Reducing the glycemic index of short dough biscuits by using apple pomace as a functional ingredient

The present research aimed at enriching short dough biscuits with apple pomace to reduce their glycemic index. Apple pomace produced on a laboratory scale was dehydrated and milled to a powder, which was characterized for soluble and insoluble dietary fiber, and for phenolic content. Apple pomace was used to partially replace wheat flour (10 and 20% w/w) in biscuits, which were characterized for their sensory properties and submitted to in vitro digestion to predict the glycemic index. Results indicated that apple pomace contained impressive amounts of dietary fiber (nearly 40%), mainly represented by insoluble fiber (more than 25%). Apple pomace led to a significant reduction in the expected glycemic index of reformulated biscuits. The conventional biscuit presented a glycemic index of 70 and was thus classified as high glycemic index food. Substituting wheat flour by 10 and 20% with apple pomace reduced biscuit glycemic index to 65 and 60 respectively, thus ranking the product within the intermediate glycemic index foods. Using industrial apple pomace led to analogous results, demonstrating that this by-product could be exploited to reduce the glycemic index of bakery foods, thus concomitantly satisfying the need for strategies to manage type 2 diabetes and to valorize food by-products.