In this study, we investigated the interaction of Vaccinium bracteatum Thunb. leaf (VBTL) pigment and
rice proteins. In the presence of rice protein, VBTL pigment antioxidant activity and free polyphenol content
decreased by 67.19% and 68.11%, respectively, and L* of the protein–pigment complex decreased significantly
over time. L* values of albumin, globulin and glutelin during 60-min pigment exposure
decreased by 55.00, 57.14, and 54.30%, respectively, indicating that these proteins had bound to the pigment.
A significant difference in protein surface hydrophobicity was observed between rice proteins and
pigment–protein complexes, indicating that hydrophobic interaction is a major binding mechanism
between VBTL pigment and rice proteins. A significant difference in secondary structures between proteins
and protein–pigment complexes was also uncovered, indicating that hydrogen bonding may be
another mode of interaction between VBTL pigment and rice proteins. Our results indicate that VBTL pigment
can stain rice proteins with hydrophobic and hydrogen interactions.
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