Application of phycobiliproteins from Leptolyngbya sp. KC45 for natural illuminated colourant beverages

The cyanobacterium Leptolyngbya sp. KC45, as it originally occurs in hot springs, can be cultured at high temperatures and pH values, with high phycobiliprotein content. Although phycobiliprotein has been applied as a natural dye and fluorescent labelling agent, the application of illuminated colourants in food and beverages is still limited. This study showed the properties related to phycobiliprotein application in beverages, including physical stability, safety and some antioxidant capacity. When testing at the 2500 mg mL−1 concentration of pigment extract, Vero cell viability remained above the acceptable 50% level. Furthermore, microcystin-LR and microcystin-RR were not present according to HPLC detection test. The phycobiliprotein was stable at pH 3–7 at 4 °C in the dark for 1 month. It was also stable at a pH above 4.5 and an alcohol concentration below 30%. Illumination of phycobiliprotein in beverages under UV blacklight could be enhanced by Zn2+ ions and ethanol. Mixed with ethanol (below 40%), phycobiliprotein still showed in vitro antioxidant capacity such as ferric-reducing/antioxidant power, anti-lipid peroxidation and iron-chelating activity. Our results show that pigments from Leptolyngbya sp. KC45 can be applied as a health-enhancing illuminated colourant, which may be relevant for development in other food and beverage products.