Effect of Ultrasound‐Assisted Isolation on Yield and Properties of High‐Amylose Starch from Amylomaize

Abstract

Effect of ultrasound‐assisted wet‐milling on yield and properties of high amylose starch from amylomaize was investigated. The defibered mixture of starch and protein (mill starch) was sonicated by an ultrasonic processor. The highest yield of 56.68 % was obtained with steeping time of 36 h, ultrasonic power of 200 W, ultrasonic time of 15 min, and mill starch to water ratio of 1:1, while maintaining SO2 concentration of 0.05% in steepwater and a constant ultrasound frequency of 20 kHz. The starch isolated by sonication showed significantly lower b values (yellowness). Ultrasound did not cause changes in starch granular size, morphology, surface, and ordered structures at both short‐range and long‐range scale (p>0.05). The effect of ultrasound was also insignificant on thermal properties (p>0.05). The results demonstrated that the ultrasound did not alter the structures and properties of the isolated starches. Approximately 11% of starch yield was increased, 75% of SO2 content in steepwater was reduced and 25 % of steeping time was reduced by ultrasound‐assisted method compared with those of conventional wet‐milling process.

Effects of Extrusion‐Assisted Wet‐milling Isolation on Physicochemical Properties of Corn Starch

“…As presented in Figure 2A, isolated corn starch granules showed typical polygonal and oval shapes, which was in agreement with the result of previous literature. [ 2 ] There was no obvious difference in the surface morphology among isolated corn starches with different methods (Figure 2A−A), suggesting that extrusion pretreatment did not damage the surface of isolated corn starch granules. This phenomenon was consistent with the results of damaged starch content (Table 1).…”

“…Optimal steeping time, concentration of SO 2 , duration time, and sonication power are beneficial for obtaining the starch with a high yield and degree of purity. [ 2 ] However, sonication could destroy the internal structure of starch granules, which restricts the industrial application of isolated starch. Additionally, a new reducing agent ( l ‐cysteine) was successfully introduced in the corn wet‐milling process in order to reduce the amount of SO 2 .…”

Critical role of glutelin in ultrasound‐assisted isolation of corn starch

“…Corn protein (gluten meal) was obtained according to the method described by Liu et al . (2019). Briefly, ultrasound was used to separate corn starch and protein via laboratory‐scale corn wet‐milling.…”

“…Previous investigations have proved that starch isolated by laboratoryscale corn wet-milling with the assistance of ultrasound can maintain its granular, exterior and crystalline structure. Ultrasound treatment was reported to effectively enhance starch-protein separation in the wetmilling of dent corn starch, as well as high-amylose starch isolation (Liu et al, 2019(Liu et al, , 2020. Approximately 10% of the starch yield was increased, 75% of sulphur dioxide (SO 2 ) content in steepwater was reduced, and there was a 33% reduction in steeping time with the ultrasound-assisted method compared with the conventional wet-milling process (Liu et al, 2020).…”

“…Approximately 10% of the starch yield was increased, 75% of sulphur dioxide (SO 2 ) content in steepwater was reduced, and there was a 33% reduction in steeping time with the ultrasound‐assisted method compared with the conventional wet‐milling process (Liu et al ., 2020). Furthermore, the whiteness and the physical properties of ultrasound‐produced starches also improved (Liu et al ., 2019). Other cereal starches, such as those isolated from wheat, barley, rice and sorghum by sonication, presented similar results (Park et al ., 2006).…”