Bio synthesis of chitosan from shrimp shell chitin using Streptomyces griseoincarnatus RB7AG:Characterization and application as coating material to enhance shelf life of tomatoes (var. Ruby pusa) in post-harvest storgae condition

Abstract

In this investigation, chitosan was successfully obtained from shrimp shell chitin through microbial degradation by Streptomyces griseoincarnatus RB7AG. The resulting chitosan showcased remarkable characteristics, including high solubility, a high degree of deacetylation, a well-defined crystalline structure, and a rough surface with minimal pores. The application of chitosan as a coating material for tomatoes demonstrated significant preservation benefits compared to commercially available chitosan. The chitosan coating proved effective in minimizing weight loss, reducing the production of reactive oxygen species (ROS), and preserving essential compounds such as anthocyanin content and antioxidant enzymes in tomatoes. Firstly, the chitosan coating served as a physical barrier, preventing moisture loss and maintaining the tomatoes' structural integrity. Secondly, the antimicrobial properties of chitosan hindered the growth of spoilage-causing microorganisms, extending the shelf life of the tomatoes. Additionally, the chitosan coating exhibited antioxidant properties, scavenging ROS and preserving the natural antioxidants in tomatoes. Furthermore, the chitosan coating facilitated controlled gas exchange, allowing optimal levels of oxygen and carbon dioxide to maintain the freshness of the tomatoes without accelerating the ripening process. With the help of the above-mentioned mechanisms, the potential of the microbially synthesized chitosan to enhance the shelf life of the tomatoes can be explained which was found better than the commercially synthesized chitosan coating. This research underscores the potential of microbially synthesized chitosan as an effective coating material but also provides insights into the intricate mechanisms involved in preserving tomatoes. The findings pave the way for innovative applications of chitosan-based coatings in the food industry, ensuring prolonged freshness and nutritional quality of perishable fruits and vegetables. © 2024 Elsevier Ltd