Green processing sprouted brown rice for beverage formulations: Protein characteristics

Authors: Beaulieu, John; Hojilla-Evangelista, Milagros - Mila; OBANDO, ULLOA - Institute Of Technology; Boue, Stephen

Submitted to: Institute of Food Technologies
Publication Type: Abstract Only
Publication Acceptance Date: 1/31/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary: Brown rice is nutritionally superior to white rice but oils and rancidity can be problematic regarding sensory attributes during processing and storage. Germinating brown rice is known to generally increase several health-promoting compounds. In response to increasing consumption of plant-based beverages, we sprouted brown rice using green technologies and enzymes for making value-added rice beverages. We define “green technologies” for beverage processing as sustainable, less harmful to the environment, and safe natural physical processes used to transform raw product into value-added foods and ingredients, including use of endogenous and food grade enzymes which, provide reaction specificity, sensitivity and non-toxicity. Paddy rice was dehulled, germinated and beverages produced and compared against the non-germinated brown and white brewers rice. Native gel electrophoresis, SDS-PAGE, protein determination and solubility tests were performed to assess differences between the three beverage types, with comparison to commercial rice beverages. Germinated brown rice beverages contained higher protein levels than non-germinated beverages, but all three beverages had markedly higher protein concentrations (~5%) than commercial rice beverages (generally = 1%). The in-house developed beverage protein was roughly 10% soluble. A unique 6.5 kDa polypeptide band was attributed to possible increased solubility in both sprouted and non-sprouted brown rice beverages. Sieving losses resulted in significant protein losses. Nonetheless, significant amounts of proteins were retained in the germinated brown rice beverages.

Technical Abstract: Brown rice is nutritionally superior to white rice but oils and rancidity can be problematic during processing and storage. Germinating brown rice is known to generally increase several health-promoting compounds. Plant-based drinks are rapidly becoming a strong segment in the functional beverages marketplace, and the global plant-based beverage market is expected to surpass $34 billion by 2024. We therefore sprouted brown rice using green technologies and saccharification enzymes for making value-added rice beverages. The goal is to convey and/or augment health-beneficial compounds from brown rice into a completely natural (no additives or fortification) improved beverage. Paddy rice was dehulled, sorted/graded and soaked/germinated at 35 °C for 48 hours. Materials were pre-softened thermally at 70 °C, wet milled then gelatinized to facilitate saccharification with food-grade enzymes. Beverages were produced from germinated brown rice (GBR), and non-germinated brewers white rice (WR) and brown Rondo rice (BRR). A green processing method was optimized for GBR, which was compared against the BRR and WR preliminary beverages. Native gel electrophoresis, SDS-PAGE, protein determination and solubility tests were performed to assess differences between the three beverage types, with comparison to commercial rice beverages. Data were processed through one-way analysis of variance using JMP 13 PRO for Windows. Crude protein content for starting materials were BRR > WR > GBR. Germinated brown rice beverages contained higher protein levels (5.5%) than non-germinated beverages (BRR 4.6%, and WR 4.8%, respectively), but all three beverages had markedly higher protein concentrations (~5%) than commercial rice beverages (generally = 1%). The protein was roughly 10% soluble. A unique 6.5 kDa polypeptide band was attributed to possible increased solubility in both sprouted and unsprouted brown rice beverages. Faded/less dense gel bands indicated less amounts of polypeptides, indicating protein loss, due to process conditions (commercial samples); and lost in heating (denatured/hydrolyzed) and discard streams during processing the GBR, BRR and WR beverages. Sieving losses resulted in significant protein losses. Significant amounts of proteins were retained in the GBR beverages, similar to non-germinated brown rice and white rice beverages. The green processing regime had significantly greater protein content compared to commercial samples analyzed.