Author(s):
Pereira, Nelson ; Ramos, Ana Cristina ; Alves, Marco ; Alves, Vítor D. ; Moldão, Margarida ; Abreu, Marta
Date: 2025
Persistent ID: http://hdl.handle.net/10362/187139
Origin: Repositório Institucional da UNL
Project/scholarship:
info:eu-repo/grantAgreement/FCT/Concurso de avaliação no âmbito do Programa Plurianual de Financiamento de Unidades de I&D (2017%2F2018) - Financiamento Base/UIDB%2F04129%2F2020/PT;
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04035%2F2020/PT;
info:eu-repo/grantAgreement/FCT//2023.00711.BDANA/PT;
Subject(s): Flour properties; Freeze-drying; Gelation behaviour; Gluten-free; Hot-air drying; Oil absorption capacity; Water absorption capacity; Analytical Chemistry; Chemistry (miscellaneous); Molecular Medicine; Pharmaceutical Science; Drug Discovery; Physical and Theoretical Chemistry; Organic Chemistry
Description
Funding Information: This work was funded by national funds through FCT—Fundação para a Ciência e a Tecnologia, IP, under the projects UIDB/04129/2020 of LEAF-Linking Landscape, Environment, Agriculture and Food Research Center and UIDB/04035/2020 of GeoBioTec—Geobiociências, Geoengenharias e Geotecnologias, and through doctoral grant 2023.00711.BDANA. Publisher Copyright: © 2025 by the authors.
Sweet potato (Ipomoea batatas (L.) Lam.; SP) flour enhances food nutrition and bioactivity while functioning as a thickening/gelling agent. This study investigated the impact of two drying methods [hot-air (75 °C/20 h) and freeze-drying (−41–30 °C/70 h)] on the physical–functional properties of flours from three SP varieties: Bonita (white-fleshed), Bellevue (orange-fleshed), and NP1648 (purple-fleshed). Particle size, morphology, water/oil absorption capacities (WAC/OAC), bulk density, swelling power (SwP), water solubility (WS), foaming/emulsifying properties, least gelation concentration (LGC), and gelatinisation temperature (GT) were analysed. Both the drying method and variety significantly influenced these properties. Hot-air-dried flours exhibited bimodal particle distribution, compact microstructure, and aggregated starch granules, yielding higher WAC (≈3.2 g/g) and SwP (≈3.6 g/g). Freeze-dried flours displayed smaller particles, porous microstructure, and fragmented granules, enhancing OAC (≈3.0 g/g) and foaming capacity (≈17.6%). GT was mainly variety-dependent, increasing as Bellevue (74.3 °C) < NP1648 (78.5 °C) < Bonita (82.8 °C), all exceeding commercial potato starch (68.7 °C). NP1648 required lower LGC (10% vs. 16% for others). All flours exhibited high WS (24–39.5%) and emulsifying capacity (≈44%). These results underscore the importance of selecting the appropriate drying method and variety to optimise SP flour functionality for targeted food applications. Freeze-dried flours might suit aerated/oil-retentive products, while hot-air-dried flours could be ideal for moisture-sensitive formulations.
