Influence of natural light intensities on growth and content of catechins and caffeine in Camellia formosensis leaves and tea infusion

Camellia formosensis is a significant under the forest canopy crop in Taiwan. This study investigated the composition and yield variations of native Camellia formosensis tea leaves across different relative light intensities levels and seasons. Increasing the relative intensity of natural light resulted in a corresponding increase in the dry weight of C. formosensis leaves. At a relative light intensity of 70%, the dry weight of the leaves per unit area was 15.8 g. However, the yield of C. formosensis was lower at relative light intensities of 40% or 20%. A positive correlation was observed between relative light intensities and the contents of catechin gallate (CG), epicatechin gallate (ECG), and gallocatechin gallate (GCG) and relative light intensity. At 20% relative light intensity, the mean CG, ECG, and GCG contents were 4.97, 0.57, and 4.43 mg/g, respectively. These values surged to 6.93, 2.23, and 7.53 mg/g, respectively, at 70% relative light intensity. Caffeine content exhibited an inverse relationship with relative light intensity, declining notably after surpassing 70%. Moreover, C. formosensis leaves harvested in summer under 70% relative light intensity boasted higher contents of CG, epicatechin (EC), ECG, epigallocatechin gallate (EGCG), and caffeine than those harvested in spring. Ester catechin content surpassed non-ester catechins, with the former consistently higher at 100% relative light intensity, irrespective of the season.