilic nature, which tend to be characterized as an ineffective barrier to the loss of moisture from the fruit to the environment, and by its fragility. Thus, the addition and incorporation of nanoparticles to the chitosan biopolymeric matrix is an alternative to improve the properties of the films based on this polymer. The objective of this study was to evaluate the effect of chitosan and graphene oxide-based biodegradable bags on the postharvest quality of ‘Tommy Atkins’ and ‘Palmer’ mangoes during cold storage. Chitosan (2%) and graphene oxide (0.25%) based biodegradable bags were prepared following the casting method and evaluated for physicochemical, colorimetric and mechanical properties. The fruit were harvested at the recommended maturity stage and were stored for 42 (‘Tommy Atkins’) and 56 days (‘Palmer’) at 12° C without bagging (control), as well as in chitosan-based bag, chitosan-based bag with graphene oxide, and polyethylene-based bag. According to the results, the incorporation of graphene oxide into chitosan matrix improved the water vapor barrier and mechanical properties of the films by reducing their water vapor permeability and water vapor transmission rate in 37% and 35%, respectively, by reducing water solubility from 6.46% to 1.86%, and by increasing tensile strength and Young’s modulus in 21% and 19%, respectively. The bags evaluated in our study delayed mango ripening, maintaining external appearance, skin and pulp colors, firmness, soluble solids (SS), titratable acidity (TA), SS/TA ratio, β-carotene and chlorophyll contents in the fruit. In addition, bagging the fruit reduced weight loss, respiration rate and anthracnose (Colletotrichum gloeosporioides) incidence and severity during storage. Our results suggest that chitosan-based biodegradable bags are an ecological and effective alternative for maintaining postharvest quality of ‘Tommy Atkins’ and ‘Palmer’ mangoes during cold storage