Green chemically developed metal oxide polymeric composites for improving strawberry storage

Abstract

Globally, the rising environmental concerns and issues related plastic wastage and spoilage of food enlightens the development of ecofriendly and sustainable alternatives for food storage to replace traditional plastic packaging material with biodegradable packaging. Polymeric coatings such as CH become a possible alternate of plastic due to its biocompatible, biodegradable and antimicrobial properties. This thesis investigates the synthesis of CH coatings for strawberry preservation. However, pure CH can limit the storage due to barrier and mechanical properties. This hindering effect in coating can be overcome by incorporating metal oxide NPs such as ZnO and Fe3O4. CH coatings were enhanced with green synthesized NPs including ZnO and Fe3O4 with the aim of prolonging food shelf life by maintaining the quality of food. The research integrates green chemistry to synthesize NPs using garlic and ginger extracts to maintain the purpose of ecofriendly coatings. The ginger and garlic extract not only serves sustainability but also act as stabilizing, reducing and capping agents for NPs synthesis. Usually, citric acid or acetic acid is used for the dissolution of CH but it is non-friendly to the environment. The preparation of citric acid and acetic acid produces toxic byproducts which is an environmental concern. Therefore, this study uses lemon juice, ginger and garlic extracts to provide acidic medium to CH for dissolution. The main objective of this research is to introduce an ecofriendly and sustainable approach in the form of polymeric nanocomposites coating solutions to preserve food. CH-ZnO and CH-Fe3O4 coatings were developed and assessed their effectiveness in preserving strawberries. Various quality parameters such as weight loss, mold growth, antioxidant activity, etc., were checked for the under-observation samples. The addition of ZnO and Fe3O4 NPs was found to enhance the barrier properties, mechanical stability as well as additional antimicrobial properties. The results concluded that CH-ZnO coatings achieved an improvement of 40% in weight loss as compared to uncoated sample. Additionally, CHFe3O4 coatings reduced the infection rate by 60% as compared to uncoated sample. The findings clearly supported the hypothesis that CH-ZnO and CH-Fe3O4 coatings present a viable, sustainable, and ecofriendly solution for extending the shelf life of strawberries. Rheological study was conducted for the coating solutions with and without NPs, showing that NPs enhancement influences the viscosity and flow behavior of coating solutions. These developed coating solutions address both food waste and environmental concerns offering a potential contribution to reduce plastic dependency in the food industry. Future work can be done to industrialize these coatings by doing further studies such as toxicity. The scalability of this approach can also be investigated in future.