1 Introduction

Tea fermentation is a critical process in the production of various types of tea, particularly black and oolong teas. This biochemical process involves the oxidation of tea leaves, catalyzed by naturally occurring enzymes, which leads to the development of the tea's characteristic flavor, color, and aroma. During fermentation, polyphenolic compounds in the tea leaves are oxidized, resulting in the formation of theaflavins and thearubigins, which contribute to the tea's taste and color profile (Huang et al., 2021; Josephine et al., 2023). The duration and conditions of fermentation, such as temperature and humidity, play a significant role in determining the final quality of the tea (Josephine et al., 2023).

Fermentation is essential in tea production as it directly influences the sensory attributes and chemical composition of the final product. The process enhances the flavor complexity and reduces the bitterness and astringency of the tea, making it more palatable (Huang et al., 2021). Additionally, fermentation can increase the antioxidant properties of tea, which are beneficial for health. For instance, the fermentation of cherry leaf kombucha tea has been shown to enhance its antioxidant activity, phenolic content, and vitamin C levels, thereby improving its overall quality (Josephine et al., 2023). The optimization of fermentation conditions is crucial for producing high-quality tea with desirable organoleptic properties and health benefits.

This study investigated the impact of different fermentation times and conditions on the chemical and sensory characteristics of tea, aiming to optimize fermentation conditions to enhance tea flavor and quality. By systematically analyzing the effects of these variables, the study sought to determine the optimal fermentation parameters to maximize the tea's taste, aroma, and health benefits. Additionally, the research explored the relationship between fermentation conditions and the antioxidant activity of tea, providing insights into producing high-quality, health-promoting tea.

2 Chemical Changes During Fermentation

2.1 Biochemical processes in tea fermentation

Tea fermentation involves a series of complex biochemical processes that significantly impact the final quality and flavor of the tea (Figure 1). During fermentation, enzymatic oxidation of polyphenols, particularly catechins, leads to the formation of theaflavins and thearubigins, which are crucial for the color and taste of black tea (Rahman et al., 2020; Hua et al., 2021). The process begins with the withering and maceration of tea leaves, which initiates the breakdown of cellular structures and the release of enzymes such as polyphenol oxidase and peroxidase. These enzymes catalyze the oxidation of catechins, resulting in the formation of various oxidation products that contribute to the tea's sensory attributes (Xu et al., 2019). Additionally, the fermentation temperature and oxygen levels play a critical role in modulating these biochemical reactions, thereby influencing the overall quality of the tea (Qu et al., 2020; Chen et al., 2021).

The research of Assad et al. (2023) outlined the distinct processing steps involved in transforming fresh Camellia sinensis leaves into four different types of tea: white, green, oolong, and black tea (Figure 1). White tea production is the simplest, involving only steaming and drying, which preserves the natural antioxidants and delicate flavor of the leaves. Green tea follows a similar process but includes an additional rolling or shaping step after steaming or roasting, enhancing its distinct taste and retaining more nutrients. Oolong tea production is more complex, involving withering, partial fermentation, tumbling, and enzymatic oxidation before drying. This process imparts a unique flavor profile that balances between green and black tea. Black tea undergoes the most extensive processing, including withering, distortion or maceration, full fermentation, and enzymatic oxidation. The final steps are drying and grading, which develop its strong flavor and dark color. Each tea type's specific processing method significantly influences its taste, aroma, and health benefits.

2.2 Key compounds influencing flavor and quality

The key compounds that influence the flavor and quality of tea during fermentation include catechins, theaflavins, thearubigins, amino acids, and volatile organic compounds (VOCs). Catechins, which are abundant in fresh tea leaves, undergo oxidation to form theaflavins and thearubigins, imparting the characteristic color and astringency to black tea (Hua et al., 2021; Chen et al., 2021). Theaflavins contribute to the briskness and brightness of the tea liquor, while thearubigins add depth and body to the flavor (Rahman et al., 2020). Amino acids, such as theanine, enhance the umami taste and overall flavor profile of the tea (Xiao et al., 2021; Chen et al., 2021). VOCs, including terpene alcohols and esters, are responsible for the aroma and are significantly influenced by the fermentation conditions (Xiao et al., 2021; Chun et al., 2021). The balance and concentration of these compounds are critical for achieving the desired sensory qualities in the final tea product.

