Optimization of Withering and Drying Processes for Jinggu White Tea

Fresh leaves with one bud and two leaves of Yangta Da Bai tea in Jinggu County were processed into Moonlight White Tea using two withering methods and three drying methods. Sensory evaluation, analysis of characteristic components, and aroma substances were conducted to optimize the processing technology of Jinggu White Tea. Sensory evaluation revealed that white tea produced through compound withering and 50 ℃ hot-air drying exhibited a pekoe aroma with floral notes, a sweet and mellow taste with a lasting aftertaste, and uniformly tender yellow-green leaves. The content of 11 amino acids, soluble sugars, ellagic acid, epicatechin, and gallic acid were significantly higher in samples processed by this method than in other samples. In contrast, the content of catechin gallate, epigallocatechin gallate, epigallocatechin gallate, theophylline, quercetin, myricetin, kaempferol, and catechin were lower than those in other samples. A total of 187 volatile compounds were identified in the optimized samples using GC-MS, mainly including terpenes, esters, alcohols, aldehydes, and heterocyclic compounds. Calculations have found that 20 compounds had odor activity values (OAV) ＞ 1, including: terpinenes (OAV = 411.86), imparting fresh and lemon-like aromas; linalool (OAV = 20.48), contributing sweet and floral notes; and sotolon (OAV = 208.18), associated with sweet aromas, all significantly contributing to the floral and sweet aroma profile. This study optimized the processing technology of Jinggu Moonlight White Tea and provided experimental evidence for the standardized processing of Jinggu Da Bai Tea.