Yong-Quan Xu

To improve the flavor of green tea juice processed from summer tea leaves, the enzyme-assisted dynamic extraction method was applied. The chemical components and taste of fresh green tea juice prepared under different extraction conditions with enzyme treatment (EM: tannase or its combination with protease/cellulase/ pectinase) were investigated. T...

Color is critical factor in the commercialization of Matcha. In this study, sensory evaluation, color difference analysis, as well as targeted and non-targeted analyses were employed to investigate the impact of different drying temperature settings on the color characteristics of Tencha. The ffndings revealed that compared to a single drying te...

Scenting is an important process for the formation of aroma quality in floral Longjing tea. There are differences in the aroma quality of osmanthus Longjing teas processed by different scenting processes. The efficient isolated scenting method was employed to process a new product of osmanthus Longjing tea in this study, and this was compared with...

Tea leaves have a good natural adsorption capacity due to their numerous pore structures and high specific surface area. Along with the advancement of tea process technology, more and more sites of adsorption and binding have been found in tea leaves, thus further improving the adsorption performance. Based on the original biological structure and...

The flavor stability of tea beverages during storage has long been a concern. The study aimed to explore the flavor stability of Longjing green tea beverage using accelerated heat treatment trials, addressing the shortage of lengthy storage trials. Sensory evaluations revealed changes in bitterness, umami, overall harmonization, astringency, and ri...

The flavor stability of tea beverages during storage has long been a concern. The study aimed to explore the flavor stability of Longjing green tea beverage using accelerated heat treatment trials, addressing the shortage of lengthy storage trials. Sensory evaluations revealed changes in bitterness, umami, overall harmonization, astringency, and ri...

Mellow and thick taste (MTT) is considered to be a typical taste characteristic of high-quality Pu-erh ripe tea. However, the role of polysaccharide conjugates remains unclear. In this study, the infusion of different grades of Pu-erh ripe tea was isolated to fractions by sensory-guided ultrafiltration technology and the key taste substances of MTT...

Tea is the second largest nonalcoholic beverage in the world due to its characteristic flavor and well‐known functional properties in vitro and in vivo. Global tea production reaches 6.397 million tons in 2022 and continues to rise. Fresh tea leaves are mainly harvested in spring, whereas thousands of tons are discarded in summer and autumn. Herein...

Osmanthus fragrans is an evergreen shrub with a pleasant fragrance and a wide range of applications in many fields. The condensed hydrolat obtained during the drying process of its fresh flowers was collected in a low-temperature vacuum environment and its sensory evaluation and volatile components were studied. The main aroma compounds in Osmanthu...

This study aimed to investigate the effects of tea green leafhopper damage on the sensory quality and metabolite composition of Oriental Beauty by using tea leaves from different varieties of tea plants and processing factories. The results indicated that tea green leafhopper damage could reduce bitterness and increase the level of fruity aroma, wh...

Astringency has an important impact on the taste quality of tea infusion, a process which occurs when polyphenols complex with salivary proteins to form an impermeable membrane. (-)-Epigallocatechin gallate (EGCG) is the main astringent compound found in green tea and mucin is the main protein present in saliva. Determining the turbidity of EGCG–mu...

Polyphenol oxidase (PPO) is an important metalloenzyme in the tea plant (Camellia sinensis). However, there has recently been a lack of comprehensive reviews on Camellia sinensis PPO. In this study, the methods for extracting PPO from Camellia sinensis, including acetone extraction, buffer extraction, and surfactant extraction, are compared in deta...

This study aimed to obtain an anthocyanin extract from the purple leaves of Camellia sinensis cv. Zijuan using a sustainable, non-toxic, and low-cost solid-liquid extraction, employing an aqueous citric acid solution (0.2 mol/L) as the extracting solvent, and to evaluate its chemical stability at different pH values, as well as its in vitro antioxi...

A popular non-alcoholic beverage worldwide, tea can regulate blood glucose levels, lipid levels, and blood pressure, and may even prevent type 2 diabetes mellitus (T2DM). Different tea fermentation levels impact these effects. Tea products with different fermentation degrees containing different functional ingredients can lower post-meal blood gluc...

Variations in the quality of brewing water profoundly impact tea flavor. This study systematically investigated the effects of four common water sources, including pure water (PW), mountain spring water (MSW), mineral water (MW) and natural water (NW) on the flavor of Tieguanyin tea infusion. Brewing with MW resulted in a flat taste and turbid arom...

