Pereira Nelson, Ramos Ana Cristina, Alves Marco, Alves Vítor D, Moldão Margarida, Abreu Marta
Unidade de Tecnologia e Inovação, INIAV-Instituto Nacional de Investigação Agrária e Veterinária, 2780-157 Oeiras, Portugal.
LEAF-Linking Landscape, Environment, Agriculture and Food Research Center, Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisboa, Portugal.
Molecules. 2025 Apr 20;30(8):1846. doi: 10.3390/molecules30081846.
Sweet potato ( (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: (white-fleshed), (orange-fleshed), and (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 (74.3 °C) < (78.5 °C) < (82.8 °C), all exceeding commercial potato starch (68.7 °C). 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.
甘薯（(L.) Lam.；SP）粉在作为增稠/胶凝剂的同时，还能提高食品的营养和生物活性。本研究调查了两种干燥方法[热风干燥（75 °C/20小时）和冷冻干燥（-41 - 30 °C/70小时）]对三个甘薯品种（白肉、橙肉和紫肉）面粉物理功能特性的影响。分析了粒度、形态、水/油吸收能力（WAC/OAC）、堆积密度、膨胀力（SwP）、水溶性（WS）、发泡/乳化特性、最低胶凝浓度（LGC）和糊化温度（GT）。干燥方法和品种均对这些特性有显著影响。热风干燥的面粉呈现双峰粒度分布、致密的微观结构和聚集的淀粉颗粒，具有较高的WAC（约3.2 g/g）和SwP（约3.6 g/g）。冷冻干燥的面粉颗粒较小、微观结构多孔且颗粒破碎，提高了OAC（约3.0 g/g）和发泡能力（约17.6%）。GT主要取决于品种，随着白肉（74.3 °C）<橙肉（78.5 °C）<紫肉（82.8 °C）而增加，均超过商业马铃薯淀粉（68.7 °C）。白肉品种所需的LGC较低（10%，其他品种为16%）。所有面粉均表现出高WS（24 - 39.5%）和乳化能力（约44%）。这些结果强调了选择合适的干燥方法和品种以优化甘薯粉功能用于特定食品应用的重要性。冷冻干燥的面粉可能适合充气/保油产品，而热风干燥的面粉可能适用于对水分敏感的配方。
