Flavorings: Salt, Sugar, Acid

Starch and water are the basis for a sauce’s structure, and most other ingredients have only secondary effects on that structure. Salt, acid, and sugar are frequently added for their contributions to flavor. Salt slightly lowers the gelation temperature of starch, while sugars increase it. Acids in the form of wine or vinegar encourage the fragmentation of starch chains into much shorter lengths, so that starch granules gelate and disintegrate at lower temperatures, and the final product is less viscous for a given amount of starch. Root starches are noticeably affected by moderate acidity (a pH lower than 5), while grain starches can withstand the acidities typical of yogurt and many fruits (pH 4). Gentle and brief cooking will minimize acid breakdown.