GABA Tea Research Articles

HS-SPME-GC-MS combined with relative odor activity value identify the key aroma components of flowery and fruity aroma in different types of GABA tea

HS-SPME-GC-MS combined with relative odor activity value identify the key aroma components of flowery and fruity aroma in different types of GABA tea

Process Optimization and Quality Components Analysis of γ-Aminobutyric Acid Pickled Tea.

Pickled tea is an anaerobically fermented tea common in Thailand, Myanmar and Yunnan minority areas. γ-aminobutyric acid (GABA) is non-protein amino acid with multiple bioactives, which can be easily produced under anaerobic conditions. During the processing of pickled tea, controlling the process parameters is effective for the production of GABA-rich products; however, the precise parameters remain to be clarified. In the present study, the fresh leaves of Camellia sinensis (L.) Kuntze (C. sinensis) 'FudingDabai', C. sinensis 'MabianLv No. 1', C. sinensis 'Wuniuzao' and C. sinensis 'Fuxuan No. 9' were used as raw materials to process GABA-rich pickled tea. Single-factor and orthogonal experiments were conducted to determine the best tea cultivars and optimize the best processing parameters via comparing the content of GABA, tea polyphenols (TPs) and other biochemical components of GABA-rich pickled tea. The results of the signal-factor experiment showed that the fresh leaves of C. sinensis 'MabianLv No. 1' had the highest GABA content of 2.61 mg·g-1 after treatment with vacuum for 6 h; therefore, C. sinensis 'MabianLv No. 1' was selected as the raw material for the subsequent experiments. Orthogonal experiments showed that the highest GABA content of 2.53 mg·g-1 was found in the pickled tea with 8 h of vacuum treatment, 20 min of rolling after microwave fixing, 20 min of spreading and 20 d of anaerobic fermentation at room temperature. Further, the sensory evaluation showed that it possesses a strong sour taste with a slight sweetness and a light yellow color and better comprehensive quality. This indicates that these parameters are optimal for the processing of GABA-rich pickled tea. This study will provide scientific basis for the subsequent production of high GABA tea.

GABA-enriched old Oolong tea fermentation

Oolong tea, being a semi-fermented variety, holds significance in the tea production industry. However, an important portion of stocked Oolong tea (old Oolong tea) was discarded from the market. Oolong GABA tea, known for its potential health benefits, can be produced through fermentation under oxygen-depleted conditions. Therefore, improving old tea into GABA-rich tea will contribute to limiting the discard of old tea from the market. In this study, old Oolong tea underwent fermentation at temperatures of 30ºC, 35ºC, and 40ºC for a duration of 48 hours. Key parameters, including GABA, tannins, total polyphenols, TF/TR ratio, and tea color, were monitored at six-hour intervals over the 48-hour fermentation period. The findings revealed that optimal conditions to produce high GABA content in old Oolong tea were identified at 35ºC for 42 hours, resulting in a GABA content of 121.2 mg/kg, which was five times higher than the control, accompanied by a clear and standard color characteristic of fermented tea. This underscores the importance of controlled fermentation conditions for enhancing the quality of GABA-enriched old Oolong tea.

Comparative analysis of anti-obesity effects of green, fermented, and γ-aminobutyric acid teas in a high-fat diet-induced mouse model

Obesity, a prevalent disease associated with numerous chronic conditions, including hyperlipidemia, hyperglycemia, diabetes, and metabolic syndrome, remains a major global health challenge. This study investigated the potential of green tea (GT), fermented tea (FT), and γ-aminobutyric acid (GABA) tea (GBT), which are rich in phytonutrients and polyphenols, for the management of obesity. Using a high-fat diet-induced obese mouse model (C57BL/6N), we explored the effect of these teas on various obesity-related parameters. The mice were categorized into five groups: normal diet with water, high-fat diet with water, and high-fat diet supplemented with GT, FT, or GBT. Over 13 weeks, we monitored body weight, perirenal and liver fat, adipocyte lipid accumulation, and key metabolic indicators, such as serum cholesterol, leptin, insulin, and fasting blood glucose. These teas contain beneficial phytochemicals such as GABA, theanine, and caffeine, and have demonstrated an enhanced antioxidant capacity, which increases the scavenging of free radicals and may reduce oxidative stress. The animal study indicated a decrease in feeding efficiency and significant reductions in body weight liver fat, epididymal fat, and perirenal fat, as well as in adipocyte lipid accumulation. Additionally, notable improvements were observed in metabolic health indicators, including reductions in serum cholesterol, leptin, insulin, and fasting blood glucose levels. Our findings revealed that GT, FT, or GBT significantly counteracted the negative effects of a high-fat diet, suggesting their potential in combating obesity and related metabolic disorders.

