CHINA
Guangzhou Pharmaceutical Group’s Wanglaoji accounts for 42% of China’s herbal tea exports. It also won the first ever China National Science Award in 2017 for its development of a DNA barcoding database for identifying and authenticating raw materials and genetic ingredients. This established a quality standard for Chinese herbal teas.
This is one milestone in what has been a strikingly successful area of genetic research that has been slower to reach commercial application. DNA barcoding uses a snippet of an organism’s DNA as a genetic marker that uniquely identifies it as belonging to a variety within a species. For tea, it distinguishes right down to country of origin, regional differences, presence in databases of approved ingredients, and unlisted plant materials. Here are just a few instances:
SNP – single nucleotide polymorphisms, the most common genetic variation among living species. A “snip” represents a difference in a single DNA building block, of which there are 10 million in the human genome. It provides a genetic fingerprint which since it is in 0-1 digital coding, can literally be used as a barcode. Studies report a consistent 99%+ accuracy in classifying 40 or more teas, from just a leaf fragment.
A Taiwanese study picked out domestic versus imported (and hence counterfeit) whole leaf teas out of a population of over 60 varieties. A 2017 US project created a DNA Verity Test for 32 commercial teas. It was able to reliably authenticate teabag ingredients, where the original leaf is “morphologically unrecognizable” and not reliably categorized by chemical methods. This protocol is less expensive and requires simpler equipment than alternative tests, such as isotope ratio mass spectrometry.
A group of high school students in New York published a widely-cited paper that used low cost “tabletop technologies” to identify unlisted ingredients in teas from 33 manufacturers and 17 countries. They were picked up from 25 locations, including stores, college dining rooms, and workplaces. The cost per sample for gene sequencing by a commercial lab was $15. The markers were matched against the National Laboratory of Medicine’s growing GenBank. The analysis showed traces of such weeds as white goosefoot, parsley, blackberry, and many others. It found clusters of what appeared to be deliberate adulteration.
New York City’s district attorney seems to have been the first to use DNA barcoding as evidence in issuing a cease-and-desist order to major retailers for substantial mismatches between the labels on tea supplements and the actual ingredients. The generic analysis was more accurate than their own high standards of quality control.