Oxidative stability of functional phytosterol-enriched dark chocolate

A dark chocolate containing phytosterols (PS) esters was developed to reduce cholesterol in individuals. However, oxidative instability during chocolate processing and storage could reduce the PS bioactivity. Chocolate bars were prepared containing palm oil (CONT) or 2.2 g of PS (PHYT). All samples were stored at 20°C and 30°C during 5 months. A peak of hydroperoxides formation was observed after 60 days at 20°C and after 30 days at 30°C. PS-enriched samples presented higher values of hydroperoxides than control samples, which could be attributed to the higher level of alpha-linolenic acid present in the PHYT samples. All chocolate bars became lighter and softer after 90 days of storage. However, these physical changes did not reduce their sensory acceptability. In addition, PS bioactivity was kept during the storage, since no significant alterations in the PS esters were observed up to 5 months. However, some PS oxidation occurred in the PHYT bars, being sitostanetriol, 6-ketositosterol, 6beta-hydroxycampesterol and 7-ketocampesterol the major phytosterol oxidation products (POPs). The POPs/PS ratio was low (0.001). Therefore, the dark chocolate bars developed in this study kept their potential functionality after 5 months of storage at room temperature, representing an option as a functional food.