The Characteristic Aroma Compounds of GABA Sun-Dried Green Tea and Raw Pu-Erh Tea Determined by Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry and Relative Odor Activity Value.

We aim to improve the product quality of GABA raw Pu-erh tea during development and processing. In this study, headspace solid-phase microextraction gas chromatography-mass spectrometry technology combined with relative odor activity evaluations was used to compare the volatile compounds of GABA sun-dried green tea and GABA raw Pu-erh tea. Sensory evaluation showed a higher aroma score of GABA raw Pu-erh tea than that of GABA sun-dried green tea, with significant differences in aroma type and purity. A total of 147 volatile compounds of 13 categories were detected, which differed in composition and quantity between the two teas. 2-Buten-1-one,1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-,(E)- and beta.-myrcene largely contributed to the aroma formation of both teas. Five volatile compounds were screened as potential markers for tea aroma. Metabolic pathway analysis showed that monoterpenoid biosynthesis may be beneficial to the formation of flowery and fruity aromas in the teas. We suggest that the findings of this study may provide important guidance for the processing and optimization of GABA tea.

Investigation on the Quality of Commercially Available GABA Tea in Taiwan

This study collected 220 commercially available samples of γ-Aminobutyric acid (GABA) tea produced in Taiwan from 2016 to 2021. The 220 tea samples were categorized into five types of GABA tea, including 108 GABA Oolong tea, 71 GABA Black tea, 21 GABA Paochong tea, 12 GABA Green tea, and 8 GABA Puerh tea samples. The most common type of GABA tea in Taiwan is GABA Oolong tea, followed by GABA Black tea. The physico-chemical constituents and consumer acceptance of the GABA tea samples were analyzed. The GABA content varied among the different types of GABA tea: GABA Oolong tea ranged from 128–286 mg/100 g, GABA Black tea ranged from 182–360 mg/100 g, GABA Paochong tea ranged from 98–203 mg/100 g, GABA Green tea ranged from 56–174 mg/100 g, and GABA Puerh tea ranged from 142–191 mg/100 g. In terms of the commercial standard of GABA tea, 22 out of the 220 GABA tea samples failed to meet the commercial standard, with a failure rate of 10%. During the fermentation process of GABA tea, the contents of GABA increased significantly, but the total polyphenol and total catechin contents remained stable. In terms of consumer acceptance, GABA Black tea is the most accepted by consumers, followed by GABA Puerh tea, GABA Paochong, and GABA Oolong tea. The sour flavor in GABA tea is similar to the original sour sensory properties found in black tea. It is assumed that this is the main reason GABA Black tea has the highest acceptance.

Variations in phenolic content in tea under various processing methods

Variations in the phenolic content (total polyphenols, theaflavins, and thearubigins) of unconventional brands of ready-made tea (white, red, GABA) depending on different processing methods are discussed. Research in this direction has been carried out at the Subtropical Scientific Center of the Russian Academy of Sciences (FRC SSC RAS, Sochi) since 2017. Krasnodar tea was shown to contain polyphenols, theaflavins, and thearubigins in the amount of 18.47, 0.14, and 0.79 mg/g, respectively. Non-fermented and semi-fermented teas contain the highest amounts of polyphenols: white (16.63 mg/g), green (16.51 mg/g), and light GABA (16.47 mg/g). When processing light GABA tea, no change in the content of polyphenols occurs; however, the number of flavonoid pigments reduces significantly. Thus, the content of theaflavins (0.02 mg/g) remains at the level of white tea (0.03 mg/g), while that of thearubigins decreases significantly (0.26 mg/g as compared to 0.43–0.46 mg/g in white and green tea, respectively). The content of polyphenols in fermented teas (black, red) is significantly lower than that in raw material and non-fermented teas (НСР05 = 1.18). At the same time, black tea contains theaflavins (0.04 mg/g) and thearubigins (0.95 mg/g) in higher levels. To a certain extent, red tea is inferior to black tea in terms of polyphenols, although red tea is comparable to white and green teas in terms of flavonoids (0.04 mg/g of theaflavins and 0.39 mg/g of thearubigins). With respect to phenolic components, dark GABA tea approaches nonfermented and semi-fermented teas, which increases its nutritional value. The obtained data can be used when developing approaches to regulating the quality characteristics of ready-made tea produced under humid subtropical conditions in Russia, ensuring the preservation and improvement of product quality.

