**5. Anthocyanins in food products and pharmaceuticals**

Incorporation of anthocyanins as an ingredient in foods and pharmaceutical has undergone several challenges. The prime issue with their use, is their stability and hence their effectiveness as a beneficial component in food and pharmaceutical. Anthocyanins are used as colorants in pharmaceuticals and food products as a substitute to synthetic colors. Studies have compared the stability of anthocyanins as colors with synthetic colors and have found that the synthetic colors have better stability than anthocyanins. In a study, stability of synthetic colors such as Carmoisine, Allura red and Ponceau were compared with natural anthocyanin colors, viz. enocyanin, dark carrot and cochineal. The results of the study indicate that at higher temperatures and higher pH conditions the stability of natural anthocyanins was much lower that the synthetic colors [74]. However, the beneficial effects of anthocyanins cannot be ignored due to their stability issue.

In another study, the stability of freeze-dried powder of anthocyanin extract of wild blueberry was compared at various temperature values over a storage period of more than a month. It was observed that the total anthocyanin content and the content of individual anthocyanins was most retained at 25°C and reduced significantly at higher temperatures [75]. A combination of ascorbic acid with anthocyanins from plant extracts was evaluated for stability under varying humidity, temperature and pH conditions in both freeze dried and solution form. It was observed that in solution form the stability of the combination reduced with increase in pH and temperature. In freeze dried form the stability of the combination decreased with increase in humidity [76]. Commercially several yoghurt variants are available with a variety of fruits. Some studies carried out on extracts of blackcurrant and wine grape extracts in yoghurt indicate that the fermentation process and addition of some probiotics reduce the stability of anthocyanins [77–79].

Microencapsulation is another technique tested for anthocyanin release and stability. In a cell line study carried out microencapsulated glycons and aglycons of some anthocyanins, glycons of anthocyanins were found to be more stable than the aglycon counterparts [80]. The conventional extraction methods are cost intensive and employ application of heat for extraction. Ground breaking research has been carried out in metabolic engineering of microbes for production of anthocyanins. Cyanidin 3-O-glucoside has been successfully produced by *E. coli.* However, its production at commercial scale poses challenges due to imbalances in the expression of other genes and lack of optimized transporters for extracellular secretion [81]. The merger of metabolic engineering with plant chemistry holds a promising future for anthocyanins and their application in food and drug industry.
