Functional ready-to-eat cereal-based snacks supplemented with food by-products

With the increasing population and food shortages, the need for innovative approaches to producing foods with high nutritional value has become more pronounced. In this study, we investigated the impact of incorporating apple pomace (AP) and wheat bran (WB) which are rich in phenolics and fiber into extruded snacks made from oat and broken rice. The central composite design was used to examine the effects of screw speed (120-200 rpm), feed moisture (14-22%), and AP/WB ratios (25:75, 50:50, 75:25) on the physicochemical, microstructural, functional, and antioxidant properties of the snacks. Our results demonstrated that incorporating AP and WB significantly enhanced the nutritional and functional properties of the extruded snacks. Increasing the AP ratio led to improved functional properties while concurrently reducing the expansion index and cell wall thickness. Furthermore, an increase in screw speed from 120 to 160 rpm resulted in a noticeable increase in total phenolic content without reaching statistical significance (192.33-211.77 µg GA/g). Increasing the screw speed also increased the antioxidant activity (55.35-64.75%), while a further increase to 200 rpm led to a decrease in the water absorption index. Additionally, increasing feed moisture content increased water solubility index while decreasing the expansion and water absorption indices. We identified the optimal processing conditions as an AP ratio of 53.39%, a screw speed of 120 rpm, and a feed moisture content of 15.45%. These findings highlight the potential of utilizing food by-products, such as AP and WB, to create healthier and more sustainable extruded snacks while simultaneously reducing food waste and mitigating environmental pollution.

The online version contains supplementary material available at 10.1007/s13197-025-06247-6.