We investigated the importance of the large intestine on the bioavailability of anthocyanins from bilberries in humans with/without a colon. Low bioavailability of anthocyanins in plasma and urine was observed in the frame of this study. Anthocyanins reached the circulation mainly as glucuronides. Analysis of ileal effluents (at end of small intestine) demonstrated that 30% of ingested anthocyanins were stable during 8h passage through the upper intestine. Only 20% degradants were formed and mostly intact anthocyanins were absorbed from the small intestine. Higher amounts of degradants than anthocyanins reached the circulation after bilberry extract consumption in both groups of subjects. Comparison of the bioavailability of anthocyanins in healthy subjects versus ileostomists revealed substantially higher amounts of anthocyanins and degradants in the plasma/urine of subjects with an intact gut. The results suggested that the colon is a significant site for absorption of bioactive components such as anthocyanins and their degradation products.

Anthocyanins are flavonoids that have been suggested to provide beneficial health effects. The biological activity of anthocyanins is influenced by their pharmacokinetic properties, but anthocyanins are associated with limited bioavailability in humans. In the presented study, we investigated how the encapsulation of bilberry extract (BE), a source of anthocyanins, with either whey protein or citrus pectin influences the bioavailability and intestinal accessibility of anthocyanins in humans. We performed an intervention study that analyzed anthocyanins and their degradation products in the urine, plasma, and ileal effluent of healthy volunteers and ileostomists (subjects without an intact colon). We were able to show, that whey protein encapsulation modulated short-term bioavailability and that citrus pectin encapsulation increased intestinal accessibility during passage through the small intestine and modulated the formation of the degradation product phloroglucinol aldehyde (PGAL) in human plasma.

Volatile constituents of fresh blackcurrant (Ribes nigrum L.) berries were isolated via vacuum-headspace extraction and analyzed by capillary gas chromatography-mass spectrometry. In agreement with previous studies with frozen fruits, short-chain esters and terpenes were major compound classes. However, rather high concentrations of C-compounds (e.g., (E)-hex-2-enal, (Z)-hex-3-enal) constituted a striking difference to data reported for frozen fruits. Frozen storage of blackcurrant berries was shown to result in drastically reduced concentrations of C-compounds and a shift of the volatile profile in favor of terpenes. The time-dependent enzymatic formation and isomerization of C-compounds adds an additional element of variability to the spectrum of fresh blackcurrant volatiles. Nevertheless, blackcurrant cultivars can be classified according to the major classes of the volatiles of the fresh fruits, if prerequisites, such as the same growing location and the same state of ripeness, are met. The sensory contributions of volatiles of blackcurrant berries were assessed by gas chromatography-olfactometry in combination with aroma extract dilution analysis. 4-Methoxy-2-methyl-2-butanethiol, (Z)-3-hexenal, ethyl butanoate, 1,8-cineole, oct-1-en-3-one, and alkyl-substituted 3-methoxypyrazines were among the volatiles showing the highest aroma activity values.

4‐Methoxy‐2‐methyl‐2‐butanethiol is a powerful sulfur‐containing aroma compound identified several decades ago in blackcurrant buds (Ribes nigrum L.). However, an unambiguous identification in blackcurrant fruits has been lacking. In this study the occurrence of 4‐methoxy‐2‐methyl‐2‐butanethiol in blackcurrant berries has been demonstrated for the first time by the analysis of seven cultivars. After isolation of the volatiles by vacuum‐headspace‐extraction, the sulfur‐containing compound was enriched on mercurated agarose gel. Identification was performed via capillary gas chromatography/mass spectrometry. Quantitation was performed in the single ion monitoring mode using 4‐methyl‐4‐sulfanylpentan‐2‐one as internal standard. The concentration of 4‐methoxy‐2‐methyl‐2‐butanethiol in Andega (4.5 µg/kg) was significantly higher than those in the other cultivars investigated in this study (from 0.16 to 0.72 µg/kg). Calculation of the odour activity values indicated that this sulfur‐containing volatile contributes to the aroma of blackcurrant berries. Copyright © 2016 John Wiley & Sons, Ltd.

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