2.3 Role of enzymes in fermentation

Enzymes play a pivotal role in the fermentation process of tea, driving the chemical transformations that determine the tea's flavor and quality. Polyphenol oxidase (PPO) and peroxidase (POD) are the primary enzymes involved in the oxidation of catechins to theaflavins and thearubigins (Xu et al., 2019; Hua et al., 2021). The activity of these enzymes is influenced by factors such as temperature, humidity, and oxygen levels during fermentation (Chen et al., 2021; Saikia et al., 2023). For instance, optimal fermentation temperatures can enhance enzyme activity, leading to a higher formation rate of theaflavins and thearubigins, which are essential for the quality of black tea (Qu et al., 2020). Additionally, enzymes such as α-amylase, proteinase, and β-glucosidase, which are secreted by specific fungi during fermentation, contribute to the modification of chemical properties and the enhancement of flavor (Xu et al., 2019). Understanding the role of these enzymes and optimizing fermentation conditions can significantly improve the sensory attributes and overall quality of tea.

3 Factors Affecting Fermentation Conditions

3.1 Temperature and its impact on fermentation

Temperature is a critical factor influencing the fermentation process of tea, significantly affecting its chemical composition and sensory properties. Research has shown that the optimal fermentation temperature for black tea is around 28 °C, which results in the best sensory quality, including the highest scores for aroma and taste. At this temperature, the tea exhibits strong antioxidant activities and inhibitory effects on enzymes such as α-glucosidase (Qu et al., 2020). As the temperature increases, the levels of polyphenols, polysaccharides, and catechins decrease, while amino acids and soluble sugars increase, which can alter the flavor profile of the tea. Additionally, a study on the fermentation of tea juice indicated that a temperature of 35 °C, combined with specific time and pH conditions, resulted in the highest content of theaflavins and the best sensory quality (Tang et al., 2018).

3.2 Humidity and its role in fermentation

Humidity during fermentation also plays a significant role in determining the quality of tea. Different levels of humidity can affect the appearance, aroma, and taste of the tea. For instance, fermentation at lower humidity levels (75% or below) tends to produce tea with a greenish, astringent, and bitter taste, while higher humidity levels (85% or above) result in a sweet and mellow flavor (Zhang et al., 2023). The content of various chemical compounds such as flavones, tea polyphenols, and catechins decreases with increasing humidity, whereas the levels of soluble sugars, thearubigins, and theabrownins increase, contributing to the development of a sweeter taste. This indicates that maintaining an optimal humidity level is crucial for achieving the desired tea quality.

3.3 Fermentation time and its effects

The duration of fermentation is another crucial factor that impacts the quality of tea. The fermentation time affects the chemical composition and sensory attributes of the tea. For example, a study on the fermentation of tea juice found that a fermentation time of 75 minutes at a specific temperature and pH resulted in the highest content of theaflavins and the best overall acceptability (Tang et al., 2018). Additionally, the quantitative prediction and visualization of key components in black tea fermentation revealed that different fermentation times significantly influence the levels of theafuscin, thearubigin, catechin, caffeine, and soluble sugars (Yang et al., 2021). These findings highlight the importance of optimizing fermentation time to enhance the quality and flavor of tea.

4 Impact on Tea Flavor

4.1 Development of aroma compounds

The development of aroma compounds during tea fermentation is influenced by various factors, including fermentation temperature, oxygen levels, and specific fermentation methods. For instance, the study by Qu et al. (2020) demonstrated that black tea fermented at 28 °C exhibited the highest sensory quality, with significant increases in VOCs contributing to its aroma. Similarly, the re-rolling treatment in the fermentation process was found to enhance the floral and fruity scents of Congou black tea by altering the levels of various VOCs, such as hexanoic acid and β-ionone (Chen et al., 2023). Additionally, the application of methyl jasmonate (MeJA) during tea processing significantly improved the aroma quality of green, oolong, and black teas by modulating the levels of key aroma compounds like benzyl alcohol and linalool (Shi et al., 2019).

4.2 Influence on taste profiles

Fermentation conditions also play a crucial role in shaping the taste profiles of tea. Oxygen-enriched fermentation, for example, was shown to reduce the levels of bitter and astringent metabolites, such as catechins and phenolic acids, while increasing the concentration of theaflavins and amino acids, thereby enhancing the umami intensity of black tea (Chen et al., 2021). The study on autumn green tea revealed that fermentation with Eurotium cristatum significantly reduced astringency and improved the umami taste by oxidizing catechins and increasing theabrownins content (Xiao et al., 2021). Furthermore, a novel dynamic fermentation method (DFM) was found to enhance the sensory quality of Congou black tea by increasing the formation rate of theaflavins and thearubigins, which are crucial for the taste profile (Hua et al., 2021).

