LAUSR

A primary focus of the Journal of Agricultural and Food Chemistry (JAFC) is the chemical identification of natural constituents of foodstuffs, especially bioactive constituents beneficial to consumers and organoleptic properties responsible for quality attributes. Such constituents occur as a complex matrix and influence the characteristics of any particular food. JAFC Perspectives have dealt with the way in which bioactivity studies should be conducted, and as a primarily chemistryoriented journal the way in which individual compounds should be identified. However, there has been little attention regarding samples investigated. Where do they originate; are they genuine and unadulterated; and how can they be preserved in such a way that the work can be repeated? Without such validation, the underlying chemistry will remain suspect. Generally, this process conforms to the legal concept of “Chain of Custody”, namely, the chronological and physical steps in the transfer and ultimate disposition of evidence. With respect to food and agricultural products, it is best identified by the term “Traceability”, as exemplified by the European Union (EU) General Food Law, which requires the adoption of a barcoded tracking system throughout production, processing, and distribution. However, the primary aim of this, and similar national systems, is to protect consumers, not to authenticate samples. When a cultivated or wild plant sample for research purposes is obtained “in the field”, the traceability process conforms to botanical practice. As stated in the JAFC Author Guidelines, this should consist of identification by scientific name (genus, species, authority, and family) and cultivar, if appropriate, 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 and identified by a collection number. In contrast, the 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 purchase in markets is therefore likely to be compromised by such differences. Processed foods such as honey, coffee, tea, chocolate, etc. add even more complexity to the problem of traceability. For highvalue products, adulteration with cheaper varieties or even other plant species may be frequent. Furthermore, such products have been subject to many more steps prior to pointof-sale than fresh produce. Given such problems, it is obvious that market-sampling should be avoided whenever possible, and the analyzed samples obtained directly from reputable growers who can vouch for the species and variety that they produce, with a documented summary of the overall growth environment. If market purchasing is unavoidable, then care should be taken to address three criteria, namely, provenance, authentication, and curation. Provenance. Establishment of provenance requires that the origin of the sample be determined to the best extent possible. Conventional grocery stores generally maintain extensive records of product sources and investigators should inquire about these from managers. If the name of the producer is provided, further inquiry should establish growing conditions. Unless the vendor is also the producer, farmers’ markets rarely record such details, and even then different lots may be combined for ultimate sale. Farmers’ markets should therefore be avoided for sampling purposes. Authentication. It is extremely important that the authenticity and homogeneity of a sample be substantiated. By visual examination an expert (botanist, horticulturist, breeder/geneticist, etc.) should be able to establish that the