Sensory evaluation and characterisation of roasted coffee hulls for beverage production using compostable capsules

The consumption of easy-to-prepare products has increased in recent decades, such as beverages obtained from capsule extraction, which are typically produced with conventional materials, affecting their environmental sustainability. In addition, the generation of residual biomass in coffee processing, such as hulls, leads to under-utilisation of the crop. Therefore, the development of a new product using compostable capsules is a viable alternative to add value to the residual biomass. For this reason, this study aims to identify the roast curve and grind level that achieve the highest sensory acceptance and highlight positive attributes in the sensory profile. The raw material was subjected to density classification, Timsen disinfection, maturity classification, pulping and drying in forced convection ovens at 50°C. Four roasting curves and two grinding stages were designed using Keurig-type compostable capsules. In the physical characterisation of the roasted dehydrated husks, the values for °Brix (1.65+/-0.44), moisture content (6.62+/-0.28), tapped density (0.62+/-0.04) and colour in CIELAB were consistent (L*: 25.30+/-0.67 to 27.97+/-0.88; a*: 6.23 +/- 0.37 to 8.13+/- 0.26; b*: 7.17 +/- 0.46 to 9.77+/-0.25). Finally, the sensory profile and acceptance of the beverage parameters were determined with a trained panel, with curve 2 showing 100% acceptance for acidity, body and beverage, with sensory descriptors associated with honey, caramel, dried pineapple, mandarin, vanilla, tamarind and floral notes. It can be observed that the capsules are not only functional in terms of preparation, but also offer a pleasant and distinctive sensory profile. This makes them potentially attractive to consumers and a market niche who are interested in sustainability. However, areas for future research are highlighted, such as optimising the manufacturing process and assessing the environmental impact of this approach and consumer acceptance.