Targeted metabolomics and DIA proteomics-based analyses of proteinaceous amino acids and driving proteins in black tea during withering

Effects of Sun Withering Degree on Black Tea Quality Revealed via Non-Targeted Metabolomics

“…At the same time, the amino acid species showed a different change trend, with an uptrend in L-glutamine, L-glutamic acid, L-methionine, L-arginine, L-theanine and L-proline; a downtrend in L-phenylalanine, L-tryptophan, L-tyrosine, L-leucine, L-isoleucine, L-threonine and L-asparagine; and an uptrend followed by a downtrend for L-valine. Amino acids were further classified according to umami, sweet, and bitter tastes [ 9 , 23 ], and the variation of amino acid content in each category for different degrees of sun withering is shown in Figure 4 A; the ratio of each category was calculated ( Figure 4 B). Compared with CK, the sun withering treatment groups showed an increase of nearly 20% in the percentage of umami amino acids and a decrease of about 17% in the percentage of bitter amino acids, indicating that the amino acid categories changed after sun withering, which could significantly improve the taste quality of tea [ 23 ].…”

“…Amino acids were further classified according to umami, sweet, and bitter tastes [ 9 , 23 ], and the variation of amino acid content in each category for different degrees of sun withering is shown in Figure 4 A; the ratio of each category was calculated ( Figure 4 B). Compared with CK, the sun withering treatment groups showed an increase of nearly 20% in the percentage of umami amino acids and a decrease of about 17% in the percentage of bitter amino acids, indicating that the amino acid categories changed after sun withering, which could significantly improve the taste quality of tea [ 23 ].…”

“…The potential differential metabolites in different sun withering treatments were explored using a combined analysis of OPLS-DA (VIP > 1; p < 0.05) and OAV (OAV > 1), and the results are shown in Figure 6C. A total of 11 differential metabolites were screened, namely linalool (OAV: 404-504), geraniol (OAV: 426-488), benzeneethanol (OAV: 1-2), (Z)-3hexen-1-ol (OAV: 4-10), benzeneacetaldehyde (OAV: 3120-5027), (E)-2-hexenal (OAV: 264-308), (E)-citral (OAV: 4-7), jasmone (OAV: 130-182), β-damascenone (OAV: 18,714-28,318), methyl salicylate (OAV: [19][20][21][22][23][24][25][26], and β-myrcene (OAV: 1-2). The 11 volatiles can be considered as the potential major aroma differential metabolites in black teas with a different degree of sun withering.…”