What is Cornstarch and How is it Made?
Cornstarch is a fine, white powder extracted from the starchy endosperm of the corn kernel. Unlike corn flour, which uses the entire dried corn kernel, cornstarch undergoes a complex industrial process called wet milling.
The Wet Milling Process
- Steeping: Corn kernels are soaked in large tanks of warm water and sulfur dioxide for 30 to 48 hours, which softens the kernels and causes slight fermentation.
- Milling and Separation: The softened kernels are ground to separate the components. The lighter germ, which contains oil, is removed. The heavier hulls and endosperm are further processed.
- Refining: The endosperm is separated into a slurry. High-speed centrifuges then remove the protein (gluten), leaving behind a pure starch slurry.
- Drying: The final pure starch is washed and dried, often using vacuum dehydration and flash drying, to create the fine white powder known as cornstarch.
This process is crucial to understanding why cornstarch is not considered grain-free. By separating the endosperm and refining it, all other components of the grain—like the bran and germ, which contain fiber, protein, and nutrients—are stripped away. The final product is essentially 100% refined carbohydrate.
Cornstarch vs. Truly Grain-Free Alternatives
When on a grain-free diet, it's essential to understand the difference between cornstarch and other thickeners. While cornstarch is technically gluten-free, its origin as a refined grain product makes it a no-go for strict grain-free regimens. Here is a comparison with common alternatives:
| Feature | Cornstarch | Arrowroot Powder | Tapioca Flour |
|---|---|---|---|
| Source | Endosperm of corn kernel (a grain) | Root of the tropical arrowroot plant | Starch from the cassava root |
| Grain-Free Status | No; highly processed grain derivative | Yes; derived from a tuber | Yes; derived from a tuber |
| Processing | Extensive wet milling to remove fiber and protein | Less processed than cornstarch | Processed from a starchy root |
| Best Uses | Thickening sauces, gravies; crisping fried foods | Thickening sauces and fruit fillings | Thickening and adding chewiness to baked goods |
| Nutritional Value | High in carbs, low in vitamins and fiber | Small amounts of nutrients, fiber | Mostly carbohydrates, minimal nutrients |
Cornstarch and Restrictive Diets: Paleo, Keto, and Whole30
For many who follow restrictive diets, the grain-free requirement is based on more than just gluten intolerance. The rationale often includes avoiding processed foods and focusing on nutrient-dense, whole food sources.
Paleo Diet
The Paleo diet, based on the eating habits of hunter-gatherer ancestors, emphasizes whole, unprocessed foods like fruits, vegetables, lean meats, and nuts. Cornstarch is not Paleo-friendly because it is a highly processed grain product with minimal nutritional value. Though it comes from a plant, the industrial process used to create cornstarch violates the diet's principles of consuming foods as they would have been found in nature.
Keto Diet
The ketogenic (Keto) diet requires a very low carbohydrate intake to trigger a metabolic state called ketosis. Cornstarch is almost pure carbohydrate, with one tablespoon containing approximately 7 grams of net carbs. This high carb count makes cornstarch incompatible with the typical Keto diet, which limits daily carb intake to a much lower amount.
Whole30
The Whole30 program is a 30-day elimination diet that strictly prohibits grains, legumes, dairy, sugar, and processed foods. Since cornstarch is a processed grain derivative, it is not compliant with the Whole30 rules. The program aims to reset the body by removing potentially inflammatory foods, and highly refined carbs like cornstarch are excluded.
Corn and Gluten-Free Diets
It's important to distinguish between "grain-free" and "gluten-free." While cornstarch is derived from a grain, corn is a naturally gluten-free grain. As a result, pure cornstarch is also gluten-free and is a common thickening agent in gluten-free recipes. However, individuals with Celiac disease or a gluten sensitivity must still exercise caution. Cross-contamination can occur if cornstarch is manufactured in the same facility as wheat or other gluten-containing products. For this reason, many health organizations recommend looking for a product that is certified gluten-free.
Conclusion
While derived from the naturally gluten-free corn grain, cornstarch is not considered grain-free by most health and diet standards, including Paleo, Keto, and Whole30. The intensive refining process strips the kernel of all fiber and nutrients, leaving behind a pure, processed carbohydrate. For those seeking truly grain-free alternatives for thickening or baking, options like arrowroot or tapioca flour are more appropriate and align better with the principles of these restrictive diets. Ultimately, the decision depends on the specific dietary rules being followed and the level of adherence to avoiding processed foods.
