HPLC-UV Analysis of Commercial
Bilberry, Blueberry, Cranberry, and Lingonberry Supplements Shows that
Adulteration Is Still an Issue
Reviewed: Lee J. Anthocyanin analyses of Vaccinium fruit dietary supplements. Food Sci
Nutr. 2016;
[epub ahead of print]. doi: 10.1002/fsn3.339.
This investigation by Jungmin Lee from the
US Department of Agriculture is a continuation of her work on the ingredient
identity of dietary supplements labeled to contain berry fruit extracts, e.g., black raspberry (Rubus occidentalis, Rosaceae) and bokbunja (Rubus
coreanus).1,2 In this publication, the results from the
high-performance liquid chromatography using ultraviolet/visible
spectrophotometry detection (HPLC-UV/Vis) analysis of 45 dietary supplements
labeled to contain extracts from bilberry (Vaccinium myrtillus,
Ericaceae), blueberry (V. angustifolium,
V. corymbosum,
and V. pallidum), cranberry (V.
macrocarpon), or lingonberry (V. vitis-idaea)
are reported.
The samples were purchased from local
markets in Boise, Nampa, and Caldwell, Idaho, or online at Amazon.com. For
bilberry, eight out of 15 (53%) samples were found to be adulterated, although
in one sample, a liquid extract, absence of anthocyanins could be due to
degradation. One sample was made from blueberry and one sample contained Andean
blueberry (V. floribundum). The latter product had
a label statement indicating “Ecuador” as the country of origin. Since the
natural growing range of bilberry is restricted to Europe and northern Asia,
any bilberry with provenance from Ecuador is likely to contain a species other
than V. myrtillus.
The identity of the adulterants in the
remaining samples could not be determined. In the case of the blueberry
products, two out of eight (25%) did not contain any anthocyanins. Both of
these products were liquids, so degradation of anthocyanins cannot be excluded.
Most of the cranberry supplements contained the typical cranberry anthocyanins;
only one product, again a liquid, did not contain anthocyanins. Two products
contained additional peaks in the chromatogram, possibly due to the presence of
food coloring and beet (Beta spp.,
Chenopodiaceae) juice as indicated on the label. The two lingonberry
supplements did not show the expected anthocyanin pattern; one product was
highly degraded, while the other was made from cranberry.
The author suggests that a consumer may
more likely receive the authentic product when eating fresh whole fruit. Since
the HPLC-UV/Vis technique can help in authenticating processed fruit extracts, she
suggests creating an anthocyanin profile database to assist processors in
verifying their fruit ingredient sources.
Comment: Adulteration of
anthocyanin-containing fruit extracts continues to plague the dietary
supplement market. The approach using an HPLC-UV/Vis fingerprint to
authenticate berries from the Vaccinium genus
has been shown to be successful. The author reports that 14 out of 45 (31%) products
were adulterated. A closer look at the data shows that liquid supplements,
where absence of anthocyanins could be due to degradation, and two cranberry
supplements containing additional peaks possibly due to other labeled
ingredients, were included in the number of adulterated samples. Therefore,
reporting an adulteration range of 18-31% would be more accurate. Additionally,
based on the results of this study, the health benefits obtained from liquid Vaccinium spp. berry supplements, where anthocyanins are likely
prone to degradation, have to be questioned.
References
1. Lee
J. Marketplace analysis demonstrates quality control standards needed for black
raspberry dietary supplements. Plant Foods Hum Nutr.
2014;69(2):161-167.
2. Lee J. Analysis of bokbunja products show they contain Rubus occidentalis L. fruit. J Funct
Foods. 2015;12:144-149.
