Abstract

Anthocyanin’s have been suggested as promising dietary compounds with an important role in human health. This study focuses on the effect of temperature and pH on stability of anthocyanins from red sorghum bran. The sorghum anthocyanins were found to be stable at 0°C even when exposed to light and dark conditions. The anthocyanins extracted using acidified methanol showed higher stability than methanol extracts. The study on anthocyanin stability over the pH range (1.1 to 10.5) during 20 days storage was conducted on sorghum anthocyanins compared to methanol and acidified methanol extracts afforded higher colour intensity and higher or similar stability throughout the whole pH range. At pH 8.9, the colour intensity of sorghum anthocyanins was even higher than at the lowest pH values. The sorghum 3-deoxyanthocyanins were a rare class of plant pigments, and were stable to light, heat and change in pH. The use of sorghum anthocyanins as food colourants in slightly alkaline products (bakery, milk, egg, etc.) can therefore be considered.

Key words: Sorghum, bran, anthocyanins, temperature, pH stability.