Adulteration of Crude Palm Oil with Red Dye from the Leaf Sheath of Sorghum Bicolor

Abstract

The present work was undertaken to investigate the possibility of adulterating CPO with natural potash (lake salt) and red dye from the leaf sheath of sorghum bicolour. Concentrations of potash and red dye ranging from 0.01-0.1% and 0.1-1.0% respectively were prepared in water; and then added to fresh CPO at oil/adulterant ratios ranging from 10:1-10:10, to obtain adulterated CPO with known concentrations and adulterant ratios. Adulterated samples were examined visually for appearance, and evaluated for quality indices and sensory attributes. Values of quality indices were similar for both the adulterated and unadulterated samples, while the acceptability of taste and mouthfeel were clearly higher for the unadulterated sample. The use of potash changed the characteristic orange red color of CPO to yellowish red even at levels below 0.01%; and also resulted in product with increased consistency. CPO can be successfully adulterated with 0.25% red dye from the leaf sheath of sorghum bicolor at a maximum oil/dye ratio of 1:1. The adulterated oil can remain unidentified by consumers for at least 30 days. A simple, rapid and effective test by means of which a consumer can easily detect the presence of red dye in CPO was also developed.

Keywords: Crude palm oil; Adulteration; Red dye; Natural potash; Sorghum bicolor.