Comparative effect of chitosan, clove oil, and their combination on the shelf life of tomato (Solanum lycopersicum) and bell pepper (Capsicum annuum)

Introduction: Tomatoes and bell peppers, essential vegetables rich in nutrients and antioxidants, are also highly perishable. This study, therefore, examined the potential of chitosan solution (CS), clove oil emulsion (COE), and chitosan nanoparticle-loaded clove oil (CNLCO) as edible coatings to extend the shelf life of these vegetables.

Methods: Coated samples were stored at room temperature (28 ± 7 °C) for a period of 30 days. Changes in sample ripening were evaluated based on colour and weight every 3 days, and chemical analyses were conducted every 5 days.

Results: Only CNLCO-coated bell peppers lasted 15 days before turning red, while all categories of tomatoes turned red by day 12. There was a substantial weight loss of up to 71.9% in the first 2 weeks of storage for the bell pepper groups, while the tomato groups experienced an average weekly weight loss of 5.2%. The pH, total soluble solid (TSS), total sugar (TS), reducing sugar (RS) and non-reducing sugar (NRS) values of the treated samples' ranges were as follows: pH (4.3-4.9), TSS (2.9-3.8 Brix), TS (1.5-2.1%), RS (0.9-1.0%), and NRS (0.5-0.9%) for tomatoes and pH (4.9-6.0), TSS (3.1-5.5 Brix), TS (2.1-5.2%), RS (0.2-0.4%), and NRS (0.5-1.0%)] for bell peppers. The titratable acidity (TTA) values for the tomato groups (0.5-0.9%) were normal, while both bell pepper groups with chitosan in their coating showed deteriorating values (CS: 1.2%; CNLCO: 0.6%) on day 25.

Conclusion: The pH, TSS, TS, RS, and NRS values of the treated samples did not reach levels indicative of spoilage during storage, unlike the untreated samples. Applying the studied edible coatings, alone or in combination, is important in reducing postharvest losses of tomatoes and bell peppers and will offer new possibilities for the field.