. 2022 Apr 24;11(5):828. doi: 10.3390/antiox11050828

Table 3.

Identification and quantification of individual phenolic compounds in the aqueous and hydroethanolic olive pomace extracts obtained by ohmic heating (OH) and conventional heating (CH) techniques.

Phenolic Compound	OH		CH
Phenolic Compound	H₂O	EtOH 50%	H₂O	EtOH 50%
Hydroxytyrosol and tyrosol derivatives
Hydroxytyrosol	28.71 ± 0.42 ^a	33.36 ± 0.57 ^b	31.20 ± 0.29 ^c	33.49 ± 0.40 ^b
Tyrosol	10.63 ± 0.06 ^a	21.09 ± 0.12 ^b	11.13 ± 0.15 ^a	11.09 ± 0.99 ^a
Oleuropein	n.d.	254.38 ± 13.24 ^a	n.d.	369.05 ± 23.00 ^b
Phenolic acids
Caffeic acid	n.d.	2.59 ± 0.47 ^a	n.d.	2.27 ± 0.35 ^a
Cinnamic acid	18.45 ± 0.95 ^a	19.99 ± 0.46 ^b	n.d.	n.d.
p-Coumaric acid	44.99 ± 3.01 ^a	48.41 ± 2.84 ^a	20.91 ± 0.91 ^b	48.76 ± 1.49 ^a
o-Coumaric acid	23.26 ± 1.24 ^a	69.81 ± 1.14 ^b	25.45 ± 0.41 ^a	48.93 ± 1.02 ^c
Ferulic acid	22.31 ± 1.38 ^a	13.83 ± 1.28 ^b	23.60 ± 1.22 ^a	22.40 ± 0.51 ^a
Vanillic acid	39.51 ± 0.48 ^a	72.77 ± 1.11 ^b	43.96 ± 1.79 ^c	59.41 ± 0.50 ^d
3,4-Dihidroxibenzoic acid	14.20 ± 0.28 ^a	17.61 ± 0.94 ^b	15.60 ± 0.37 ^ac	16.61 ± 0.39 ^bc
Syringic acid	n.d.	42.98 ± 3.74 ^a	n.d.	n.d.
Ellagic acid	142.93 ± 4.49 ^a	147.82 ± 3.40 ^a	162.01 ± 0.61 ^b	148.40 ± 3.85 ^a
Homovanillic acid	103.45 ± 6.24 ^a	75.54 ± 0.56 ^b	118.62 ± 5.56 ^c	n.d.
Rosmarinic acid	22.05 ± 0.80 ^a	62.79 ± 2.27 ^b	n.d.	n.d.
Flavonoids
Apigenin	n.d.	43.13 ± 1.28 ^a	n.d.	42.48 ± 1.31 ^a
Rutin	21.33 ± 0.62 ^a	31.46 ± 2.68 ^b	n.d.	n.d.
Taxifolin	83.10 ± 2.23 ^a	94.44 ± 4.01 ^b	85.82 ± 3.40 ^a	89.03 ± 2.42 ^a
Naringenin	125.11 ± 0.56 ^a	247.42 ± 10.19 ^b	99.96 ± 4.62 ^c	137.67 ± 10.14 ^a
Hesperidin	137.30 ± 5.22 ^a	93.15 ± 4.24 ^b	62.77 ± 1.46 ^c	85.75 ± 2.44 ^b
Quercetin	168.62 ± 15.47 ^a	134.94 ± 0.89 ^b	206.01 ± 6.29 ^c	134.14 ± 2.85 ^b
Catechin	63.15 ± 2.39 ^a	77.68 ± 1.06 ^b	55.29 ± 1.58 ^c	49.04 ± 0.78 ^d
Stilbene
Resveratrol	6.68 ± 1.02 ^a	10.34 ± 0.29 ^b	n.d.	n.d.
Total	1075.88	1615.54	962.23	1298.53

All the results are expressed as mean ± SD (n = 3) and reported as milligrams of phenolic compound per 100 g of dry material (mg/100 g OP). Different letters in the same row correspond to a statistical difference (95% confidence level) between the samples with respect to analyzed compound; n.d.: not detected.