Effect of oil viscosity on oil migration in a two-phase model system (cream-filled chocolate)

•Viscosity of oil affects oil migration in non-tempered cocoa butter matrix.•High oil viscosity results in low oil migration rate and diffusion coefficient.•Critical viscosity above 60 cP results in significant decrease in oil migration.•Use of high viscosity oil could extend shelf-life of cream-filled chocolate.

Using tricaprylin, flaxseed oil, safflower oil, and peanut oil, we investigated the effect of oil viscosity on oil migration in a two-phase model system, to understand oil migration in cream-filled chocolate products. Non-tempered cocoa butter was used as the matrix, while interesterified hydrogenated palm oil mixed with each of the oils (60:40 w/w) was used as the cream phase. Oil migration was monitored using a flatbed scanner. Results of our study showed that tricaprylin, which had the lowest viscosity of about 37.2 mPa·s at 18 °C, exhibited the highest oil migration rate and diffusion coefficient; while flaxseed oil, safflower oil, and peanut oil with viscosities of about 60, 73.6, and 97.2 mPa·s at 18 °C, respectively, showed low oil migration rates and diffusion coefficients. These findings support the fact that as oil viscosity increases, oil migration rate decreases. Furthermore, a critical viscosity of above 60 mPa·s was found to significantly decrease oil migration rate, and therefore extend the shelf life of cream-filled chocolate products. The current study provides an experimental evidence and practical information to confirm existing knowledge, which is valuable for the understanding of oil migration in cream-filled chocolate products.