Thickening Calculator

Cornstarch produces clearer, glossier sauces and is twice as potent as flour (use half as much). Flour produces opaque, matte sauces with a more traditional flavor profile due to its protein content and requires full cooking to eliminate raw flour taste. Flour is more tolerant of overcooking and acid than cornstarch. Use cornstarch for Asian-style sauces, glazes, and clear gravies; use flour for roux-based French sauces, béchamel, and traditional gravies.

Yes, use approximately 75% as much arrowroot as cornstarch (0.75 tsp arrowroot per 1 tsp cornstarch). Arrowroot produces a more transparent, glossier result and works at slightly lower temperatures. It is ideal for sauces that should not be opaque. However, avoid using arrowroot in dairy-based sauces (it can become slimy), in acidic preparations, or in dishes that will be frozen (arrowroot gels break down on freezing).

Several causes: (1) Over-thickening followed by dilution from condensed steam — keep the lid off while cooling. (2) Retrogradation in the refrigerator — cornstarch gels can thin slightly when warmed after cold storage. (3) Enzymatic breakdown from amylase enzymes in raw flour, saliva contamination, or naturally present in some fruits. (4) Acidic ingredients (vinegar, citrus, tomato) hydrolyze starch chains over time — use modified food starch or waxy cornstarch for acid sauces.

Xanthan gum must be dispersed evenly to prevent clumping. Best methods: (1) Blend dry xanthan with oil or other dry ingredients before adding to liquid. (2) Use a high-speed blender — add xanthan while the blender is running. (3) Mix with a small amount of sugar or salt first to disperse particles, then whisk into liquid. Use 0.1–0.3% by weight for thin sauces and dressings, 0.4–0.6% for thick sauces. Xanthan thickens immediately without heating and maintains viscosity when cooled or frozen.

Arrowroot is the best natural thickener for mildly acidic sauces (pH 4.5–6). For strongly acidic preparations (pH below 4, e.g., pure lemon juice, vinegar-based sauces), modified food starch (e.g., Instant ClearJel, Ultra-Sperse) or xanthan gum are more acid-stable. Regular cornstarch and flour are susceptible to acid hydrolysis during prolonged cooking in acidic media. Pectin can also thicken acidic fruit preparations at concentrations of 0.5–1.5%.

Acid cleaves the glycosidic bonds in starch molecules, reducing chain length and thereby decreasing viscosity. This happens faster at higher temperatures and lower pH. To prevent this: (1) Add the acid (lemon juice, vinegar, wine) after removing the thickened sauce from heat. (2) Use acid-resistant modified starch. (3) Use xanthan gum or pectin which are more acid-stable. (4) Accept some thinning and slightly over-thicken before adding acidic components.

Generally, cornstarch-thickened sauces do not freeze well. Upon thawing, the starch retrograde structure collapses, releasing water (syneresis) and producing a watery, grainy texture. For freeze-stable thickening, use waxy cornstarch (waxy maize), tapioca starch, or modified food starches labeled as freeze-thaw stable. Flour-thickened sauces also freeze poorly. Xanthan gum is excellent for freeze-thaw stability and is often used in frozen foods.

A classic French roux for béchamel uses equal weights of butter and flour. For sauce consistency: thin sauce (velouté) uses 15 g flour + 15 g butter per 500 ml; medium béchamel uses 25 g flour + 25 g butter per 500 ml; thick béchamel uses 35 g flour + 35 g butter per 500 ml. In volume terms, this corresponds to approximately 1.5–3.5 tbsp flour per cup of liquid, which aligns with this calculator's flour recommendations.

Modified food starches are chemically or physically altered versions of native starches (cornstarch, tapioca, potato) engineered for specific functional properties. Common modifications include: cross-linking (improves stability to heat, acid, shear), substitution (inhibits retrogradation, improves freeze-thaw stability), pregelatinization (cold-water swelling, no cooking needed). Modified starches are used extensively in processed foods, sauces, dressings, and convenience products where regular starches would fail due to processing conditions.