Carnauba wax-based composite films and coatings: recent advancement in prolonging postharvest shelf-life of fruits and vegetables

High rate of water loss and rapid respiration cause significant decrease in firmness, turgor, crunchiness, and weight loss resulting in rapid postharvest quality deterioration and shorter shelf-life of fruits and vegetables. Wax-based coatings can effectively maintain postharvest quality of these perishables, and enhance their shelf life. However, petroleum-based synthetic waxes are harmful for consumers' health and environment. Carnauba wax is a plant-based natural wax, extracted from the leaves of the Brazilian palm tree ( Copernicia prunifera ). Carnauba wax is a GRAS substance, and recognized as a food additive (E 903), which is highly hydrophobic in nature. This review is a comprehensive account of extraction of carnauba wax, its composition, functional properties, and application in fabrication of films and coatings for packaging/preservation of fruits and vegetables. Coating formulation and film fabrication techniques are also elaborated. Moreover, safety aspects of carnauba wax for food applications are also discussed. Carnauba wax coatings effectively enhance postharvest shelf life by reducing water loss, respiration rate, and maintaining firmness, crunchiness and consumer acceptability for longer duration of numerous fruits like orange, guava, apple, pomegranate, tomato and egg plant. Incorporated of the wax in biopolymer (e.g., starch, chitosan, gelatin, fish protein, glucomannan, etc.) based composite films exhibit excellent moisture, gas and light barrier properties, improve mechanical and thermal stability. This review highlights potential uses of carnauba wax as a natural coating or in biopolymer based composite films for sustainable preservation and packaging of postharvest fruits and vegetables.