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Traceability of Food Samples: Provenance, Authentication, and Curation Russell J. Molyneux* Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 34 Rainbow Drive, Hilo, Hawaii 96720, United States procedure to be used when research samples are obtained in the markets has not been codified. Observation and experience of food products inform us that products obtained “from the market” are often not homogeneous. While chain supermarkets usually maintain a record of their suppliers, vendors in farmers’ markets often obtain products from multiple producers, each of whom has harvested their crop from quite different locations and growing environments (altitude, soil type, fertilization, water-stress, predation, organic vs nonorganic regimens, etc.). Comparative experiments with foodstuffs grown under carefully controlled conditions have shown that phenotypic plasticity induced by such differences can have significant effects on individual phytochemicals. Nevertheless, vendors often combine these individual lots into a common bulk sample for ultimate sale. Even more problematic is the habit of consumers in selecting their purchase to transfer some items into adjacent lots, thereby mixing different varieties. Research to isolate and identify bioactive constituents from samples obtained by primary focus of the Journal of Agricultural and Food purchase in markets is therefore likely to be compromised by Chemistry (JAFC) is the chemical identification of natural such differences. constituents of foodstuffs, especially bioactive constituents Processed foods such as honey, coffee, tea, chocolate, etc. add beneficial to consumers and organoleptic properties responsible even more complexity to the problem of traceability. For highfor quality attributes. Such constituents occur as a complex value products, adulteration with cheaper varieties or even matrix and influence the characteristics of any particular food. other plant species may be frequent.5 Furthermore, such JAFC Perspectives have dealt with the way in which bioactivity products have been subject to many more steps prior to pointstudies should be conducted,1 and as a primarily chemistryof-sale than fresh produce. oriented journal the way in which individual compounds should Given such problems, it is obvious that market-sampling be identified.2 However, there has been little attention should be avoided whenever possible, and the analyzed samples regarding samples investigated. Where do they originate; are obtained directly from reputable growers who can vouch for the they genuine and unadulterated; and how can they be preserved species and variety that they produce, with a documented in such a way that the work can be repeated? Without such summary of the overall growth environment. If market validation, the underlying chemistry will remain suspect. purchasing is unavoidable, then care should be taken to address Generally, this process conforms to the legal concept of three criteria, namely, provenance, authentication, and curation. “Chain of Custody”, namely, the chronological and physical Provenance. Establishment of provenance requires that the steps in the transfer and ultimate disposition of evidence. With origin of the sample be determined to the best extent possible. respect to food and agricultural products, it is best identified by Conventional grocery stores generally maintain extensive the term “Traceability”, as exemplified by the European Union records of product sources and investigators should inquire (EU) General Food Law, which requires the adoption of a barabout these from managers. If the name of the producer is coded tracking system throughout production, processing, and provided, further inquiry should establish growing conditions. 3 distribution. However, the primary aim of this, and similar Unless the vendor is also the producer, farmers’ markets rarely national systems, is to protect consumers, not to authenticate record such details, and even then different lots may be samples. combined for ultimate sale. Farmers’ markets should therefore When a cultivated or wild plant sample for research purposes be avoided for sampling purposes. is obtained “in the field”, the traceability process conforms to Authentication. It is extremely important that the botanical practice.4 As stated in the JAFC Author Guidelines, authenticity and homogeneity of a sample be substantiated. this should consist of identification by scientific name (genus, By visual examination an expert (botanist, horticulturist, species, authority, and family) and cultivar, if appropriate, breeder/geneticist, etc.) should be able to establish that the together with a geographic information regarding the location from which the samples were obtained and name of the collector. Specimens are preserved by deposit in a herbarium Received: September 9, 2017 and identified by a collection number. In contrast, the
