Stability of β-carotene microcapsules with Maillard reaction products derived from whey protein isolate and galactose as coating materials.

The stability of β-carotene microcapsules using Maillard reaction products (MRPs) derived from whey protein isolate (WPI) and galactose as coating materials, was studied under the varying environmental conditions of temperature, pH, air, incandescent light, and ultraviolet (UV) light. Scanning electron microscopy showed that microcapsules prepared by WPI-galactose MRPs displayed a smooth and less concave-convex surface and that the particle size (D) of the microcapsules made with WPI-galactose MRPs was smaller than those made with WPI-galactose mixture. The storage stability of β-carotene microencapsulated in WPI-galactose MRPs was remarkably better than that of β-carotene microencapsulated in the WPI-galactose mixture and that of β-carotene crystal, in respect of temperature, pH, air, incandescent light, and UV light measurements. When the storage temperature was increased from 5 to 105 °C, the retention rate of β-carotene microcapsules significantly decreased (P<0.05). When pH values were increased from 1 to 12, the β-carotene retention rate of the microcapsules significantly increased and afterward decreased. Compared with the retention rate of β-carotene microencapsulated in a WPI-galactose mixture, the retention rate of β-carotene microencapsulated in WPI-galactose MRPs was at a maximum between pH 8 and 9. Under the actions of air, incandescent light, and UV light, the retention rates of β-carotene microcapsules in WPI-galactose MRPs and WPI-galactose mixture, as well as in β-carotene crystal, decreased significantly as the storage time increased (P<0.05). Therefore, the use of WPI-galactose MRPs as coating materials can aid in improving the storage stability of β-carotene microcapsules.