Study on quality components and sleep-promoting effect of GABA Maoyecha tea

Role of short germination and milling on physical properties, amino acid and metabolomic profiles of high amylose rice fractions

Short germination is a process that can improve bioactive compounds in rice. This work aimed investigate the physical properties, phenolic compounds (PC), antioxidant activity and amino acids composition of husk + bran, brown and milled rice with high amylose content after short germination (16 h). α-amylase activity (Falling Number, FN) and enthalpy (ΔH) were unchanged (p < 0.05). RVA curve profiles were similar, even though after short germination and milling. Globally, metabolomics analysis identified 117 PC, in which 111 (bound), 104 (free) and 21 revealed in both extracts. p-Coumaric, trans-ferulic and ferulic acids were the most abundant PC revealed in all fractions. The portion husk + bran showed the highest level of total antioxidant activity (709.90 µmol TE) in both free and bound fractions. In terms of total amino acids, there was no statistical difference (p < 0.05) among non-germinated and germinated samples, contrary to free amino acids content. Glutamic acid (Glu) presented the highest values combining short germination and milling (1725-1900 mg/100 g) consequently, leads to higher value of GABA (12.21 mg/100 g). The combination of short germination and milling demonstrated a good strategy to improve the nutritional quality of rice, unless the thermal and pasting properties have been altered, contribute to potential health benefits on human nutrition.

Four novel sleep-promoting peptides screened and identified from bovine casein hydrolysates using a patch-clamp model in vitro and Caenorhabditis elegans in vivo

Bovine casein hydrolysates (CHs) have demonstrated sleep-promoting activities. However, only few peptides were identified from CHs with sleep-promoting effects. In this work, an in vitro model based on the electrophysiology of brain neurons was established for the evaluation of sleep-promoting effects. Based on this model, four novel peptides were systematically separated from CH. Compared with the control group, the action potential (AP) inhibitory rate of four peptides increased by 38.63%, 340.93%, 233.28%, and 900%, respectively, and the membrane potential (MP) change rate of four peptides increased by 319.78%, 503.09%, 381.22%, and 547.10%, respectively. These results suggested that four peptides have sleep-promoting activities. Furthermore, Caenorhabditis elegans (C. elegans) sleep behavior results indicated that all the four peptides could significantly increase the total sleep duration, the motionless sleep duration of C. elegans, implying that these four peptides can significantly improve sleep. The LC-MS/MS results showed that the primary structures of these novel peptides were HQGLPQEVLNENLLR (α_s1-CN, f8-22), YKVPQLEIVPNSAEER (α_s1-CN, f104-119), HPIKHQGLPQEVLNENLLR (α_s1-CN, f4-22), and VPQLEIVPNSAEER (α_s1-CN, f106-119). Overall, this study revealed that the four novel sleep-promoting peptides identified were strong candidates as potential functional ingredients in the development of sleep-promoting products.

Gamma-aminobutyric acid (GABA): a comprehensive review of dietary sources, enrichment technologies, processing effects, health benefits, and its applications

Gamma-aminobutyric acid (GABA) is a naturally occurring potential bioactive compound present in plants, microorganisms, animals, and humans. Especially, as a main inhibitory neurotransmitter in the central nervous system, GABA possesses a broad spectrum of promising bioactivities. Thus, functional foods enriched with GABA have been widely sought after by consumers. However, the GABA levels in natural foods are usually low, which cannot meet people's demand for health effects. With the increasing public awareness on the food securities and naturally occurring processes, using enrichment technologies to elevate the GABA contents in foods instead of exogenous addition can enhance the acceptability of health-conscious consumers. Herein, this review provides a comprehensive insight on the dietary sources, enrichment technologies, processing effects of GABA, and its applications in food industry. Furthermore, the various health benefits of GABA-enriched foods, mainly including neuroprotection, anti-insomnia, anti-depression, anti-hypertensive, anti-diabetes, and anti-inflammatory are also summarized. The main challenges for future research on GABA are related to exploring high GABA producing strains, enhancing the stability of GABA during storage, and developing emerging enrichment technologies without affecting food quality and other active ingredients. A better understanding of GABA may introduce new windows for its application in developing functional foods.

