Effect of water content on the formation and dissociation of the amylose-lipid complex in wheat flour
1992
Jovanovich, G. | Zamponi, R.A. | Lupano, C.E. | Anon, M.C.
The effect of the water content on the formation and dissociation of the amylose-lipid complex was analyzed by differential scanning calorimetry in wheat flour, starch, and isolated complex. At low and intermediate water contents (36-64%, wet basis) the enthalpy change of formation and dissociation of the amylose-lipid complex after the first heating was related to the water content. The enthalpy of complex dissociation during the second heating decreased sharply with regard to the first heating for water contents lower than 43, 45, and 34% (wet basis) for flour, starch, and isolated complex, respectively. On the other hand, addition of water to a sample already heated at a lower water content led to an endothermic transition when the sample was reheated, this transition being higher than that observed in the first heating. The melting point of the undiluted polymer (166.2 degrees C), calculated with the Flory-Huggins equation, was similar to that obtained experimentally (170 degrees C). Results suggest that water would be necessary as plasticizer during complex formation.
显示更多 [+] 显示较少 [-]