Influence of Copigmentation and Encapsulation on Stability and Antioxidant Activity of Anthocyanins from Blue and Pink Cornflower (Centaurea cyanus L.) Flowers

Abstract

The aim of this study was to determine the optimal conditions for copigmentation and encapsulation of anthocyanins extracted from blue and pink cornflower (Centaurea cyanus L.) flowers and to produce encapsulates resistant to environmental factors. Extracts rich in anthocyanins were encapsulated using spray-drying and sublimation techniques. Baicalin and chlorogenic acid were successfully used as copigmentation agents for blue and pink cornflower anthocyanins. The extracts and encapsulates obtained were subjected to stability tests to assess the stability of color and changes in total anthocyanins content, total phenolic compounds content, and antioxidant activity under exposure to high temperature and UV radiation. The developed encapsulation method effectively protects anthocyanins from adverse environmental conditions. The obtained preparations were characterized by a high content of anthocyanins and phenolic compounds as well as a strong antioxidant potential. The highest stability was demonstrated by anthocyanin encapsulates isolated from the pink flowers of the cornflower, obtained by spray-drying with the addition of a copigment (chlorogenic acid or baicalin) and with a weight ratio of anthocyanin extract to carrier of 1:10. The results of this study suggest that anthocyanin preparations from cornflower, after encapsulation and copigmentation with baicalin or chlorogenic acid, can be used as stable colorants in the food industry as well as functional ingredients providing high levels of antioxidant activity.

Keywords: anthocyanins; copigmentation; cornflower; encapsulation.

Figure 1

The content of individual anthocyanins and other phenolic compounds in the extracts of blue and pink cornflower flowers (mg/g dry weight), (a) blue variety, (b) pink variety.

Figure 2

Absorption spectra of anthocyanins/copigments solutions in different molar ratios: (a) anthocyanins from blue cornflower/baicalin solutions; (b) anthocyanins from blue cornflower/chlorogenic acid solutions; (c) anthocyanins from pink cornflower/baicalin solutions; (d) anthocyanins from pink cornflower/chlorogenic acid solutions.

Figure 3

Changes in the total anthocyanin content of blue cornflower extracts and encapsulates during thermal and light treatments, expressed as percentage.

Figure 4

Changes in the total anthocyanin content of pink cornflower extracts and encapsulates during thermal and light treatments, expressed as percentage.

Figure 5

Changes in the total phenolic compounds content of blue cornflower extracts and encapsulates during thermal and light treatments, expressed as percentage.

Figure 6

Changes in the total phenolic compounds content of pink cornflower extracts and encapsulates during thermal and light treatments, expressed as percentage.