Background. The fruit and vegetable processing industry plays a key role in the agri-food industry. Nowadays, the huge quantities of fruit and waste disposed have attracted the attention of several sectors worldwide, not only because of the concern over environmental impacts but also because of the high proportions of nutrients and bioactive compounds these inedible parts can  provide. This study explores the valorization of fruit waste through the incorporation of banana and mandarin peel powder (PP) into cerealbased products as an approach to support  sustainability and healthy diet. Banana and mandarin peels were processed into a powder form and added to muffins and cookies at concentrations of 3 %, 5 % and 8 %. The samples were  analyzed on the day of preparation as well as after 1, 2, 3 and 5 days of storage.
Results and conclusions. Comprehensive physico-chemical analyses demonstrated improvements in nutritional and functional properties compared to control samples. Specifically, the addition of peel powder resulted in elevated energy values, enhanced the nutritional quality by increasing the protein content (up to 12.8 %), total fat (up to 7.84 %), total carbohydrates (up to 11.4 %),  total ash (up to 76.9 %), and total vitamin C content (up to 3.95-fold). Furthermore, fruit peel powder acted as a moisture binder agent, by reducing the moisture content and water activity  potentially extending product shelf life. Mandarin peel powder exerted a more pronounced effect on physico-chemical characteristics compared to banana peel powder. Additionally, the  incorporation of fruit peel powder substantially elevated the levels of total polyphenols, flavonoids and antioxidant activity, with values up to 2.7-fold higher than the control samples. Sensory evaluations confirmed the acceptability of the products, with overall quality ratings ranging from 6.6 to 8.2 on a 9-point hedonic scale. This research underscores the viability of fruit peel  powder as a sustainable ingredient for reducing food waste, while enhancing the nutritional profile and functionality of cereal-based products.