WHEAT-FLOUR AND DEFATTED MILK FRACTIONS CHARACTERIZED BY DIFFERENTIALSCANNING CALORIMETRY .1. DSC OF FLOUR AND MILK FRACTIONS

Differential scanning calorimetry (DSC) thermograms were determined fo r wheat flour and milk fractions. Compositional and structural differe nces between prime and tailings starch apparently affected their DSC t hermograms and interaction patterns. Tailings starch had a lower gelat inization enthalpy and a higher amylose-lipid complex transition entha lpy than did prime starch. These observations were attributed to the f aster rate of heat transfer and higher accessibility to water, presuma bly related to the smaller granule size of tailings starch. Gluten low ered the temperatures of the amylose-lipid complex endotherm of both p rime and tailings starches. Water solubles increased the gelatinizatio n temperatures of the starches due to the competition for available wa ter. Laboratory-prepared acid whey showed higher denaturation temperat ures than sweet whey, which is explained by the acid-resistant charact er of the major whey protein beta-lg. A commercial whey protein concen trate showed endotherm temperatures that were considerably higher (>40 degrees C) than those of whey powders. Ultrafiltration in commercial processing could be responsible for this temperature shift. The degree to which protein is concentrated by ultrafiltration or dialysis affec ts the relative concentration of water solubles and influences the fun ctional properties and interactions of whey protein concentrates with wheat flour components.