No abstract

Previously, we reported that apple polyphenols and their major active compounds, the flavan-3-ols and the procyanidins, can result in various health benefits in animals and humans, according to clinical studies. Here, we developed a rapid method for quantifying flavan-3-ols and procyanidins using high-performance liquid chromatography with fluorescence detection, where we investigated the amounts of flavan-3-ols and procyanidins in the Japanese major apple production centre, the Aomori Prefecture, from 2016 to 2018. The non-bagged ‘Fuji (n = 609)’, the bagged ‘Fuji (n = 1101)’, and the ‘Orin (n = 504)’ apples were evaluated in terms of their differences in flavan-3-ols and procyanidins based on apple variety and the controlled atmosphere storage. The bagging treatments of the ‘Fuji’ apples resulted in significantly higher concentrations of procyanidins, while changes in flavan-3-ols concentrations were not clearly observed by treatment. In addition, ‘Orin’ had a significantly higher concentration of procyanidins than that of ‘Fuji’. In contrast, the controlled atmosphere storage hardly caused any changes in the flavan-3-ol and procyanidin contents. Hence, we present the concentrations of flavan-3-ols and procyanidins in major Japanese apples using the rapid high-performance liquid chromatography method with fluorescence detection.

We investigated the amount of polyphenols present in three types of stone fruits (peaches, plums, and prunes) that were produced in Japan during 2018 and 2019 using reversed-phase high-performance liquid chromatography (HPLC) with photodiode arrays and by normal-phase HPLC with fluorescence-based detection. Principal component analysis revealed the characteristics of the three fruit types: the major contributors of polyphenolic content in peaches were catechin, procyanidin B1, and 5-caffeoylquinic acid; those in plums, procyanidin B4, epicatechin, and procyanidin B5; and those in prunes, 3-caffeoylquinic acid and peonidine-3-rutinoside. Next, their antioxidative activity was assessed using hydrophilic oxygen radical absorbance capacity (H-ORAC). The sum of all polyphenol contents was significantly correlated with H-ORAC values (R 2 = 0.6205). Both the concentrations of flavan-3-ols and procyanidins measured by reversed- and normal-phase HPLC were significantly correlated with H-ORAC values (R 2 = 0.7248 and 0.7036, respectively). This work provides a reference for further investigations of stone fruit functions.