Wu, Shufen, Bao, Yuxin, Wang, Danyang, Wang, Xiaochan, Liu, Huanhuan, Li, Zhenjing, Chen, Mianhua, Wang, Changlu, and Guo, Qingbin
Monascus pigments (Mps) have been utilized as natural food colourants in Asia for centuries. However, the poor water-solubility and photo-instability greatly restrict their applications in food industry. As a kind of orange Mps, monascorubrin (denoted as O 1) is easy to react with substances containing amino groups (named amination reactions) and turn to red colour consequently. In this study, to maintain the original colour, solid inclusion complexes of O 1 with hydroxypropyl-β-cyclodextrin (HP-β-CD) were prepared using freeze-drying method, and then investigated by SEM, FT-IR, PXRD, 1HNMR as well as molecular simulation method. Obtained results indicated that water solubility of O 1 is significantly improved and its orange colour is successfully maintained at pH 3.5–9.0 upon complexation with HP-β-CD. Structural analysis suggested that O 1 is encapsulated into the cavity of HP-β-CD, probably preventing it from amination reactions. Moreover, the pH and photo stability of Mps are markedly enhanced by complexation. This study provides an effective method for preparing water-soluble orange Mps that might be applicable in the beverage industry. • HP-β-CD was loaded by monascorubrin through freeze-drying method. • Orange-coloured complexes obtained were water soluble. • The formation of inclusion complexes was confirmed by modern testing technology. • The photostability of orange pigments was improved by the inclusion of HP-β-CD. • The orange colour of the inclusion complexes was retained at pH 3.5–9.0. [ABSTRACT FROM AUTHOR]