Varietal Differences among the Polyphenol Profiles of Seven Table Grape Cultivars Studied by LC−DAD−MS−MS

TLDR

Polyphenols in seven table grape cultivars were quantified by HPLC‑DAD‑MS/MS. Red grapes contained 69–151 mg/kg of anthocyanins, white grapes 52–81 mg/kg of flavan‑3‑ols, total phenolics ranged 115–361 mg/kg, and a 200‑g serving of unpeeled grapes could provide up to 72 mg of phenolics, supporting their recommendation as a dietary antioxidant source. Keywords: anthocyanins, hydroxycinnamic acid derivatives, flavan‑3‑ols, flavonols, HPLC‑DAD‑MS, stilbenoids, table grapes, total phenolics, Vitis vinifera.

Abstract

Polyphenols present in red table grape varieties Red Globe, Flame Seedless, Crimson Seedless, and Napoleon, and the white varieties Superior Seedless, Dominga, and Moscatel Italica were analyzed by HPLC−DAD−MS. The anthocyanins peonidin 3-glucoside, cyanidin 3-glucoside (and their corresponding p-coumaroyl derivatives), malvidin 3-glucoside, petunidin 3-glucoside, and delphinidin 3-glucoside were found. In addition, caffeoyltartaric acid, p-coumaroyltartaric acid, and the flavonols quercetin 3-glucuronide, quercetin 3-rutinoside, quercetin 3-glucoside, kaempferol 3-galactoside, kaempferol 3-glucoside, and isorhamnetin 3-glucoside were detected. Flavan-3-ols were also detected, and were identified as gallocatechin, procyanidin B1, procyanidin B2, procyanidin B4, procyanidin C1, catechin, and epigallocatechin. These phenolics were present only in the skin, as the flesh of these grape cultivars was almost devoid of these compounds. Anthocyanins were the main phenolics in red grapes ranging from 69 (Crimson Seedless) to 151 (Flame Seedless) mg/kg fresh weight of grapes, whereas flavan-3-ols were the most abundant phenolics in the white varieties ranging from 52 (Dominga) to 81 (Moscatel Italica) mg/kg fresh weight of grapes. Total phenolics ranged from 115 (Dominga) to 361 (Flame Seedless) mg/kg fresh weight of grapes. This means that a serving of unpeeled table grapes (200 g) could provide up to 72 mg of total phenolics (Flame Seedless). These results indicate that the intake of unpeeled table grapes should be recommended in dietary habits as a potential source of antioxidant and anticarcinogenic phenolic compounds. Keywords: Anthocyanins; hydroxycinnamic acid derivatives; flavan-3-ols; flavonols; HPLC−DAD−MS; stilbenoids; table grapes; total phenolics; Vitis vinifera