Special tea products featuring functional components: Health benefits and processing strategies

The functional components in tea confer various potential health benefits to humans. To date, several special tea products featuring functional components (STPFCs) have been successfully developed, such as O-methylated catechin-rich tea, γ-aminobutyric acid-rich tea, low-caffeine tea, and selenium-rich tea products. STPFCs have some unique and enhanced health benefits when compared with conventional tea products, which can meet the specific needs and preferences of different groups and have huge market potential. The processing strategies to improve the health benefits of tea products by regulating the functional component content have been an active area of research in food science. The fresh leaves of some specific tea varieties rich in functional components are used as raw materials, and special processing technologies are employed to prepare STPFCs. Huge progress has been achieved in the research and development of these STPFCs. However, the current status of these STPFCs has not yet been systematically reviewed. Here, studies on STPFCs have been comprehensively reviewed with a focus on their potential health benefits and processing strategies. Additionally, other chemical components with the potential to be developed into special teas and the application of tea functional components in the food industry have been discussed. Finally, suggestions on the promises and challenges for the future study of these STPFCs have been provided. This paper might shed light on the current status of the research and development of these STPFCs. Future studies on STPFCs should focus on screening specific tea varieties, identifying new functional components, evaluating health-promoting effects, improving flavor quality, and elucidating the interactions between functional components.

Characterization of triterpenoids as possible bitter-tasting compounds in teas infected with bird’s eye spot disease

Tea infected with bird's eye spot disease generally imparts a long-lasting bitter taste, which is unacceptable to most consumers. This study has comprehensively evaluated the taste profiles of infected and healthy teas and investigated their known bitter compounds previously reported in tea. Quantification analyses and calculation of dose-over-threshold (DoT) factors revealed that no obvious difference was visualized in catechins, caffeine, bitter amino acids, and flavonols and their glycosides between infected and healthy tea samples, which was also verified by principal component analysis (PCA) and hierarchical cluster analysis (HCA). Therefore, these known bitter compounds have been ruled out as critical contributors to the long-lasting bitterness of infected teas. Furthermore, Gel permeation chromatography, sensory analysis, and UPLC-Q-TOF-MS were employed and identified 13 substances from the target bitter fractions, including caffeine, ten triterpenoids, and two oxylipins. The higher triterpenoid levels were supposed to be the reason causing the long-lasting bitterness. This study has provided a research direction for the molecular basis of the long-lasting bitterness of infected tea leaves with bird's eye spot disease.

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.

Unique Probiotic Properties and Bioactive Metabolites of Saccharomyces boulardii

Saccharomyces boulardii (S. boulardii) is a probiotic and is widely used to improve the nutritional and functional value of food. This study aimed to compare the probiotic properties of S. boulardii and Saccharomyces cerevisiae. A series of in vitro probiotic experiments was performed, including simulated gastrointestinal digestion, bile salt tolerance, hydrophobicity, self-aggregation, and antioxidant and antibacterial properties. Self-aggregation and hydrophobic properties of S. boulardii were relatively poor, but they showed high tolerance, antioxidant properties, and broad antibacterial properties. In addition, non-targeted metabolomics was used to comprehensively analyze the active metabolites of S. boulardii and the metabolic differences between S. boulardii and S. cerevisiae were compared. Saccharomyces boulardii produced many bioactive metabolites, which generally showed antioxidant, antibacterial, antitumor, anti-inflammatory, and other properties. In contrast to S. cerevisiae, S. boulardii produced phenyllactic acid and 2-hydroxyisocaproic acid. There were also significant differences in their metabolic pathways. These results may be of great significance in the medical and food industries and provide a basis for understanding the metabolism of S. boulardii. It also shows that metabolomics is an effective and novel method for screening microbial functional metabolites and identifying functional differences between similar microorganisms.

