Table 2.

Phenolic content in almond products and by-products. Quantitative data extracted from [4,14,20] ¹.

Compounds	Blanched Skin (μg/g)	Whole Almonds (μg/g)	Blanch Water (μg/g)
Hydroxybenzoic acids and aldehydes	26.3–57.3	2.4–7.0
p-Hydroxybenzoic acid	3.1–7.2	0.03–0.06
Vanillic acid	11.1–19.2	1.1–2.5
Protocatechuic acid	6.7–17.2	1.3–4.4
Protocatechuic aldehyde	5.4–13.7	-
Hydroxycinnamic acids	1.8–4.9	-
trans p-Coumaric acid	0–1.1	-
3-O-Caffeoylquinic acid	1.8–3.8	-
Flavan-3-ols	61.5–134	12.7–51.3
(+)-Catechin	20.1–38.3	9.5–38.6
(−)-Epicatechin	7.2–26.5	3.2–12.7
Procyanidin B1-3, B5, B7, C1	25.0–46.1	-
Unknown dimers/trimers A [(epi)catechin → A → (epi)catechin]	9.2–23.0	-
Flavonol glycosides	15.6–130	113–231
Kaempferol-3-O-rutinoside	5.3–40.7	7.1–14.3
Kaempferol-3-O-glucoside	0–14.2	0.08–0.2
Kaempferol-3-O-galactoside	-	0.05–0.2
Isorhamnetin-3-O-rutinoside	5.3–58.0	99–191
Isorhamnetin-3-O-glucoside	5.0–15.3	-
Isorhamnetin-3-O-galactoside	-	3.0–7.1
Quercetin-3-O-glucoside	0–1.7	0.5–1.6
Quercetin-3-O-galactoside	-	3.1–12.6
Quercetin-3-O-rutinoside	-	0.6–3.7
Flavanone glycosides	4.8–28.6	0.9–1.9
Naringenin-7-O-glucoside	2.3–25.9	0.9–1.9
Eriodictyol-7-O-glucoside	2.5–2.7	-
Flavonol aglycones	9.6–33.0	1.1–4.9
Kaempferol	2.7–12.1	0–0.04
Quercetin	1.0–4.9	0.2–0.3
Isorhamnetin	5.9–16.0	0.9–4.6
Dihydroflavonol aglycones	0–10.3	0.4–3.0
Dihydroquercetin	0–10.3	-
Dihydroxykaempferol	-	0.4–3.0
Flavanone aglycones	6.7–19.9	1.2–6.9
Naringenin	3.7–12.1	0.4–1.2
Eriodictyol	3.0–7.8	0.8–5.7
Stilbenes	0.002	0.008	0.07–0.11
Polydatin	1.5–2.2 ng/g	7.2–8.5 ng/g	63–84 ng/g
Piceatannol + oxyresveratrol	ND	ND	9.1–25.5 ng/g
trans-Resveratrol	ND	<LOD
Pterostilbene	ND	<LOD
Total	111–418	132–306

¹ Bold letters indicate the sum of total concentration referred to each subfamily of phenolic compounds. LOD: limit of detection; ND: not determined.