Green processing, germinating and wet milling brown rice (Oryza sativa) for beverages: Physicochemical effects

Authors: Beaulieu, John; Reed, Shawndrika; OBANDO-ULLOA, JAVIER - The Technological Of Costa Rica (TEC); Boue, Stephen; COLE, MARSHA - Louisiana Technical University

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2020
Publication Date: 7/29/2020
Citation: Beaulieu, J.C., Reed, S.S., Obando-Ulloa, J.M., Boue, S.M., Cole, M.R. 2020. Green processing, germinating and wet milling brown rice (Oryza sativa) for beverages: Physicochemical effects. Foods. 9:1016. https://doi.org/10.3390/foods9081016.
DOI: https://doi.org/10.3390/foods9081016

Interpretive Summary: Brown rice is nutritionally superior to white rice but oils and rancidity can be problematic regarding organoleptics during storage. There has been a re-invigorated health trend using sprouted whole grain products (bread flours, cereals and beverages), resulting in several new food and beverage products in the marketplace. Activation of metabolism occurs during the germination process, which results in the synthesis and/or accumulation of metabolites with health-promoting properties. Rice beverages offer options for those with lactose intolerance, gluten sensitivities, health-related issues and desires to cut back on animal products. With plant-based healthier nutrition in consumer’s minds, national and worldwide consumption and production of plant-based beverages are overtaking the beverage industry. Between 2009 and 2015, worldwide sales of non-dairy milk alternatives more than doubled to $21 billion. Herein, we are using green technologies, focusing on brown rice processing regimes with enzymatic treatments, which do not rely upon stabilization, to produce value-added rice beverages. We define “green technologies” for food processing as sustainable, less harmful to the environment, and safe natural chemical processes used to transform raw produce into value-added foods and ingredients, including use of endogenous and food grade enzymes which provide reaction specificity, sensitivity and non-toxicity. Rough Rondo rice was dehulled using a pilot plant dehusker, sorted, cleaned, rinsed, and germinated under various conditions (times and temperatures). Based upon proximate analysis, phytic acid and processing efficiency, we have established a germination process that engages the natural enzymatic hydrolysis of starch and other biochemical changes, which was stopped before appreciable protein, oil and carbohydrate loss occurred. The process was termed “free-flowing”, referring to a matrix that is predominately soluble without clumps or gelled materials that pass both 30-mesh and 140-mesh sieves, flowing and pouring smoothly. Rapid visco analyser data of in-house prepared brown rice and standard white rice flour samples established that the brown rice had a higher gelatinization temperature than previously attributed to this long grain white rice. Particle size analysis and viscometric evaluations indicated that the developed sprouted brown rice beverage was on track to have properties close to commercial samples, even though the sprouted brown rice beverage developed was 100% completely natural and had no additives or oils or salts added. Higher viscometry values in the sprouted brown rice beverages have been attributed to oil and protein remaining partially soluble, which could deliver positive mouthfeel and textural attributes. '-aminobutyric acid and phenolics increased slightly in germinated brown rice however, the increases were not maintained throughout the processing. Germinating dehulled brown rice resulted in significantly lower inorganic arsenic levels (113 ng/g) than both the starting brown rice and Rondo white rice, far below the current U.S. threshold level of 200 ng/g.

Technical Abstract: Plant-based beverage consumption is increasing markedly. Value-added dehulled rice (Oryza sativa) germination was investigated to improve beverage qualities. Germinating brown rice has been shown to increase health-promoting compounds. Utilizing green processing, the wholesome constituents including bran, vitamins, minerals, oils, fiber and proteins should convey forward into germinated brown rice beverages. Rapid visco analyser data and trends established brown rice, preheated brown rice and germinated brown rice had higher pasting temperatures than white rice. As pasting temperature in similar samples may be related to gelatinzation, RVA helped guide the free-flowing processing protocol using temperatures slightly above previously reported Rondo gelatinization. Particle size analysis and viscometric evaluations indicate the developed sprouted brown rice beverage is on track to have properties close to commercial samples, even though the sprouted brown rice beverage developed has no additives, fortifications, added oils or salts. Phenolics and '-aminobutyric acid increased slightly in germinated brown rice however, increases were not maintained throughout most stages of processing. Significantly lower inorganic arsenic levels (113 ng/g) were found in germinated brown rice, far below the U.S. threshold level of 200 ng/g, compared to the starting Rondo white and brown rice. This will become diluted further upon pilot plant scale-up and pasteurization.