Recent advances in the utilization of tea active ingredients to regulate sleep through neuroendocrine pathway, immune system and intestinal microbiota

Sleep disorders have received widespread attention nowadays, which have been promoted by the accelerated pace of life, unhealthy diets and lack of exercise in modern society. The chemical medications to improve sleep has shown serious side effects and risks with high costs. Therefore, it is urgent to develop efficient nutraceuticals from natural sources to ensure sleep quality as a sustainable strategy. As the second most consumed beverage worldwide, the health-promoting effects of tea have long been widely recognized. However, the modulatory effect of teas on sleep disorders has received much less attention. Tea contains various natural sleep-modulating active ingredients such as L-theanine (LTA), caffeine, tea polyphenols (TPP), tea pigments, tea polysaccharides (TPS) and γ-aminobutyric acid (GABA). This review focuses on the potential influence and main regulating mechanisms of different tea active ingredients on sleep, including being absorbed by the small intestine and then cross the blood-brain barrier to act on neurons in the brain as neurotransmitters, manipulating the immune system and further affect sleep-wake cycle by regulating the levels of cytokines, and controlling the gut microbes to maintain the homeostasis of circadian rhythm. Current research progress and limitations are summarized and several future development directions are also proposed. This review hopes to provide new insights into the future elucidation of the sleep-regulating mechanisms of different teas and their natural active ingredients and the development of tea-based functional foods for alleviating sleep disorders. HighlightsNatural sleep-modulating active ingredients in tea have been summarized.Influences of drinking tea or tea active ingredients on sleep are reviewed.Three main regulating mechanisms of tea active ingredients on sleep are explained.The associations among nervous system, immune system and intestinal microbiota are investigated.The potential of developing delivery carriers for tea active ingredients is proposed.

Characterization of waste cell biomass derived glutamate decarboxylase for in vitro γ-aminobutyric acid production and value-addition

Waste biomass of Lactobacillus brevis obtained from in vivo γ-aminobutyric acid (GABA) production was used for value-addition. This study aims to extract glutamate decarboxylase (GAD) and characterize it for in vitro GABA production. Extracted GAD showed an excellent activity for in vitro GABA production. 52 W ultrasonic output was best in crude GAD extraction which was purified by Q HP anion-exchange column followed by Superdex-200 colloid separation column. The molecular weight of the purified GAD was determined to be ~53 kDa, and the K_m value for L-glutamic acid was calculated ~7.65 mM. Pyridoxal 5'-phosphate (PLP) acted as the best cofactor for GAD. Optimum temperature and PLP dosing were deferring for crude and purified enzyme forms which respectively exhibited at 45°C, 55°C, 200 µmol and 20 µmol whereas optimum pH was the same at 4.5. GAD finds applications in food industries hence its detailed characterization would be promising for commercial exploitations.

Study on the Sleep-Improvement Effects of Hemerocallis citrina Baroni in Drosophila melanogaster and Targeted Screening to Identify Its Active Components and Mechanism

Hemerocallis citrina Baroni (HC) is an edible plant in Asia, and it has been traditionally used for sleep-improvement. However, the bioactive components and mechanism of HC in sleep-improvement are still unclear. In this study, the sleep-improvement effect of HC hydroalcoholic extract was investigated based on a caffeine-induced insomnia model in Drosophila melanogaster (D. melanogaster), and the ultrahigh-performance liquid chromatography coupled with electrospray ionization quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-ESI-Orbitrap-MS) and network pharmacology strategy were further combined to screen systematically the active constituents and mechanism of HC in sleep-improvement. The results suggested HC effectively regulated the number of nighttime activities and total sleep time of D. melanogaster in a dose-dependent manner and positively regulated the sleep bouts and sleep duration of D. melanogaster. The target screening suggested that quercetin, luteolin, kaempferol, caffeic acid, and nicotinic acid were the main bioactive components of HC in sleep-improvements. Moreover, the core targets (Akt1, Cat, Ple, and Sod) affected by HC were verified by the expression of the mRNA of D. melanogaster. In summary, this study showed that HC could effectively regulate the sleep of D. melanogaster and further clarifies the multi-component and multi-target features of HC in sleep-improvement, which provides a new insight for the research and utilization of HC.

