Impact of silver nanoparticles infused biopolymer coatings on post-harvest quality attributes of guava

Guava (Psidium guajava L.) is a climacteric fruit characterised by sustained ethylene production even after ripening, which induces rapid physiological and biochemical changes, thereby reducing shelf-life and increasing susceptibility to chilling injury and microbial spoilage during storage. This underlines the imperative need for an innovative method to overcome postharvest losses. This work attempts to bridge the research gaps to improve the post-harvest shelf life and improve the quality attributes of guava fruits by coating it with different polymers imbedded with antimicrobial silver nanoparticles (AgNPs). The antimicrobial efficiency of AgNPs peaked at the concentration of 100 µg mL-1 with the inhibition zone of 33 mm against postharvest pathogen Aspergillus flavus using agar well diffusion method. Biopolymer coatings like beeswax, xanthan gum, gelatin and guar gum which are naturally available, edible and eco-friendly, act as an impervious barrier against water loss, improve the peel coloration and maintain the firmness and texture. These AgNPs imbedded biopolymer coatings created an immense impact on post-harvest quality attributes like titratable acidity (TA), reducing and non-reducing sugars. The best results were observed in the T2 (Beeswax + AgNPs) as revealed by the highest TA of 0.38 %, lowest decay rate of 60 % and lowest reducing and non-reducing sugars of 3.02 % and 2.65 % on the 12th day after imposing the treatments. These coatings not only act as a barrier against water loss but also reduce respiration, slow down the metabolic rate, and prevent microbial decay, which leads to a better acid–sugar balance, thereby imparting improved sensory attributes.