Effect of Evening Primrose-Derived Ingredients on the Fatty Acid Profile, Tocopherol Content, and Quality Attributes of Dark Chocolate

This study evaluated the effect of evening primrose seed, cold-pressed oil, and defatted seed meal on the fatty acid composition, tocopherol content, physical properties, sensory acceptance, and oxidative stability of dark chocolate. Samples were prepared under controlled laboratory conditions with 2.5% or 5% of the tested ingredients and stored for 8 months. All ingredients introduced α-linolenic and γ-linolenic acids, and increased tocopherol content, with the strongest effect observed in the oil-fortified chocolate. After storage, moderate losses of tocopherols were detected, while oxidation indices confirmed acceptable oxidative stability of the fortified chocolates. Viscosity dependent on the type of added ingredient, with the oil-containing formulation showing the most favorable technological profile. Color parameters remained largely unchanged, except for the sample with added oil, and hardness was affected mainly by seed and meal additions. Sensory scores remained within the acceptable range for all samples (5–8.5 points on a 9-point hedonic scale). Overall, evening primrose ingredients can be successfully used as functional additives in dark chocolate. Among the tested formulations, evening primrose oil provided the greatest improvement in the lipid profile and maintained acceptable physical and sensory properties. However, the slightly greater changes observed in this formulation may be important when determining shelf life.