Green Processing Technologies for Improving Germinated Brown Rice Milk Beverages

Authors: Beaulieu, John; Reed, Shawndrika; COLE, MARSHA - Louisiana Technical University; Daigle, Kim; Boue, Stephen

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/30/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rice feeds approximately half the world’s population. Rice-derived beverages offer non-soy, lactose-free, hypoallergenic, cholesterol and gluten free value-added food sources. Rice milk beverages offer exceptional options for those with lactose intolerance, gluten sensitivities, obesity, heart disease, diabetes and consumers desiring to cut back on animal products. Worldwide sales of non-dairy milk alternatives more than doubled between 2009 and 2015 to $21 billion. Brown rice is nutritionally superior to white rice but, oils and rancidity can be problematic regarding storage and organoleptics. To avoid rancidity issues, stabilized rice or rice flour has been used for much past research and invention. The use of stabilized hulled rice and bran indicates that costly and/or chemically abusive treatments have already occurred to deliver many shelf-stable commercially available processed bran and rice products/beverages. Much past research and invention was based on enzymatic conversion processes for starch that were uncomplicated because defatted or stabilized bran and/or flours (having minimal fat, fiber and protein contaminants) were used as the starting materials. The stabilized materials seldom negatively affect enzymatic actions. That was “good” (manufacturing-wise) and indeed that is why those processes were studied and used. However, abusive extraction methods and old-school proven extraction techniques are no longer favored by many manufacturers and consumers who, desire less processed, healthier, “greener” products with “clean labels”. Sprouting and/or germinating brown rice has been shown to increase the concentration of several health-promoting compounds which, are beneficial in the diet. Herein, we are attempting to use green technologies, focusing on sprouted brown rice and processing with enzymatic treatments which, do not rely upon stabilization, to produce novel, value-added rice milk products. Through green technologies, focusing on sprouting organic brown rice and processing which does not rely upon stabilization, along with food-grade enzymatic treatments, we will deliver preliminary analysis of novel value-added health-beneficial rice milk beverages. The hulls of organic ‘Rondo’ paddy rice were removed on a Satake in a pilot plant followed by sorting, grading and culling then brown rice was pre-rinsed, placed into sprouting jars with screen lids for soaking treatments at elevcated temperature (e.g. 35°C) in water with and without 30 and 300 ppm peracetic acid, followed by a soak/sprouting cycle for 48 hours. Samples were thermally softened and wet-milled using several rice to water ratios, ultimately passing a 140-mesh sieve before gelatinization and saccharification with food-grade enzymes. Initial rice and post-sprouted samples (proximate analysis) and several quality-related parameters at key processing steps were evaluated. ‘Rondo’ brown rice pH was approximately 7.14 which dropped after sprouting to 5.28±0.07, with germination rates of 97.0 to 99.0±1.0%. During germination/sprouting, the rice absorbed 31.1±1.6% water. Peracetic acid rinses markedly reduced microbial counts (total plate counts and mold). The coleoptile lengths (2.30±0.89mm) decreased slightly (~2.09±0.71mm) in peracetic acid treatments. Phytic acid decreased 67% after sprouting, 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 further to 8.65±0.80 mg GAE/g in crude beverages. Proximate analysis of the freshly de-hulled brown rice for crude protein (%), fat (%), fiber (%), ash (g/100g) and moisture content (%) was: 7.23±0.10, 4.16±0.13, 1.70±0.10, 1.40±0.03 and 9.88±0.09, respectively. Carbohydrates decreased from 75.6% to 53.0% after sprouting, and likewise, catabolic decreases in protein (27.2%) and fat (38.7%), occurred during spr

Technical Abstract: Rice feeds approximately half the world’s population. Rice-derived beverages offer non-soy, lactose-free, hypoallergenic, cholesterol and gluten free value-added food sources. Rice milk beverages offer exceptional options for those with lactose intolerance, gluten sensitivities, obesity, heart disease, diabetes and consumers desiring to cut back on animal products. Worldwide sales of non-dairy milk alternatives more than doubled between 2009 and 2015 to $21 billion. Brown rice is nutritionally superior to white rice but, oils and rancidity can be problematic regarding storage and organoleptics. To avoid rancidity issues, stabilized rice or rice flour has been used for much past research and invention. Germinating brown rice is known to increase several health-promoting compounds. Herein, we are attempting to use green technologies, focusing on sprouted brown rice and processing with enzymatic treatments which, do not rely upon stabilization, to produce novel, value-added rice milk products. Through green technologies, focusing on sprouting organic brown rice and processing which does not rely upon stabilization, along with food-grade enzymatic treatments, we will deliver preliminary analysis of novel value-added health-beneficial rice milk beverages. Organic ‘Rondo’ paddy rice was freshly de-hulled on a Satake in a pilot plant followed by sorting, grading and culling then 400-600g brown rice was pre-rinsed, placed into sprouting jars with screen lids for 30 min soaking treatments at 35°C in water ± 30 and 300 ppm peracetic acid, followed by a soak/sprouting cycle for 48 hr at 35°C. Samples were thermally softened and wet-milled using several rice to water ratios, ultimately passing a 140-mesh sieve before gelatinization and saccharification with food-grade enzymes. Initial rice and post-sprouted samples (proximate analysis) and several quality-related parameters at key processing steps were evaluated. ‘Rondo’ brown rice pH was ~7.14 which dropped after sprouting to 5.28±0.07, with germination rates of 97.0-99.0±1.0%. At 35 °C, rice absorbed 31.1±1.6% water. Peracetic acid rinses markedly reduced TPC and mold. Coleoptile lengths (2.30±0.89mm) decreased slightly in peracetic acid (~2.09±0.71mm). Phytic acid decreased 67% after sprouting, 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 further to 8.65±0.80 mg GAE/g in crude beverages. 30 ppm peracetic acid only slightly decreased phenolics compared to germinated samples, and 300 ppm was apparently lethal (data not shown). Proximate analysis of the freshly de-hulled brown rice for crude protein (%), fat (%), fiber (%), ash (g/100g) and moisture content (%) was: 7.23±0.10, 4.16±0.13, 1.70±0.10, 1.40±0.03 and 9.88±0.09, respectively. Carbohydrates decreased from 75.6% to 53.0% after sprouting, and likewise, catabolic decreases in protein (27.2%) and fat (38.7%), occurred after sprouting. Initial processing regimes lost what appeared to be insoluble fiber and/or high molecular weight protein through sieves (e.g. 69.28, 0.73 and 13.60 for L*, a* and b*, respectively) yet, after refining the processing methods, no longer was tan colored residual lost after passing mesh sieves, and crude liquids appeared whiter in color (e.g. 78.45, -0.78 and 6.83 for L*, a* and b*, respectively). In germinated gelatinized samples, after 30 min, a-amylase liquefaction, 13.7 °Brix soluble solids were attained which, stabilized at 15.1 °Brix after 72h. Additional liquefaction enzyme treatments for starch/sugar conversions and analyses are in progress. Likewise sample analyses for starch/sugar, particle size, viscosity and gamma-aminobutyric acid are proceeding.