Abstract

The foaming conditions and air-drying temperature for producing instant powder from black rice bran anthocyanin extracts were studied. The conditions required for forming a foam to possess the maximum overrun, foam density, and foam stability, which contributed to boost the efficiency of drying foams using a hot-air dryer, were optimized using response surface methodology (RSM). Two independent variables were studied: the foaming agent concentrations (0.02–0.10%, w/w) and the whipping times (7.93–22.1 min). The optimal foaming conditions from RSM were 0.06% (w/w) foaming agent and 16.1 min whipping time, providing foams with the highest overrun (218%), foam density (0.31 g/mL), and foam stability (79.3%). The foams were dried at different temperatures (60, 70, and 80 °C). The best qualities of foam mat-dried powders were observed at 80 °C. Compared to spray- and freeze-dried anthocyanin powders, the total anthocyanin content and encapsulation efficiency of the foam mat-dried powders were comparable and higher to those of the spray- and freeze-dried powders, respectively. However, the solubility and dispersibility of the foam mat-dried powders were lower. The morphology of the foam mat-dried powder showed a smooth, flat shape, with a larger size than the spray- and freeze-dried powders.

摘要

研究了黑米糠花青素提取物制备速溶粉的发泡条件和风干温度。使用响应面法 (RSM) 优化了形成具有最大膨胀度、泡沫密度和泡沫稳定性的泡沫所需的条件，这些条件有助于提高使用热空气干燥器干燥泡沫的效率。研究了两个自变量：发泡剂浓度（0.02-0.10%，w/w）和搅打时间（7.93-22.1 分钟）。RSM 的最佳发泡条件是 0.06% (w/w) 的发泡剂和 16.1 分钟的搅打时间，提供具有最高膨胀度 (218%)、泡沫密度 (0.31 g/mL) 和泡沫稳定性 (79.3%) 的泡沫。泡沫在不同温度（60、70 和 80 °C）下干燥。在 80 °C 时观察到泡沫垫干燥粉末的最佳质量。与喷雾干燥和冷冻干燥的花青素粉末相比，泡沫垫干燥粉末的总花青素含量和包封率分别与喷雾干燥粉末和冷冻干燥粉末相当，甚至更高。然而，泡沫垫干燥粉末的溶解度和分散性较低。泡沫垫干燥粉末的形态呈光滑、扁平的形状，尺寸大于喷雾干燥和冷冻干燥的粉末。