HPLC-UV Analysis of Commercial Blackberry,
Black Raspberry, Red Raspberry, Strawberry, and Cherry Food and Dietary Supplement
Products Provides Evidence for Quality Issues
Reviewed: Lee J. Rosaceae products: Anthocyanin
quality and comparisons between dietary supplements and foods. NFS Journal. 2016;4:1-8.
Keywords: Rosaceae, Rubus
spp., Prunus spp., Fragaria
spp., blackberry, black raspberry, blackberry, cherry, red raspberry,
strawberry, adulteration, anthocyanins, HPLC-UV
Jungmin Lee from the US Department of
Agriculture investigated the anthocyanin contents and composition of fruit
products made from species of the Rosaceae family. As part of the project, 74
products were analyzed. The selection contained 33 dietary supplements and 41
food products including juice, juice concentrate, dried whole fruit, fruit
powders, jams, preserves, spreads, and pie fillings.
Products were purchased from local markets
in Boise and Nampa, Idaho, or online at Amazon.com. The exact species used to
make a given product was not always clear, especially in the food category.
Dietary supplements were labeled to contain blackberry (Rubus
fruticosus, R. corchorifolius,
R. laciniatus), black raspberry (R. occidentalis), red raspberry (R. idaeus ssp.
idaeus or R. idaeus
ssp. strigosus), black cherry (Prunus serotina), sour cherry (P. cerasus),
sweet cherry (P. avium), or strawberry (Fragaria vesca, F. virginiana).
Of the dietary supplements analyzed, 9 (27%) were considered to be adulterated
(see Table 1). One particularly troubling product marketed as “red raspberry” did
not even list red raspberry on the ingredient panel, but cranberry (Vaccinium spp., Ericaceae) fruit extract and beet (Beta spp., Chenopodiaceae) color instead.
Table 1: Results from the
analysis of herbal supplements made with fruits from members of the Rosaceae
family
|
Dietary Supplement
|
Total samples
|
Samples considered adulterated*
|
Possible adulterant (number
of adulterated samples)
|
|
Blackberry
Black raspberry
Red raspberry
Cherry
Strawberry
|
3
8
4
16
3
|
1
2
2
4
0
|
Blueberry (Vaccinium angustifolium,
V. corymbosum)(1)
Blackberry (1), unknown* (1)
Unknown* (2)
Bilberry (V. myrtillus)
(1), unknown* (3)
|
*Cases where no anthocyanins were detected
were deemed to be adulterated by the author. However, absence of anthocyanins
does not necessarily mean absence of the fruit extract, since anthocyanins are known
to degrade easily.
With regard to food products, five (12%)
were found to be devoid of anthocyanins, and four out of these five products
were spreads, which are known to contain lower amounts of fruits than jams or
preserves. The author speculates that some of the dietary supplements might be
made from dehydrated fruit processing waste, and therefore may show varying
anthocyanin patterns and lower amounts than whole fruit, or that the use of
excipients may lead to a lower-than-expected anthocyanin intake. She suggests
the use of anthocyanin profiling by high-performance liquid chromatography with
ultraviolet/visible spectrophotometry detection (HPLC-UV/Vis) to improve the
quality of anthocyanin-containing dietary supplements.
Comment: The usefulness of the
anthocyanin-fingerprint approach using an HPLC-UV/Vis method has been shown in
previous papers by the same author, which were reviewed in issue #2 and issue #7 of the Botanical Adulterants Monitor.1,2 Due
to the purported health benefits of these pigments, consumers expect that
anthocyanins are present in appreciable amounts in dietary supplements labeled
to contain authentic fruit material, even if certain processing methods may
remove or degrade anthocyanins. While the absence of anthocyanins does not mean
that the labeled fruit is not in the product, it seems that such products are potentially
deceptive (unless the lack of anthocyanins is clearly indicated on the label)
by the fact that they do not meet consumers’ expectations.
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. Anthocyanin
analyses of Vaccinium fruit dietary supplements. Food Sci Nutr. 2016;4(5):742-752.
