DEAR DR. BLONZ: I prefer brown rice to white because of the fiber and additional nutrients, but I recently saw on a cooking show that brown rice must be refrigerated or else it will become rancid. In the markets, it is sold in sealed packages, but is often available for less from bulk bins. I want to save money, but not if it means the product is less safe. -- J.K. Deerfield, Illinois
DEAR J.K.: Brown rice is a whole grain, the seed of the rice plant. It contains a starchy endosperm pellet which, after the milling process, becomes what we know as “white rice.” Brown rice also has a seed germ surrounded by layers of fibrous bran, and in the plant, all this is surrounded by a protective husk.
Some of the oils that would nourish the growing seed are in the germ, but most are in the inner layers of the rice bran. The composition of the oil is 47 percent monounsaturated, 33 percent polyunsaturated and 20 percent saturated. (This is very similar to the profile of peanut oil.)
The unsaturated bonds are the part of an oil that are most susceptible to oxidative attack, so the more highly unsaturated an oil, the greater the risk of oxidation. Temperature is also a factor, with higher temps facilitating the oxidation reaction.
While there is a protective bran coat surrounding the whole-grain rice, it is not airtight. Then there is the fact that some of the oil is in the inner layers of the bran. All this explains why brown rice has a shelf life. Six months is often used, but there are manufacturers that put a “Best by” date on their product with an 18-month window from the date of manufacture.
When buying in bulk, I would make purchases consistent with a six-month use pattern, and I would opt for a store with a consistent flow of customers through the sold-in-bulk section. This makes it less likely that the products have been sitting in the bins for too long. A great practice is for the store to post “Best by” dates on the bulk bins themselves.
While refrigeration is not essential for brown rice, it can extend shelf life up to a year. Absent that, brown rice should be kept in a cool place in a well-sealed container, away from any source of moisture.
Rice oil, usually called rice bran oil, has many healthful attributes. As mentioned above, it has a good fatty acid composition, but it also has some other components that are receiving attention lately. The phytochemicals of note include the tocopherols and tocotrienols (vitamin E and its relatives), and certain triterpene alcohols, most notably a compound named gamma oryzanol. We are not talking large doses of any of these healthy compounds, here, but assets are assets. And this speaks to the big-picture healthfulness of opting for whole foods whenever possible.
Rice bran oil has a high smoke point (490 degrees F), which makes it good for cooking and frying. (Note: The smoke point is the temperature at which an oil will begin to break down. At or about that point, it tends to give off a bluish-grey, acrid-smelling smoke. Food cooked in such oil will have an “off” taste and be unhealthful to eat.)
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