Ginsenoside Rg5/Rk1 ameliorated sleep via regulating the GABAergic/serotoninergic signaling pathway in a rodent model

As the most common sleep disorder, insomnia seriously affects people's everyday lives. Phytochemicals have been shown to have excellent sleep-promoting effects. Therefore, this study was designed to investigate whether Rg5 and Rk1 extracted from ginseng had sleep-promoting effects and to explore their potential mechanisms. The results showed that Rg5 and Rk1 could significantly lessen the locomotor activity of mice and promote the sleep quality index, including increasing the amount of sleep in a pentobarbital sodium experiment with a threshold dose. In parallel, Rg5 and Rk1 could significantly shorten the sleep latency of mice and prolong the sleep time of mice. Furthermore, Rg5 and Rk1 augmented the GABA/Glu ratio, up-regulating the expression of the GABAA receptor and the GABAB receptor, whereas the GABAA receptor antagonist picrotoxin could antagonize the sleep quality of Rg5/Rk1. In addition, 5-HTP, the precursor of 5-HT, could enhance the sleep effect of Rg5 and Rk1 in mice, and both Rg5 and Rk1 could up-regulate the expression of 5-HT1A. These results were also confirmed by the detection of GABA and 5-HT in mouse cecum content. In conclusion, ginsenoside Rg5/Rk1 can exert sedative and hypnotic effects by affecting the GABA nervous system and the serotonin nervous system.

Immobilization and enzymatic properties of glutamate decarboxylase from Enterococcus faecium by affinity adsorption on regenerated chitin

Glutamate decarboxylase (GAD, EC 4.1.1.15) is an important enzyme in gamma-aminobutyric acid biosynthesis and DL-glutamic acid resolution. In this study, the Enterococcus faecium-derived GAD was successfully immobilized by regenerated chitin (RC) via specific adsorption of cellulose-binding domain (CBD). The optimal binding buffer was 20 mmol/L phosphate buffer saline (pH 8.0), and the RC binding capacity was 1.77 ± 0.11 mg_cbd-gad/g_rc under this condition. The ratio of wet RC and crude enzyme solution used for immobilization was recommended to 3:50 (g/mL). To evaluate the effect of RC immobilization on GAD, properties of the immobilize GAD (RC-CBD-GAD) were investigated. Results indicated RC-CBD-GAD was relatively stable at pH 4.4-5.6 and temperature - 20-40 °C, and the optimal reaction pH value and temperature were pH 4.8 and 50 °C, respectively. When it was reacted with 5 mmol/L of follow chemical reagents respectively, the activity of RC-CBD-GAD was hardly affected by EDTA, KCl, and NaCl, and significantly inactivated by AgNO₃, MnSO₄, MgSO₄, CuSO₄, ZnSO₄, FeCl₂, FeCl₃, AlCl₃, CaCl_2, and Pb(CH₃COO)₂. The apparent K_m and V_max were 28.35 mmol/L and 147.06 μmol/(g_RC-CBD-GAD·min), respectively. The optimum time for a batch of catalytic reaction without exogenous pH control was 2 h. Under this reaction time, RC-CBD-GAD had a good reusability with a half-life of 23 cycles, indicating that it was very attractive for GABA industry. As a novel, efficient, and green CBD binding carrier, RC provides an alternative way to protein immobilization.

Predictors of sleep quality among university students: the use of advanced machine learning techniques

PURPOSE

To assess the prevalence of sleep disturbances among university students and investigate potential correlated factors and their relative importance in quantifying sleep quality using advanced machine learning techniques.

