Effects of β-Amylolysis on the Resistant Starch Formation of Debranched Corn Starches

Abstract

Retrograded amylose is resistant to digestion by amylolytic enzymes, which is known as resistant starch type III (RS3). In this study we investigated the effect of β-amylase hydrolysis on the formation and physicochemical properties of RS3 from debranched corn starches. Three types of corn starch (Hylon VII, Hylon V, and common corn) were first gelatinized and then hydrolyzed using β-amylase to varying degrees. The resultant hydrolyzed starch was debranched with isoamylase and then exposed to temperature cycling to promote RS formation. A broad endotherm from approximately 45 to 120 °C and a small endotherm above 150 °C were noted for all retrograded starches. All three corn starches had increased RS contents after moderate β-amylolysis, with Hylon V having the highest RS content at 70.7% after 4 h of β-amylolysis. The results suggest that RS3 formation is affected by the starch composition as well as the starch structure and can be increased by moderate β-amylolysis.

Effects of α‐maltotriohydrolase hydrolysis prior to debranching on the structure and digestibility of normal maize starch

“…The debranched‐only and AMTS‐treated starches showed a B‐type crystalline pattern, with major peaks at 17.8°, 22.4°, and 24.1° and minor peaks at 14.1°, 15.1°, and 19.5°. The B‐type crystalline patterns have also been reported in studies on retrograded maize starch , chickpea starch , and potato starch and arrowroot starch . The diffraction patterns of AMTS‐pullulanase‐treated starches displayed more intense and defined peaks than the debranched‐only and native starch.…”

“…For F3, which comprises short chains of amylopectin with a DP of 13-30, normal maize starch exhibited an initial decrease, followed by an increase later on in the AMTS hydrolysis. Similar trends of an initial increase in medium-length chains and a decrease in short chains were observed in normal maize starch during moderate b-amylolysis [7]. The F4 fraction consisted of very short chains from amylopectin with a DP of less than 13, and changed slightly during moderate levels of AMTS hydrolysis, and significantly increased at higher levels of hydrolysis.…”

“…The AMTS hydrolyisis before debranching significantly improved the RS3 formation in retrograded starches. The breakdown of the starch molecules into lower molecular weight molecules increased the number of smaller linear molecules with greater mobility and a greater tendency toward retrogradation . The linear starch chains released after AMTS action followed by debranching by pullulanase were more appropriate in size for reaccociation and recrystallization during starch retrogradation.…”

“…To the best of our knowledge, this is the first report on using AMTS and debranching enzyme in RS3‐rich products preparation. Moreover, normal maize starch was one of the most largely produced starch in the world and frequently used in RS3 preparation as the raw material . Therefore, in this study, normal maize starch was gelatinized and hydrolyzed to various degrees by AMTS, debranched by pullulanase and then retrograded.…”

Analysis of crystals of retrograded starch with sharp X-ray diffraction peaks made by recrystallization of amylose and amylopectin

“…[33] Figures 4b and 4c show the X-ray diffraction of the blending of sweet potato amylose and amylopectin. The results show that the interaction of sweet potato amylose and amylopectin during retrogradation gives rise to crystal with 2θ angles at 14 [ [35][36][37] According to literature, retrograded corn/pulse starch displays a typical B + V [35] or A + B-type [37] crystalline structure, which is obviously distinct from the results in Fig. 4b and 4c.…”