That's important, as rice remains a major staple for half the world's population, yet micronutrient deficiencies and malnutrition endure as serious global concerns, especially for women, infants and schoolchildren. "Golden Rice," fortified with vitamin A, is one example of efforts to add nutrients to rice to help counter such deficiencies in the world's poor and hungry people.
The new Cornell-developed method also opens up new opportunities to fortify puffed rice in breakfast cereals, snack foods and nutrient bars in school lunch programs with vitamins and soy protein.
"Rice is a good source of energy but not very high in protein and micronutrients," said Syed Rizvi, Cornell professor of food science and senior author of a paper, "Micronutrient and Protein-fortified Whole Grain Puffed Rice Made by Supercritical Fluid Extrusion," published in December's Journal of Agricultural and Food Chemistry.
"What we can do is create kernels of puffed rice that have a cocktail of nutrients added to them to improve nutritional quality. We can add all the vitamins, protein, iron and zinc," Rizvi said.
Also, the new process improves rice economics by allowing producers to use cheap broken kernels, which are otherwise used with other foods or fed to animals.
Commercially, puffed rice is made with steam at temperatures of 130 to 180 degrees Celsius, which destroys heat-sensitive nutrients, some flavor and color.
The new method uses supercritical carbon dioxide (CO2) to make puffed rice from rice flour with added protein and nutrients. Supercritical CO2 has properties of both a liquid and a gas at temperatures and pressures above certain thresholds. By using supercritical CO2, the researchers were able to keep the temperatures low enough to both make puffed rice and retain and add nutrients.
The method is already used to decaffeinate coffee and can be applied to create puffed products from any cereal, including corn and wheat.
"Here is an example of how a processed food improves upon the nutritional quality of what Mother Nature has given us," said Rizvi.
Cornell researchers partnered on this project with Wenger Manufacturing Inc. of Sabetha, Kan., that provided the machine for research and development of a new generation of foods like nutritious puffed rice, said Rizvi.