United States tea: A synopsis of ongoing tea research and solutions to United States tea production issues

Abstract

Tea is a steeped beverage made from the leaves of Camellia sinensis. Globally, this healthy, caffeine-containing drink is one of the most widely consumed beverages. At least 50 countries produce tea and most of the production information and tea research is derived from international sources. Here, we discuss information related to tea production, genetics, and chemistry as well as production issues that affect or are likely to affect emerging tea production and research in the United States. With this review, we relay current knowledge on tea production, threats to tea production, and solutions to production problems to inform this emerging market in the United States.

Understanding and exploring the diversity of soil microorganisms in tea (Camellia sinensis) gardens: toward sustainable tea production

“…Tea plant is frequently pruned to enable the development of new shoots and maintain the shape and height and can take up to two years to maturity. The leaves are harvested by plucking new leaves and terminal buds from the tip of the branches at regular intervals from the second year onwards (Mukhopadhyay and Mondal, 2017;Auria et al, 2022). The plucking of the new leaves also enables the emergence of new buds and leaves.…”

“…assamica can be separated into two subtypes, namely, Southern Yunnan Assam (China) and Indian Assam (India), which although may have originated from the same parent, appears to represent two independent domestication events. Furthermore, some subvarieties appear to have undergone hybridization with closely related species such as C. taliensis and C. pubicosta (Mukhopadhyay and Mondal, 2017;Auria et al, 2022). In addition to the occurrence of different regional varieties, tea is further classified post-harvest via the different means and methods for processing of the leaves that result in significant differences in the final consumed product (Auria et al, 2022).…”

“…Furthermore, some subvarieties appear to have undergone hybridization with closely related species such as C. taliensis and C. pubicosta (Mukhopadhyay and Mondal, 2017;Auria et al, 2022). In addition to the occurrence of different regional varieties, tea is further classified post-harvest via the different means and methods for processing of the leaves that result in significant differences in the final consumed product (Auria et al, 2022). These different post-harvest processing methods result in the commonly referred to black, green, white, oolong, dark, and yellow teas (among others), and involve a series of steps that can include, depending upon the final outcome, the following: (picking), (i) withering-drying of the leaves; under sun for darker teas, in a cool ventilated room for lighter teas, (ii) bruising-crushing, shaking, rolling, and/or other forms of manipulating the leaves; mainly for darker teas, (iii) oxidation-exposure leaves to air for different period of time; darkens teas depending upon time, (iv) heating-after oxidation, leaves are heated to stop oxidation process, also referred to as "fixation, " (v) yellowing-light heating in closed chamber, (vi) fermentation-leaves are allowed to ferment for a period of time; results in increase in sweetness, (vii) drying-remove moisture via baking, sun and/or air-drying, (viii) sorting and shaping-stems, seeds, and impurities are removed and the tea "shaped" into various forms, e.g., bricks, circles, etc., for aging and/or storage.…”

“…Thus, "black" tea involves withering, bruising, oxidation, shaping, and drying, "white" tea (freshly picked leaf buds): only withering, heating, shaping, and drying (with white tea often considered the least "processed" of the final tea forms). In addition, many of these steps can have important production differences with respect to leaf treatment for any given step in terms of time, temperature, and other conditions that can result in significant differences in the final products even if all are considered "black" teas (Auria et al, 2022;Aaqil et al, 2023).…”