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© XXXX American Chemical Society
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DOI: 10.1021/acs.jafc.7b04214 J. Agric. Food Chem. XXXX, XXX, XXX−XXX
Journal of Agricultural and Food Chemistry
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product is that claimed by the vendor and consists of a single species/variety. Microscopic examination of the sample can be definitive when a particular tissue or organ (leaf, seed, pollen, etc.) is analyzed. For example, microscopy of the pollen in honey samples can determine whether it is unifloral or a blend. Organoleptic evaluation of samples is also effective. This method is particularly useful when applied to processed foods, and experts can often distinguish between different varieties and cultivars by aroma and/or flavor. This is commonplace in the beverage industry, where wines can be distinguished by grape varieties and locales and the types of hops used in beers can be identified. Similarly, coffee roasters and tasters can easily discriminate Arabica and Robusta coffee varieties. An added advantage of organoleptic examination is that it is possible to determine whether the sample has been contaminated by chemicals or micro-organisms or is in the process of spoilage. Curation. In general practice, botanical samples are curated for future reference and reidentification by depositing them in an institutional herbarium. Typically, herbaria confine their collections to plant material from a natural growth habitat. Investigators should inquire whether samples obtained from retail sources can be deposited similarly. If not, the samples should be prepared in the same manner as for herbarium deposit but retained in the investigator’s institution and noted as such in publications. Obviously, large objects, such as whole fruits, perishable items, and some processed foods, are not suitable for preservation in this way. In this case photographs should be taken and retained in digital format so that they can be provided to interested parties for comparison purposes. Processed foods that are dried (coffee, tea, dried fruits, etc.) or in containers (honey, jellies, etc.) can be subsampled and these stored, preferably refrigerated, for future reference. All curated materials should be kept in clean glass containers, not plastic bags from which plasticizers such as phthalates can leach into the sample and contaminate analyses. Implications. The scientific method relies on other research groups being able to replicate published work to the greatest extent possible. In the absence of proper authentication of the samples originally examined, this is clearly unachievable. It is therefore imperative that investigators working with samples not obtained from an original growth habitat make a conscientious attempt to establish their source and identity as specified above. A corollary is that a record of the samples should be preserved by the best possible method, so that future investigators will have a point of comparison. In the absence of all such types of information, research results are purely observational and resulting publications will not have appreciable impact on advancement of food and agricultural chemistry. On the other hand, traceability will ensure that research findings are securely founded and provide an authoritative basis for future investigations.
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REFERENCES
(1) Somoza, V.; Molyneux, R. J.; Chen, Z.-Y.; Tomás-Barberán, F.; Hofmann, T. Guidelines for research on bioactive constituents − A Journal of Agricultural and Food Chemistry Perspective. J. Agric. Food Chem. 2015, 63, 8103−8105. (2) Molyneux, R. J.; Schieberle, P. Compound identification: A Journal of Agricultural and Food Chemistry Perspective. J. Agric. Food Chem. 2007, 55, 4625−4629. (3) Food Traceability, June 2007 https://ec.europa.eu/food/sites/ food/files/safety/docs/gfl_req_factsheet_traceability_2007_en.pdf (accessed September 9, 2017). (4) Hildreth, J.; Hrabeta-Robinson, E.; Applequist, W.; Betz, J.; Miller, J. Standard operating procedure for the collection and preparation of voucher plant specimens for use in the nutraceutical industry. Anal. Bioanal. Chem. 2007, 389, 13−17. (5) Winkler-Moser, J. K.; Singh, M.; Rennick, K. A.; Bakota, E. L.; Jham, G.; Liu, S. X.; Vaughn, S. F. Detection of corn adulteration in Brazilian coffee (Cof fea arabica) by tocopherol profiling and nearinfrared (NIR) spectroscopy. J. Agric. Food Chem. 2015, 63, 10662− 10668.
AUTHOR INFORMATION
Corresponding Author
*Phone: (808) 933-1661. Fax: (808) 933-2974. E-mail:
[email protected]. ORCID
Russell J. Molyneux: 0000-0001-6285-8449 Notes
The author declares no competing financial interest. B
DOI: 10.1021/acs.jafc.7b04214 J. Agric. Food Chem. XXXX, XXX, XXX−XXX