Flavonoids are important compounds in tea leaves imparting bitter and astringent taste, which also play key roles in tea plants responding to environmental stress. Our previous study showed that the expression level of CsMYB67 was positively correlated with the accumulation of flavonoids in tea leaves as exposed to sunlight. Here, we newly reported...

To improve the quality of osmanthus black tea, samples produced with different scenting methods were prepared. The sensory quality was assessed and the characteristic aromatic components were explored using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. According to the results, osmanthus black tea obtained by...

The origins of tea, a traditional beverage in China, can be traced back to the Shennong period, about 2737 years before the birth of Christ [...]

Chinese Oolong tea is widely known for its intricate aroma. However, the degradation of volatile organic compounds (VOCs) poses significant challenges for the tea products. In this study, glutathione (GSH) has an excellent preservation effect on VOCs in both the VOCs extract and the tea infusion during storage, specifically slowing the degradation...

Introduction Instant teas are particularly rich in tea polyphenols and caffeine and have great potential as food ingredients or additives to improve the quality of food and enhance their nutritional and commercial value. Methods To determine the relationships between raw material, drying method, and sensory and other quality attributes, instant te...

Introduction In recent years, scented black tea has attracted much attention due to its pleasant floral aroma and mellow flavor, but little research has been carried out on its flavor metabolic profile. Methods In this study, the flavor metabolic profiles of unscented, Chloranthus spicatus scented, and Osmanthus fragrans (Thunb.) Lour. scented Con...

Roasting is essential for processing large-leaf yellow tea (LYT). However, the effect of the roasting on the metabolic and sensory profiles of LYT remains unknown. Herein, the metabolomics and sensory quality of LYT at five roasting degrees were evaluated by liquid/gas chromatography mass spectrometry and quantitative descriptive analysis. A higher...

The elegant orchid-like fragrance of tea has always been tea processors and consumers' top priority. Controlling the production process is very important for tea aroma formation. This study aims to investigate the synthesis of (Z)-methyl epijasmonate (epi-MeJA), a key contributor to orchid-like aroma properties in tea, during tea processing. The ch...

Volatiles are important quality components in tea (Camellia sinensis) flowers. Albino tea plants are mutant tea plants with diverse abnormal metabolisms. However, whether the metabolisms of volatiles in tea flowers from albino cultivars are abnormal remains unclear. In this study, headspace solid-phase microextraction coupled to gas chromatography-...

Kombucha is a fermented beverage obtained from the fermentation of sweetened tea by a consortium of yeasts and bacteria. The beverage contains many bioactive compounds from tea extraction and microbial synthesis. In this chapter, we describe two preparation methods of Kombucha using a symbiotic culture of bacteria and yeast or a synthetic microbial...

Matcha, a powder processed from tea leaves, has a unique green tea flavor and appealing color, in addition to many other sought after functional properties for a wide range of formulated food applications (e.g., dairy products, bakery products, and beverage). The properties of matcha are influenced by cultivation method and processing post-harvest....

The sensory quality of tea is influenced by water quality, with natural spring water (NSW) gaining much attention for its natural and healthy qualities. The effects of NSW on the sensory attributes, physicochemical composition, and antioxidant capacity of Chinese tea were investigated. Tea brewed with pure water was the most resistant to oxidation...

Albino tea cultivars are mutant tea plants with altered metabolisms. Current studies focus on the leaves while little is known about the flowers. To evaluate tea flowers from different albino cultivars, the chemical composition and anti-cholesterol activity of tea flowers from three albino cultivars (i.e., Baiye No.1, Huangjinya, and Yujinxiang) we...

Hops provide the characteristic bitter taste and attractive aroma to beer; in this study, hops were replaced by jasmine tea extract (JTE) during late-hopping. The addition of JTE improved the beer foam stability 1.52-fold, and increased the polyphenol and organic acid contents. Linalool was the most important aroma compound in hopped (HOPB) and jas...

Nanostructured cellulose (NC) represents an emerging sustainable biomaterial for diverse biotechnological applications; however, its production requires hazardous chemicals that render the process ecologically unfriendly. Using commercial plant-derived cellulose, an innovative strategy for NC production based on the combination of mechanical and en...

Introduction Tea is the main raw material for preparing tea wine. Methods In this research, four types of tea wine were prepared using different categories of tea leaves, including green tea, oolong tea, black tea, and dark tea, and the comparative study looking their physicochemical, sensorial, and antioxidant profiles were carried out. Results...