4.3 Sensory evaluation of fermented teas

Sensory evaluation is a critical aspect of assessing the quality of fermented teas. The study by Qu et al. (2020) highlighted that black tea fermented at 28 °C received the highest scores for aroma and taste during sensory evaluation. Similarly, the sensory quality of fermented autumn green tea was significantly improved, with a notable increase in aroma quality and a reduction in astringency. The re-rolling treatment in the fermentation process also resulted in higher sensory scores for aroma quality in Congou black tea (Chen et al., 2023). Additionally, the application of MeJA during tea processing was confirmed by sensory evaluation to enhance the aroma quality of various tea types, including green, oolong, and black teas (Shi et al., 2019).

In summary, optimizing fermentation conditions, such as temperature, oxygen levels, and specific fermentation methods, can significantly impact the development of aroma compounds, taste profiles, and overall sensory quality of tea. These findings provide valuable insights for improving tea flavor and quality through controlled fermentation processes.

5 Impact on Tea Quality

5.1 Physical attributes (color, texture)

Fermentation conditions significantly influence the physical attributes of tea, including color and texture. For instance, the brightness of tea liquor is a critical quality attribute affected by fermentation parameters such as temperature and humidity. Studies have shown that maintaining optimal fermentation conditions can enhance the brightness and overall appearance of tea liquor. Specifically, a low fermentation temperature helps maintain a bright orange-red liquor color and promotes the accumulation of theaflavins and thearubigins, which are essential for the desirable color of black tea (Zhu et al., 2022; Saikia et al., 2023). Additionally, the texture of tea leaves can be altered through fermentation, with changes in the structure and color of tea dregs observed when fermented with specific fungi (Cui et al., 2021).

5.2 Chemical composition and health benefits

The chemical composition of tea, including its polyphenols, amino acids, and other bioactive compounds, is profoundly affected by fermentation conditions. For example, fermentation temperature has been shown to influence the levels of polyphenols, polysaccharides, and catechins in black tea. Lower fermentation temperatures can enhance the antioxidant activities and inhibitory effects on enzymes such as α-glucosidase, contributing to the health benefits of tea (Qu et al., 2020). Oxygen-enriched fermentation can also modify the non-volatile metabolites in black tea, reducing bitterness and astringency while enhancing umami intensity by altering the levels of catechins, flavonoid glycosides, and phenolic acids (Chen et al., 2021). Furthermore, the use of specific microorganisms during fermentation can improve the nutritional value and functional components of tea, such as increasing the content of amino acids and reducing caffeine levels (Li et al., 2018; Cui et al., 2021).

5.3 Consumer preferences and quality perception

Consumer preferences and quality perception of tea are closely linked to its sensory attributes, which are influenced by fermentation conditions. Sensory evaluations have shown that black tea fermented at optimal temperatures, such as 28 °C, received higher scores for aroma and taste compared to those fermented at higher temperatures (Qu et al., 2020). The reduction of bitter and astringent metabolites through oxygen-enriched fermentation also contributes to a more favorable taste profile, enhancing consumer satisfaction (Chen et al., 2021). Additionally, the fermentation of autumn green tea with specific fungi has been found to improve its aroma and reduce astringency, making it more appealing to consumers (Xiao et al., 2021). The optimization of fermentation conditions, including temperature, time, and pH, can thus lead to the production of tea with superior sensory qualities and higher overall acceptability (Tang et al., 2018).

By understanding and optimizing the fermentation conditions, tea producers can significantly enhance the physical attributes, chemical composition, and sensory qualities of tea, ultimately improving its marketability and consumer satisfaction.

6 Case Studies

6.1 Optimized fermentation in black tea production

Optimizing fermentation conditions is crucial for enhancing the flavor and quality of black tea. Various studies have explored different parameters to achieve the best results (Figure 2). For instance, oxygen-enriched fermentation has been shown to significantly improve the taste of black tea by reducing bitter and astringent metabolites. This process involved a 10%-30% decrease in catechins, flavonoid glycosides, and phenolic acids, and a 5% increase in theaflavins, glutamate, and glutamine, which collectively enhanced the umami intensity and reduced astringency and bitterness (Chen et al., 2021). Another study identified that fermenting black tea at 28 °C yielded the best sensory quality, with the highest scores for aroma and taste, and also demonstrated strong antioxidant activities (Qu et al., 2020). Additionally, re-rolling treatment during fermentation has been found to improve the aroma quality of black tea, imparting floral and fruity scents by altering the levels of various VOCs (Chen et al., 2023).

