Abstract:

Tomato peel is a by-product of tomato sauce processing. Dietary fiber from tomato peel was subjected to
ordinary extrusion or carbon dioxide blasting enhanced extrusion for modification. The changes in the composition, surface
morphology, primary structure and crystal structure before and after modification were monitored to assess the effectiveness
of both treatments. The results showed that both treatments did not alter the content of total dietary fiber from the tomato
skin, but significantly increased the content of soluble dietary fiber, and also significantly changed its composition and
structural properties. The amount of soluble dietary fiber from the tomato skin treated with ordinary extrusion and carbon
dioxide blasting enhanced extrusion, respectively, could increase from (3.40 ± 0.23) g/100 g to (5.86 ± 0.29) g/100 g and
(12.13 ± 0.37) g/100 g, indicating better performance of carbon dioxide blasting enhanced extrusion. The increase of soluble
dietary fiber was derived from the degradation of insoluble dietary fiber. After being treated with carbon dioxide blasting enhanced
extrusion, the tomato peel dietary fiber had rough surface, significantly reduced size and decreased crystallinity.

Key words: dietary fiber, extrusion, tomato peel, chemical composition, modification