In vitro fecal fermentation of alginate-starch microspheres shows slow fermentation rate and increased production of butyrate.

The development of dietary fibers with slow fermentation profiles that deliver desirable fermentation products, such as butyrate, to distal regions of the colon may be beneficial for colonic health. The purpose of this study was to determine whether alginate-entrapped starch might be used for such a designed dietary fiber. Alginate-starch microspheres were prepared from 1, 2, or 3% alginate and 10% starch. A blank was also prepared using only alginate. Samples were subjected to in vitro digestion and fermentation. A sample of normal corn starch was included as a control. During fermentation, total gas volume was measured using a graduated syringe, and short chain fatty acids (SCFAs) were quantified by gas chromatography. Alginate entrapment significantly reduced starch digestion to less than 20%. During fermentation, higher alginate concentrations significantly reduced both the total and rate of gas production. This implies that the starch microspheres would not contribute to the uncomfortable bloating experienced with many dietary fibers. Increasing alginate concentration changed the rate of SCFA production from a parabolic to more linear profile, while simultaneously and substantially increasing the proportion of butyrate (of total SCFAs) produced. This suggests than starch entrapment may allow for a significant and constant, slow delivery of butyrate throughout the colon. [ABSTRACT FROM AUTHOR]