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Cocoa Husk Extract as the Source of Functional Ingredients for Production of Edible Packaging Films Based on Alginate, Pectin and Chitosan

Owing to the increased tendency of producing bioactives-enriched films and coatings for food applications, in this study the potential of formulating edible films from polymeric hydrocolloid materials (alginate, pectin, chitosan) in cocoa (Theobroma cacao L.) husk extract as the source of macroconstituent (polysaccharides) and bioactive compounds (polyphenols and methylxanthines) was investigated. Since cocoa husk extract represents the main cocoa processing by-product in the chocolate industry, valorization of this material by expoiting it as a source of added-value functional ingredients was examined. A comparative study of the physical, mechanical, bioactive and sensory properties of produced films, prior and after drying of films at 60°C, was undertaken, and the relation between specific properties (colour, sensory and mechanical properties) was deduced by correlation analysis. The effect of enrichment with polyphenolic compounds and theobromine derived from cocoa husk extract was determined by comparing the produced films with control films obtained only in distilled water. According to the obtained results, edible films were produced with thickness ranging from 30-100 μm, which was primarily in dependance of the solubilization media (water or cocoa husk extract), while the water and dry matter content were more affected by the employed biopolymer material. Control alginate film generally exhibited the best mechanical (highest tensile strenght - 6, 17 N and lowest deformation - 0, 73 %) and sensory properties, while the enriched chitosan film prepared in cocoa husk extract exhibited the poorest respective properties and the most potent thickness (104, 67 μm). By preparing the films in cocoa husk extract a significant increase of bioactive compounds content was achieved (even up to 3-fold higher) in relation to control films, while the bioactive properties remained preserved even after drying of films at 60°C. Enrichment of films in cocoa husk extract enabled to markedly enhance the bioactive content, but it negatively affected the physical, mechanical and sensory properties of produced films, which were better for control films (especially alginate one).

Alginate; Bioactive compounds; Chitosan; Cocoa husk extract; Edible films; Pectin

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