Vela Antonio J, Villanueva Marina, Náthia-Neves Grazielle, Ronda Felicidad
Department of Agriculture and Forestry Engineering, Food Technology, PROCEREALtech Research Group, University of Valladolid, 34004 Valladolid, Spain.
Foods. 2023 Jan 20;12(3):484. doi: 10.3390/foods12030484.
The modification of flours by ultrasound (US) treatments requires excess water to suspend the sample to be treated, which must be removed after treatment to recover the ultrasonicated flour. The aim of this study was to determine the influence that the water removal method has on the final characteristics of US-treated gluten-free flours (rice, brown tef, corn and quinoa). US treatment parameters were constant, and two water removal methods were studied: freeze-drying and centrifugation + drying. The elimination of water by centrifugation resulted in the loss of solubilized compounds from the treated flours, which led to important differences between the final characteristics of US-treated flours. Ultrasonication resulted in the reduction of flours' particle size and modification of their color parameters. Techno-functional properties were modified by US treatment, where the water removal method was more influential in whole grain samples (brown tef and quinoa). Few differences were found in thermal properties among pairs of US-treated samples, indicative that the effect caused to starch was mainly attributed to ultrasonication conditions than to the drying method. The water removal method markedly influenced the pasting properties of US-treated flours, resulting in lower profiles when freeze-drying was applied and higher profiles when flours were retrieved by centrifugation. Gels made with tef, corn and quinoa presented reduced tan(δ)₁ values after sonication, while gels made with rice did not show any modification. The water removal method is a decisive step in US treatments, defining the final characteristics of the treated matter, and having a great influence in the modification attributed to ultrasonication.
通过超声（US）处理对面粉进行改性需要过量的水来悬浮待处理的样品，处理后必须将其除去以回收超声处理过的面粉。本研究的目的是确定脱水方法对经超声处理的无麸质面粉（大米、棕色画眉草、玉米和藜麦）最终特性的影响。超声处理参数保持不变，并研究了两种脱水方法：冷冻干燥和离心+干燥。通过离心去除水分导致处理过的面粉中溶解的化合物损失，这导致经超声处理的面粉最终特性之间存在重要差异。超声处理导致面粉粒径减小及其颜色参数发生改变。经超声处理改变了面粉的技术功能特性，其中脱水方法对全谷物样品（棕色画眉草和藜麦）的影响更大。在成对的经超声处理的样品之间，热性能方面几乎没有发现差异，这表明对淀粉造成的影响主要归因于超声处理条件而非干燥方法。脱水方法显著影响经超声处理的面粉的糊化特性，冷冻干燥时糊化特性曲线较低，通过离心回收面粉时糊化特性曲线较高。用画眉草、玉米和藜麦制成的凝胶在超声处理后tan(δ)₁值降低，而用大米制成的凝胶没有显示出任何变化。脱水方法是超声处理中的一个决定性步骤，它决定了处理后物质的最终特性，并对超声处理引起的改性有很大影响。
