Replacement of artificial colourings of a carbonated soft drink with natural colour pigments from red-layered hibiscus.

Abstract

A natural red colouring was developed from petals of Red-layered Hibiscus flowers, which are rich in anthocyanins, to replace artificial colourings that are being added to a carbonated soft drink. Boiling distilled water acidified with citric acid (0.8%) was found to be the most suitable solvent to extract the pigments from the petals. Immersing 1 g of petals for 10 minutes in 10 ml of the solvent was identified as the most suitable method to extract the pigments. Natural colouring was prepared in liquid form by concentrating 10 ml of pigment extract down to 1 ml. When storing in a clear glass bottle at 4oC, minimum shelf life of the colouring was 8 weeks. Carbonated soft drink test samples were prepared by adding the developed red colouring to match the colour of the standard beverage. Sensory evaluation, microbial analysis, Brix, pH and Carbonation Level measurements were done, using standard methods, for test samples stored under direct sunlight, indirect sunlight and in a refrigerator. No significant (P>0.05) differences were detected between preferences for standard beverage and test sample, which also contained additional 2% citric acid amount and essence volume. The maximum shelf-life of test samples was limited to 5 days, when storing under direct sunlight. When storing under indirect sunlight or in a refrigerator, their minimum shelf-life was 8 weeks.