Assessing green-processing technologies for wet milling freshly hulled and germinated brown rice, leading to naturally fortified plant-based beverages

Authors: Beaulieu, John; TULLY, MAUREEN - Department Of Energy; Daigle, Kim; Boue, Stephen

Submitted to: Annual Meeting Horticultural Society
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Since 1999, plant-based dairy alternatives like soy, almond, and rice milk had averaged annual sales growth of ~10.9%. By 2011, U.S. retail sales of plant-based nondairy beverages (almond, coconut, hemp, rice and soy milk) attained $1.3 billion. Worldwide sales of non-dairy milk alternatives more than doubled between 2009 and 2015 to $21 billion. More recently, almond, soy and rice milk beverages have experienced phenomenal growth rates. Rice-derived plant-based milks offer non-soy, lactose-free, hypoallergenic, cholesterol and gluten free value-added food sources which, with natural fortifications, may offer well balanced nutrition that is less expensive compared with nut-based products which come from significantly limited acreage. 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 which has minimal fat, fiber, protein and contaminants. However, extraction methods and techniques are no longer favored by many manufacturers and consumers, who desire less processed, “greener” products. The ultimate objective is using green technologies focusing on brown and colored rice with berry-based infusions and enzymatic treatments (not relying upon stabilization) to produce rice milk products. ‘Rondo’ paddy rice was freshly hulled using a pilot plant dehusker, manually sorted in mesh sieves along with culling out rough rice kernels. Then brown rice was pre-rinsed, placed into mason sprouting jars with screen lids, for 30 minute soaking treatments at 35°C in water and peracetic acid (30 and 300ppm). Rice was soaked 24 hours in water at 35°C then was inverted for 24 hours germination; both with 4 hour periodic rinses. Samples were softened at 65-70°C in a hot water bath until wet-milled kernels passed through a 30-mesh sieve prior to gelatinization at 75-90 °C. Measurements included the proximate analysis, pH, phytase, arsenic content, germination % and coleoptile lengths, total phenolics, microbial, starch/sugar and °Brix. Initial ‘Rondo’ pH was ~7.00-7.16 which dropped after germination to 5.20±0.05, with germination rate of 97.0-99.0±1.0%. Proximate brown rice analysis 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. Protein, fat and ash decreased in all treatments after germination, and coleoptile lengths (2.30±0.89mm) decreased slightly in peracetic acid (~2.09±0.71mm). Phytic acid (0.78%) decreased markedly after germination, and with increasing treatment acidity, as there was 0.25±0.01, 0.21±0.01 and 0.17±0.00% in control, 30 and 300ppm peracetic acid, respectively. Total phenolics increased from initial brown rice (7.21±0.48µl/ml); however, the highest acidity was detrimental whereby there was 7.52±0.44, 7.61±0.36 and 6.93±0.73µl/ml in germinated control, 30 and 300 ppm peracetic acid respectively. Initial liquefaction enzyme treatments for starch/sugar conversions and analyses are in progress.

Technical Abstract: Rice milk beverages can well balanced nutrition. With healthier nutrition in consumer’s minds, national. Worldwide consumption/production of plant-based milk beverages are increasing. Much past research and invention was based on enzymatic conversion processes for starch that were uncomplicated because the utilized stabilized rice or rice flour had minimal fat, fiber, protein and contaminants. The ultimate objective is using green technologies focusing on brown and colored rice with berry-based infusions and enzymatic treatments (not relying upon stabilization) to produce rice milk products. Herein, we focus on preliminary details regarding wet-milling and pre-germinating brown rice prior to gelatinization and enzyme treatments. ‘Rondo’ paddy rice was freshly hulled using a pilot plant dehusker, manually sorted in mesh sieves along with culling out rough rice kernels and rice stinkbug/smutty grains. Then 400g brown rice was pre-rinsed, placed into 1L mason sprouting jars with screen lids, for 30min soaking treatments at 35°C in water and peracetic acid (30 and 300ppm). Rice was soaked 24 hr in water at 35°C then was inverted for 24 hr germination; both with 4 hr periodic rinses. Samples were softened at 65-70°C in a hot water bath until wet-milled kernels passed through a 30-mesh sieve prior to gelatinization at 75-90 °C. Measurements included proximate analysis, pH, phytase, arsenic content, germination % and coleoptile lengths, total phenolics, microbial, starch/sugar and °Brix. Initial ‘Rondo’ pH was ~7.00-7.16 which dropped after germination to 5.20±0.05, with germination rate of 97.0-99.0±1.0%. Proximate brown rice analysis 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. Protein, fat and ash decreased in all treatments after germination, and coleoptile lengths (2.30±0.89mm) decreased slightly in peracetic acid (~2.09±0.71mm). Phytic acid (0.78%) decreased markedly after germination, and with increasing treatment acidity, as there was 0.25±0.01, 0.21±0.01 and 0.17±0.00% in control, 30 and 300ppm peracetic acid, respectively. Total phenolics increased from initial brown rice (7.21±0.48µl/ml); however, the highest acidity was detrimental whereby there was 7.52±0.44, 7.61±0.36 and 6.93±0.73µl/ml in germinated control, 30 and 300 ppm peracetic acid respectively. The initial total arsenic was 0.52±0.01mg/kg, comprised by inorganic (0.22±0.01) and organic (0.25±0.02) species. Initial liquefaction enzyme treatments for starch/sugar conversions and analyses are in progress.