The plots for Theaflavin (A, B, C) showed that its levels were significantly influenced by fermentation time and temperature, with optimal conditions leading to higher concentrations. Similarly, Thearubigin (D, E, F) levels were affected by all three factors, showing complex interactions that required precise control for desired outcomes. High Polymeric Substances (G, H, I) and Total Liquor Color (J, K, L) were also sensitive to these variables, impacting the overall quality and appearance of the tea. Total Phenolic Content (M, N, O) showed less variation with changes in conditions, suggesting a more stable component during fermentation. Finally, the TF to TR ratio (P, Q, R) was crucial for determining the balance of astringency and color in tea, highlighting the importance of optimizing fermentation conditions for the best sensory attributes.

6.2 Fermentation practices in green and oolong tea

Fermentation practices also play a significant role in the production of green and oolong teas. The application of methyl jasmonate (MeJA) has been shown to enhance the aroma quality of green, oolong, and black teas. MeJA treatment modulates the aroma profiles by increasing the levels of specific VOCs such as benzyl alcohol, benzaldehyde, and 2-phenylethyl alcohol, which contribute to a more pleasant aroma (Shi et al., 2019) (Figure 3). In the case of oolong tea, optimizing processing techniques to balance high retention of catechins and sensory quality are essential. A study demonstrated that specific processing steps, including red light withering, leaf rotating, drum roasting, low-temperature rolling, and microwave drying, significantly increased the retention of catechins, contributing to the mellow and brisk tastes of oolong tea (Lu et al., 2023). Furthermore, the fermentation of autumn green tea with Eurotium cristatum has been shown to improve its taste quality by reducing astringency and enhancing the umami intensity, primarily through the oxidation of catechins (Xiao et al., 2021).

The research of Shi et al. (2019) presented an analysis of key VOCs in green, oolong, and black tea products derived from methyl jasmonate (MeJA)-treated fresh tea leaves. The heat map (A) highlighted the differential abundance of VOCs, showing varied responses to MeJA treatment over time. Compounds such as cis-3-hexenol, benzyl alcohol, and eugenol displayed significant fluctuations, indicating their potential roles in VOCs enhancement. Radar charts (B, C, D) for each tea type illustrated the changes in VOCs categories, including alcohols, aldehydes, ketones, esters, and others, over different time intervals (0, 12, 24, 48, and 168 hours). Green tea (B) showed a notable increase in alcohols and aldehydes initially, while oolong tea (C) exhibited balanced changes across all categories. Black tea (D) demonstrated substantial shifts in aldehydes and esters over time. This analysis underscored the influence of MeJA treatment on the aroma profiles of tea, contributing to enhanced flavor and potential health benefits.

6.3 Innovations in fermentation for specialty teas

Innovations in fermentation techniques have led to the development of specialty teas with unique flavors and enhanced quality. For instance, the production of instant dark tea using submerged fermentation with Aspergillus niger as a starter has been optimized through the response surface methodology. This process resulted in a product with high theabrownins content, redness, and turbidity, and a sensory profile characterized by a mellow mouthfeel and mint aroma (Wang et al., 2018). Another innovative approach involved optimizing the fermentation process for dandelion black tea using the Box-Behnken response surface method. This method considered various fermentation conditions such as temperature, time, and humidity to enhance the functional components, activity, and sensory quality of the tea (Yaru et al., 2020). Additionally, determining the optimum fermentation time during black tea manufacturing is crucial for achieving the best quality. A study found that the highest theaflavins and thearubigins ratio, which was indicative of good quality, was achieved at a fermentation time of 50 minutes (Rahman et al., 2020).

7 Technological Advancements

7.1 Modern equipment and techniques in fermentation

The advancement of modern equipment and techniques has significantly improved the fermentation process of tea, enhancing both its flavor and quality. For instance, the use of oxygen-enriched fermentation systems has been shown to improve the taste of black tea by reducing bitter and astringent metabolites. This method involved controlling oxygen concentrations during fermentation, which promoted the oxidation of catechins and other phenolic compounds, leading to a more desirable flavor profile (Chen et al., 2021). Additionally, the integration of high-throughput techniques such as 16S rRNA sequencing has allowed for a more detailed analysis of microbial community dynamics during fermentation, providing insights into how specific microorganisms influence tea quality (Liu et al., 2023).

