The effect of ammonia concentration on the properties of canola meals produced by the ammonia-methanol/hexane extraction system

Abstract

Rapeseed (Tower variety) was extracted by a two-phase solvent system consisting of methanol containing dissolved anhydrous ammonia, and hexane. The effect of ammonia concentration in the polar phase on the composition and functional properties of the resulting meal was investigated. In the absence of ammonia, the two-phase extraction system removed 76% of the phenolic compounds and 50% of the glucosinolates, resulting in a meal containing 0.8mg/g of glucosinolates. The glucosinolate content decreased with increasing ammonia concentration until it levelled off at 0.3 mg/g at 10% ammonia. The presence of ammonia did not affect the total phosphorus or phytate levels of the meal. The content of phenolic compounds rose slightly with an increase of the ammonia concentration in the polar solvent. Extraction with the two-phase solvent system did not affect the water absorption of the meal. However, fat absorption rose sharply with increasing levels of ammonia in the polar phase. The opposite was true for the protein dispersibility index, which fell to 25% of the original level.