With a distinctive aroma, Shanhuangpi (SHP), the fruit of the plant Clausena anisum-olens (Blanco) Merr., has been newly developed as a commercial fruit resource. The fresh fruit deteriorates rapidly due to its high respiration and metabolism. Therefore, an effective drying process is urgently needed for its preservation. The influence of two commo...

Changes in key odorants and aroma profiles of three types of green tea during storage and after baking treatment were determined using headspace solid-phase microextraction–gas chromatography–mass spectrometry/olfactometry, odor activity value (OAV) and orthogonal partial least-squares discriminant analysis. As the stale odor developed during stora...

To develop objective methods of oolong tea grading for importers and customs, metabolomics and sensory evaluation were applied to screen the characteristic compounds associated with Tieguanyin (TGY) tea grades T, 1, 2, and 3, and types (fresh scent flavor and high fragrance). With decreasing TGY grade/quality, the astringency and content of most fl...

Background Nowadays, consumers increasingly prefer food with original, natural, and delicious flavors, which is closely linked to the content of volatile organic compounds (VOCs) in food. In recent years, the function of plant VOCs as natural food additives (flavoring and aromatizing agents, antibacterial agents) and their health benefits have attr...

Phenolic acids are important taste components in green tea. The aim of this study was to analyze the taste characteristics of phenolic acids and their influence on the bitterness and astringency of green tea by sensory evaluation and chemical determination. The major tea phenolic acids and quercetin-3- O -rutinoside (Que-rut) were significantly pos...

Tieguanyin is one of the most consumed oolong teas because of its distinctive flavor. The brewing process is crucial for the flavor performance of traditional teas, thus the effects of brewing conditions, including water/tea ratio (R), brewing temperature (T), and time (S) on the sensory traits, chemical composition, and antioxidant activity of Tie...

Atmospheric solids analysis probe-mass spectrometry (ASAP-MS), an ambient mass spectrometry technique, was used to differentiate spring and autumn Tieguanyin teas. Two configurations were used to obtain their chemical fingerprints – ASAP attached to a high-resolution quadrupole time-of-flight mass spectrometer (i.e., ASAP-QTOF) and to a single-quad...

Camellia sinensis var. assamica cv. Zijuan (purple tea) is known for its content of anthocyanins, flavan-3-ols, and bioactivities. This study aimed to verify the influence of solvent polarity, in a solid-liquid extraction, on the content of phenolic compounds and chlorophylls, instrumental color, and antioxidant activity. Different proportions of w...

Oriental Beauty, a deeply fermented variety of oolong tea, is famous for its fruity aroma and sweet taste. A targeted and untargeted metabolomics was used to comprehensively analyze the dynamic changes of taste and aroma metabolites during the processing stage. During the enzyme reaction stage, the catechin components were oxidized and degraded int...

The effects of β-glucosidase on the volatile profiles and aroma stability of black tea juice were evaluated using gas-chromatography-mass spectrometry coupled with sensory analysis. During liquid fermentation of tea leaves, the addition of β-glucosidase increased the concentration of aldehydes, strengthening the undesirable “green grassy” odour. Ho...

Green tea and its food-grade extracts are widely used in food technology because of their rich chemical composition. Our previous study found that dynamic extraction tea extract exhibited higher quality than conventional extraction methods. Thus, the objective of this study was to develop a high-efficiency, dynamic extraction method to improve extr...

Herein, a new indicator-displacement array (IDA) sensor was developed for the quality evaluation of black tea fermentation. On the principle of the reversible covalent binding of phenylboronic acid and catechol, phenylboronic acids were selected as acceptors for targeted binding to polyphenols. Pyrocatechol violet and alizarin red S were used as in...

pH values have an important influence on the aggregation state of β-lactoglobulin (β-LG), which affects its ligand-binding properties. In this study, the pH-dependent interaction mechanisms between β-LG and epigallocatechin-3-gallate (EGCG) were explored by multi-spectroscopy and molecular dynamics simulation. Compared to β-LG, the increasing absor...

The mellow and thick taste is a unique characteristic of pu−erh ripe tea infusion, and it is closely related to the chemical composition of pu−erh ripe tea, which is less studied. This paper clarifies and compares the chemical composition of pu−erh ripe tea to that of the raw materials of sun−dried green tea, and uses membrane separation technology...

