They’re all corn-based but used differently:

• Corn flour: Very finely ground corn. It’s soft and powdery, great for tender baked goods, breading, and adding light corn flavor.
• Cornmeal: A coarser grind (fine, medium, or coarse). It adds crunch and texture to cornbread, muffins, polenta-style dishes, and breading.
• Masa harina: Corn that’s been nixtamalized (soaked in an alkaline solution), dried, and ground. It behaves differently than regular corn flour and is used for tortillas, tamales, sopes, and pupusas.
• Cornstarch: Pure starch from corn, used to thicken sauces and soups; not interchangeable with the others for baking.

When shopping, consider grind (fine vs. coarse), color (white vs. yellow), and intended use. Site filters can help you narrow options.

Corn itself doesn’t contain gluten, but processing environments can vary. For gluten-free baking:

• Check labels: Look for products labeled gluten-free and review ingredient lists and any allergen statements.
• Choose the right type: Regular corn flour adds mild flavor and softness; cornmeal adds texture; masa harina brings a distinct, tortilla-like character.
• Blend for structure: In cakes or muffins, corn flour often works best blended with other gluten-free flours or starches for better crumb and lift.
• Test small batches: Grinds and moisture absorption differ, so results can vary by brand and recipe.

Filters on Walmart.com can help you find gluten-free and grind options suited to your baking plans.

Proper storage can help maintain freshness and flavor:

• Use airtight containers: Seal tightly to keep out moisture, air, and pantry pests.
• Keep it cool and dry: Store in a pantry away from heat and sunlight. For longer storage, refrigerate or freeze in sealed bags or containers.
• Consider the type: Whole-grain or whole-corn products may have natural oils that can go stale faster than degerminated versions.
• Date and rotate: Label when opened and use older stock first.
• Check before use: If you notice off smells or flavors, it’s best to replace.

Timeframes vary, but many corn flours and meals keep for a few months in the pantry and longer when chilled or frozen.

It depends on the recipe and texture you want:

• For baking: Corn flour is finer than cornmeal. In cornbread or muffins, you can replace part of the cornmeal with corn flour (for example, half-and-half) to reduce grittiness. You may need slight liquid adjustments.
• For breading: Corn flour gives a thinner, more delicate crust; cornmeal adds crunch. Choose based on texture preference.
• For tortillas and tamales: Don’t substitute regular corn flour for masa harina; they behave differently due to nixtamalization.
• For polenta-style dishes: Use cornmeal, not corn flour or cornstarch, to achieve the expected texture.

Grind size and moisture absorption vary, so start small and adjust as needed.

Here’s a simple starting approach:

1. Mix dough: Combine masa harina with warm water and a pinch of salt until a soft, pliable dough forms. Let it rest for 10–15 minutes.
2. Portion and press: Roll into small balls. Press each between plastic in a tortilla press (or use a rolling pin) to about 5–6 inches.
3. Cook: Place on a hot, dry skillet. Cook about 30–60 seconds per side until lightly browned and flexible. Keep warm wrapped in a clean towel.

If dough cracks, add a bit more water; if sticky, dust with more masa harina. Water ratios and cook times can vary with brand, humidity, and pan temperature.