starches can withstand the acidities typical of
yogurt and many fruits (pH 4). Gentle and
brief cooking will minimize acid breakdown.
Proteins and Fats Two other materials are
commonly found in sauces and have some
influence on their texture. Flour is about 10%
protein by weight, and much of this fraction is
insoluble gluten. Gluten aggregations
probably get caught in the starch network and
so slightly increase the viscosity of the
solution, though the pure starches are
generally more powerful thickeners overall.
Sauces based on concentrated meat stocks
also contain a good deal of gelatin, but gelatin
and starch seem not to affect each other’s
behavior.
Finally, fats are usually present in the form
of butter, oil, or the drippings from a roast.
They do not mix with water or water-soluble
compounds, but they do slow the penetration
of water into starch granules. Fat does