Understanding Young Taiwanese Consumers' Acceptance, Sensory Profile, and Drivers of Liking for GABA Oolong Tea Beverages with Cold Infusions.

The sensory qualities of Taiwanese teas are evaluated by the experts from the Tea Research and Extension Station (TRES) at tea competitions held annually. The prices of Taiwanese teas are also influenced by the results of these tea competitions. However, a tea winning an award and having a high sensory quality and price does not mean that it is liked by Taiwanese consumers. The check all that apply method (CATA) is a scientific method of sensory evaluation. It is able to evaluate the sensory characteristics with consumers and is cheap and time-saving. Twelve samples of γ-aminobutyric acid (GABA) Oolong tea made by the Taiwan Tea No. 12 cultivar were selected from the first Taiwanese GABA tea competition in 2020. The aim of this research was to study young Taiwanese consumers’ acceptability for GABA Oolong tea infusions, and their opinions towards the sensory qualities of teas through questionnaires composed of CATA questions and hedonic scales. Based on the results, the CATA method identified 21 important descriptive terms for GABA tea that were selected by over 20% of consumers. It was found that the consumers like GABA Oolong teas with 13 specific sensory characteristics, but dislike the ones with another 6 specific sensory characteristics. We conjecture that the different process of tea production will affect consumers’ preference for GABA Oolong tea. Overall, GABA Oolong tea has the same delightful sensory characteristics as traditional Taiwanese specialty Oolong teas, and is liked by the young Taiwanese consumers.

CsCuAOs and CsAMADH1 Are Required for Putrescine-Derived γ-Aminobutyric Acid Accumulation in Tea.

Polyamines are a potential source of γ-aminobutyric acid (GABA) in plants under abiotic stress. However, studies on GABA enrichment in tea mostly focus on the GABA shunt, while the correlation between polyamine degradation and GABA formation in tea is largely unknown. In this study, tea plants responded to exogenous putrescine, resulting in a significant increase in GABA content, while the glutamate level did not change. At the same time, five copper-containing amine oxidase (CuAO) and eight aminoaldehyde dehydrogenase (AMADH) genes involved in the putrescine-derived GABA pathway were identified from the Tea Plant Information Archive. Expression analysis indicated that CsCuAO1, CsCuAO3 as well as CsAMADH1 were induced to play an important function in response to exogenous putrescine. Thus, the three genes were cloned and the catalytic efficiency of soluble recombinant proteins was determined. CsCuAOs and CsAMADH1 exhibited indispensable functions in the GABA production from putrescine in vitro. Subcellular localization assays indicated that CsAMADH1 was localized in plastid, while both CsCuAO1 and CsCuAO3 were localized in peroxisome. In addition, the synergistic effects of CsCuAOs and CsAMADH1 were investigated by a transient co-expression system in Nicotiana benthamiana. Our data suggest that these three genes regulate the accumulation of GABA in tea by participating in the polyamine degradation pathway and improve the content of GABA in tea to a certain extent. The results will greatly contribute to the production of GABA tea.

NMR, RP-HPLC-PDA-ESI-MSn, and RP-HPLC-FD Characterization of Green and Oolong Teas (Camellia sinensis L.)

Untargeted (NMR) and targeted (RP-HPLC-PDA-ESI-MSn, RP-HPLC-FD) analytical methodologies were used to determine the bioactive components of 19 tea samples, characterized by different production processes (common tea and GABA tea), degrees of fermentation (green and oolong teas), and harvesting season (autumn and spring). The combination of NMR data and a multivariate statistical approach led to a statistical model able to discriminate between GABA and non-GABA teas and green and oolong teas. Targeted analyses showed that green and GABA green teas had similar polyphenol and caffeine contents, but the GABA level was higher in GABA green teas than in regular green tea samples. GABA oolong teas showed lower contents of polyphenols, caffeine, and amino acids, and a higher content of GABA, in comparison with non-GABA oolong teas. In conclusion, the results of this study suggest that the healthy properties of teas, especially GABA teas, have to be evaluated via comprehensive metabolic profiling rather than only the GABA content.

