New biodegradable film produced from cocoa shell nanofibrils containing bioactive compounds

Abstract

Cellulosic nanofibrils from cocoa shells were used in this study to produce biodegradable films from a residue naturally rich in bioactive compounds, while reserving these compounds. The nanofibrils were obtained by mechanical defibrillation without chemical or enzymatic pretreatment. The nanofibril gel was evaluated in biodegradable films, for the first time, with the addition of glycerol as a plasticizer in the proportions of 0, 1, 3, 5, and 7% (w/w). The morphological characteristics, thermal analysis, mechanical properties (rupture tensile, maximum rupture elongation, and Young’s modulus), water vapor permeability, and water solubility of the films were investigated. In addition, the residue was analyzed and compared to the films by the FTIR technique to prove the maintenance of functional groups characteristic of antioxidant activity. The use of 3% and 5% glycerol as a plasticizer showed the best mechanical characteristics—reduced water vapor permeation and increased degradation in water. The pure nanofibril film demonstrated greater thermal stability. It was possible to identify the maintenance of aromatic groups and phenols in the residue from all cocoa shell nanofibril films. This study contributes to the future application of cocoa shell nanofibers in the production of edible films, coatings, and packaging materials. It recommends their application in cocoa and chocolate products due to the compatibility of smell and color.