Matrix-Dependent Antimicrobial Effects of Elderberry Extract and Juice in Protein-Rich Foods

ABSTRACTObjective: Microbial spoilage is often controlled with synthetic preservatives in protein-rich foods. Although elderberry (Sambucus nigra L.), rich in phenolics and anthocyanins, has strong antimicrobial potential, its effects in different food matrices have not yet been adequately investigated. This study aimed to comparatively evaluate the antimicrobial activity of elderberry ethanol extract (EE) and elderberry juice (EJ) in yoghurt, curd cheese, and fish cutlets. Materials and Methods: EE and EJ were prepared from dried elderberries and tested at 0.05%, 0.1%, 0.75%, and 1% in yogurt, curd cheese, and fish cutlets stored at 4 °C for 14 days. Microbial loads were measured on days 1, 7, and 14 using plate counts, expressed as log CFU/g. Data were analyzed with Mann–Whitney U and Kruskal–Wallis H tests. Results: EE had a higher °Brix value (39.8 °Bx) than EJ (10.2 °Bx), indicating more soluble solids. EE and EJ produced matrix-dependent antimicrobial effects. EE showed stronger inhibition in curd cheese and fish cutlets, especially at higher doses, while EJ was more effective in reducing mold-yeast load in yogurt. Meaningful reductions appeared mainly at ≥0.75%. Conclusion: Elderberry juice and ethanol extract demonstrated matrix-dependent antimicrobial effects, indicating their potential as natural preservatives in protein-rich foods.