Physico-chemical characteristics of flours obtained from raw, roasted and autoclaved Cucurbita, Passiflora and Annona seeds

Fruit seeds often have interesting nutritional characteristics as well as antinutrients, which may be inactivated by thermal processes. The aim of this work was to study the characteristics of flours obtained from raw, roasted or autoclaved (121 degrees C, 10 min) seeds of Cucurbita maxima, Cucurbita ficifolia, Passiflora ligularis, Annona cherimola and Annona muricata by analysing their chemical composition, protein in vitro digestibility, content of antinutrients (tannins, phytates and oxalates) and functional properties. All the flours presented high protein (15.3-36.7 g/100 g) and fat (22.7-41.8 g/100 g) contents. Roasting and autoclaving increased in vitro protein digestibility (from 45.6% to 57.8% and 72.1%, respectively) and decreased antinutrient content (from 100.3 to 75.6 and 82.0 mg tannins/100 g; from 158.1 to 137.8 and 104.0 mg phytates/100 g; from 19.6 to 12.8 and 13.3 mg oxalates/100 g, respectively). Water and oil absorption capacities increased, while emulsion and foaming capacities as well as bulk density decreased during thermal processing. The flours from autoclaved seeds showed improved nutritional and functional characteristics and could be considered as functional food ingredients for direct human consumption and/or in food mixtures. Future studies should be performed to evaluate the presence of allergens and other possible risk factors.