Health benefits of apple polyphenols for different chronic diseases are postulated. To exert bioactive properties, absorption into the body is required (bioavailability), which is strongly influenced by matrix release (bioaccessibility). For seven apple varieties, in vitro experiments with simulated saliva fluid (SSF) and ex vivo digestion with centrifuged human saliva were conducted. Polyphenol characterization (high-performance liquid chromatography-tandem mass spectrometry) and quantification (high performance liquid chromatography-diode array detection) was related to an aqueous methanolic extraction. A polyphenol release of 63−82% from flesh and 42−58% from peel was estimated. While hydroxycinnamic acid derivatives were released in total, a significant retention was observed for flavanes and flavones. In particular, procyanidins were retained with increasing molecular weight. The data reveal a considerable polyphenol release during the oral digestion; however, differences among the varieties as well as flesh and peel were obvious. Due to negligible differences between both digestion media, the data supported the use of SSF instead of human saliva in further experiments.
Patients who suffer from birch pollinosis often develop
adverse
reactions to the consumption of fresh apples due to the structural
similarity of the allergens Bet v 1 and Mal d 1 from birch and apples,
respectively. A different allergenic potential for Mal d 1 isoallergens
is postulated, but approaches to quantify the Mal d 1 isoallergen-specific
are missing. Therefore, a bottom-up proteomics approach was developed
to quantify Mal d 1 by stable isotope dilution and microHPLC-QTOF
analyses. Marker peptides for individual isoallergens (Mal d 1.01–Mal
d 1.03 and Mal d 1.06), combinations thereof (Mal d 1.01 + 1.02, Mal
d 1.02 + 1.06, and Mal d 1.04 + 1.05), and two global marker peptides,
comprising Mal d 1.01 + 1.02 + 1.04 + 1.05 and Mal d 1.03 + 1.06 +
1.07 + 1.08 + 1.09, were identified. By the use of an extraction standard
(r-Mal d 1_mut), an optimized protocol for extraction and tryptic
digestion of apple proteins was developed, and the variety-specific
extraction efficiency was monitored for the flesh and peel of apples.
The Mal d 1 contents in flesh and peel of five commercial apple breeds
and four apple varieties from orchard meadows were quantified isoallergen-specific.
The apple allergy
in Northern Europe is a cross-reaction to the
birch pollen allergy. No correlation between the allergenicity of
an apple variety and the content of the major apple allergen Mal d
1, a homologue to the Bet v 1 allergen in birch, could be found using
ELISA, so far. Therefore, an impact of polyphenols and/or differences
in the isoallergen profile are discussed. To allow a more detailed
analysis of the Mal d 1 content and the isoallergen profile, a mass
spectrometric method was applied to investigate differences in the
flesh and peel of 10 traditional varieties and 10 commercial breeds.
The data revealed often, but not always, lower Mal d 1 contents in
traditional varieties grown in orchard meadows, which was more obvious
in the flesh. Differences among the peels were less pronounced. A
closer look at the individual isoallergens 1.01, 1.02, 1.03, and 1.06
reveals an increased impact of the minor isoallergens 1.03 and 1.06
on the allergenic potential, since commercial breeds like Braeburn,
Santana, and Holstein Cox, which are considered to have reduced allergenic
potentials, were characterized by low levels of these isoallergens.
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