7.2 Role of microbiome in tea fermentation

The microbiome plays a crucial role in the fermentation of tea, affecting both its chemical composition and sensory characteristics. Studies have shown that the microbial community in natural solid-state fermentation (SSF) is essential for the formation of unique flavors in Pu-erh tea. For example, Aspergillus is identified as a key flavor-producing microorganism in the early stages of SSF, while other genera such as Bacillus and Debaryomyces contribute to flavor production in the later stages (Li et al., 2018). Integrated meta-omics approaches have further advanced our understanding of the microbiome's role in tea fermentation, revealing the complex interactions between microbiota, metabolites, and enzymes that contribute to the quality of Pu-erh tea (Zhao et al., 2019). Moreover, the modulation effects of microorganisms on tea during fermentation have been extensively reviewed, highlighting their impact on polyphenol composition, biological activities, and sensory characteristics (Hu et al., 2022).

7.3 Automation and control in fermentation processes

Automation and control technologies have revolutionized the fermentation processes, ensuring consistent quality and efficiency. The use of synthetic microbiota and environmental control factors can regulate spontaneous food fermentations, making them more predictable and controllable. For instance, in the fermentation of Chinese liquor, core microbiota associated with flavor compounds formation can be identified and used to construct synthetic microbiota, which can then be regulated through environmental factors to optimize flavor production (Wu et al., 2021). Additionally, the application of multistarter fermentation techniques, such as those used in the fermentation of glutinous rice with Fu brick tea, has demonstrated increased fermentation efficiency and enhanced flavor profiles, showcasing the potential of controlled fermentation processes (Xu et al., 2019).

8 Challenges and Limitations

8.1 Variability in raw materials

One of the primary challenges in optimizing fermentation conditions for tea is the inherent variability in raw materials. The quality and chemical composition of tea leaves can vary significantly based on factors such as the plucking standards, geographical location, and seasonal variations. For instance, the study by Tang et al. (2018) highlighted how different plucking standards (one leaf and a bud to four leaves and a bud) affected the chemical components and sensory quality of the fermented juices. Similarly, Wen et al. (2023) discussed how summer tea, which had a higher content of polyphenols and lower content of amino acids compared to spring tea, resulted in a more bitter and astringent taste. This variability necessitates careful selection and standardization of raw materials to ensure consistent quality in the final product.

8.2 Balancing traditional methods with modern innovations

Balancing traditional fermentation methods with modern innovations presents another significant challenge. Traditional methods are often valued for their ability to produce unique flavors and high-quality tea, but they can be inconsistent and difficult to control. Modern techniques, such as the use of response surface methodology (RSM) for optimizing fermentation conditions (Wang et al., 2018; Ding et al., 2020), offer more precise control over the fermentation process, leading to improved consistency and quality. For example, Hua et al. (2021) demonstrated how a novel dynamic fermentation method (DFM) could enhance the sensory quality and biochemical components of Congou black tea compared to traditional methods. However, integrating these modern techniques without compromising the traditional characteristics of the tea requires careful consideration and expertise.

8.3 Regulatory and quality control issues

Regulatory and quality control issues are also critical challenges in the optimization of fermentation conditions. Ensuring that the fermentation process complies with food safety regulations and quality standards are essential for consumer safety and market acceptance. The study by Saikia et al. (2023) emphasized the importance of maintaining optimal process parameters such as temperature and relative humidity to achieve the desired quality attributes like brightness in tea liquor. Additionally, Chen et al. (2021) highlighted the role of oxygen-enriched fermentation in altering the metabolites in black tea, which could impact both the flavor and safety of the final product. Implementing robust quality control measures and adhering to regulatory standards are crucial to overcoming these challenges and ensuring the production of high-quality, safe tea products.

