The answer is: resistant starch. Resistant starch, as its name implies, resists digestion in the small intestine and ferments in the large intestine (1). The fermentation acts as a prebiotic to make the intestinal microbiome healthier. And we all know how much I love that microbiome.
What is more, since resistant starch is not digested in the small intestine, it makes you feel more full, helps prevent constipation, doesn’t raise blood levels of glucose, and lowers your cholesterol.
So what’s the deal with cold rice? It seems as though some alchemy is involved: when you cook rice (or even potatoes or pasta) and then refrigerate it, more of the starch becomes resistant starch. And that doesn’t change if you then reheat the food!
Other resistant starches include (2):
Plantains and unripe bananas (because as a bananas ripen, the resistant starch changes to regular starch)
Beans, lentils, and peas
Whole grains, such as oats and barley
Here’s a wonderful recipe invented by my daughter Joanna that makes perfect use of cold rice:
Joanna’s Cold Thai Rice Salad
2 cups brown rice, cooked and refrigerated
1-2 peeled and diced cucumbers
4-5 carrots, peeled and diced
2 daikon radishes, peeled and diced
1 cup fresh herbs, such as Thai basil, cilantro, &/or mint, diced
Joanna’s curry paste (see note)
1” chunk of fresh gingerroot
1 stalk lemongrass, outer tough leaves removed, and cut into 1” chunks
1 serrano or jalapeño pepper, seeded and cut into chunks
1 shallot (or a chunk of onion), peeled
2 Tbsp honey
3 Tbsp fish sauce
Juice of 1 lime
Make the curry paste:
With the motor of a food processor running, add the ginger root and lemongrass. Process until minced.
Add the pepper and shallot, and thoroughly process again.
Add the honey and fish sauce. Process until reasonably smooth.
Pour the mixture into a small pot, and cook over low/medium heat until fragrant.
Add the lime juice, and stir.
Stir the curry sauce into the cold rice. Add the cucumbers, carrots, radishes, and herbs. Stir again.
Note: if you want an easier curry paste, you can use a jar of green curry paste and add the honey, fish sauce, and lime juice. No cooking necessary.
Chemistry lesson done!
(1)Snelson N et al. Metabolic Effects of Resistant Starch Type 2: A Systematic Literature Review and Meta-Analysis of Randomized Controlled Trials. Nutrients 2019, 11(8), 1833