Health-promoting germinated rice and valueadded foods: a comprehensive and systematic review of germination effects on brown rice

Authors: Beaulieu, John; Boue, Stephen; GOUFO, PIEBIEP - University Of Tras-Os-montes And Alto Douro

Submitted to: Critical Reviews in Food Science and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2021
Publication Date: 7/11/2022
Citation: Beaulieu JC, Boue SM, Goufo P. 2022. Health-promoting germinated rice and value-added foods: a comprehensive and systematic review of germination effects on brown rice. Crit Rev Food Sci Nutr. doi: 10.1080/10408398.2022.2094887.
DOI: https://doi.org/10.1080/10408398.2022.2094887

Interpretive Summary: Rice (Oryza sativa L.) is a major cereal crop and staple food source for half of the world population, especially in developing nations. Rice is a major agronomic crop, accounting for roughly 25% of the world’s cereal grain production. In 2020, the U.S. rice crop was valued at 2459 million dollars. After eating, white rice is rapidly digested and absorbed as glucose, potentiating a hyperglycemic response and triggering insulin secretion and tissue-specific intracellular uptake of glucose that can then result in hypoglycemia. However, rice enriched with polyphenols as found in brown, red, purple and black varieties contribute many health-promoting activities. Germinating brown rice is known to generally increase several health-promoting compounds. Brown rice (defined as bran-included brown, red, purple or black rice) germination has been extensively investigated over the last 30 to 40 years with hundreds of articles published. There exist a myriad of methods employed and parameters assessed which oftentimes muddles the overall data, as inconstant outcomes occur and unified approaches and consensus are occasionally variable, difficult to govern and utilize with absolute confidence. A comprehensive review has been amassed, attempting to solidify the literature on sprouting and/or germinating brown rice, by reviewing most of the important chemical changes, their potential health benefits and value-added product considerations. Higher levels of dietary fiber, a modest quantity of protein, unsaturated lipids and a number of bioactive compounds are present in BR, and often augmented through germination. Utilization of red, purple and black rice, which have even more phenolic compounds and greater antioxidant capacity, is of additional benefit to consumer. Therefore, rice bran inclusion and germination and consumption are strongly recommended. In this review we have also assessed several parameters for several compound classes, and performed a pair-wise T-test comparison using literature meeting strict provenance requirements (defining the context via unifying units, removing papers with poorly detailed methods and their attributed data sets, removing data from figures and graphically manipulated sources and removal of data where no brown rice control values were reported) from 117 papers to deliver an overall approach indicating, with significance denoted, when a given compound has been found to increase or decrease through rice germination. The goal is to deliver a meaningful appraisal of rice germination effects through a global database with clear representation of effects on dozens of parameters examined over the last decades. Hopefully, this resource will likewise stimulate interest in germinating rice and increase both production and consumption of highly nutritious, health-beneficial rice with colorful bran.

Technical Abstract: Over the last 30 years, thousands of articles have appeared examining the effects of soaking and germinating brown rice (BR). Variable germination conditions and methods have been employed to measure different health-beneficial parameters in a diverse germplasm of BR. Research results may therefore appear inconsistent with occasional anomalies, and it may be difficult to reach consensus concerning expected trends. Herein, we amassed a comprehensive review on germinated brown rice (GBR), attempting to codify 133 peer-reviewed articles regarding the effects on 164 chemical parameters related to health and nutrition in BR and in value-added food products. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-2020) approach was used to direct the flow of the literature search. A pair-wise comparison t-test was performed to deliver an overall approach indicating when a given compound has been found to significantly increase or decrease through germination, which was grouped into GABA and polyamines, '-oryzanol and phytosterols, phenolic compounds, vitamins, proteins and amino acids, starchy carbohydrates, free sugars, lipids, minerals and phytic acid. This resource will stimulate interest in germinating rice and optimistically help increase both production and consumption of highly nutritious, health-beneficial rice with pigmented bran.