Involvement of TGF-β and Autophagy Pathways in Pathogenesis of Diabetes: A Comprehensive Review on Biological and Pharmacological Insights.

Despite recent advancements in clinical drugs, diabetes treatment still needs further progress. As such, ongoing research has attempted to determine the precise molecular mechanisms of the disorder. Specifically, evidence supports that several signaling pathways play pivotal roles in the development of diabetes. However, the exact molecular mechanisms of diabetes still need to be explored. This study examines exciting new hallmarks for the strict involvement of autophagy and TGF-β signaling pathways in the pathogenesis of diabetes and the design of novel therapeutic strategies. Dysregulated autophagy in pancreatic β cells due to hyperglycemia, oxidative stress, and inflammation is associated with diabetes and accompanied by dysregulated autophagy in insulin target tissues and the progression of diabetic complications. Consequently, several therapeutic agents such as adiponectin, ezetimibe, GABA tea, geniposide, liraglutide, guava extract, and vitamin D were shown to inhibit diabetes and its complications through modulation of the autophagy pathway. Another pathway, TGF-β signaling pathway, appears to play a part in the progression of diabetes, insulin resistance, and autoimmunity in both type 1 and 2 diabetes and complications in diabetes. Subsequently, drugs that target TGF-β signaling, especially naturally derived ones such as resveratrol, puerarin, curcumin, hesperidin, and silymarin, as well as Propolis, Lycopus lucidus, and Momordica charantia extracts, may become promising alternatives to current drugs in diabetes treatment. This review provides keen insights into novel therapeutic strategies for the medical care of diabetes.

Mangrove leaves with outstanding content of free amino acids especially GABA, makes them candidates for functional food

Herbal remedies by using mangrove plants have been recognized in several countries, and the plant materials are often consumed as a tea, which are infusions of dried plant parts steeped in boiling water. These infusions from mangrove plants are believed to be effective agents for treating and/or prevent infections, ailments, and diseases, and some mangrove plants have attracted attention as functional food resources in recent years. To reveal the beneficial properties of mangrove plants, clarification of the chemical ingredient and its characteristics of mangrove plants is required. This study focused on amino acids, which were functional ingredients (i.e., bioactive compounds) because amino acids are expected to function as ‘functional ingredients’ in addition to conventional ‘nutrients’ in recent years. To demonstrate the further possibilities of mangrove tea, we firstly evaluated the content of total amino acids in the leaf of several dominant mangrove species with commercial teas as references. Next, we clarified the composition of amino acids by using LC-MS analysis. As the results, free amino acid content (FAC) in leaf sample of Rhizophora stylosa, Bruguira gymnorrhiza, Kandelia obovata, Avicennia marina, Sonneratia alba, and Lumnitzera racemosa was 747, 1056, 946, 829, 623, and 896 mg/100 g DW, respectively. The FAC in all mangrove leaf samples were higher than those in green tea of low price, black tea, oolong tea, barley tea, and mate tea. Moreover, it was found that GABA accounts for over 10% of the total amino acid in the mangrove leaf samples. Especially in mature leaves of K. obovata, the ratio was very high levels 35%. In the case of K. obovata, the contents were higher than GABA tea. Based on this, we concluded that several mangrove plants, especially K. obovata has the potential of a functional food which is GABA-rich.

A nontargeted and targeted metabolomics study on the dynamic changes in metabolite levels during the anaerobic treatment of γ-aminobutyric acid (GABA) tea

γ-Aminobutyric acid (GABA) tea is a popular tea with high GABA content (>1.5 mg/g). In this study, the influence of anaerobic treatment, which is a key manufacturing process for GABA tea, was investigated by a nontargeted metabolomics method combining with targeted compounds quantifications. The results showed that the anaerobic treatment not only led to a ~16-fold increase in GABA content but also caused significant changes in the levels of TCA cycle metabolites, dimeric flavanols, lipids, bases/nucleosides, and most of amino acids (p < 0.05). The levels of alkaloids, flavanols, and flavonol/flavone glycosides were slightly fluctuated. After the removal of anoxic conditions, the GABA content remained stable, while dimeric flavanols, flavanols, aroma glycosides, and most of amino acids varied. This study provides a comprehensive characterization of GABA tea processing in a view of dynamic metabolome and offers a theoretical basis for quality control of GABA tea processing.

