College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164-6120, USA.
Int J Biol Macromol. 2024 Aug;275(Pt 2):133717. doi: 10.1016/j.ijbiomac.2024.133717. Epub 2024 Jul 6.
Tiger nut (TN) is a valuable nutrient and gluten-free tuber. To achieve high-quality TN flour as functional ingredients in food, it is essential to develop effective drying technologies for TN. Five drying methods including natural drying (Control), hot-air drying (HD), radio frequency single drying (RFSD), RF assisted hot-air drying (RFHD), and RF- vacuum drying (RFVD) were selected and compared to determine their effects on physiochemical, structural, and rheological properties of TN flour. Results showed that RF drying (RFD) significantly improved the hydration, oil-absorbing, and antioxidant activity capacity, especially for RFVD. RFHD exhibited greater color (BI = 13.80 ± 0.05 and C = 10.26 ± 0.05) and reducing sugar content (253.50 ± 2.27 mg d.b.) than RFSD and RFVD. The gelatinization temperature, enthalpy value, and particle size (57.30-269.33 μm) of TN flour were reduced. The structural property results indicated that RFD reduced the relative crystallinity and short-range ordering of the flour, altered protein secondary structure, and caused the damaged microstructure in comparison with Control and HD groups. All sample gels exhibited a weak strain overshoot behavior (type III) under large amplitude oscillations, and RFD resulted in a reduced viscoelastic behavior. RFD could be an effective method to produce functional TN flour.
西亚米黄（TN）是一种有价值的营养和无麸质块茎。为了将高质量的 TN 面粉作为食品中的功能性成分，开发有效的 TN 干燥技术至关重要。选择了五种干燥方法，包括自然干燥（对照）、热空气干燥（HD）、射频单干燥（RFSD）、射频辅助热空气干燥（RFHD）和射频-真空干燥（RFVD），并对它们对 TN 面粉的物理化学、结构和流变特性的影响进行了比较。结果表明，射频干燥（RFD）显著提高了 TN 面粉的水合、吸油和抗氧化活性能力，特别是 RFVD。与 RFSD 和 RFVD 相比，RFHD 表现出更大的颜色（BI = 13.80 ± 0.05 和 C = 10.26 ± 0.05）和还原糖含量（253.50 ± 2.27 mg d.b.）。TN 面粉的糊化温度、焓值和粒径（57.30-269.33 μm）降低。结构特性结果表明，与对照和 HD 组相比，RFD 降低了面粉的相对结晶度和短程有序度，改变了蛋白质二级结构，并导致微观结构受损。所有样品凝胶在大振幅振荡下均表现出弱应变过冲行为（III 型），RFD 导致粘弹性降低。RFD 可能是生产功能性 TN 面粉的有效方法。
