Stability of water-soluble turmeric colourant in an extruded food product during storage

Curcumin is a fat soluble yellow pigment present in turmeric. The water soluble form of curcumin has been applied onto expanded extruded balls, made from corn and defatted soybean flours. The stability of this natural turmeric colourant has been examined and compared with that of the permitted synthetic colour like tartrazine. The products are packed in polypropylene pouches and subjected to storage studies at ambient (27 °C, 65% relative humidity), and are tested for moisture content, and colour and pigment retention. Brightness of the sample reduces markedly up to 30% during storage. After 10 weeks of storage, the retention of curcumin is about 77%, and the effective shelf life of the product is 6 weeks at ambient condition with 83 and 93% retention of curcumin and tartrazine, respectively. The retention of both colours follows first order kinetics (0.86 ⩽ r ⩽ 0.98, p ⩽ 0.01) while curcumin showing a faster rate of degradation compared to tartrazine. Turmeric colourant may be a viable alternative for tartrazine for using it onto extruded products.