Chitosan nanoemulsions as advanced edible coatings for fruits and vegetables: Composition, fabrication and developments in last decade

The rejection of chemical additives has attracted the attention of consumers and research personals to continuously improve quality and safety of food. Chitosan is a polyelectrolyte non-toxic, antimicrobial and biocompatible polysaccharide. The annual production of chitin (poly-β-(1-4)-N-acetyl-D-glucosamine), the acetylated form of chitosan has been estimated 10⁵ million tons and is approved by EU for use in plant protection (Reg. EU 2014/563). The film formation presents 20 to 30% of total chitosan activity apart from elicitation (30 to 40%) and antimicrobial activity (35 to 45%). Chitosan polymer scaffolds particularly nanoemulsions provides a protective covering to the fresh produce and acts as a carrier for antimicrobial agents and various functional compounds. The nanoemulsions are designed as smart functional coatings by microfluidization, high-pressure homogenization, ultra-sonication, phase inversion (PIC and PIT) and spontaneous emulsification. Considering the research reports available in the last decade, chitosan film production and related issues alluded to the possibilities for explorations of commercial applications on fresh foods. Chitosan-based biofilms with specific barriers and functional properties can be produced to address specific requirements of target food. Keeping in view the widespread applications of chitosan nanoemulsions for various food applications, the present review has been compiled to provide an insight into the developments and improvements made in the production, functionality, and delivery of bioactive substances for quality retention of fresh horticultural produce.