Natural antioxidants from pineapple (Ananas comosus L.Merr.) byproducts stabilized by spray drying for food products

Doutoramento em Engenharia Alimentar / Instituto Superior de Agronomia. Universidade de LisboaWorldwide, fruit sector discards tons of byproducts causing negative economic, environmental and social impacts. However, most of these byproducts, like pineapple peel, are composed of added value molecules with functional properties, such as antioxidant capacity. As such, this study was focused on the recovery of the bioactive compounds from pineapple peel using preferentially direct, environmentally friendly and low-cost techniques, for further application in food products preservation, aiming to replace synthetic antioxidants. Solid-liquid extraction processes were applied, and the one delivering an extract with higher total phenolics content and antioxidant capacity was a single extraction step with pineapple peel-solvent ratio of 1:1 (w/w) for 25 minutes at ambient temperature, using ethanol-water (80-20%) as solvent, followed by ethanol evaporation under vacuum. However, the storage of the obtained liquid extract before application compromises its antioxidant capacity due to degradation/oxidation reactions. Thus, its stabilization was explored by spray drying using different wall materials (maltodextrin, inulin, and arabic gum) and inlet air temperatures. The microencapsulation process at 150 °C using maltodextrin was the one showing higher maintenance of the antioxidant activity of compounds present in the extract before encapsulation during spray drying. In addition, the microparticles obtained maintained their antioxidant activity during storage at 6 °C for six months. These particles were used in the development of active biodegradable films that were applied in beef meat preservation. The films showed a good performance in retarding lipid oxidation, maintaining the color of red beef meat and in the inhibition of initial growth of aerobic mesophilic bacteria during storage. It is envisaged a high potential for the microparticles loaded with pineapple peel extract to be incorporated in food systems in order to enhance their stability and nutritional value, enabling simultaneously the valorization of pineapple byproducts within a circular economy conceptN/