FISH OIL-FORTIFIED EXTRUDED SNACKS: EVALUATION OF PHYSICAL PROPERTIES AND OXIDATIVE STABILITY BY RESPONSE SURFACE METHODOLOGY

Response surface methodology was employed to study the physical characteristics and oxidative stability of fish oil-fortified extruded snack. Process temperature (80-140C), feed moisture (12-20%), screw speed (300-400 rpm) and fish oil content (0.5-2.5%) were selected as the independent variables at five levels. A central composite design was developed to study the linear, quadratic and interactive effect of the selected independent variables on responses studied viz. expansion ratio, porosity, hardness, crispness and thiobarbituric acid reactive substance values. The physical properties of extruded samples such as expansion ratio, porosity and crispness were mostly influenced by feed moisture followed by fish oil content. Fish oil showed significant interactive effect with temperature on expansion ratio and porosity. The product with fish oil content up to 0.8% was found significantly oxidatively stable and fish oil can therefore be added to improve the nutritive and functional value of extruded snacks.