Low and high amylose maize starches acetylated by a commercial or a laboratory process both deliver acetate to the large bowel of rats

Short chain fatty acids (SCFA) produced by large bowel bacterial fermentation of carbohydrates promote normal colonic function and health. Previous studies in rats have shown that starches acylated with SCFA to a high degree of substitution (DS) resist small intestinal digestion and pass into the large bowel where the acids are released by bacterial enzyme activity. These studies were conducted with starches manufactured from low or high amylose starches manufactured in the laboratory or commercially. In this study, a direct comparison was made between acetylated low and high amylose maize starch manufactured in the laboratory and high amylose maize starch acetylated commercially. Compared to a standard maize starch, all acetylated starches raised large bowel pools of acetate (by as much as 10-fold) and total SCFA (by between 320% and 775%) when fed to rats. They also raised large bowel digesta mass by as much as 2-fold and lowered pH by up to 28%. These changes were observed when the background diet contained unmodified low or high amylose starch, although the changes were greatest with high amylose maize starch which is consistent with its resistance to digestion. The data confirm that acylated starches are a viable means of raising specific large bowel SCFA, independent of the manufacturing process.