Bioscience Evidence 2026, Vol.16, No.4, 235-248 http://bioscipublisher.com/index.php/be 243 when the same processing method is used. Timely harvesting therefore remains the most effective measure for maintaining spring tea quality. Figure 3 Factors affecting black tea quality and changes that occur in chemical composition during processing (Adopted from Aaqil et al., 2023) Cultivation management can further improve spring tea quality. Zhu et al. (2023) found that moderate shading during spring increased compounds related to freshness and improved the quality of premium green tea. However, the effects of shading differed among seasons, so the same shading treatment should not be used throughout the year. Regarding fertilization, Raza et al. (2024) suggested that organic fertilizer or a combination of organic and inorganic fertilizers can improve fresh leaf quality, promote the accumulation of freshness-related compounds, and reduce bitterness and astringency. Long-term application of chemical fertilizer alone may promote plant growth, but it can also increase the polyphenol-to-amino acid ratio, which is unfavorable for premium green tea production. Tea gardens should therefore establish a fertilization system based mainly on organic fertilizer, supplemented with an appropriate amount of chemical fertilizer. Moderate spring shading, reasonable pruning, and environmentally friendly pest and disease control should also be combined to improve spring tea quality. 5.3 How to increase the utilization value of summer and autumn tea Summer and autumn fresh leaves usually account for a large proportion of annual tea yield. However, high temperatures promote the rapid accumulation of tea polyphenols while reducing amino acid contents. As a result, processing summer and autumn leaves into green tea using the same standards as spring tea often produces strong bitterness and astringency and results in a low market price. The key to increasing the value of summer and autumn tea is not to make them resemble spring tea, but to adjust the processing direction according to their own chemical characteristics and achieve differentiated utilization. Fermentation processing can effectively improve the quality of summer and autumn tea. Wu et al. (2025) found that optimizing processing conditions reduced some bitter and astringent compounds and increased substances related to umami and sweetness, resulting in a more balanced taste in summer tea products (Figure 4). Chiang et al. (2022) showed that appropriate enzymatic transformation or fermentation promoted the formation of quality-related compounds such as theaflavins and thearubigins, thereby improving flavor and overall product quality. For small tea enterprises and family farms, part of the summer and autumn harvest can be used to produce black tea, white tea, dark tea, or specialty fermented tea instead of being processed entirely into traditional green tea. Producers may also develop tea bags, flavored tea, instant tea, and raw materials for tea beverages. These products can improve the use efficiency of summer and autumn tea resources, reduce unharvested leaves, and increase annual operating income.
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