Browsing by Subject "keittoekstruusio"

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  • Kurttila, Krista (Helsingin yliopisto, 2018)
    The literature review dealed with the extrusion processing, producing protein-rich extrudates, the attributes of extrudates and the future of snack-foods produced by extrusion cooking. The aim of the experimental study was to examine the influences of broiler meat and extrusion parameters to the structure of extrudates. The following variables were used: meat content of processed flour mixture, water content of processed dough and temperature of the sixth section and the die. Response variables were hardness of extrudates, expansion index (SEI) of extrudates, water content of extrudates, torque of the extruder’s screws and pressure of the extrusion dough at the die. The CCF modified Box-Behnken’s experimental design was used with total of 21 experiments. The meat content of the processed flour mixture was 10, 20 or 30%, the water content of the processed dough was 16, 18 or 20% and the processing temperature of the sixth section and the die was 110, 130 or 150 °C. Screw speed was 400 rpm and the feed rate was 68 g/min. The results were analyzed by Partial least squares regression (PLSR) and by Multiple linear regression (MLR) analysis with Matlab R2017b software. The sensory attributes of the extrudates were also observed. Regression analysis showed that torque of the screws was statistically significantly lower when the meat content of the processed flour mixture increased. Pressure at the die was statistically significantly lower when the water content of the dough, the temperature of the sixth section and the die or the meat content of the processed flour mixture increased. The water content of the extrudates was statistically significantly higher when the temperature of the sixth section and the die or the water content of the processed dough increased. The hardness of the extrudates was statistically significantly higher and the expansion index of the extrudates was statistically significantly smaller when the meat content of the processed flour mixture increased. Extrudates containing broiler meat were successfully prepared using extrusion cooking and differences of changing process parameters on structure of extrudates were detected.
  • Mäkinen, Tero (Helsingfors universitet, 2007)
    The literature review deals with the composition of rye flour and the significance of en-zymes and sourdough in rye flour processing. The operational principles of twin screw extruders, the extrusion of grain based materials and the formation of aroma during grain based extrusion are also reviewed. The aim of this study was to determine the influence of the amount of powered rye sourdough and extrusion cooking parameters on the structure and properties of rye extrudate. Three process parameters were varied: content of rye sourdough powder, process temperature during the final stages of extrusion and revolution speed of the extruder's screws. A Box-Behnken's experimental design was used with 3 levels of dried sourdough powder content (0, 20 and 40%), 3 screws revolution speeds (200, 350 and 500 rpm) and 3 exit temperatures (120, 150 and 180°C). Feed rate was set at 4.0 kg/h and the moisture of the feed was 17.4%. A total of 15 experiments were perfomed. Pasting properties, acidity, acid value and D- and L-lactic acid concentration of full grain rye flour, dried rye sourdough flour and ground extrudate powder were determined. Acetic acid concentration of dried rye sourdough powder was also determined. Moisture content, expansion, texture, bubble sizes and colour of extrudate were determined. Extrusion cooking produce very different types of rye extrudates and the effect of process parameters on structure of extrudate was significant. When the pressure at the die was 30–40 bar, structure of extrudates were porous. Freeze dried extrudates were harder than extru-dates stored for one day at room temperature. Young's modulus decreased with increasing screws speed and processing temperature. Extrudate’s expansion increased as a function of increased revolution speed of screws and decreased processing temperature. As the content of dried sourdough increased, the bubble sizes of extrudate increased and also yellow (a) and red (b) colour and acidity of extrudates became stronger. Lightness (L) was statistical significantly higher when temperature was higher. As expected, the concentration of D- and L-lactic acid increased with increasing dried sourdough content. Decreased content of dried rye sourdough and slower revolution speed of screws increased cold peak viscosity signifi-cant. Peak and hold viscosities increased with slower revolution speed of the screws and decreased content of dried sourdough. Final viscosity and setback value increased signifi-cantly with slower revolution speed of the screws. The optimal extrudate, which was crispy and had a good flavour, was obtained when the content of dried sourdough powder was 20%, revolution speed of the screws was 500 rpm and processing temperature was 120°C.