Bioscience Methods 2024, Vol.15, No.5, 237-243 http://bioscipublisher.com/index.php/bm 238 2 Tea Fermentation and Probiotic Development 2.1 Types of tea fermentation (green, black, oolong, etc.) Tea fermentation is a critical process that influences the flavor, aroma, and health benefits of the final product. The primary types of tea fermentation include green, black, and oolong tea. Green tea undergoes minimal oxidation, preserving its natural polyphenols and antioxidants. Black tea, on the other hand, is fully oxidized, resulting in a darker color and richer flavor profile. Oolong tea falls between green and black tea in terms of oxidation, offering a unique balance of taste and health benefits. Each type of tea fermentation provides a distinct environment for microbial activity, which can influence the development of probiotics (Zhang et al., 2013). 2.2 Microbial diversity involved in tea fermentation The microbial diversity in tea fermentation is vast and includes various bacteria, yeasts, and fungi. For example, green tea fermentation involves a diverse microbial community, primarily dominated by lactic acid bacteria (LAB) and yeasts (Li and Huang, 2024). Lactic acid bacteria (LAB) are commonly found in fermented teas and are known for their probiotic properties. For instance, Lactobacillus species such as L. pentosus, L. plantarum, and Pediococcus pentosaceus have been isolated from traditional fermented teas like Miang from Northern Thailand (Unban et al., 2021). Additionally, fungi such as Eurotium cristatumplay a significant role in the fermentation of Fuzhuan brick tea, contributing to its unique flavor and potential health benefits (Lu et al., 2022). The microbial communities involved in tea fermentation can vary significantly depending on the type of tea and the specific fermentation conditions (Huligere et al., 2023). 2.3 Mechanisms of probiotic development during tea fermentation The development of probiotics during tea fermentation involves several mechanisms. Firstly, the fermentation process creates an anaerobic environment that favors the growth of beneficial microbes like LAB. These bacteria can produce lactic acid, which lowers the pH and inhibits the growth of pathogenic microorganisms. Additionally, the fermentation process can enhance the bioavailability of tea polyphenols, which act as prebiotics and support the growth of probiotic bacteria (Chan et al., 2020). For example, the fermentation of green tea with Lactobacillus gasseri has been shown to produce high concentrations of probiotic cells, making it a promising functional food (Lima et al., 2022). Furthermore, the interaction between tea polyphenols and gut microbiota can lead to the production of short-chain fatty acids (SCFAs), which have various health benefits, including anti-inflammatory effects (Guo et al., 2019; Chen et al., 2020). 3 Probiotic Strains in Fermented Tea 3.1 Common probiotic strains identified in fermented tea Fermented tea, such as Miang from Northern Thailand, is known to host a variety of beneficial probiotic bacteria. Common strains identified include Lactobacillus pentosus, Lactobacillus plantarum, and Pediococcus pentosaceus. These strains have shown high tolerance to bile and acidic conditions, making them suitable for probiotic applications. Additionally, other studies have identified Lactobacillus rhamnosus, Lactobacillus paracasei, and Lactobacillus acidophilus in various fermented beverages, indicating their widespread presence and potential health benefits (Lima et al., 2022). 3.2 Factors influencing probiotic composition in tea fermentation Several factors influence the composition of probiotics during tea fermentation. These include the initial microbial community present in the tea leaves, the fermentation conditions such as pH, temperature, and the presence of nutrients or additives. For instance, the addition of green tea to passion fruit juice significantly enhanced the growth of Lactobacillus gasseri, demonstrating the impact of substrate composition on probiotic viability. Moreover, nutrient supplementation, such as adding glucose and inactivated yeast derivatives, has been shown to support the growth and survival of probiotics like Lactobacillus rhamnosus and Lactobacillus paracasei in fermented coffee brews (Chan et al., 2020). 3.3 Stability and viability of probiotics in tea-based products The stability and viability of probiotics in tea-based products are crucial for their effectiveness as health supplements. Probiotic strains such as Lactobacillus pentosus and Lactobacillus plantarum have demonstrated
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