Journal of Tea Science Research, 2024, Vol.14, No.1, 19-43 http://hortherbpublisher.com/index.php/jtsr 20 anti-inflammatory activity, anticarcinogenic properties, etc. (Hinojosa-Nogueira et al., 2021; Sonawane et al., 2021; Zhou et al., 2023). Figure 1 White tea production in China from 2015 to 2020 (Source: https://mp.weixin.qq.com/s/t6xOjNQTdaRw4Zob7vjgYA) Efficient extraction of bioactive compounds is the basis for optimal utilization of the health-promoting phytochemicals in white tea, such as polyphenols, caffeine, theogallin, gallic acid, theaflavin, flavonol glycosides, and catechins, especially epigallocathechins (EGC), epigallocatechins gallate (EGCG), and epicatchin gallate (ECG). There are generally two main purposes for white tea extraction: one is for human consumption as a type of beverage, which involves the conventional aqueous brewing/infusion practice to produce household or commercial tea drinks (Zhang et al., 2017b); the other one is for food preservation or nutrient supplementation as natural antioxidants, which involves solvent extraction coupled with novel techniques to produce functional ingredients (Kowalska et al., 2021). The extraction parameters are important because they would determine not only the extraction efficiency but also the chemical composition of white tea extract (WTE). It is inevitable that the freshly prepared phytochemicals in WTE would usually go through the storage phase before use, during which time they are susceptible to degradations. Therefore, it is important to understand the stability of WTE during storage and develop effective stabilization strategies to maximize its health benefits. With the growing global awareness and booming production of white tea, recent research has been conducted to explore efficient extraction methods for WTE production and to investigate stabilization approach for its feasible applications. However, the knowledge of white tea is relatively new and less well known compared with other teas, such as green tea. To fill this gap in the literature, the present review attempts to provide a comprehensive summary of published research on the extraction, stabilization, and bioactivities of white tea. Specifically, efficiency comparison between different extraction techniques, recent advances in stabilizing bioactive components, antioxidant or antimicrobial functions of white tea extract in food preservation, and health benefits proven by animal experiments or clinical trials will be discussed. 1 Varieties and Phytochemical Compositions 1.1 Classifications and compositions Originating from China, white tea has traditionally been defined by the subspecies of Camellia sinensis harvested from: Fuding and Zhenghe Big White Da Bai, found only in Fujian Province (Hilal and Engelhardt, 2007). With the increasing worldwide recognition and popularity of white tea, it is now grown not only in other parts of China but also in other countries, leading to the international definition by plucking standard. White tea mainly consisting of the silvery buds and young leaves of the plant are hand-picked, steamed and dried without further processing, which gives the whitish appearance (Mao, 2013). Based on the origin, leaf composition, and processing protocols, white tea can be classified into several major categories (Table 1). There are four main varieties of white tea from China: Silver Needle (Yin Zhen), White Peony (Bai Mu Dan), Longevity Eyebrow (Shou Mei), and Tribute Eyebrow (Gong Mei). Each of the sub-varieties has its own physical appearance: the silver needle consists mostly of tea buds covered with fine white hairs; White Peony is a mixture of buds and
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