Impact of ultrasound-assisted intermittent hydration during pumpkin seed germination on the structure, nutritional, bioactive, physical and techno-functional properties of flours
Flaviana Coelho Pacheco, Irene Andressa, Ana Flávia Coelho Pacheco, Fábio Ribeiro dos Santos, Jeferson Silva Cunha, Nathália de Andrade Neves, Raquel Guidetti Vendruscolo, Márcio Schmiele, Paulo Henrique Costa Paiva, Alline Artigiani Lima Tribst, Pedro Esteves Duarte Augusto, Bruno Ricardo de Castro Leite Júnior
Abstract
This study investigated the ultrasound (US)-assisted intermittent hydration of pumpkin seeds (2 cycles of 10 min, at 25 or 45 °C, 38 W/L, 25 kHz), followed by germination (3 days, 25 °C), evaluating the structure, nutritional, bioactive, color, and techno-functional properties of the obtained flours. US-assisted hydration produced flours that were more porous and lighter in color. Germination reduced starch crystallinity (≤14.3 %) and altered the flour's aliphatic hydrocarbons, amino acids and carbohydrates, particularly in the C-H and C-O bonds, as evidenced by Fourier transform infrared (FTIR) spectroscopy. US treatment did not affect the flours' mineral nor fatty acid profiles. On the other hand, sonication effectively increased the content of gamma-aminobutyric acid (GABA) (15.6 % and 13.7 %) and the antioxidant activities, measured both by 2,2′-azino-bis (3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) (29.4 % and 9.7 %) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (40.8 % and 2.4 %) methods compared to non-sonicated flours at 25 °C and 45 °C, respectively. US increased the water retention capacity, solubility index, foam capacity and foam stability by up to 49 %, 68 %, 143 % and 208 %, respectively. The enhanced nutritional and techno-functional properties suggest that germinated pumpkin seed flour hydrated under US, especially at 25 °C, is a promising and sustainable ingredient that can be used in products such as bread, cakes, cookies, and beverages. • Ultrasound increased the flour GABA content (<15.6 %) and antioxidant capacity (≤40.8 %). • Sonicated pumpkin seed flour showed improved techno-functional properties. • Sonication changed the three-dimensional structure of the proteins. • Germination and sonication decreased starch crystallinity (≤14.3 %). • US preserved the minerals and fatty acids profile of germinated pumpkin seed flour.