Natural
rapeseed oil contains erucic acid, which is mildly toxic to humans
in large doses but is used as a food additive in smaller doses.
Canola is one of many selected cultivars of rapeseed bred to have a
low erucic acid content. Canola was developed in Canada and its
name is a contraction of "Canadian oil, low acid". The name was
also chosen partly for marketing reasons, so successfully that the
name is sometimes mis-applied to other cultivars of rapeseed.
Processing of rapeseed for oil production provides rapeseed animal
meal as a by-product. The by-product is a high-protein animal feed,
competitive with soya. The feed is mostly employed for cattle
feeding, but also for pigs and chickens (though less valuable for
these). The meal has a very low content of the glucosinolates
responsible for metabolism disruption in cattle and pigs.
Rapeseed leaves are also edible, similar to those of the related
kale. Some varieties of rapeseed are sold as greens, primarily in
Asian groceries.
Rapeseed is a heavy nectar producer, and honeybees produce a light
colored, but peppery honey from it. It must be extracted
immediately after processing is finished, as it will quickly
granulate in the honeycomb and will be impossible to extract. The
honey is usually blended with milder honeys, if used for table use,
or sold as bakery grade. Rapeseed growers contract with beekeepers
for the pollination of the crop.
