Evaluation of Physico-chemical Properties of Yogurt Low Fat Enriched with Malus sylvestris Peel Extract for Antioxidant

Background: The rising demand for functional foods has encouraged the utilization of natural antioxidants from agricultural byproducts to enhance food quality and sustainability. Apple peels (Malus sylvestris), rich in phenolic compounds like quercetin, offer strong antioxidant properties and health benefits, yet are often discarded as waste. Fortifying yogurt with such bioactive-rich extracts presents an opportunity to improve its functional value while addressing environmental concerns. However, this process requires careful evaluation of how the extract affects yogurt’s physico-chemical characteristics and antioxidant capacity. Methods: A completely randomized design with six treatment groups (0%, 2%, 4%, 6%, 8% and 10% fruit peel extract) and triplicate samples was used. The test parameters performed were viscosity, syneresis, water holding capacity, emulsion activity index, antioxidant DPPH IC₅₀ and phenolic content, with one-way ANOVA and Duncan’s test (P<0.05) applied to analyze the differences. Fourier transform infrared spectroscopy (FTIR) was analyzed descriptively. Higher concentrations of fruit peel extract resulted in decreased viscosity and syneresis, increased water holding capacity and emulsion activity. Result: Higher concentrations of fruit peel extract resulted in decreased viscosity and syneresis, but increased water holding capacity and emulsion activity. Antioxidant metrics showed a significant decrease in IC₅₀ values and an increase in total phenolic content. The enrichment of yogurt with apple peel extract not only improved functional properties but also enhanced compositional parameters, particularly phenolic compounds such as quercetin, which were confirmed by FTIR analysis. These compositional changes were strongly correlated with the improved antioxidant activity and stability of the yogurt matrix.