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1‐Butanol‐Hydrochloric Acid Hydrolysis of High‐Amylose Maize Starch

Hu, Xiuting, Wang, Yu, Liu, Chengmei, Jin, Zhengyu, Tian, Yaoqi
DieStärke = 2018 v.70 no.5-6 pp. e1700359
acid hydrolysis, amylose, anion exchange chromatography, butanol, corn starch, granules, hydrochloric acid, iodine, molecular weight, staining
The 1‐butanol‐hydrochloric acid (1‐butanol‐HCl) degradation mechanism of high‐amylose maize starch, represented by amylomaize V, is investigated using different methods. More pores are formed in the amylomaize V granules during 1‐butanol‐HCl hydrolysis and these pores become larger and change into cracks. Correspondingly, the average granule size slightly decreases from 13.49 to 10.87 µm after 1‐butanol‐HCl hydrolysis for 7 d. The crystalline areas of amylomaize V are hydrolyzed by 1‐butanol‐HCl and the amylose‐1‐butanol complex might form. In addition, the weight‐average molecular weight of amylomaize V dramatically decreases from 1.25 × 10⁷ to 3.57 × 10⁵ Da after hydrolysis for 4 h, then slowly decreases, and stabilizes at about 2.00 × 10⁴ Da after hydrolysis for 4 d, which is in accordance with the result of iodine staining analysis. High‐performance anion‐exchange chromatography analysis indicates that 1‐butanol‐HCl can hydrolyze the starch like hydrolysis patterns of both the endo‐enzyme and the exo‐enzyme. These results suggests that HCl in 1‐butanol quickly diffuses into the whole amylomazie V granule and simultaneously attacks the crystalline and disorder areas, while the compact periphery of amylomaize V keeps the granules from disintegrating.