Effects of Cooking Temperatures and Starch Source on the Gelatinization and Thickening Power of Roux

Roux made from three wheat flours and cornstarch and cooked to six different temperatures were tested for gelatinization onset temperatures and thickening power. All roux showed an increase in thickening power on moderate heating. Cooking to higher temperatures greatly reduced thickening power. Bread flour and all-purpose flour showed increasing gelatinization onset temperatures on heating, whereas pastry flour and cornstarch showed the opposite trend. Only roux made with wheat flours developed color during cooking. These results suggest that the browning during roux cooking is due to Maillard reactions and that caramelization is only a minor contributor to color change.