EVALUATION OF MICROENCAPSULATED TURMERIC OLEORESIN FOR PRE-EXTRUSION COLORING USING RESPONSE SURFACE METHODOLOGY

Abstract

ABSTRACT This work evaluates turmeric oleoresin (TO) vis-a-vis that microencapsulated in two wall materials, viz. gum arabic (TO-GA) and n-octenyl succinic anhydride (n-OSA) starch (TO-MS), as pre-extrusion coloring of sorghum extrudate for maximum retention of color. The effect of the extrusion conditions on the retention of turmeric color during extrusion of sorghum flour – chosen as a model having parameters die temperature, screw speed and moisture content – was studied using response surface methodology. Experiments were carried out by extrusion of sorghum flour containing 1% oleoresin, and microencapsulated oleoresins using a single-screw extruder at a constant feed rate of 55 g/min. At all conditions of extrusion, both the microencapsulated oleoresins gave a better retention of color than the free oleoresin. Experiments using the optimized levels of the parameters showed a good agreement between the experimental and the predicted values of color. PRACTICAL APPLICATIONS Natural colors are a diverse group of colorants with widely differing solubility and stability properties. As the majority of food and beverage products are water-based, microencapsulation of colors is especially beneficial for pigments that are not soluble in water. Examples of these are various carotenoids such as β-carotene, lutein, annatto and paprika, as well as turmeric, carmine and chlorophyll. Generally, coloring of the extruded products is done post-extrusion. Hence, an attempt was made to evaluate microencapsulated turmeric oleoresin for pre-extrusion coloring using response surface methodology.