Rheological, texture, structural, and functional properties of Greek-style yogurt fortified with cheese whey-spent coffee ground powder

Abstract The present study evaluated the feasibility of the fortification of Greek-style yogurt with a newly developed ingredient consisting of cheese whey-spent coffee ground (CW-SCG) powder. The yogurts were analyzed using a battery of tests, including whey production, water holding capacity, firmness, rheological properties, protein content, available lysine, and antioxidant activity. The milk base was fortified to 15% dry matter with different skim milk powder to CW-SCG ratios (100/0, 75/25, 25/75, and 0/100 wt/wt.). Fortification of the yogurt with CW-SCG decreased the water holding capacity by 13–25%, depending on the level of fortification. Similarly, the addition of CW-SCG significantly decreased the hardness of the yogurts from 76.57 ± 1.18 to 30.27 ± 1.73 N s. Additionally, fortified yogurts with CW-SCG yielded a product with less shear-thinning behavior as compared to control. The microstructure of the fortified yogurts revealed the incorporation of spent coffee ground particles within the protein network. Polyphenol-protein associations may explain the texture and rheological behavior of the yogurts. The fortification of the yogurt up to 25% of CW-SCG yielded comparable properties than the control.