Thermo-mechanical rice flour modification by planetary ball milling

Abstract

Planetary ball milling is presented as an alternative way to improve the native flour properties by physical modification. A grinding protocol was developed by combination of grinding and pause stages. The effect of rotational speed (450–650 rpm) and milling time (10–20 min) on flour properties were determined using RSM method. The effect of milling conditions on flour attributes was significant. With increasing milling speed and time a significant increase in damaged starch, water-absorption and solubility indexes was observed. Changes in functional attributes, intrinsically related to structural and morphological properties of rice flour, were satisfactorily correlated with crystallinity loss, specific surface area and gelatinization degree. Modified rice flours presented pre-gelatinized characteristics which can offer new opportunities for flour applications, for example as ingredient for instant meal product. Flour modification can be controlled by selecting milling conditions. The distinctive characteristic of the planetary ball mill was the fast speed with which the modified flour was obtained which presented intermediate characteristics in relation with native and amorphous state.