Relationship between cellulose chemical substitution, structure and fat digestion in o/w emulsions

Abstract

The effect of cellulose ether chemical substitution on the reduction of fat digestion in an o/w emulsion was investigated. Emulsions containing 47% sunflower oil and water were prepared with two types of hydroxypropyl methylcellulose (HPMC) and two types of methyl cellulose (MC), with different hydroxypropyl and methoxyl content. The changes in the emulsion structure were evaluated after mouth, stomach and small intestine in vitro digestion by Confocal laser microscopy and by small amplitude oscillatory shear (viscoelastic properties). The total amount of fat present in the supernatant after digesta centrifugation, serving as an indicator of fat bioaccessibility, and the free fatty acids, serving as an indicator of fat digestion, were determined at the end of the digestion. A relationship was found between cellulose ether chemical substitution, initial structure, structural changes during digestion, fat bioaccessibility and fat digestion. All the cellulose ether emulsions showed a lower level of fat digestion in comparison with a whey protein emulsion, the cellulose ether containing the highest amount of methoxyl being the most effective. The rise in the methoxyl content increases the emulsion viscoelastic properties before and after digestion and reduces fat bioaccessibility and the generation of free fatty acids. The decrease in the fat digestibility of the cellulose ether emulsions was mainly associated with a physical effect, which limits the emulsification of appropriate fats by bile salts, and the subsequent lipase digestion effect.