METHODS

A total of 1600 university students participated in this cross-sectional study. Sociodemographic information was collected, and the Pittsburgh Sleep Quality Index (PSQI) was administered to assess sleep quality among university students. Study variables were evaluated using logistic regression and advanced machine learning techniques. Study variables that were significant in the logistic regression and had high mean decrease in model accuracy in the machine learning technique were considered important predictors of sleep quality.

RESULTS

The mean (SD) age of the sample was 26.65 (6.38) and 57% of them were females. The prevalence of poor sleep quality in our sample was 70%. The most accurate and balanced predictive model was the random forest model with a 74% accuracy and a 95% specificity. Age and number of cups of tea per day were identified as protective factors for a better sleep quality, while electronics usage hours, headache, other systematic diseases, and neck pain were found risk factors for poor sleep quality.

CONCLUSIONS

Six predictors of poor sleep quality were identified in university students in which 2 of them were protective and 3 were risk factors. The results of this study can be used to promote health and well-being in university students, improve their academic performance, and assist in developing appropriate interventions.

A study of the mechanism of small-molecule soybean-protein-derived peptide supplement to promote sleep in a mouse model

Here, the effects of dietary supplementation with small-molecule soybean-protein-derived peptide (SBP) on sleep duration in mice are described.

Purification and characterization of theobromine synthase in a Theobromine-Enriched wild tea plant (Camellia gymnogyna Chang) from Dayao Mountain, China

Camellia gymnogyna Chang (CgC), a wild tea plant, was discovered on Dayao Mountain, China. However, research regarding this tea plant is limited. Our study found that CgC contains theobromine, caffeine, and theacrine, among which theobromine content was the highest (14.37-39.72 mg/g). In addition, theobromine synthase (TS) was partially purified from CgC leaves, up to 35.87-fold, with consecutive chromatography, and its molecular weight was found to be approximately 62 kDa. The optimum reaction time, pH, and temperature for theobromine synthase from 7-methylxanthine was found to be 6 h, 4, and 45 °C, respectively. TS expression at both mRNA and protein stages was higher in the first than in the fourth leaf (P < 0.05). Subcellular localization of TS indicated that it was localized in the nucleus. These results indicate that CgC can be of scientific value and could lead to efficient utilization of this rare wild tea germplasm.

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

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.

Enhanced accumulation of gamma-aminobutyric acid in rice bran using anaerobic incubation with various additives

An anaerobic incubation for the enzymatic production of gamma-aminobutyric acid (GABA) in rice bran with the addition of glutamate, hydrolyzed wheat protein (HWP), yeast extract (YE) and pyridoxal-5-phosphate (PLP) was investigated. Rice bran was moistened (30% moisture content) with an electrolyzed oxidizing water and anaerobically incubated under nitrogen at 40 °C for 8 h. The incubation activated the glutamate decarboxylase (GAD) in rice bran and increased the GABA content from 10.7 to 171.5 mg/100 g. The addition of glutamate and protein hydrolysates further amplified the GABA content in the treated rice bran: 974.9, 487.4, and 372.8 mg/100 g, with 2.25% glutamate, 6% HWP, and 8% YE, respectively. Furthermore, addition of PLP (1.48 mg/100 g) as a coenzyme for GAD, together with 2.25% glutamate addition, could raise the GABA accumulation in rice bran to 2242 mg/100 g. Other amino acids in rice bran were changed in their composition by the anaerobic treatment.

Quality components and antidepressant-like effects of GABA green tea

After vacuum anaerobic and aerobic treatment, the GABA content in green tea is significantly increased, reaching the standard of GABA tea. And daily oral GABA green tea extract can prevent depression or improve the depressive state of animals.

A study on quality components and sleep-promoting effects of GABA black tea

The aims of this study were to analyze the changes in quality components of gamma (γ)-aminobutyric acid (GABA) black tea during processing, and to investigate the effect of three dosages of GABA black tea on sleep improvement.