2.10.2. Determination of Combination Index

In this study, the concept of combination index (CI) for the theoretical basis simulation of synergism and antagonism in drug combination studies, proposed in the studies of Chou [29], was applied for the determination of the effect of phenolics–food matrix interactions.

The combination index was calculated as follows:

where: PV—predicted value for phenolic content or antioxidant activity; EV—experimental value for phenolic content or antioxidant activity.

CI = 1 indicates the lack of an influence of the phenolics–food matrix interactions on the phenolics content or antioxidant activity (PV = EV), CI > 1 indicates a negative effect of the phenolics–food matrix interactions on the phenolics content or antioxidant activity (PV > EV), and CI < 1 indicates a positive effect of the phenolics–food matrix interactions on the phenolics content or antioxidant activity (PV < EV).