Influence of Replacing Raw Cocoa with Cocoa Shell Husk on Chemical Composition, Physicochemical Properties, and Sensory Attributes of Apple-Cocoa Fruit Leathers

Fruit leathers, also called fruit rolls, are popular healthy snacks amongst children. Apple-cocoa rolls were prepared using apple puree (AP) and either raw cocoa (RC), cocoa husk powder (CW) or a blend of both (2,5% RC and 2,5% of CW). They were prepared by mixing concentrated apple puree with cocoa powder at 5% (w/w) and drying on sheets at 55℃ for 2 h. This strategy aimed to valorise the food industry’s by-product and characterise the physicochemical and sensory properties of the obtained leathers. Each formulation was evaluated for its effect on sensory attributes, structure, wetting, mechanical, antioxidant, chemical, and optical properties. The colour and the texture of the developed fruit leathers were affected by the components and the drying process. CW as fine powder showed a good compatibility with the fruit matrix and the RC. The obtained snacks were characterised by dark chololate colour. While the AP samples were significantly lighter. Different microstructure reorganization was observed which was also resulted in surface roughtness. The addition of CW lowered the water vapour sorption rate in prepared snacks. The water contact angle was measured using the sessile drop technique with a goniometer and ranged from 44.43° to 61.56°, indicating the material hydrophilic nature. Additionally, Fourier-transform infrared spectroscopy indicated compatibility of AP, RC and CW. Sensory analysis revealed that fruit leathers with a mix of CW+RC were preferred by panelists for texture. With regard to overall quality, appearance, flavour and chewiness, CW+RC rolls and RC rolls had comparable results. This idea poses a feasible and cost-effective solution to prepare a clean-label product with incorporation of a by-product. However, further studies are recommended, including formulating the snacks with different concentrations of RC and CW, which could enhance the sensory properties.