9 Future Research Directions

9.1 Emerging trends in fermentation research

Recent studies have highlighted several emerging trends in the field of tea fermentation research. One significant trend is the exploration of optimal fermentation conditions, such as temperature and oxygen levels, to enhance the sensory quality and bioactivity of tea. For instance, research has shown that fermenting black tea at 28 °C could improve both its sensory quality and antioxidant activities (Qu et al., 2020). Additionally, oxygen-enriched fermentation has been found to reduce bitter and astringent metabolites, thereby improving the taste of black tea (Chen et al., 2021). Another trend is the use of novel fermentation methods, such as dynamic fermentation, which has been shown to significantly enhance the biochemical components and sensory quality of Congou black tea (Hua et al., 2021). Furthermore, the role of microbiota in the fermentation process is gaining attention, with studies revealing the impact of microbial communities on the quality of Pu-erh tea (Li et al., 2018).

9.2 Integration of AI and data analytics in optimizing conditions

The integration of artificial intelligence (AI) and data analytics in optimizing fermentation conditions is a promising area of research. AI models, such as artificial neural networks (ANN), have been successfully used to predict and optimize tea quality attributes based on fermentation conditions. For example, ANN models have demonstrated high accuracy in correlating fermentation conditions with tea liquor brightness, outperforming traditional multivariate linear regression methods (Saikia et al., 2023). Additionally, response surface methodology (RSM) has been employed to optimize fermentation parameters for producing instant dark tea, showing good correlation between predicted and experimental values (Wang et al., 2018). These advancements suggest that AI and data analytics can play a crucial role in standardizing and improving tea fermentation processes.

9.3 Potential for personalized tea fermentation processes

The potential for personalized tea fermentation processes is an exciting avenue for future research. Personalized fermentation could cater to individual preferences for taste, aroma, and health benefits by adjusting fermentation conditions and microbial communities. Studies have shown that different fermentation conditions could significantly alter the chemical composition and sensory quality of tea (Qu et al., 2020; Chen et al., 2021; Hua et al., 2021). Moreover, the use of specific microbial strains, such as Eurotium cristatum, has been found to improve the taste and aroma of autumn green tea (Xiao et al., 2021). By leveraging these insights, personalized fermentation processes could be developed to produce customized tea products that meet the unique preferences and health needs of consumers.

10 Concluding Remarks

The research on optimizing fermentation conditions for tea has revealed significant insights into how various factors influence tea flavor and quality. Studies have shown that the duration and temperature of fermentation play crucial roles in determining the chemical composition and sensory attributes of tea. For instance, prolonged fermentation tends to degrade polyphenols, which are essential for the astringency and bitterness of tea, while enhancing the sweetness and smoothness of the final product. Additionally, the presence of specific microbial communities during fermentation can significantly alter the flavor profile, as seen in the increased abundance of beneficial bacteria like Lactobacillus and Bifidobacterium in certain fermentation conditions. These findings underscore the importance of carefully controlled fermentation processes to achieve the desired tea quality.

To optimize tea fermentation and enhance flavor and quality, the industry should adopt several best practices. Firstly, monitoring and controlling the fermentation temperature and duration are essential to maintain the balance of polyphenols and other flavor compounds. Implementing precise temperature control systems can help achieve consistent results. Secondly, fostering beneficial microbial communities through the use of specific starter cultures can improve the flavor profile and health benefits of the tea. Regular microbiota assessments can guide adjustments in fermentation practices to favor desirable microbial populations. Lastly, continuous research and development efforts should focus on understanding the complex interactions between fermentation conditions and tea chemistry to refine and innovate fermentation techniques further.

The future of tea fermentation holds promising potential for innovation and quality enhancement. Advances in biotechnology and microbiology will likely lead to the development of tailored microbial consortia that can be used to produce teas with specific flavor profiles and health benefits. Additionally, the integration of modern analytical techniques, such as metabolomics, will provide deeper insights into the chemical changes occurring during fermentation, enabling more precise control over the process. As consumer preferences evolve towards more diverse and health-conscious options, the tea industry must continue to adapt and innovate its fermentation practices to meet these demands. By leveraging scientific advancements and maintaining a commitment to quality, the industry can ensure the production of superior teas that cater to a wide range of tastes and preferences.

Acknowledgments

The authors sincerely thank two anonymous peer reviewers for their invaluable feedback on the manuscript of this study. Their thorough review and suggestions contributed to the improvement of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (No. 32160077), the Guizhou Academy of Agricultural Sciences Talent Special Project [grant number (2022-02 and 2023-02)], the Guizhou Provincial Science and Technology Project (QKHPTRC-CXTD [2022] 002), the Education Department of Guizhou Province - Natural Science Research Project (QJJ [2023] 042).

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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