Pomegranate Adulteration and Test Methods Evaluated in New Guidance Document

Photo © iStockphoto.com/© Alexei Zaycev

Pomegranate adulteration is the focus of a new guidance document from the nonprofit Botanical Adulterants Prevention Program (BAPP). The Laboratory Guidance Document examines several common pomegranate (Punica granatum) adulteration methods, including diluting those juices and extracts with lower-cost fruit juices or adding ellagic acid from non-pomegranate sources. The document also covers current methods for detecting adulteration in pomegranate juices and extracts.

BAPP was created by the American Botanical Council (ABC; Austin, TX), the American Herbal Pharmacopoeia (Scotts Valley, CA), and the University of Mississippi’s National Center for Natural Products Research (NCNPR; University, MS). As with other BAPP guidance documents, the current pomegranate guidance was peer-reviewed by 20 experts from academia and industry.

The document was prepared by John Cardellina, PhD, chief technical consultant and associate editor of BAPP. In the document, Cardellina writes that pomegranate is fast becoming one of the most popular “healthy” fruits, both in dietary supplements and in juices and other beverages. However, he writes, pomegranate’s rapid rise in popularity has also given rise to increased instances of adulteration, particularly adulteration with lower-cost ingredients.

The document details the chemical composition of pomegranate fruit, and describes current adulteration testing methods for pomegranate-derived fruits and extracts, which include high-performance liquid chromatography (HPLC) with ultraviolet (HPLC-UV), mass spectrometric (HPLC-MS) detection, or with photodiode array detector (HPLC-PDA), among other methods. While many of these testing methods can be applied to both juices and extracts, others are form-specific. The document also covers the advantages and disadvantages of each testing method, including cost of equipment and multi-step sample preparation, among other factors, and examines the usefulness of each method for detecting adulteration in pomegranate.

One of the key points addressed in this Laboratory Guidance Document is that different pomegranate products-beverages versus supplements, for instance-may be adulterated in different ways. Thus, each product category requires different testing methods to detect adulteration. In pomegranate juices, for example, adulteration most often takes the form of dilution with lower-cost juices. Pomegranate juice has been adulterated and diluted often includes added colorants to ensure that the color of the product more closely aligns with the deep-purple color associated with true pomegranate juice. Per the document, various sugars, organic acids, amino acids, and polyphenols may also indicate adulteration by other fruit juices.

Pomegranate extract products, meanwhile, are often adulterated via the addition of ellagic acid from non-pomegranate sources, or even with ellagic acid made entirely from unknown or unidentified source materials. In these cases, there is little-to-no actual pomegranate extract present, but a significant amount of ellagic acid. In a press statement from BAPP, it stated that ellagic acid is a naturally occurring polyphenolic compound found in pomegranate and other plants. It is the “principal chemical adulterant of extracts,” and can be obtained in highly purified form from several lower-cost botanical sources, including from various tree barks. Ellagic acid can be made also be made via chemical synthesis. And this is notable because some commercial “pomegranate” extracts contain as much as 90% ellagic acid, it said.

Stefan Gafner, PhD, chief science officer, ABC, and technical director, BAPP, explained in the press release that higher concentrations of ellagic acid in pomegranate supplements have actually become a marketing tool, with product labels prominently featuring ellagic acid percentages. This marketing strategy, he added, may suggest to the consumer that higher levels of ellagic acid equal a more potent and efficacious extract. “But high concentrations of ellagic acid may actually be an indicator of adulteration,” he said, “since these materials may be from plants other than pomegranate. As explained in this Laboratory Guidance Document, there are no simple analytical methods to distinguish ellagic acid derived from pomegranate or other botanical sources. However, the absence of characteristic polyphenols, such as the punicalagins, in ingredients labeled as pomegranate extracts, should raise a red flag.”

In the document, Cardellina states that the methods described therein apply only to juice or extract products, and thus, may not be applicable to other pomegranate food products-for example, yogurts or jellies-or to medicinal products derived from pomegranate plant parts.

Cardellina added: “While the nature of adulteration may be different for juice or other food forms of botanical materials relative to supplements, the motivation for the fraudulent behavior is the same: higher profits. The analytical targets and laboratory methods may be different in the two product categories, but the challenge is the same: identifying effective methods and tools to ensure that products in the marketplace are properly composed and convey the expected nutrients and benefits. This might be a great opportunity for the food and supplement sectors to recognize common ground and work toward resolving this challenging issue.”

Mark Blumenthal, founder, executive director, ABC, and founder/director, BAPP, stated that the new document “provides industry quality-control personnel with the tools they need to use only laboratory methods that can successfully authenticate true, unadulterated pomegranate ingredients and determine if any adulterants are present.”

This Laboratory Guidance Document is the 40th peer-reviewed publication published by the Botanical Adulterants Prevention Program, as well as its fifth Laboratory Guidance Document. All the program’s publications, which includes a quarterly e-newsletter, the Botanical Adulterants Monitor, highlighting scientific publications related to botanical authenticity, are freely accessible to all ABC members, registered users of the ABC website, and all members of the public on the Program’s website (registration required).

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