Table 2.

Comparison of the content (mean; standard deviation; mg/L) of the major phenolic compounds from different studies. Our results are presented for each type of balsamic vinegar separately. Greek vinegars (n = 3; sample No. 1 was not included because a lack or different content of these compounds), BVM (n = 4), “premium” BVM (n = 5), TBVM (n = 1), [8] (n = 8), [16] (n = 6), [14] (n = 1). Average values from current study are calculated for samples containing the compounds in higher levels than limits of quantification (according to Table S6).

Compound	Greek Vinegars	BVM	“Premium” BVM	TBVM	Barnaba et al. [8]	Natera et al. [16]	Liu et al. [14]
Gallic acid	6.97 ± 4.03	11.61 ± 9.43	33.53 ± 9.33	21.42 ± 0.16	12.4 ± 11.8	64.50 ± 10.20	12.56 ± 0.86
Protocatechuic acid	1.69 ± 0.23	3.48 ± 1.00	12.06 ± 1.73	5.09 ± 1.42	6.11 ± 7.14	13.40 ± 29.94	3.29 ± 0.05
Caffeic acid	0.86 ± 0.43	1.52 ± 1.32	10.22 ± 3.21	1.61 ± 0.10	3.14 ± 3.17	28.70 ± 12.40	3.58 ± 0.14
p-Coumaric acid	0.47 ± 0.37	1.00 ± 1.02	7.09 ± 4.09	4.707 ± 0.69	2.45 ± 2.52	22.40 ± 33.00	1.97 ± 0.05
Salicylic acid	0.26 ± 0.01	0.63 ± 0.13	1.21 ± 0.45	1.51 ± 0.05	0.29 ± 0.26
Syringic acid	n.d.	1.90 ± 1.81	2.71 ± 0.57	8.14 ± 1.04	1.05 ± 1.11	n.d.
Pyrogallol	0.80 ± 0.03	0.80 ± 0.23	1.06 ± 0.26	1.12 ± 0.003
Ethyl gallate	1.13 ± 0.41	0.96 ± 0.63	3.44 ± 1.47	2.63 ± 0.04
Tyrosol	0.99 ± 0.19	1.88 ± 1.52	1.85 ± 1.16	2.906 ± 0.08	0.27 ± 0.36	109.40 ± 60.10
Protocatechuic aldehyde	0.32 ± 0.08	0.92 ± 1.07	2.10 ± 1.44	4.62 ± 0.07	6.41 ± 8.35	15.70 ± 2.40

n.d.—not detected.