Characterizing germinated brown rice milk beverage processes using green technologies

Authors: Beaulieu, John; Boue, Stephen; Reed, Shawndrika; Daigle, Kim

Submitted to: Regional Meeting of American Chemical Society
Publication Type: Abstract Only
Publication Acceptance Date: 12/13/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rice feeds approximately half the world’s population. However, due to milling losses, white rice is a poor source of vitamins and minerals. Brown rice is nutritionally superior yet oils and rancidity can be problematic regarding storage and organoleptics. Germinating brown rice is known to increase several health-promoting compounds. To avoid rancidity issues, stabilized rice or rice flour has been used for most past research and invention. Worldwide sales of non-dairy milk alternatives more than doubled between 2009 and 2015 to $21 billion. Much past research and invention was based on enzymatic conversion processes for starch that were uncomplicated because the processes utilized stabilized rice or rice flour. Extraction methods and proven extraction techniques are no longer favored by many manufacturers and consumers, who desire less processed, products. Herein, we are attempting to use green technologies, focusing on brown rice processing regimes with enzymatic treatments which, do not rely upon stabilization, to produce value-added rice milk products. Paddy rice was freshly de-hulled in a pilot plant and brown rice pre-rinsed, placed into sprouting jars with screen lids for 30 minute soaking treatments at 35°C in water ± peracetic acid, followed by soak/germination for 48 hours at 35°C. Samples were thermally softened and wet-milled using several rice:water ratios then passed a 140-mesh sieve before gelatinization and saccharification. Key processing steps were evaluated such as: proximate analysis, pH, germination %, coleoptile length, water absorption, phytase, arsenic, total phenolics, gamma-aminobutyric acid, microbial counts, color, starch/sugar analysis, particle size and °Brix. ‘Rondo’ brown rice pH was ~7.14 which dropped after germination to 5.28±0.07, with germination rate of 97.0-99.0±1.0%. At 35 °C, rice absorbed 31.1±1.6% water. Peracetic acid rinses significantly reduced total plate count and mold. After germination, protein and fat catabolically decreased 27.2 and 38.7%, respectively. Phytic acid decreased markedly (67%) after germination, and total phenolics increased from 6.95±0.73 to 7.73±0.48 mg GAE/g. After an optimized softening and milling process, phenolics increased to 8.65±0.80 mg GAE/g in crude beverages. After 30 min, alpha-amylase liquefaction resulted in a 13.7 °Brix (soluble solids) which stabilized at 15.1 °Brix after 72h. Analyses for color, starch/sugar, particle size and GABA are proceeding.

Technical Abstract: Rice feeds approximately half the world’s population. However, due to milling losses, white rice is a poor source of vitamins and minerals. Brown rice is nutritionally superior yet oils and rancidity can be problematic regarding storage and organoleptics. Germinating brown rice is known to increase several health-promoting compounds. To avoid rancidity issues, stabilized rice or rice flour has been used for most past research and invention. Worldwide sales of non-dairy milk alternatives more than doubled between 2009 and 2015 to $21 billion. Herein, we are attempting to use green technologies, focusing on brown rice processing technologies with enzymatic treatments which, do not rely upon stabilization, to produce value-added rice milk products. Paddy rice was freshly de-hulled in a pilot plant and 400-600g brown rice pre-rinsed, placed into sprouting jars with screen lids for 30min soaking treatments at 35°C in water ± peracetic acid, followed by soak/germination for 48 hr at 35°C. Samples were thermally softened and wet-milled using several rice:water ratios then passed a 140-mesh sieve before gelatinization and saccharification. Key processing steps were evaluated (proximate analysis, pH, germination %, coleoptile length, water absorption, phytase, arsenic, total phenolics, gamma-aminobutyric acid, microbial counts, color, starch/sugar analysis, particle size and °Brix). ‘Rondo’ pH was ~7.14 which dropped after germination to 5.28±0.07, with germination rate of 97.0-99.0±1.0%. At 35 °C, rice absorbed 31.1±1.6% water. Peracetic acid rinses significantly reduced TPC and mold. After germination protein and fat catabolically decreased 27.2 and 38.7%, respectively. Phytic acid decreased markedly (67%) after germination, and total phenolics increased from 6.95±0.73 to 7.73±0.48 mg GAE/g. After an optimized softening and milling process, phenolics increased to 8.65±0.80 mg GAE/g in crude beverages. After 30 min, a-amylase liquefaction resulted in a 13.7 °Brix which stabilized at 15.1 °Brix after 72h. Analyses for color, starch/sugar, particle size and GABA are proceeding.