How did nouvelle cuisine change the use of sauces in French cooking?

Nouvelle cuisine fundamentally transformed French cooking by rejecting the heavy, flour-thickened sauces that were central to traditional grande cuisine.12

In reaction to the rich, calorie-laden extravagances of the past, practitioners of nouvelle cuisine implemented several key changes regarding sauces:

• Elimination of Roux: Chefs discarded traditional sauces that relied on meat extracts and flour-based thickeners like roux.2
• Focus on Reductions: Instead of thickening agents, the movement emphasized the use of reductions—concentrating stocks and cooking liquids to achieve depth of flavor and a lighter consistency.1
• Emphasis on Lightness: The style prioritized clarity of flavor and health, leading to the introduction of lower-fat sauces and the use of vegetable purees as alternatives to heavier preparations.34
• Dietary Awareness: One of the movement's core tenets, as outlined in the "Ten Commandments of Nouvelle Cuisine," was to explicitly eliminate rich sauces and consider dietetics in food preparation.4

By moving away from these heavy, regimented techniques, nouvelle cuisine sought to emphasize the natural flavors and textures of ingredients.31