Tea, Camellia sinensis, is grown around the world under diverse geographic and climatic conditions and can be cultivated as a specialty crop in the U.S. U.S. specialty tea growers cater to the high-quality specialty tea niche market, and innovations in mechanization and novel products increase profitability. The objective of this study was to develop a cold brew methodology that would maximize the flavor characteristics and shelf life of cold brew black teas to facilitate the development of new products. 'Black Magnolia' from the Great Mississippi Tea Co. (Brookhaven, MS) was used to determine combinations of cold brew conditions affecting taste and health-promoting compositions (polyphenol and caffeine), including selected combinations of tea-to-water ratio (1, 2, and 3g of tea per cup of water), temperature (40, 45, 50, 55, and 60°F), brewing time (6, 8, 10, 12, and 14 hours), and particle size (whole-leaf, coarse, and fine). Selected conditions were then used in a UV light experiment to compare shelf life (microbial growth at 2, 4, and 6 days after brewing) using hot water-brewed tea as a control. Results indicate that, for this specific black tea, 2g per cup at higher temperatures of 55 to 60°F resulted in comparable polyphenol contents to hot water brew, but lower caffeine concentrations. However, compared to lower temperatures, teas made at this range of temperatures resulted in a higher number of yeast and mold by day 4. Brewing at 45°F for 14 hours resulted in comparable polyphenol contents as hot water brew and was described with more positive words compared to a shorter brewing time during sensory surveys conducted on campus with over 100 students. Initial testing of UV light treatments for 0, 0.5, 1.0, and 2.0 hours of duration before cold brew indicated that UV light is insignificant in reducing microbial growth. Further research is needed to improve the UV treatment or use other methods to extend the shelf life of cold brew tea. The best brewing conditions obtained from this study could be of guidance for future large-scale consumer sensory evaluations that will compare the flavor of four U.S.-grown black teas to imported specialty teas and their health-benefiting compounds. This next study will provide essential and important information for U.S. tea growers and consumers on how U.S.-grown tea performs in comparison with internationally known black teas and potential enhancements to maximize the health benefits and popularity of U.S.-grown specialty tea.
