The Science of Resistant Starch and Rice
When rice is cooked normally, its starches are primarily digestible, meaning the body easily breaks them down into glucose for energy. However, a study from the College of Chemical Sciences in Sri Lanka found a way to alter this process significantly. By adding a specific type of lipid—in this case, coconut oil—and then refrigerating the cooked rice, a portion of the digestible starch is converted into resistant starch.
How Coconut Oil and Chilling Work
The chemical transformation is a two-step process. First, adding a teaspoon of coconut oil per half-cup of rice during cooking allows the lipid molecules to interact with the starch granules. This interaction creates a protective layer that changes the internal structure of the starch. As the rice cooks, the oil penetrates the outer layers of the granules.
The second, and most crucial, step involves cooling the rice. When the cooked rice is refrigerated for at least 12 hours, the amylose (the starchy part) moves out of the granules. Hydrogen bonds form between the amylose molecules, creating a new structure that is resistant to digestive enzymes. This newly formed resistant starch is indigestible by the human body and acts more like fiber than a carbohydrate.
Impact on Calories, Not Carbs
It is important to clarify that adding coconut oil to rice does not literally reduce the total carbohydrate content. The rice contains the same amount of macronutrients. What changes is the amount of those carbohydrates that your body can actually absorb. The conversion to resistant starch means a portion of the calories and carbs pass through your digestive system undigested, reducing the overall caloric load and glycemic impact of the meal. A single tablespoon of coconut oil contains about 120 calories, so this method is only beneficial if the reduction in absorbed rice calories outweighs the calories from the added oil.
Comparison of Cooking Methods
| Feature | Standard Cooked Rice | Coconut Oil & Chilled Rice | Brown Rice |
|---|---|---|---|
| Starch Type | High in digestible starch | High in resistant starch | Moderate resistant starch |
| Glycemic Index (GI) | High | Lower | Lower |
| Calorie Absorption | High | Lower (up to 50-60% reported in studies) | Lower due to fiber |
| Satiety | Less filling | Increased satiety due to slower digestion | Increased satiety due to fiber |
| Flavor | Plain | Subtle coconut flavor | Nutty, earthy flavor |
| Preparation | Simple | Requires cooking, cooling (12 hours), and reheating | Longer cooking time |
Health Benefits Beyond Calorie Reduction
The benefits of increasing resistant starch extend beyond just managing calorie intake. Resistant starch acts as a prebiotic, nourishing the good bacteria in your large intestine. This can lead to improved gut health and better digestive function. The fermentation of resistant starch by gut bacteria produces short-chain fatty acids like butyrate, which are beneficial for colon health. Additionally, a lower glycemic index means a smaller and more stable rise in blood sugar levels after eating, which can be particularly advantageous for people managing blood sugar.
A Simple Step-by-Step Recipe
Ingredients
- 1 cup of rice (white rice is used in the Sri Lankan study)
- 2 teaspoons of virgin coconut oil
- 1.5-2 cups of water (depending on rice type)
Method
- Bring the water to a boil in a saucepan.
- Add the coconut oil and wait for it to melt completely.
- Stir in the rinsed rice.
- Cook on low heat, covered, for 20-25 minutes, or until the water is absorbed.
- Transfer the cooked rice to a covered container and refrigerate for at least 12 hours.
- Reheat the rice and serve. Reheating does not destroy the resistant starch.
For more detailed nutritional insights into this cooking method, a study summary can be found at the American Chemical Society.
Conclusion
While adding coconut oil to rice does not remove carbohydrates, the innovative cooking and cooling method triggers a chemical change that increases resistant starch. This makes the starches less digestible, effectively reducing the net calorie absorption and lowering the glycemic impact of the rice. This simple technique offers a practical way to enjoy rice with a smaller blood sugar spike and potential benefits for gut health. However, it requires forethought and planning, as the chilling period is a crucial step. This method provides a useful tool for those seeking to manage their carbohydrate and calorie intake while still enjoying a staple food.
