Barley (Hordeum vulgare) is rich in dietary fiber and nutrients such as starch, protein, fat, vitamins B1 & B2, calcium, phosphorus, iron, and phenolic compounds. Roasted barley tea is very popular in Japan and Korea where it is believed to contribute to the digestion of greasy food and to be beneficial for the stomach after long term alcoholism. Roasted barley tea, known in Japanese as mugicha or in Korean as boricha, is available as loose grains, in tea bags or as prepared tea drinks and is traditionally used for detoxification, to improve digestion and for urinary tract infections, among other applications although no such effect has been proven by research yet. However, a few studies found that it inhibits bacterial colonization and adhesion, specifically with the major cause of tooth decay, Streptococcus mutans, which also has been implicated to play a big role in cardiovascular diseases. It also has been shown to lower blood viscosity.
A group of Chinese researchers recently used DNA Barcoding to help with a trade dispute that involved roasted barley products that were returned by an unnamed country because it was suspected of being adulterated with other plant components apart from barley. Because the tea product consisted of ultra-fine powder, morphological identification was impossible. The colleagues used the two standard plant markers (rbcL, matK) and two other ones (trnH-psbA, ITS2) that have been discussed as supplementing barcodes.
Of the 13 batches they analysed, one turned out to be exclusively made of Mulberry (Morus sp.). The remaining twelve contained Hordeum vulgare but only two of them were pure. Ten samples were contaminated with other plant material such as Mulberry (again), oats (Avena spp.), wheat (Triticum spp.), and fig-leaved goosefoot (Chenopodium ficifolium). There is a good chance that most of the other crops were introduced by sloppy sorting and unclean handling. Even the goosefoot could have entered the production at this stage as it is known as an agricultural weed. That clearly shouldn't happen but could be explained by accidental incidents. The mulberry that occurred quite frequently and in one case exclusively cannot not be explained so easily. Its ripe fruit is edible and is widely used in pies, tarts, wines, cordials and tea. Its leaves, particularly those of the white mulberry, are ecologically important as the sole food source of the silkworm (Bombyx mori) which hints to possible sources of the contamination given the extend of the silk industry in China.
I guess the country sending this batch back was right especially because the product was labelled as ‘pure’ or ‘100%’ barley powder.