Porosity and hardness of corn extrudates using dry tomato pomace

¹ Departament of Technology of Cereal, Animal Feed, Bakery and Confectionery Products, Technological Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
² Department of Machines and Apparatuses for Food Industry, Technical Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
³ Institute of Food Preservation and Quality, Agricultural Academy, 4000 Plovdiv, Bulgaria
⁴ Department of Analytical Chemistry and Physical Chemistry, Technological Faculty, University of Food Technologies, 4002 Plovdiv, Bulgaria
⁵ Departament of Engineering Ecology, Faculty of Economics, University of Food Technologies, 4002 Plovdiv, Bulgaria

^* Corresponding author: n_dimitrov@uft-plovdiv.bg

Abstract

The incorporation of fiber-rich non-starchy wastes from various industries, into ready-to-eat extrudates, changes their structure and therefore affects their physical properties. The study explored the impact of varying levels of tomato pomace (ranging from 0% to 20%), moisture content in the mixture (ranging from 14.5% to 21.4% on a wet basis), and screw speed (ranging from 156 to 224 rpm) on the hardness of corn extrudates, as well as on parameters such as the number of pores, pore area, average pore size, and pore circularity. It was observed that, the inclusion of tomato pomace increases the hardness of the extrudates by decreasing the average pore size. On the other hand, the average pore size increases, and the hardness decreases with the increase of the screw speed. It was also observed that the higher initial moisture content of the mixtures increases the hardness and results in a more porous structure in the extruded products. The results show that the amount of tomato pomace and the process parameters significantly influence the structure of the extrudates.