Volatile organic compounds (VOCs) are produced by plants responding to biotic and abiotic stresses. According to their biosynthetic sources, induced VOCs are divided into three major classes: terpenoids, phenylpropanoid/benzenoid, and fatty acid derivatives. These compounds with specific aroma characteristics importantly contribute to the aroma qua...

Tieguanyin (TGY) is one kind of oolong tea that is widely appreciated for its aroma and taste. To study the difference of volatile compounds among different types of TGY and other oolong teas, solid-phase microextraction–gas chromatography–mass spectrometry and chemometrics analysis were conducted in this experiment. Based on variable importance in...

Tieguanyin oolong tea (TOT), a semi-oxidized tea originating from Anxi county in China, is categorized into jade TOT, medium-baked TOT, and deep-baked TOT, based on different baking processes. To study the effects of baking, chemical analysis, sensory evaluation, and bioactivity assessments of the three TOTs were conducted. The results indicated th...

The effects of pH (2.2–8.0) and temperature (25–100 °C) on the instrumental color of a model beverage containing (−)-epigallocatechin-3-gallate (EGCG) were investigated. As the pH and temperature increased, the lightness (L*) decreased while the redness and yellowness (a* and b*, respectively) increased. Using spectral scanning, it was possible to...

Tea, made from the second of the world’s three most popular non-alcoholic beverage plants Camellia sinensis, has long been recognized worldwide as a healthy drink. To retain bioactive substances like tea polyphenols in tea leaves and simplify the traditional brewing method, tea beverage manufacturers have made great efforts to increase the extracti...

Hydrogen peroxide has a significant effect on the flavor of tea beverages. In this study, the yield of hydrogen peroxide in (–)-epigallocatechin gallate (EGCG) solution was first investigated and found to be significantly enhanced under specific conditions, and the above phenomenon was amplified by the addition of linalool. Then, an aqueous hydroge...

Background The bitter and astringent taste of tea and tea extract is still not favored by many consumers, which limits its applications to bakery foods and functional foods. Many bitter and astringent compounds in tea leaves are susceptible, which transform during tea processing or can be modified by food production technologies. Besides, the accum...

Seven batches of raw tea leaves, processed by different methods (steaming, pan-frying) and from two different harvesting seasons (spring, autumn), were used to investigate the effect of baking treatment on changes in the composition and content of nonvolatile and volatile compounds. The results showed that baking had a greater impact on sensory and...

Taking aryl propargyl ether and o-iodibenzoic acid as substrates, a series of aryl cyclolactones bearing an exocyclized C═C bond were constructed with moderate to good yields. Diverse substituent groups could be tolerant in the reaction, which indicated excellent compatibility of the reaction. In this tandem reaction, Ag2O was employed as the media...

Oral processing (OP), referring to the whole process of food digestion in human mouth, has a major influence on food flavor perception. This study focused on the compositional changes of the four green tea epicatechins (viz., EC, EGC, ECG, EGCG) during OP, based on targeted and nontargeted metabolomics. It was found that the four epicatechins were...

Brewing water plays a crucial role in flavor and potential healthy functions of tea infusion. In this study, seven water samples with different physicochemical properties were selected to brew green tea. Results showed that the brewing water with higher minerals level and pH value would reduce the yield of catechins in tea infusion, which in turn c...

The prevalence of age-related cognitive impairment is increasing as the proportion of older individuals in the population grows. It is therefore necessary and urgent to find agents to prevent or ameliorate age-related cognitive impairment. Selenomethionine (SeMet) is a natural amino acid occurring in yeast and Brazil nuts. It mitigates cognitive im...

This work aimed at optimizing the extraction of theaflavins for the development of a potentially functional tea beverage using different technological parameters as factors. Green tea leaves treated with tannase provided a beverage with significant higher amount (4.7-fold) of theaflavin (TF) compared to the pure withered leaf fermentation. For blac...

Roasting, a critical process for oolong tea, has been applied to Tieguanyin tea to improve flavor attributes. To investigate the effects of the roasting on the flavor of Tieguanyin, the global metabolomics analysis on the non-volatile and volatile components were proceeded. The weakening of bitterness and astringency, caused by roasting, may be att...

In this study, a synthetic microbial community (SMC) was used to enhance the proportion of gluconic acid in order to improve the taste quality of Kombucha. The sensory properties of gluconic acid were analyzed for the first time. The proportions of gluconic acid (r = 0.986, p < 0.05) and acetic acid (r = −0.986, p < 0.05) were significantly correla...

