Carboxymethyl Cellulose from Banana Rachis: A Potential Edible Coating to Extend the Shelf Life of Strawberry Fruit

Abstract

Cellulose derivatives, as edible coating for fruits and vegetables, have been broadly applied due to their availability, stability, solubility, safety, and low price. Therefore, this study was conducted to (1) extract cellulose from the banana plant rachis, (2) convert it into carboxymethyl (CMC), and (3) use the produced CMC as an edible coating to retard senescence and prolong the storage life of strawberry fruit. Preparation of CMC was accomplished by an etherification process, utilizing sodium hydroxide and monochloroacetic acid (MCA), with ethanol as a supporting medium. Characterization of CMC was done by analyzing the spectra of FTIR, degree of substitution (DS), ash content, CMC yield, water and oil holding capacity, in addition to physical characteristics. A storage study with CMC as an edible coating was conducted to investigate its impact on the shelf life of stored strawberry fruits. High purity food-grade CMC was successfully produced. CMC showed a yield of 156.25% with a DS of 0.78, a water holding capacity of 11.24 g/g, and an oil holding capacity of 1.60 g/g. The resulted CMC was well suited for edible coating preparation and was used effectively to prolong the shelf life of stored strawberry fruits at 22 °C to 6 days and to 16 days for that stored at 4 °C. Weight loss, total soluble solids (TSS), decay percentage, pH, anthocyanin content, ascorbic acid content, firmness, and sensory characteristics of CMC coated strawberry fruit stored at 4 °C were better than those stored at 22 °C. Thus, CMC edible coating prepared from banana rachis could be recommended as a potential postharvest treatment to delay postharvest senescence and maintain the quality of ambient and cold stored fruits.