Effects of extrusion on the polyphenols, vitamins and antioxidant activity of foods

Greater consumer demand for nutritious extruded food products with enhanced bioactive compounds has shifted research focus towards incorporation of bioactive rich ingredients with traditionally extruded starch materials. Recent research has highlighted the importance of bioactive compounds in human health and nutrition. An evaluation of the available literature reveals that the level of bioactive compounds in extruded products is influenced by extrusion process variables. Shear, temperature, resonance time and water content are all factors which contribute to the overall composition of extruded products. In addition, food structure may also exhibit a role in the potential release of functional bioactives. This paper reviews the effect of extrusion on bioactive compounds such as phenolic compounds, anthocyanins, isoflavones and their antioxidant activity. Factors influencing levels and stability during extrusion are also discussed.