Extrudabilite et stabilite des melanges riches en matieres grasses en cuisson-extrusion. Comparaison entre extrudeurs mono-vis et bi-vis.Study on extrusion and stability of fat meals. Comparison between single- and twin-screw extruders

摘要

A study on doughs formed by pregelled wheat flour, almond flour, water and two kinds of additives (soy lecithin et mono and diglyceride of fatty acids) was carried out in order to evaluate the capability of those additives to retain the fatty fraction during the extrusion of fatty flours. Electrical conductivity measurements showed that both additives prevent the loss of fat in o/w emulsions. Furthermore, extruded flakes and sticks were produced using doughs formed by pregelled wheat flour, almond flour, mono and diglycerides of fatty acids and soy lecithin in a single- and twin-screws extruder. The obtained products were submitted to rheological, physical, and chemical analyses. The results regarding the oil extraction during extrusion showed that the soy lecithin is the most suitable emulsifiant to retain the fatty fraction during the extrusion of fatty flours. The twin-screw extruder is more efficient to extrude fat meals, than the single one because it leads to determine a smaller loss of fat during the process of extrusion and a greater expansion of the products.