Thlaspi Arvense (French Weed) in Relation to Dairy Products

Abstract

Summary Thlaspi arvense , known as penny-cress, French weed, or stink-weed, is a troublesome weed of the mustard family. It is the cause of a very objectionable taint in milk, cream, and butter. This weed is a serious pest in the grain growing areas of Manitoba, Sasketchewan, Minnesota, the Dakotas, and Montana, and reports indicate that it is spreading. The characteristic odor develops when the seed is in contact with water as the result of the action of an enzyme known as mycrosin, which hydrolyzes particular glucosides found in the plant. Apparently both oil of mustard and oil of garlic are formed. It was shown experimentally that the ingestion by a lactating cow of French weed seed to an amount between 90 and 150 grams or of the green forage to the amount of 500 grams or more results in the characteristic taint in the milk. The odor is more marked in the cream than in the milk and is most pronounced in the butter. This may be taken to indicate that the volatile products unite chiefly with fat. The most pronounced results were obtained when the interval between feeding the seed and milking was 3 hours. The effect was reduced after an interval of 5 hours and completely gone by 12 hours. Feed containing French weed seed can be fed immediately after one milking without danger to the quality of the product from the next milking. The common methods used to eliminate feed tastes from milk are only partially successful in removing the tainting of French weed. The taint could be detected in the butter from mixed cream when 15 per cent of the cream was tainted. French weed may be readily detected in mixed feeds in proportions as low as 0.5 per cent.