• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.228-234
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• 2022

Various types of tea have been cultivated to obtain different flavors and enhance their functional properties. The objective of this study was to investigate the physicochemical properties of γ-aminobutyric acid (GABA) teas produced from commercial Korean green, white, and black teas. The concentration of total minerals was reduced in GABA green tea and GABA white tea but was improved in GABA black tea. The essential, non-essential, and total free amino acid contents were remarkably increased in the GABA teas. The amino acid GABA content was increased by 561.00 and 294.20 times in GABA white tea and GABA black tea, respectively. The antioxidant potential was not reduced, although the total polyphenol and total flavonoid contents decreased in GABA green tea and GABA black tea. The results indicated that the overall nutritional value of commercial green, white, and black teas could be improved by processing them into GABA teas.

• Korean journal of food and cookery science
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• v.23 no.3 s.99
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• pp.409-412
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• 2007

The aim of this study was to examine the content of bioactive component, ${\gamma}$-aminobutyric acid (GABA) in 7 commercial green teas. The teas were grown in different regions in Sourhtern Korea, and were picked during the middle of the season. The green tea extracts were each derivatized with 6-aminoquinolyl-N-hydroxy-succinimidyl carbamate(AccQ${\cdot}$Fluor), and GABA was detected by a fluorescence detector at arf excitation of 250 nm and emission of 395 nm. The GABA contents varied depending on the regions where the green tea samples were produced. There was no significant difference in GABA contents between samples A and C, where it ranged from from 45.21${\pm}$0.99 (nmol/g) to 63.83${\pm}$0.61 (nmol/g): however, a significantly different amount of GABA was found in the green tea produced in B. The highest GABA content was 210.67${\pm}$0.85 (nmol/g), whereas the lowest content was 3.88${\pm}$0.71 (nmol/g). This variation in GABA contents was probably due to the regional differences, even within the same location, as well as the processing technology, which may retain or develop more GABA components in the final green tea.

• Korean Journal of Medicinal Crop Science
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• v.10 no.1
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• pp.37-40
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• 2002

GABA tea which was increased of GABA by anaerobic conditions in green tea leaves) was fed in the diet to spontaneously hypertensive rats(SHR). The mean systolic blood pressure of SHR fed a diet containing 1.5% GABA tea after 3 weeks was not different with zero day as 177.3mmHg. However, 1.5% green tea and control after 3 weeks were more increased 4.2 percents and 10 percents than in zero day. The plasma levels of aldosterone of SHR fed a diat containing 1.5% GABA green tea after 3 weeks was more decreased 2.5 times than in water treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1201-1206
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• 2010

As a means to increase the production and consumption of the brown colored rice with high content of GABA ($\gamma$-aminobutyric acid), this study was conducted to develop brown colored rice tea. After roasting at various temperatures and times, color values and GABA content of the brown colored rice were analyzed. Physicochemical properties such as browning, turbidity, reducing sugar, soluble solid, total polyphenol and pH of brown colored rice tea were determined after the rice powder was put into tea bags and leached in hot water. Sensory characteristics were investigated for three kinds of tea roasted at $170^{\circ}C$ for 10, 20 and 30 min. As the roasting temperature and time increased, L, a and b values decreased as well as GABA content. The brown colored rice roasted at $170^{\circ}C$ for 10 min contained the highest content of GABA. Browning, turbidity, reducing sugar, soluble solid and total polyphenol of the brown colored rice tea increased as the roasting temperature and time increased, on the contrary, pH decreased. The brown colored rice tea roasted for 30 min was preferred the most in color, flavor, taste and overall acceptance. From this result, the brown colored rice tea needs to be manufactured by a combination of the brown colored rice roasted at $170^{\circ}C$ for 10 min and 30 min to satisfy the consumer's preference and high content of GABA.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.315-319
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• 1992

Korean green tea leaves which were harvested three times(May, June, August) were treated with anaerobic conditions and were measured changes of ${\gamma}-aminobutyric$ acid(GABA) and other constituents. In anaerobically treated green tea leaves, the content of ${\gamma}-aminobutyric$ acid(GABA) and alanine increased while glutamic acid decreased. Whereas theanine, arginine, caffeine and tannin showed little change and the content of vitamine C slightly decreased with the passing of the anaerobic treatment time. Formation of GABA, a hypotensive constituents, was proportioned to the content of glutamic acid and the optimum time of the anaerobic treatment was about 12 hours. In the anaerobic treatment of green tea leaves, effect of nitrogen gas and vacuum condition was no difference between two.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.652-657
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• 2015