Characterization of two tea glutamate decarboxylase isoforms involved in GABA production

Tea (Camellia sinensis) contains two active glutamate decarboxylases (CsGADs), whose unclear properties were examined here. CsGAD1 was 4-fold higher than CsGAD2 in activity. Their Km values for L-glutamate were around 5 mM. CsGAD1 and CsGAD2 performed best at 55 and 40 °C, respectively, and were both stimulated by calcium/calmodulin (Ca2+/CaM). Over 40 °C, their calmodulin-binding domains degraded. CsGADs were most active at pH 5.6, and were stimulated by Ca2+/CaM at pH 5.6–6.6, but inactivated at pH 3.6. Ca2+/CaM restored the CsGAD1 activity suppressed by inhibitors. CsGADs and CsCaM were localized to the cytosol. CsGAD1 was more highly expressed in most tissues, while CsGAD2 expression was more induced under stresses. The characteristics we first elucidated here revealed that CsGAD1 is the predominant isoform in tea plant, with CsGAD2 exhibiting a supplementary role under certain conditions. The information will contribute to regulation of GABA tea quality.

A double-blind, placebo-controlled, randomised-designed GABA tea study in children diagnosed with autism spectrum conditions: a feasibility study clinical trial registration: ISRCTN 72571312

ABSTRACT Objective: The research has shown an association with sensorimotor integration and symptomology of Autism Spectrum Conditions (ASC). Specific areas of the brain that are involved in sensorimotor integration, such as the cerebellum and basal ganglia, are pathologically different in individuals with ASC in comparison to typically developing (TD) peers. These brain regions contain GABAergic inhibitory neurons that release an inhibitory neurotransmitter, γ-Aminobutyric acid (GABA). Brain GABA levels are decreased in ASC. This study explored the effect of introducing a non-invasive GABA substitute, in the form of GABA Oolong tea, on sensorimotor skills, ASC profiles, anxieties and sleep of children with ASC. Methods: Nine children took part: (5 male, 4 female). Each child participated in three tea conditions: high GABA, high L-Theanine (a compound that increases GABA), placebo with low GABA. A double-blind, repeated measures design was employed. Measures were taken after each tea condition. Sensory and ASC profiles were scored using parental questionnaires. Motor skills were assessed using a gold standard coordination assessment. Sleep was monitored using an actiwatch and anxiety measured through cortisol assays. Subjective views were sought from parents on ‘best’ tea. Results: The results showed significant improvement in manual dexterity and some large individual improvements in balance, sensory responsivity, DSM-5 criteria and cortisol levels with GABA tea. Improvements were also seen in the L-Theanine condition although they were more sporadic. Conclusions: These results suggest that sensorimotor abilities, anxiety levels and DSM-5 symptomology of children with ASC can benefit from the administration of GABA in the form of Oolong tea.

GABA Tea Extract Inhibit the Colony Formation and Invasion of Colorectal Cancer Cells

Objectives The study is aim at evaluating the effects of GABA tea on colorectal cancer cell proliferation colony formation and invasion Methods Colorectal cancer cell line HT treated with GABA tea extract mg mL were assessed for viability by MTT assay and for their invasion potential by evaluating their ability to penetrate through a matrix gel coated Boyden chamber Results GABA tea extract exhibited slight effect on cell proliferation of HT The colony formation was inhibited in both culture plate and Boyden chamber Conclusions GABA tea extract inhibited the colony formation and invasion of colorectal cancer cells GABA tea is a potential adjuvant agent for colorectal cancer therapy

Improvement of Antioxidant Defences and Mood Status by Oral GABA Tea Administration in a Mouse Model of Post-Stroke Depression.

