New process helps rice retain vitamins.

New process helps rice retain vitamins

Ever wonder why enriched rice carries a label warning consumers not to wash the grains" It's to keep people from rinsing away 75 to 90 percent of the vitamins, explains Esmond W. Joseph, a food scientist at CPC International/Best Foods in Union, N.J. But Joseph says a new enrichment process, which he helped develop while at Louisiana State University in Baton Rouge, can embed vitamins into white rice so effectively that they withstand not only thorough washing but also the high temperatures required for canning. Moreover, the process strengthens the rice so that it doesn't mush during cooking or canning, Joseph and his co-workers report in the July-August JOURNAL OF FOOD SCIENCE.

Though most Americans prefer white rice, they pay a nutritional price for selecting it: Milling techniques that whiten brown rice also remove much of its vitamin content. Enrichment processes can replace the lost nutrients, but "none of the methods presently used to enrich rice is rinse- and cook-proof," the Louisiana team notes.

Their process involves soaking rice for 30 minutes in water acidified to a pH of about 2.4. Then they add a mix of vitamins and acetaldehyde, a reagent that introduces new chemical crosslinks into the starch to reinforce the grains' internal structure. As the crosslinking process swells the rice, each grain draws the added vitamins deep into its starchy matrix.

During cooking and canning experiments, the researchers found that unenriched white rice lost an average 17.7 percent of its niacin, 11 percent of its pyridoxine, 53.8 percent of its thiamine and 13 percent of its riboflavin. In white rice enriched through the acetaldehyde process, levels of these vitamins dropped by an average of 2 to 25 percent. Thus, the rice survived cooking and canning temperatures with about two to four times the vitamin content of the raw untreated rice.