Content and mean polymerization degree of procyanidins in extracts obtained from clear and cloudy apple juices

Abstract

The polyphenol profile of apples and that of technologically differently treated apple juices has already been studied thoroughly; nevertheless, the content of polymeric procyanidins has not received much attention up to date. Therefore, procyanidins in extracts made from six blended apple juices and two authentic clear as well as cloudy apple juices (Malus domestica cv. Bohnapfel and Bittenfelder) were investigated. Our determinations revealed significant differences in the total procyanidin content between apple juice extracts obtained from clear and the corresponding cloudy juices under study. Depending on the apple cultivars used average amounts of total procyanidin content determined in the extracts made from clear and cloudy juices ranged from 28.4 +/- 4.4% to 49.0 +/- 5.7% and from 48.3 +/- 0.3% to 60.6 +/- 0.3%, respectively. As the mean degree of polymerization (DPm) is supposed to have an influence on bioavailability and toxicity on different cells lines used in in vitro systems, the average degree of polymerization of the juices under examination were determined. Depending on the cultivar used and the technology of juice processing the DPm ranged between 3.0 and 13.4.

Tannins: Current knowledge of food sources, intake, bioavailability and biological effects

“…Depolymerisation of highmolecular-weight condensed tannins in butanol yields red anthocyanidins that can be detected spectrophotometrically or chromatographed by RP-HPLC coupled with ESI-MS [27]. This method has been employed in several studies to estimate the proanthocyanidin content in foods [24,29,34,35]. However, proanthocyanidin polymers are cleaved into dimers or trimers instead of monomers, thus presenting a risk of underestimation.…”

Analysis of proanthocyanidins

“…3,4,5-Trimethoxycinnamic acid can be used as an internal standard, as this substance elutes very late and does not interfere with the polymeric procyanidins [96,101].…”

Impact of apple polyphenols on GSTT2 gene expression, subsequent protection of DNA and modulation of proliferation using LT97 human colon adenoma cells

“…It has been estimated that only 50% of all polyphenols in the AE have so far been identified. Recently, Huemmer et al [31] published a method that enabled the detection and quantification of oligomeric and polymeric procyanidins; using this method the elucidation of nearly all the phenolic AE composition is possible.…”

“…The procyanidins with high molecular weight (400 mg/g AE[A] [31]) might play an important role for the detected chemopreventive effects of AE, since they are a predominant polyphenolic fraction in apples and though to have beneficial health properties [11,53,54]. Procyanidins have a pronounced instability during storage [45] and they are not commercially available.…”

“…An aliquot of the AE [B] was diluted with the internal standard 3,4,5-trimethoxycinnamic acid and directly submitted to a HPLC-DAD system. Detailed infor-mation about HPLC conditions and evaluation has been published elsewhere [31,32].…”