Effect of abiotic stress on bioactive compound production in germinated brown rice

Abstract

Background and objectivesThe objective of this study was to evaluate the effect of germination and various abiotic stresses on the technological, nutritional, and sensorial characteristics of brown rice. The seeds were soaked at 40°C and 30% humidity. The soaked seeds were allowed to germinate at 30°C for 36 hr in BOD chamber. The soaked rice grains were subjected to stress conditions in the last 4 hr of germination using saline (SBR/S), low temperature (4°C) (SBR/C), or a combination of saline and low temperature (SBR/B) and, after, it was analyzed the effect of germination and those abiotic stresses on the technological, nutritional, and sensorial characteristics of brown rice by the color parameters, texture profile, γ‐aminobutyric acid content, protein, and starch digestibilities.FindingsThe sprouted grains (SBR) were darker than the brown rice. The germinated rice grains exposed to cold stress were more resistant to crushing and chewing compared to grains exposed to salinity stress and those exposed to both cold and salinity stresses. Germination enhanced the γ‐aminobutyric acid (GABA) content and starch digestibility. The GABA content increased further, whereas the protein digestibility decreased in the germinated grains upon exposure to abiotic stresses.ConclusionsThe best conditions for germination and alternative processes that can help them to intensify the nutritional value of germinated grains must be elucidated. The results of this study were satisfactory for the nutritional and technological parameters, and thus, exposure of germinated grains to abiotic stress can be an alternative method for enriched rice production.Significance and noveltyColor and texture parameters change with germination and vary according to abiotic stresses. For the same reason, the content of GABA is increased. Protein digestibility is reduced, differently about the starch digestibility.

Salinity Treatments Promote the Accumulations of Momilactones and Phenolic Compounds in Germinated Brown Rice

“…Among all treatments, B2 showed the highest antiradical activities against DPPH and ABTS (IC 50 = 1.58 and 1.78 mg/mL, respectively) compared to others. Several studies have consistently demonstrated that different germination conditions and salt stress enhanced the antioxidant capacity of GBR [ 6 , 56 , 57 ]. This result may be due to the upregulation of relevant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase in rice under abiotic stresses [ 58 ].…”

“…Additionally, enzymatic activities during seed germination modify the bioactive substances through interactions between proteins and carbohydrates in the grain endosperm [ 4 , 5 ]. Accordingly, GBR has been reported to have a proliferation of bio-functional constituents such as γ-aminobutyric acid (GABA) [ 1 , 6 ], vitamins, and amino acids [ 7 ], as well as a reduction of sugar [ 8 ], compared to non-GBR. On the other hand, previous studies indicated that subjecting germinated brown rice (GBR) to abiotic stresses and various germination conditions can lead to improved nutritional profiles and an elevated accumulation of bioactive compounds and antioxidant properties.…”

“…Different soaking and germination periods revealed stimulatory effects on the growth of sprouts and increased contents of total phenolics, total flavonoids, and GABA in GBR [ 9 , 10 , 11 ]. Meanwhile, abiotic stresses such as salt and cold conditions may improve the contents of GABA, polyphenols, and antioxidant activity [ 6 , 12 ]. Therefore, the utilization of abiotic stresses and diverse germination conditions for GBR presents a promising strategy to promote the consumption value of brown rice.…”

Effects of pulsed light on germination and gamma‐aminobutyric acid synthesis in brown rice

“…GBR is one of the plant foods rich in GABA and serves as the main raw material for the development of GABA functional foods (Shu et al, 2008). According to previous reports, GABA synthesis may be elevated by environmental stresses (Nascimento et al, 2020;Poojary et al, 2017), including mechanical and environmental stimuli such as hypoxia, darkness, visible light, ultraviolet light, heat shock, cold shock, and cytosolic acidification (Wang et al, 2019;Xia et al, 2018). In general, stressful conditions increase cytosolic Ca 2+ , calmodulin, or H + levels, leading to a reduction in cytosolic pH and subsequently to increased GAD activity (Komatsuzaki et al, 2007).…”

Gamma Irradiation Promotes the Growth Rate of Thai Pigmented Rice As Well As Inducing the Accumulation of Bioactive Compounds and Carbohydrate Hydrolyzing Enzymes Inhibitors (α-Glucosidase and α-Amylase) under Salt Conditions

“…Rice is used as a food source and a medical therapy in many countries. The improvement of bioactive compounds in rice through biotic and abiotic stress has been studied previously ( Nascimento et al, 2020 ; Katiyar et al, 2022 ). The most common abiotic stresses used to promote the synthesis of bioactive compounds in rice include gamma radiation and salt, flooding, and drought stress ( Dash et al, 2018 ; Chinvongamorn and Sansenya, 2020 ; Panda and Barik, 2021 ).…”