SOLUBLE NONSTARCH POLYSACCHARIDES DERIVED FROM COMPLEX FOOD MATRICES DO NOT INCREASE AVERAGE LIPID DROPLET SIZE DURING GASTRIC LIPID EMULSIFICATION IN RATS

The creation of a finely dispersed lipid emulsion is essential for eff icient hydrolysis of dietary triglycerides. The effectiveness of emuls ification within the stomach depends upon the shear force generated by gastric motility and the concentration of emulsifiers present in the gastric contents. Other dietary constituents can modify these factors, and previous studies have suggested that the presence of soluble non- starch polysaccharides (NSP) during digestion might increase the avera ge size of intraluminal emulsion droplets, In the present study, we de veloped a new technique for the isolation and analysis of intraluminal lipid emulsions by optical diffraction analysis. The method was appli ed to rats fed powdered semipurified diets that were free of all NSP o r supplemented with insoluble cellulose, guar gum, or NSP derived from apple, carrot or rolled oats. Cellulose had no significant effect on emulsion size, and there was no evidence that the average sizes of lip id droplets in the gastric fundus or antrum were higher than control v alues in rats fed diets supplemented with any source of soluble NSP. I n the groups fed oats and cooked carrot NSP, the mean droplet diameter s approached half the values for diets free of NSP or containing insol uble cellulose. The difference between rats fed NSP from cooked carrot and those fed cellulose was significant in the proximal stomach (P < 0.05), and that between rats fed raw oats and rats fed cellulose was s ignificant in the distal stomach (P < 0.05). Soluble dietary fiber doe s not inhibit lipid or cholesterol absorption via any inhibition of li pid emulsification.