Green GABA (GGABA) and Oolong GABA (OGABA) teas are relatively new varieties of tea, whose chemical composition and functional properties are largely under-studied, despite their promising health capacities. Post stroke depression (PSD) is a complication of stroke with high clinical relevance, yielding increasing mortality and morbidity rates, and a lower response to common therapies and rehabilitation. Methods: Two chemically characterized commercial samples of GGABA and OGABA were investigated for effects on mood following oral administration using a mouse model of PSD, through common validated tests including the Despair Swimming Test and Tail Suspension Test. Moreover, the antioxidant activity of GGABA and OGABA was evaluated by determining the levels of lipid peroxidation products and the activity of antioxidant enzymes in the mouse brain in vivo. Results: GGABA and OGABA attenuated depressed mood by influencing behavioral parameters linked to depression. GGABA was more active than OGABA in this study, and this effect may be likely due to a higher content of polyphenolic substances and amino acids in GGABA compared to OGABA. GGABA also exerted a greater antioxidant activity. Conclusions: Our data suggests that GABA tea is a promising candidate that can be used as an adjuvant in the management of PSD.

γ-Aminobutyric Acid (GABA) Accumulation in Tea (Camellia sinensis L.) through the GABA Shunt and Polyamine Degradation Pathways under Anoxia.

γ-Aminobutyric acid (GABA) is an important bioactive component of tea (Camellia sinensis) providing various health benefits. We studied GABA accumulation via the GABA shunt and polyamine degradation pathways under anoxia in tea leaves. Anoxia caused a ∼20-fold increment in GABA concentration, relative to fresh tea leaves. This increment was due to the increase of glutamate decarboxylase and diamine oxidase activities. Genes involved in GABA formation, such as CsGAD1 and CsGAD2, were significantly up-regulated by anoxia. The concentrations of putrescine and spermine, two substrates for GABA production, were also increased by anoxia. Treating tea leaves with aminoguanidine completely inhibited diamine oxidase activity during anoxia, but the concentration of GABA decreased by only ∼25%. We infer that about one-fourth of GABA formed in tea leaves under anoxia comes from the polyamine degradation pathway, opening the possibility of producing GABA tea based through the regulation of metabolism.

Technical development of production and products in organic tea farming

Technical development is necessary for overcoming some key pests and for providing economic management to organic tea growers. The cultivar TTES No. 12 is a satisfactory cultivar for organic tea farming (OTF) in Taiwan for its better resistance to pests. Infection of green leaf hopper tends to make the organic tea made having honey flavor. The key pest of OTF is tea mosquito bug. Long-term application of livestock organic fertilizer tends to accumulate high content of P and K in tea soils. Organic tea growers are recommended to apply oil-seed residues marto lower down their nutrient input costs. Organic liquid fertilizers made from fermented soybeans with sugar, molasses. Microorganism are used as auxiliary N supplements and as pest repellents by spraying on tea leaves regularly. To mitigate organic tea farmers’ burdens in summer weeding, a hand-pushed and comb type weeding machine has been developed with low machine body weight and high efficiency in weeding. Organic tea products are quite diversely developed in Taiwan. Popular marketing of organic products includes green tea, oolong tea, black tea, GABA tea, Akai (red) oolong, honey flavor tea, green tea powder, and RTD tea etc.

Quantification of γ-Aminobutyric Acid in Sri Lankan Tea by Means of Ultra Performance Tandem Mass Spectrometry

Gamma-Aminobutyric acid (GABA), an important bioactive component of tea, acts as a major inhibitory neurotransmitter and is considered to influence other physiological processes in human as well as in planta. In the hereby presented study, the content of this valuable metabolite was investigated in two novel types of Ceylon Tea, explicitly "Silver Tips" and "White Tea", originating from minimally processed buds of the unique cultivar, "TRI 2043". The samples were subjected to hot water infusion, equivalent to the traditional beverage preparation procedure, and analyzed by means of hydrophilic interaction ultra performance liquid chromatography coupled to tandem mass spectrometry (HILIC LC-MS/MS). The registered GABA levels were compared with those obtained for the classic "Black Tea" and "Green Tea" samples from Sri Lanka. A high variation of GABA content was observed among the different tea types, especially in the case of "Silver Tips" and "White Tea", indicating the crucial influence of the manufacturing procedure (processing extent) on the final abundance of the bioactive component of interest. Furthermore, "White Tea" samples boasted the highest GABA concentration reported for this type of tea so far, reaching up to 50% of that characteristic of the high-priced "GABA Tea". Therefore, "White Tea" and "Silver Tips" were proved to be high quality tea with amounts of gamma-aminobutyric acid comparable with those described for similar types before. To our knowledge, this is the first report on HILIC LC-MS/MS application for the quantification of GABA and for in-depth characterization of teas from Sri Lanka.