Composition and color stability of anthocyanin-based extract from purple sweet potato

In recent years, public concern about the safety of synthetic pigments led to increasing interest in the development of food colorants from plant tissues, especially from some edible sources. As a group of natural, water-soluble and nontoxic pigments, anthocyanins are widely distributed in plant world and display a variety of colors from orange to purple (Fossen et al., 1998; Janna et al., 2007; Lu et al., 2010). So, some anthocyanin-rich extracts from fruits and vegetables can be used as food colorants to replace the synthetic ones in consideration of consumer preference. In addition, anthocyanins also showed a number of biological functions, including antioxidant and anti-carcinogen activities, hepato-protection capacity and the ability to enhance memory (Cho et al., 2003; Hwang et al., 2011). Therefore, extending the use of anthocyanin-rich extracts is significant in food industry because they can provide products with potential health benefits besides attractive colors. Nevertheless, many anthocyanins are susceptible to heat, light, pH, oxygen and some enzymes like polyphenol oxidase, which restricts their commercial application to food processing (Cavalcanti et al., 2011; Malien-Aubert et al., 2001). This susceptibility may vary with molecular structures, and some acylated anthocyanins were proved to be more stable than others (Montilla et al., 2010).