09/04/2014 · The lignin biosynthetic pathway in ..
Because genuine vanilla extract from pods is up to 200 times more expensive than counterfeit vanilla essence using synthetic vanillin, detection of fake vanilla is important. Some fakes can be detected using chromatography, but the goalposts keep moving. One of the first detection methods relied on the fact that vanillin obtained from fresh vanilla pods had higher radiocarbon (14C) levels than vanillin from petrochemical sources (though it did not distinguish it from material obtained from fresh lignin); in response, the fakers added extra 14C to their vanillin. Analysts then examined the 13C/12C ratios in the samples by mass spectroscopy. A distinction is possible because the vanilla orchid has an unusual biosynthetic pathway for vanillin so that more 13C than usual is incorporated; "fake" vanilla extract will originate in material with a lower 13C/12C ratio; in their turn, the fakers added 13C to their molecules, usually just at one site - analysts have hit back by using site-sensitive NMR techniques (SNIF-NMR). On some levels, this problem is somewhat semantic, since the two products are identical by taste.
a key enzyme involved in the lignin biosynthesis pathway was ..
A lignin pathway may predominate in poorly drained soils and wet sediments (swamps, etc.) whereas synthesis from polyphenols may be of considerable importance in certain forest soils.
Vanholme R, Cesarino I, Rataj K, et al. (2013) Caffeoyl shikimate esterase (CSE) is an enzyme in the lignin biosynthetic pathway in Arabidopsis. Science 341: 1103–1106.