Composition in Phenolic Compounds of Black Chokeberry Fruit, Pomace, Juice, and Powdered Commercial Samples

Reviewed: Rodríguez-Werner M, Winterhalter P, Esatbeyoglu E. Phenolic composition, radical scavenging activity and an approach for authentication of Aronia melanocarpa berries, juice, and pomace. J Food Sci. 2019; doi: 10.1111/1750-3841.14660. [Epub ahead of print]

Keywords: Adulteration, anthocyanin, Aronia melanocarpa, HPLC-UV/Vis, HPLC-MSⁿ, phenolic compounds

Using a combination of HPLC-UV and HPLC-MSⁿ, Rodríguez-Werner et al. partly or fully characterized 32 phenolic compounds in black chokeberries. Fourteen phenolic compounds, including four anthocyanins and seven quercetin glycosides were quantified in pomace, fresh berries, and juice by HPLC-UV/Vis. The proanthocyanidin (PACs) content was also established using HPLC-UV on a normal-phase column with cocoa PACs as a standard. PACs with a degree of polymerization greater than 10 were quantified as a hump. The average degree of polymerization (DP) was calculated by phloroglucinolysis. The HPLC-UV/Vis and HPLC-MSⁿ methods were used to verify the authenticity of four commercially available bulk aronia berry powders obtained from botanical ingredient supplier Symrise (Holzminden, Germany).

The PAC fraction made up 9.59%, 4.65%, and 1.41% of the dry weight of pomace, berry, and juice, respectively. The anthocyanin fraction was dominated by cyanidin-3-O-galactoside (1.19%, 1.09-1.61%, and 0.408% in pomace, berry, and juice, respectively), followed by cyanidin-3-O-arabinoside (0.454%, 0.460-0.591%, and 0.144% in pomace, berry, and juice, respectively), and minor amounts of cyanidin-3-O-glucoside and cyanidin-3-O-xyloside. The main non-anthocyanin phenolic compounds were chlorogenic acid and its derivatives, which were highest in the black chokeberry juice (0.490% chlorogenic acid, 0.414% neochlorogenic acid).

Three of the four commercial aronia powders had an unusual anthocyanin pattern, dominated by cyanidin-3-O-glucoside (80-84%) and smaller amounts of peonidin-3-O-glucoside and cyanidin-3-O-rutinoside. One of the samples also contained pelargoinidin-3-O-glucoside as a minor component. Chlorogenic acid and quercetin glycosides were absent in two samples. The authors concluded that these three samples were adulterated with an anthocyanin-containing material, and suggested that blackberry (Rubus corchorifolius, R. fruticosus, and R. laciniatus, Rosaceae) may have been a possible adulterant.

Comment: A number of anthocyanin-containing materials are among the popular dietary supplement ingredients, including cranberry (Vaccinium macrocarpon, Ericaceae), elderberry (Sambucus nigra, Adoxaceae), cherry (Prunus avium, Rosaceae), açaí (Euterpe oleracea, Arecaceae), and bilberry (Vaccinium myrtillus, Ericaceae). Other anthocyanin-rich berry-derived ingredients, such as black chokeberry may not be among the top-selling dietary supplements, but are touted by marketers as a “superfruit” or “superfood”, and are sold as liquids or powders for food, beverage, and dietary supplement use.

The availability of low-cost anthocyanin extracts or blue dyes makes adulteration of all these berry ingredients financially lucrative, and the use of non-specific testing methods for the identification of such ingredients by quality control groups allows these adulterants to be found repeatedly in the natural product supply chain. Suppliers and manufacturers of anthocyanin-containing ingredients need to be aware of this issue and take the necessary steps to prevent adulterated ingredients/products being available in the marketplace. Since many of these berries exhibit a relatively consistent anthocyanin fingerprint, which allows the distinction among the various anthocyanin-rich ingredients, the detection of adulteration is straightforward and can be done with routine analytical test methods, such as HPTLC or HPLC-UV/Vis. While the authors suggested that the black chokeberry adulterant was made from blackberry, black rice extract seems to be more likely what was contained in these fraudulent samples based on the anthocyanin fingerprint,^1,2 and economic considerations (i.e., the black rice costs significantly less than blackberries).

References

1. Hou Z, Qin P, Ren G. Effect of anthocyanin-rich extract from black rice (Oryza sativa L. Japonica) on chronically alcohol-induced liver damage in rats; J Agric Food Chem. 2010:58:3191-3196.
2. Bordiga M, Gomez-Alonso S, Locatelli M, Travaglia F, Coïsson JD, Hermosin-Gutierrez I, Arlorio M. Phenolics characterization and antioxidant activity of six different pigmented Oryza sativa L. cultivars grown in Piedmont (Italy). Food Res Int. 2014;65:282-290.