Caraway and dill growers are trying to figure out what to do with the leftover hulls once the essential oils are steamed out of their spices.
Each year Saskatchewan growers of these spices end up with 1,000 tonnes of screenings. The problem is carvone, a naturally occurring compound left after the spice flavour has been removed from the seed.
While University of Saskatchewan researcher Karen Tanino is working on carvone’s ability to fight fungus, other potential uses have been counted out for now.
Many livestock won’t eat screenings with carvone in them, said Phil Leduc of the Prairie Agricultural Machinery Institute in Humboldt, Sask.
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He told the Saskatchewan Herb and Spice Association’s annual conference held in Saskatoon on Jan. 12 that pigs and poultry won’t touch the screenings. Cows will eat them if the screenings are pelleted and mixed in a 50-50 ration with other more palatable feed.
“The trouble is it (carvone) kills plants but it’s not strong enough to be an organic weed killer,” he said.
“If you put an inch of it on the ground and raked it in, it would work as a soil sterilant for several years.”
Leduc said the screenings could be burned, but PAMI is experimenting with putting them in a biodigester to create either a usable fertilizer or an energy source in methane gas.
In another project, PAMI is building an essential oil extractor that is portable and could be rented to spice growers to do the work on their farms. It already has a mobile herb dryer to enable farmers to dry foliage on their own farms.
