Investigation on brewer's spent yeast as a bio-vehicle for encapsulation of natural colorants from pumpkin (Cucurbita moschata) peels

Brewer's spent yeast (BSY) Saccharomyces cerevisiae has been explored as a bio-vehicle for the encapsulation of bioactive compounds and as a delivery system. The main objectives of this work were to encapsulate carotenoids from pumpkin peel extract using BSY as an encapsulating agent and to evaluate the influence of ultrasound treatment on the carotenoid incorporation, stability and release. The powders produced by atomization of the suspension of BSY in the extract from pumpkin peels showed physical and microbiological stability during storage, presenting low values of water activity (<0.406), moisture content (<7.0%) and hygroscopicity (<6.8 g per 100 g), characteristics of greatest importance for powder formulations. Regarding the chemical stability of the incorporated carotenoids, there was a decline in carotenoid content in the first 30 days (p ≤ 0.01), although stabilization was achieved up to the 75^th day. The best retention of carotenoids (273.3 μg g^-1 of particles) was obtained by applying ultrasound treatment before atomization, which probably led to the adsorption of carotenoids onto yeasts. Ultrasound also showed a positive effect on the color protection of powders during storage and on the protection of compounds under simulated gastrointestinal digestion. BSY released the carotenoids gradually during the digestion and higher carotenoid release occurred in the intestinal phase with bioaccessibility values of 26.9 and 30.3%. Yeasts are a suitable carrier material and show promising characteristics for technological application.