Assessment of the potential of microalgae-derived phycoerythrin as a natural colorant in beverages

Abstract

Phycobiliproteins, including phycoerythrins, are a group of water-soluble pigments produced by microalgae that show potential for being used as natural colourants. The replacement of synthetic compounds with natural colourants obtained from renewable resources is gaining increased interest in the beverages industry. The aim of the present study was to generate and characterise a phycoerythrin-rich extract from the microalga Porphyridium cruentum and to assess its potential use as a pink colourant in four commercial beverages: gin, wine, tonic water, and an isotonic drink. The extract, obtained after water extraction and protein precipitation contained B-phycoerythrin (79%) and R-phycocyanin (21%). Its B-phycoerythrin concentration was 0.75 gB-PE·L−1. The purity grade ({A}_{565}/{A}_{280}) of the extract was 2.50; purity ratios higher than 0.7 are considered as sufficient for food applications. The extract was pink and was shown to be stable at pH values ranging from 3.0 to 9.0. The staining factors, which refer to the amount of extract needed to mimic the colour of the commercial products, were 1.5, 2.9, 1.6, and 4.4 mg·L−1 for gin, wine, tonic water and the isotonic drink, respectively. The influence of temperature on the stability of the extract was studied, having found the lowest degradation ratios for 4 ºC and the gin sample. The colour of the product was stable during an 11-day storage period and the colour of the phycoerythrin-containing products was well accepted by a group of 44 semi-trained panellists. The results reported here demonstrate the potential of P. cruentum for being used as a natural source of phycobiliproteins that could be used as a natural pink colouring agent in different beverages.