Effects of Shear and Heat Milling Treatment on Thermal Properties and Molecular Structures of Rice Starch

Abstract

The effects of a previously reported shear and heat milling machine (SHMM) on the crystallinity and molecular architecture of starch are examined. The SHMM produces amorphous starch flour from rice grains containing crystalline starch. A high temperature of 120 °C and a distance of 10 µm between milling mortars were essential for the complete conversion of crystalline starch to amorphous starch. The effects of increasing the gap between mortars to 100 µm and decreasing the temperature to 15 °C were tested. The use of highly dried rice flour containing only 1% water (w/w) was also examined. The results suggest that the transition from crystalline starch to amorphous starch produced by the SHMM is a gelatinization process because a significant amount of water in the rice grains contributes to the formation of amorphous starch. It was also found that high temperature milling specifically, but only partially, cleaved the cluster‐interconnecting chains of amylopectin, resulting in the formation of glucans smaller than normal amylopectin. Novel finding from these results is that the coordinated action of high temperature milling, a small gap, and endogenous water in amylopectin induces gelatinization, accompanied by a reduction in the molecular weight of amylopectin cut at the B2‐3 branches.

13C CP/MAS NMR Can Discriminate Genetic Backgrounds of Rice Starch

“…Most rice starches have the A-type ordered structure, whereas the BEIIb-deficient mutant has the B-type ordered structure, 32 and only the starch derived from the SSIIIa/BEIIb-deficient mutant has the B-type ordered structure. Rice flour of Nipponbare was treated using a shear and heat milling machine 33 (SHMM) to obtain starch with an amorphous (nonordered) structure.…”

Effect of conditions of shear and heat milling machine on structures and properties of rice batter

“…Figure 1 shows a schematic diagram of SHMM. The crystallinity of the rice flour can be controlled by adjusting the temperature, moisture content, and the distance between the mortars of SHMM (Katsuno et al, 2010;Murakami et al, 2018).…”

“…The amount of water was arbitrarily adjusted for each sample. ing was examined at 15°C milling temperature (Katsuno et al, 2010;Murakami et al, 2018).…”

“…In order to develop a gluten-free product that can serve as a corresponding diet for people with CD, research on gluten-free bread in which wheat is replaced by rice flour has been actively conducted (Hera et al, 2013(Hera et al, , 2014Kang et al, 2015;Katsuno et al, 2010;Lorenzo et al, 2009;Murakami et al, 2015Murakami et al, , 2018Nakano et al, 2018;Shibata et al, 2018;Sivaramakrishnan et al, 2004`;Witczak et al, 2010;Yano et al, 2016). Models of rice flour batters were proposed based on their macroscopic appearances and mesoscopic polarized light microscopy images.…”

Application of Shear and Heat Milling Machine for Amorphization of Tapioca Starch

“…[9] SHMMs continuously apply mechanical shear and heat to starch granules in rice flour, weakening the double helices, and decreasing the crystallinity of the flour without additional of water. [9,10] Most amorphization studies using an SHMM have focused on rice and investigated the effect of milling temperature, moisture content (MC), and clearance between the upper and lower mortars on rice flour crystallinity, molecular structure, and thermal properties. [9,10] In this study, we examined amorphous tapioca starch produced using an SHMM by varying the milling temperature and MC of the tapioca starch before milling.…”