Value-added processing of rice and rice by-products

Abstract

World competition has encouraged United States rice farmers and rice mills to be efficient in farming and production practices. Efforts to augment economic competitiveness include development of new varieties, improvements in milling practices, and identification of uses for rice products and by-products. The research detailed in this dissertation adds to the body of knowledge in milling practices and identification of uses for rice bran. To improve the prediction of milled rice quality at industrial scale, correlations for milling quality among laboratory, pilot, and industrial scale mills were identified for Clearfield 161. Final industrial product whiteness was ten points higher than for polished rice at medium and high pilot scale settings. Jazzman, the first US-bred jasmine-type rice variety, was released by the LSU AgCenter Rice Research Station in 2009 to compete for a share of the aromatic rice market. Pilot scale evaluation of Jazzman’s milling quality supported lab scale evaluation and provided additional data for milling optimization. With milling yields from 86 to 93%, Jazzman presented as a high-yield, good-milling aromatic long grain rice variety. A purple rice variety (line number MCR02-1576) was assessed for milling quality, and its bran for oil and anthocyanin concentration. Results showed a low milling recovery (<50%); low whiteness (<15%) values indicated pigment remained in the kernel. Anthocyanin concentration increased linearly across the entire bran layer. Oil concentration increased linearly across the inner bran layer with a mean of 22 percent. Processing the inner bran layer would maximize anthocyanin and oil recovery. As rice bran oil is a potential renewable energy source, the oil concentration across the bran layer of Jazzman, Clearfield 161, and Cocodrie were determined with hexane extraction and near infrared technology (NIT). Clearfield 161 had total oil concentration 1.83 times that of Jazzman and 2.11 times that of Cocodrie. Predictions of oil content across the bran layer were made from NIT measurements and compared to hexane extraction results. Collectively this research indicates that value-added processing of rice and rice bran which optimizes milling yields and recovery of high-value components from the bran layer would favorably impact economic competitiveness.