Ambient mass spectrometry (AMS) is an emerging technique in food authenticity and traceability study due to the minimal sample preparation required and short analysis time. Herein, a non-targeted fingerprinting approach using an AMS technique, atmospheric solids analysis probe – mass spectrometry (ASAP-MS), was used to authenticate Chinese oolong t...

Background Over the past two decades, the global beverage industry has developed rapidly. Especially, the global tea beverage market reached 37 million tons in 2016, an increase of 40% in five years, and is estimated to reach 45 million tons by 2021. According to the forecast of Statista, a business data platform, the global tea beverage market is...

Aroma deterioration is one of the biggest problems in processing tea beverages. The aroma of tea infusion deteriorates fast during heat sterilization and the presence of ferrous ion (Fe²⁺) aggravates it. The underlying mechanism remains unveiled. In this study, Fe²⁺ was verified to deteriorate the aroma quality of green tea infusion with heat treat...

Abstract: According to the US National Centre for Food Protection and Defense, tea is among the top 18 food ingredient categories with high rates of economically motivated adulteration (EMA). Therefore, it is important to ensure the authenticity of tea. Some forms of EMA include mislabelling, as well as substitution adulteration, whereby a portion...

Zijuan tea is a representative anthocyanin-rich tea cultivar in China. In this study, Zijuan tea was used to produce a novel kombucha beverage (ZTK). The physicochemical, sensory properties, and antioxidant activity of ZTK were compared with that of black tea kombucha (BTK) and green tea kombucha (GTK). Results indicated that after fermentation, th...

The effects of brewing water on the sensory attributes and physicochemical properties of tea infusions made from Chinese teas were investigated. The tea infusions brewed in water with higher pH and total dissolved solids (TDS), generally had a darker color and lower overall sensory acceptability. Moreover, those infusions had less catechins, partic...

The traditional scenting process is complicated and limited by the short flower season. In this study, formulated jasmine essential oil-casein nanoparticles (JEO-CS-NPs) were prepared for scenting green tea, in this case, Huangshan Maofeng. The freeze-dried JEO-CS-NPs (FD-JEO-CS-NPs) with a JEO/CS ratio of 0.25 encapsulated more than 70% of the JEO...

In this study, the fermentation process of black tea wine was optimized, and the changes in catechins, organic acids, and aroma components during fermentation were investigated. The optimal fermentation conditions for tea wine were determined as follows: the addition of 15% sucrose and 0.75% tea leaves, and a fermentation temperature of 25 ºC. Unde...

Milky tea is popular in many countries and its color is an important sensory property. The effects of black tea infusion on the color of milky tea prepared with non-dairy creamer were investigated. The results showed that the redder black tea infusion produced milky tea with more redness, and the color of milky tea was a pleasant pink when the a* v...

Fu brick tea is a typical post-fermentation tea known for its special flavor and health benefits. Liquid chromatography-mass spectrometry, and sensory evaluation with multivariate analysis were used to characterize the dynamic changes in metabolite profile and taste characteristics. Seventy-one compounds were identified as critical metabolites, cat...

The effects of epigallocatechin gallate (EGCG), epigallocatechin (EGC) and epicatechin gallate (ECG) on the chemical and cell-based antioxidant activity, sensory properties, and cytotoxicity of a catechin-free model beverage were modeled using response surface methodology. Results showed that ECG presented the highest reducing capacity while EGCG p...

BACKGROUND The gut microbiota plays important roles in physiological and pathological processes of the host. The effect of black tea on the gut microbiota of healthy individuals remains unclear. RESULTS Healthy Sprague–Dawley (SD) rats were given black tea for 4 weeks, and cecum content, serum, intestinal, and hepatic samples were collected. The r...

Reducing sediment is important for the utilization and production of green tea infusion and concentrate. The effect of tannase on sediment formation in green tea infusion and concentrate was investigated. The results showed that the amount of sediment of green tea infusion significantly decreased after tannase treatment, which was due to the decrea...

Astringency is an important quality attribute of green tea infusion, and (−)-Epigallocatechin gallate (EGCG) is the main contributor to astringency. Turbidity was used to predict the intensity of astringency for EGCG. The interactions between the selected proteins and EGCG, and the impacts of temperature, pH, protein structure, and EGCG concentrati...

Flavor stability is important for the quality of tea beverages. Baking is a typical processing technology to improve the flavor of tea leaves. In present study, seven raw tea materials, including steamed spring and autumn tea leaves, pan-fired spring tea leaves, and their corresponding baked tea leaves, were used to investigate the effect of baking...