To produce mulberry-leaf tea abundant in ${\gamma}$-aminobutyric acid (GABA), mulberry leaves were subjected to two distinct anaerobic conditions ($N_2$ and vacuum) for 12 h before the manufacturing process. Subsequently, changes in the GABA content as well as that of other components were measured. In anaerobically treated mulberry leaves, GABA content markedly increased by 436-472% compared with the control, while the glutamic acid content decreased. However, few changes were observed in the contents of the general components (moisture, carbohydrate, lipid, protein, and ash) and water-soluble solids. Free sugar, catechin, and total phenol content decreased after anaerobic treatment. However, the sensory test scores were not different between the control and anaerobically-treated samples. Consequently, tea products, manufactured post nitrogen gas or vacuum treatment of leaves after harvest, showed functional properties without sensory loss.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.6
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• pp.911-918
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• 2007

Korean tea leaves (Camellia sinensis var. sinensis,), which were harvested in April, were fermented for various times, and then the changes in free amino acids (glutamic acid, GABA, arginine, theanine), pH, color values, and sensory qualities were evaluated. The pH in every sample became lower as fermentation time increased. Lightness also decreased as tea fermentation increased. Furthermore, glutamic acid, GABA, and arginine contents increased, while theanine content decreased, where it presented as 69% of the non-fermented tea leaves. GABA, a hypotensive compound, increased in the fermented tea leaves according to the degree of fermentation and hand rolling times. In terms of the theanine relaxation effect as well as taste, a shorter fermentation time is required, and for a hypotensive effect of GABA, fermentation needs to be increased. For the sensory evaluation, the preferred blend of taste and flavor was highest in the S8 tea sample.

• Journal of Mushroom
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• v.15 no.2
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• pp.88-93
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• 2017

This study was carried out to establish a cultivation technique for increasing the ${\gamma}$-aminobutyric acid (GABA) content in the fruit body of mushrooms by adding processed by-products. For the oyster mushroom 'Heucktari', addition of green tea powder, sea tangle powder, and green tea dregs resulted in very poor primordia formation, fruit body growth, and increased GABA. However, addition of 10% schizandra berry dregs and 1% rice bran to the basal substrate induced 100% and 10% increases, in GABA content in the fruit bodies compared to the control treatment without by-product, respectively. In addition, fruit body growth and primordia formation were greatly increased by these treatments. Therefore, GABA content was increased when the substrate was prepared by mixing an appropriate amount of schizandra berry dregs and rice bran.

• Korean Journal of Medicinal Crop Science
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• v.9 no.4
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• pp.275-279
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• 2001

The contents of chemical components such as total nitrogen, total amino acid, chlorophyll, vitamin C and free sugar were somewhat higher in $CO_2$ and $N_2$ gas treatment than those of other treatment. However, the contents of tannin and caffeine did not show any different in the 5 treatments. ${\gamma}-aminobutyric$ acid(GABA) and alanine accumulated in tea leaves under anaerovic condition. The content of GABA acid with ${CO_2\;and\;N_2}$ gas treatment was higher 8-6 times with values of ${264{\sim}215mg/100g}$ than in control (35mg/100g). The scores of sensory test was not different between anaerobic treatment and control. Consequently, tea mading within ${N_2\;and\;CO_2}$ gas treatment after plucking was considered to be the best green tea in terms of functional nature as well as taste nature.

• Korean Journal of Medicinal Crop Science
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• v.9 no.1
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• pp.26-32
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• 2001

The contents of chemical components such as total nitrogen, total amino acid and vitamin C were somewhat higher in $N_2$ gas treatment at $10^{\circ}C$ for 3 hours than those of other treatments. However, the contents of tannin and chlorophyll were slightly lower than that in the other treatments. The content of ${\gamma}-Aminobutyric$ acid with $N_2$ gas treatment was higher $1.5{\sim}6$ times with values of $51{\sim}205mg/100g$ than in control (35mg/100g). The scores of sensory test was not different between $N_2$ gas treatment for 3 hours and control. The contents of chemical components such as total nitrogen, total amino acid including theanine and caffeine were slightly higher in $N_2$ gas treatment at $20^{\circ}C$ for 3 hours than those of other treatments. However, the contents of tannin and vitamin C were slightly lower than those of other treatment. The content of GABA in tea leaves treated with $N_2$ gas was higher $2.5{\sim}7$ times with values of $85{\sim}225mg/100g$ than in control (35mg/100g). The sensory test was lower in $N_2$ gas treatment($76.3{\sim}78.1$ point) than in control(80.4 point). The contents of chemical components were not different between $N_2$ gas treatment at $30^{\circ}C$ for 3 hours and control. Whereas the contents of chemical components were somewhat lower in $N_2$ gas treatment for 1 hour and 5 hours than in control. The content of GABA in tea leaves treated with $N_2$ gas was higher $3{\sim}7$ times with values of $115{\sim}217mg/100g $than in control(35mg/100g). The sensory test was lower in $N_2$ gas treatment ($74.3{\sim}78.4$ point) than in control(80.4 point). Consequently, tea mading within 5 time $N_2$ gas treatment at $10^{\circ}C$ or 3 time $N_2$ gas treatment at 20, $30^{\circ}C$ after plucking was considered to be the best green tea in terms of functional nature as well as taste nature.