Apple Pomace as a Potential Ingredient for the Development of New Functional Foods

Apple pomace (AP) is the main by-product of cider industry being mainly composed of carbohydrates and dietary fibre, small amounts of protein, fat and ash. In addition AP is also a good source of phytochemicals such as phenolic acids and flavonoids making AP a valuable source of antioxidants. The common applications of this by-product are the direct disposal to soil in a landfill and for pectin recovery usage. These applications are not sufficient to drain the several tonnes produced every year and studies to valorise the AP for other purposes have gained momentum. AP due to its chemical composition, rich in fibre with significant amounts of antioxidants, can be incorporated in human food-chain thus generating new potential functional foods. Extruded snacks and baked scones were incorporated with increasing levels (0-30%) of AP. The incorporation of AP from the chemical and nutritional analysis was successful with 20% addition in extruded snacks and 30% addition in baked scones. At these levels of incorporation fibre content, phenolic content and antioxidant capacity (DPPH radical scavenging activity, FRAP and β-carotene/linoleic acid system) increased when compared to the products with no AP incorporation. Chlorogenic acid and quercetin were the major phenolic compounds of AP incorporated extruded and baked products. Feruloylquinic acid, isorhamnetin/rhamnetin, phloretin, luteolin and rutin were also present in the AP based products. The AP incorporated baked products also showed the presence of catechin/epicatechin and phloridzin. Nevertheless, compounds other than phenolics affected the antioxidant activities of AP incorporated extruded and baked products probably products resulting from Maillard reaction. These data suggest that AP from a chemical and nutritional point of view can be successfully incorporated in extruded and baked products conferring fibre and antioxidant properties to the final products