Development, Quantification, Method Validation, and Stability Study of a Novel Fuco­xanthin-Fortified Milk

To extend the scope of application of fuco­xanthin, a marine carotenoid, whole milk (WM) and skimmed milk (SM) were fortified with fuco­xanthin isolated from the microalga Phaeodactylum tricornutum to a final 8 μg/mL milk solution concentration. Using these liquid systems, a fuco­xanthin analysis method implementing extraction and HPLC-DAD was developed and validated by accuracy, precision, system suitability, and robustness tests. The current method demonstrated good linearity over the range of 0.125–100 μg/mL fuco­xanthin with R 2 = 1.0000, and all validation data supported its adequacy for use in fuco­xanthin analysis from milk solution. To investigate fuco­xanthin stability during milk production and distribution, fuco­xanthin content was examined during storage, pasteurization, and drying processes under various conditions. Fuco­xanthin in milk solutions showed better stabilizing effect in 1 month of storage period. Degradation rate constant (k) on fuco­xanthin during this storage period suggested that fuco­xanthin stability might be negatively correlated with decrease of temperature and increase of protein content such as casein and whey protein in milk matrix. In a comparison between SM and WM, fuco­xantin in SM always showed better stability than that in WM during storage and three kinds of drying processes. This effect was also deduced to relate with protein content. In the pasteurization step, >91% of fuco­xanthin was retained after three pasteurization processes even though the above trend was not found. This study demonstrated for the first time that milk products can be used as a basic food matrix for fuco­xanthin application and that protein content in milk is an important factor for fuco­xanthin stability.