HPLC determination of gamma amino butyric acid (GABA) and some biogenic amines (BAs) in controlled, germinated, and fermented brown rice by pre-column derivatization

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

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, γ-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.

Changes in the Bio-Compounds and Biological Activities of Eight Whole Grains Fermentation Starter with Different Oxidized Chin-Shin Oolong Teas

Chin-shin oolong tea is the most widely planted variety in Taiwan. This study fermented eight whole grains fermentation starter (EGS) with light (LOT), medium (MOT), and fully (FOT) oxidized Chin-shin oolong teas for ten weeks. Comparing the three fermentation beverages, it was found that LOT fermentation can obtain the highest catechins (1644.56 ± 60.15 ppm) among the functional and antioxidant components. MOT can obtain the highest glucuronic acid (19,040.29 ± 2903.91 ppm), tannins, total phenols, flavonoids, and angiotensin-converting enzyme (ACE) inhibitory activity. FOT can obtain the highest GABA (1360.92 ± 123.24 ppm). In addition, both the LOT and MOT showed a significant increase in their ability to scavenge DPPH radicals after fermentation. EGS fermented with lightly or moderately oxidized Chin-shin oolong tea may be considered a novel Kombucha.

Changes in Bio-Functional Compounds, ACE Inhibition, and Antioxidant Capacity after Mixed Fermentation of Eight Whole Grains

Whole grains are rich in nutrients and antioxidants and can be fermented to increase their biological functions. This study used two fermentation steps to ferment eight whole grains. The bio-functional compounds, ACE inhibition, and antioxidant capacity were measured during the second fermentation step. The results indicate that the total phenols content increased by 2605%, total flavonoid content increased by 1707%, ABTS radical scavenging capacity increased by 239%, DPPH radical scavenging capacity increased by 325%, GABA increased by 4810%, glucuronic acid increased by 4278%, ACE inhibition increased by 69.28%, and total amino acids increased by 2197.72% after 13 weeks of fermentation. These results showed that a fermentation beverage with eight whole grains could be considered a drink with health benefits.

Formation of Bioactive Tyrosine Derivatives during Sprouting and Fermenting of Selected Whole Grains

Sprouting is a popular method in cereal processing because sprouted grains are accepted to have high nutritional value. The increased proteolytic activity by sprouting increases the free amino acids in grains. It was hypothesized that an increased amount of tyrosine can be utilized by microorganisms during fermentation to form higher amounts of bioactive tyrosine derivatives. Sprouting increased the tyrosine and tyramine contents considerably, but increases and decreases in l-3,4-dihydroxyphenylalanine (l-DOPA) and dopamine were specific to the cereal. More tyramine, l-DOPA, and dopamine formation was observed during sourdough fermentation than that in yeast fermentation. As a result of the combined application of sprouting (48 h at 20 °C) and sourdough fermentation (36 h at 30 °C), the amounts of dopamine, l-DOPA, and tyramine found in rye were 27, 50, and 136 mg/kg, respectively. Cereal products rich in dopamine and l-DOPA can thus be produced as functional food ingredients with their positive effects on human health and mood.

Towards direct analysis of solid and liquid samples exploiting a 3D printed dialysis unit and sequential injection: Application for automated derivatization and determination of gamma-aminobutyric acid in foodstuff and beverages

In this work, a new design of a dialysis unit for direct analysis of solid and liquid samples is presented. The homemade unit was constructed using a 3D printer due to its simple and fast fabrication ability. The dialysis unit is composed of cylindrical-shaped donor and acceptor chambers. A stainless steel sieve is installed inside the donor chamber. SEM images clearly showed that the sieve prevented membrane blockage by suspension particles in the sample. Multiple dialysis units were connected to a sequential injection (SI) system for serial determination of gamma-aminobutyric acid (GABA) in solid and liquid samples. The dialysate from each dialysis unit was consecutively aspirated into the SI flow line for on-line derivatization of GABA with 2-hydroxy-1-naphthaldehyde (3.0% w/v). The derivative was detected spectrophotometrically at 425 nm. The linear calibration range extended to 1000 mg L^-1 GABA (r² > 0.99) with high precision (1.2 %RSD). The developed system was applied to analysis of dietary supplements, grains of germinated brown rice and milk. The samples were directly introduced into the donor chamber either as powder or liquids. The measured GABA content using the developed method was compared using high performance liquid chromatography, with good agreement using Pearson's correlation (r² = 0.9999). The method has high accuracy based on recovery studies (99.8 ± 1.5%) and high sample throughput (64 samples h^-1).