*Article*

### **Use of Phycobiliproteins from Atacama Cyanobacteria as Food Colorants in a Dairy Beverage Prototype**

**Alexandra Galetovi´c 1,\*, Francisca Seura 2, Valeska Gallardo 2, Rocío Graves 2, Juan Cortés 1, Carolina Valdivia 3, Javier Núñez 3, Claudia Tapia 3, Iván Neira 3, Sigrid Sanzana 3 and Benito Gómez-Silva 1**


Received: 25 January 2020; Accepted: 3 February 2020; Published: 24 February 2020

**Abstract:** The interest of the food industry in replacing artificial dyes with natural pigments has grown recently. Cyanobacterial phycobiliproteins (PBPs), phycoerythrin (PE) and phycocyanin (PC), are colored water-soluble proteins that are used as natural pigments. Additionally, red PE and blue PC have antioxidant capabilities. We have formulated a new food prototype based on PBP-fortified skim milk. PBPs from Andean cyanobacteria were purified by ammonium sulfate precipitation, ion-exchange chromatography, and freeze-drying. The stability of PE and PC was evaluated by changes in their absorption spectra at various pH (1–14) and temperature (0–80 ◦C) values. Purified PBPs showed chemical stability under pH values of 5 to 8 and at temperatures between 0 and 50 ◦C. The antioxidant property of PBP was confirmed by ABTS (2,2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical ion scavenging, and FRAP (Ferric Antioxidant Power) assays. The absence of PBP toxicity against *Caenorhabditis elegans* was confirmed up to 1 mg PBP/mL. Skim milk fortified with PE obtained a higher score after sensory tests. Thus, a functional food based on skim milk-containing cyanobacterial PBPs can be considered an innovative beverage for the food industry. PBPs were stable at an ultra-high temperature (138 ◦C and 4 s). PBP stability improvements by changes at its primary structure and the incorporation of freeze-dried PBPs into sachets should be considered as alternatives for their future commercialization.

**Keywords:** cyanobacteria; phycobiliproteins; natural pigment; phycoerythrin; phycocyanin; food colorant
