engleski

Twin-screw extrusion of whey protein concentrate/corn flour blends as affected by feed moisture

Breakfast cereals, snack food, biscuits, are some of the products that can be manufactured with twin-screw extrusion processing. A two level factorial experimental design was used to study the influence of feed moisture on textural properties of extrudates prepared with varied ratios of corn flour and whey protein concentrate (WPC). Blends were made as follows: 92, 5% corn flour:7, 5% WPC ; 85% corn flour:15% WPC ; 77, 5% corn flour:22, 5% WPC. Also, three control samples of a pure corn flour were extruded under the same processing conditions. An APV Baker, MPF 50:15 co-rotating twin-screw extruder was used for extrudates manufacturing. The temperature profile in extruder was 30-60-90-110-130°C. The diameter of the die was 4×2 mm for each screw, screw speed was 300 rpm and feed rate was 70 kg/h. Blends were extruded under input conditions of feed moisture content (FMC) of: 10, 08 L/h, 12, 18 L/h, 14, 28 L/h. Textural properties: breaking strength index (BSI) and expansion ratio (ER) were determined. Sample with 22, 5% of WPC and feed moisture of 14, 28 L/h has largest value for the BSI. Sample with 7, 5% of WPC and 10, 08 L/h had largest ER. Calculated textural properties confirmed validity of samples. This results suggest that textural properties of extrudates with WPC addition up to 22, 5% depend mainly on feed moisture, WPC addition and their interaction.

whey protein concentrate; corn flour; extrusion

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