# Effect of Blue Light Intensity During Spreading on the Aroma of Green Tea  
[PERSON]  
1 Wenzhou Key Laboratory of Early Sprouting Tea Breeding, Wenzhou Vocational College of Science and Technology (Wenzhou Academy of Agricultural Sciences), Wenzhou 325006, China; [EMAIL_ADDRESS]  
[PERSON]  
1 Wenzhou Key Laboratory of Early Sprouting Tea Breeding, Wenzhou Vocational College of Science and Technology (Wenzhou Academy of Agricultural Sciences), Wenzhou 325006, China; [EMAIL_ADDRESS]  
[PERSON]  
2 College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China; [EMAIL_ADDRESS]  
Lailong Li  
significantly affects their physical and chemical characteristics, such as tannins, polyphenols, theine, amino acids, vitamins, and minerals [4]. In general, spreading is a preliminary and indispensable craft closely related to the formation of the desired sensory quality of made tea [5]. The quality of tea's flavor is determined by aroma and taste, which are dependent on volatile and non-volatile compounds [6]. Aroma plays a vital role in determining the quality of tea, which includes a variety of aroma compounds, such as esters, alcohols, acids, ketones, and terpenes [7]. Although green tea has 260 volatile compounds, not all of them have an impact on the tea's aroma [8]. In Laoshan green tea, a total of 50 aroma compounds were detected, of which 24 were key contributors to OAV \(>1\), indicating that these compounds contributed significantly to the overall aroma of tea [9]. Furthermore, in Enshi Yulu green tea, 134 volatile compounds were found using HS-SPME and GC-MS; however, only 25 of these were considered significant because their roAV was more than 1 [10]. Thus, the overall fragrance of green tea is determined by only a few significant compounds. Light is a major environmental factor that influences the production of metabolites in plants. Stimulating with particular monochromatic or polychromatic light can boost the biosynthesis of various secondary metabolites [11]. During the withering/spreading process of tea in the postharvest period, light can improve the quality of tea. Using blue and red light during the withering process significantly decreased the grassy taste in tea leaves; blue light boosted the floral scent, while red light boosted the fruity scent [12]. Red-light withering, as opposed to natural withering, can greatly enhance the taste quality of summer-autumn black tea by lessening its bitterness and astringency. Exposure to red light during withering can greatly enhance glycosidase activity in the later stages, thereby boosting the aroma quality of black tea in later processing [13]. Exposure to red light primarily interferes with the biosynthesis of secondary metabolites and pathways related to amino acid synthesis and metabolism. It enhances the accumulation of amino acids and theaflavins, affecting the chemical foundation of black tea quality [14]. Under red and blue light treatments, the tea retained its natural form, dark green color, fresh aroma, and mellow taste; the tea exposed to green light had a pure aroma and a smooth taste, while the red light added a floral aroma [15]. Using warm-colored light during the spreading process greatly enhanced the overall quality of green tea, especially with yellow light [16]. Nonetheless, with our present knowledge, the impact of changes in blue light intensity on green tea volatiles remains unclear, necessitating additional research. This study used DARK spreading as a control and designed blue light intensity treatments to uncover how different blue light intensities affects the aroma and volatile metabolites of green tea. Through the quantification and analysis of volatile compounds, the study elucidated the influence of various blue light intensities on green tea aroma and found the best conditions for spreading. Key differential volatile compounds resulting from varying blue light intensity treatments were identified using significant difference, variables important in the projection (VIP), and rOAV analysis.