The effects of feed moisture content (14, 17 and 20% db), die temperature (120, 145 and 170 °C) and carrot pomace content (10, 17.5 and 25%) on the sectional expansion index, hardness, porosity, micro and macro structure and sensory properties of high fiber expanded barley–carrot pomace snack were investigated using a central composite design. Results showed that with increasing the moisture content the hardness of the extruded snacks increased while their expansion ratio decreased. The hardness decreased with increasing the die temperature, but the expansion ratio increased with increasing the die temperatures to up to 145 °C and decreased afterwards. An increase in carrot pomace content decreased the expansion ratio and cell average size while the hardness and cell wall thickness increased. The optimum condition for production of expanded barley–carrot pomace snack was 10% carrot pomace content, 142.7 °C die temperature and 14.02% moisture content. During extrusion cooking, the soluble dietary fiber of barley–carrot pomace snack increased, but no change on the total dietary fiber content was observed. Therefore, the extruded snacks prepared from barley flour and carrot pomace had high nutritional value.

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