Influence of cocoa shell addition on properties of corn extrudates

Extrusion is one of the most significant processes in food industry, where corn grits is often used as main raw material. In order to increase nutritive value and improve physical and chemical properties, in corn grits can be added flours of different grains, dehydrated fruits and vegetables, etc. Cocoa shell as a by-product of cocoa beans processing is a significant problem in the food industry. Since it is a good source of dietary fiber and polyphenols, it could be used as raw material for development of new products. Therefore, the aim of this study was to investigate the influence of extrusion process and cocoa shell addition (in proportions of 5%, 10% and 15%) on properties of extrudates based on corn grits. On obtained extrudates physical properties were determined, which included: expansion ratio, bulk density, texture, color, water absorption index and water solubility index. It was established that addition of cocoa shell resulted in decrease of expansion ratio and fracturability, but in increase of bulk density and hardness of extrudates. Extrusion caused lightening of control sample of corn grits, but darkening of extrudates with added cocoa shell. Water absorption index and water solubility index increased significantly after extrusion. From all above it can be concluded that cocoa shell can be successfully added to corn grits in order to produce new extruded products.