Understanding the changes in particle size, structure, and functional properties of waxy maize starch after jet‐milling treatments

Abstract

AbstractWaxy maize starch was subjected to fluidized bed jet milling treatments at classifier frequencies of 2,400, 3,000, and 3,600 rpm. Changes in the structure and physicochemical properties of waxy maize starch after jet milling were investigated and compared with the untreated starch. With an increase in classifier frequency, the particle size of starch significantly (p < .05) decreased and showed bimodal distribution after jet milling. The microscopy analysis indicated that surface of starch granules became rough with irregular shapes after jet milling treatment compared to smooth and regular shape for the untreated starch. The birefringence and X‐ray diffraction analyses showed that the jet milling destroyed the crystalline areas and decreased crystallinity of the starch. The micronized starch samples showed significantly lower (p < .05) gelatinization temperature, enthalpy, and viscosity than those of the untreated starch. However, an increase in special surface area, water solubility, swelling power, and pasting stability was found after jet milling of the waxy maize starch. Additionally, light transparency of the starch increased as temperature increased but decreased with storage time. The observed results showed that modified starch can be produced by jet milling.