This study investigates the effects of free (OLE) and encapsulated olive leaf extract (E-OLE) on the functional and quality parameters of Cantal-type cheese during 63 days of cold storage at 2 °C. Cheeses were supplemented with 1.0%, 2.0%, and 3.0% (w/w) of OLE or E-OLE. To ensure comparability between extract forms, E-OLE concentrations were normalized based on total phenolic content (TPC) to match the corresponding OLE levels.

Analyses were conducted to evaluate effects on physicochemical composition, antioxidant activity (TPC and ABTS), microbial counts, texture, rheological behavior, and color. E-OLE significantly increased protein and dry matter content while reducing fat and chloride levels. Both extracts enhanced antioxidant capacity and reduced the abundance of total aerobic mesophilic bacteria, indicating improved microbial stability.

Textural analysis showed that E-OLE increased firmness and cohesiveness while reducing elasticity, likely due to interactions between phenolics and the cheese matrix. OLE caused minimal textural changes, especially at 1.0–2.0%. In terms of color, both extracts caused a concentration-dependent reduction in lightness (L*) and an increase in redness (a*) and yellowness (b*). OLE led to more pronounced and progressive color changes over time, attributed to pigment diffusion. In contrast, E-OLE caused more moderate and stable changes due to the protective effect of the encapsulation matrix (sodium caseinate and maltodextrin), which limited pigment release and preserved visual clarity.

Although no sensory analysis was conducted, the integrated data suggest that 2.0% E-OLE achieves an optimal balance of antioxidant activity, microbial quality, physicochemical integrity, texture, and acceptable color. For OLE, this balance appears optimal at 1.0%. These findings support E-OLE as a promising natural additive for enhancing the functional quality of dairy products, particularly in cheese fortification.