Effects of soluble corn fiber on in vitro hydrolytic digestion in dogs

The objective of these experiments was to measure in vitro hydrolytic digestion and glycemic and insulinemic responses of select carbohydrate blends, all containing the novel carbohydrate soluble corn fiber (SCF), in dogs.

Two SCFs that varied in their method of production were used to formulate the carbohydrate blends. One set of blends contained a SCF that was spray-dried (SCFsd), then blended with different amounts of either pullulan, sorbitol or fructose. The other set of blends contained a SCF produced using longer evaporation time (SCF), then blended with different ratios of pullulan, sorbitol and fructose.

Free sugar concentrations found in the individual SCFsd and SCF substrates were low, but varied. Spray-dried soluble corn fiber had a lower free sugar concentration compared with SCF. Glucose was the main free sugar found in both SCFsd and SCF, but at different concentrations. The majority of the SCFsd blends were completely hydrolyzed to their monosaccharide components. Glucose accounted for most of the hydrolyzed monosaccharides for SCFsd and all the SCFsd blends. Hydrolyzed monosaccharide concentrations for the SCF:pullulan:sorbitol:fructose blends followed similar trends to the SCFsd blends where greater percentages of fructose and sorbitol resulted in lower hydrolyzed monosaccharide concentrations.

The SCFsd blends had intermediate to high amounts of monosaccharides released as a result of in vitro hydrolytic digestion. The SCFsd:pullulan blends were more digestible in vitro than SCFsd:fructose or SCFsd:sorbitol. Total released monosaccharides were high in SCFsd blends containing either 50% fructose or sorbitol, but the combination resulted in lower concentrations of glucose released. The SCF:pullulan:sorbitol:fructose blends also had intermediate to high released monosaccharides as a result of in vitro hydrolytic digestion.

All SCF blends resulted in lower glycemic and insulinemic responses compared with the maltodextrin control using a canine model. The addition of pullulan reduced the glycemic response compared with maltodextrin at all concentrations, but only 50:50 SCFsd:pullulan resulted in a lowering of the glycemic response compared with SCFsd alone. The addition of fructose and sorbitol in the blends had the greatest impact on glycemic and insulinemic responses, even at concentrations as low as 5% of the blends.

Overall, SCF and their blends may prove beneficial as components of low glycemic foodstuffs.

Source:  M. R. C. de Godoy et al., 2013. Blending of soluble corn fiber with pullulan, sorbitol, or fructose attenuates glycemic and insulinemic responses in the dog and affects hydrolytic digestion in vitro. J Anim Sci online June 2013. doi: 10.2527/jas.2013-6296

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