Edible Coatings Based on Pectin, Carboxymethylcellulose and Chitosan for Postharvest Quality Preservation of Fresh Tomatoes

Abstract: Edible coatings are sustainable postharvest strategies that may reduce water loss and delay quality deterioration in climacteric fruits such as tomato. This study evaluated the effect of pectin, carboxymethylcellulose (CMC) and chitosan-based edible coatings, applied alone or in binary combinations, on the postharvest quality of green tomatoes during storage at 25 ± 1 °C. Tomatoes at immature green stage were selected, sanitized and randomly assigned to seven treatments: uncoated (control), pectin 1%, CMC 1%, chitosan 1%, pectin-CMC 0.5%+0.5%, pectin-chitosan 0.5%+0.5% and CMC-chitosan 0.5%+0.5% (w/v). Coatings were applied by immersion for 3 minutes, followed by draining and drying at room temperature. Total soluble solids (°Brix), pH, cumulative weight loss and instrumental color parameters (L*, a*, b*, C* and hue angle) were determined during storage. Chitosan showed the lowest cumulative weight loss after 192 h (2.45%), whereas the control reached 6.31%, corresponding to an approximate 61% reduction. However, binary coatings containing chitosan increased weight loss over the control, with final losses of 12.40 ± 2.08% for pectin-chitosan and 11.20 ± 0.68% for CMC-chitosan. Total soluble solids varied slightly among treatments, remaining between 1.9 and 2.5 °Brix, while final pH values ranged from 4.20 to 4.60. Color changes indicated more intense ripening in the control, which reached a* = 15.51 ± 2.50 and hue angle = 41.94 ± 2.30 at 192 h. In contrast, pectin and CMC better preserved the green-yellow color, with lower a* values (3.69 ± 2.80 and 5.51 ± 2.70, respectively) and higher hue angles (79.29 ± 2.30 and 71.11 ± 2.30, respectively). The results suggest that chitosan formed a more effective barrier against water loss, whereas pectin and CMC were more efficient in delaying visual color transition. The absence of superior performance in binary coatings suggests limited polymeric synergism under the tested conditions. Chitosan was the most promising coating for reducing mass loss, while pectin and CMC showed greater potential for maintaining tomato appearance, indicating that coating selection should depend on the main postharvest quality target. 

Enter the project / scholarship number (FAPESP, CAPES, CNPq, etc):  88887.981628/2024-00 The authors would like to thank the Foundation for the Improvement of Higher Education Personnel (Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -CAPES).