Table 1. Tentative identification of major citrus peel metabolites analyzed using UPLC-Q-TOF MS and their fold changes

RT1)	Compound	Exact mass (m/z)	MS fragment	MSI2) level3)	Adducts	VIP4)	p-value5)	Fold changes (vs. early stage of storage)
								K16)	K2	N1	N2	T
0.65	Arginine	173.0997	88, 131, 156	1	M-H	1.23	2.44 × 10−5	1.40	1.70	1.14	1.62	3.86
0.66	Glutamine	145.0572	88, 102, 127	1	M-H	1.46	1.91 × 10−4	−1.45	−1.28	−1.02	−1.79	−1.20
0.72	Alliin	176.0342	150	1	M-H	1.20	4.65 × 10−4	−1.69	−1.77	−1.15	−1.49	−1.40
0.74	Sucrose	341.1056	59, 179, 209, 221	1	M-H	1.15	5.50 × 10−2	−1.05	1.44	1.19	1.26	3.09
0.77	Maltopentose	827.2671	545	2	M-H	0.85	2.81 × 10−2	2.81	4.65	4.15	2.42	6.06
0.80	Malic acid	133.0099	115	1	M-H	1.27	6.08 × 10−2	−3.76	1.20	−1.38	−1.78	−1.38
0.87	Citric acid	191.0152	87, 173	1	M-H	1.22	6.09 × 10−4	1.31	2.53	1.34	1.52	2.87
0.98	Cellotriose	503.1594	101, 179, 221, 251, 323, 341	2	M-H	0.76	2.49 × 10−2	3.11	5.98	1.77	1.77	6.91
1.00	di-Galactosyl pinitol	549.1657	101, 179, 251, 341, 503	2	M-H	0.68	3.41 × 10−2	1.80	7.29	2.72	2.44	5.64
1.06	Isocitric acid	191.0152	87, 173	2	M-H	1.12	1.13 × 10−1	−1.24	1.97	1.14	1.33	2.71
1.19	N-Acetyldehydroalanine	128.0304		3	M-H	1.33	6.69 × 10−2	−1.83	−1.03	−1.20	−1.17	1.45
1.24	Gly-l-Pro	171.0722	153	2	M-H	1.13	1.17 × 10−5	18.58	92.56	10.29	39.53	+
1.25	γ-L-Gln-S-(1-propenyl)-Cys sulfoxide	305.0769	171, 215, 264	2	M-H	1.18	2.43 × 10−6	1.73	7.92	7.39	3.34	8.74
1.70	Pyroglutamic acid	128.0316		1	M-H	0.47	3.36 × 10−1	1.96	5.08	2.40	2.93	18.57
1.71	Met-Asp	263.0652		3	M-H	0.97	3.59 × 10−5	62.36	3.42	29.40	45.15	283.21
1.86	Leucine	130.0817		1	M-H	0.46	9.42 × 10−2	−17.61	−3.04	−1.74	−7.88	−18.84
2.44	N-Acetylcystathionine	263.065	128	2	M-H	1.00	1.38 × 10−3	−3.05	−1.85	1.10	−1.36	−2.94
2.62	Boc-Gln-Oh	245.1089	143, 99	2	M-H	1.26	6.82 × 10−6	3.98	13.62	2.77	4.88	93.74
2.64	Dihydrotanshinone I	277.0812		3	M-H	1.26	7.37 × 10−8	2.57	4.25	2.50	3.24	17.53
2.66	Phenylalanine	164.066		1	M-H	1.09	1.63 × 10−3	−1.34	1.07	−1.25	−1.06	1.58
2.73	Glutathione glycylmethyl ester	392.1088	99, 143, 254, 272, 306, 374	2	M-H	1.29	1.12 × 10−10	2.68	3.16	1.38	2.11	14.60
3.09	Tryptophan	203.0768		1	M-H	0.52	6.57 × 10−1	2.37	4.97	1.50	2.29	26.11
3.13	L-γ-Gln-L-Leu	259.1245	128, 230 197, 223, 241	2	M-H	1.19	1.83 × 10−4	−1.67	−19.39	−6.57	2.29	22.19
3.20	Delphinidin-3-O-β-glucopyranoside	465.1009	303, 125, 177	2	M-H	0.33	7.78 × 10−1	1.00	1.83	1.26	1.14	3.74
3.22	Glutamyl-S-allylcysteine	289.0814	73, 86, 160, 171	2	M-H	1.33	1.30 × 10−6	2.53	4.66	1.45	2.62	43.85
3.36	Gln-Phe	293.1091	128, 147, 164, 249, 257, 275	2	M-H	1.39	2.72 × 10−5	1.07	1.52	1.31	1.12	1.37
3.61	Quercetin 3,4’-diglucoside	625.1405	301, 463, 609	1	M-H	0.66	2.38 × 10−1	−1.25	−1.08	1.09	−1.09	−1.19
3.69	Astragaloside	639.1568	285, 313, 446, 476, 519, 609	2	M-H	1.09	1.04 × 10−3	−2.11	−1.33	−1.97	−1.62	−1.90
3.84	Met-Glu-Cys	380.0916	99, 128, 143	2	M-H	1.21	1.25 × 10−4	−2.17	−2.35	−2.91	−2.49	−2.17
4.22	Ascaloniside A2	963.4846	609, 771	2	HCOO-	0.70	1.56 × 10−2	−9.49	−1.20	−3.06	−8.30	−4.12
4.27	Isorhamnetin 3-glucoside	477.1009	299, 314	2	M-H	0.52	3.75 × 10−2	1.14	1.51	1.24	1.44	−1.81
4.33	Quercetin-4’-glucoside	463.0857	151, 300, 301	1	M-H	0.39	5.10 × 10−1	−1.18	1.03	1.41	1.09	−1.03
4.35	Schidigera saponin F1	933.4742	741	2	HCOO-	0.47	8.69 × 10−2	−4.21	1.36	−1.26	−2.90	−2.39
4.48	Nepitrin	477.1016	299, 314	2	M-H	0.81	6.68 × 10−2	−1.49	−1.02	−1.27	−1.15	−1.58
4.86	Rhaponticin	419.1313	121, 228, 257, 287	2	M-H	0.82	5.10 × 10−3	−1.68	−1.16	1.08	−1.22	−1.40
4.87	Auriculoside	449.1421	257, 419	2	M-H	1.11	5.22 × 10−3	−1.71	−1.50	−1.48	−1.25	1.06
5.00	Quercetin	301.0296	93, 151, 243, 245	1	M-H	0.93	2.00 × 10−1	−1.50	−2.02	1.14	1.46	1.12

RT, retention time.
MSI, metabolomics standards initiative.
MSI levels are assigned according to the metabolomics standards initiative. Level 1, confirmed with authentic standards; Level 2, presumptive identification through MS/MS matching; Level 3, tentative identification based solely on accurate mass.
VIP, variable importance in the projection.
p-values were analyzed by ANOVA with Duncan’s multiple range test.
K, Katamaru; N, New Mars, T, Terius.