Crambe meal: removal of glucosinolates by heating with additives and water extraction

Abstract

In order to remove glucosinolates from dehulled and defatted crambe meal, various treatments involving heating with or without chemical additives and aqueous extraction were investigated on a laboratory scale. The results showed that the levels of vinyl-oxazolidine-thione (OZT) and isothiocyanates (ITC) in crambe cake were reduced by 60% after heating at 100–110°C for 60–80 min and reduced by 95% upon addition of 2–3% sodium carbonate (Na 2CO 3) or 1% ferrous sulphate (FeSO 4 · 7H 2O). Simultaneously, up to 2.5% dry matter of crambe cake was lost during heating, which is mainly attributed to the evaporation of the glucosinolates as well as their derivatives. More glucosinolates were decomposed in the presence of a high moisture content. A 10% reduction of lysine content was observed during heating and a further 10% by addition of the chemicals. Water extraction removed nearly all the glucosinolates from the meal, but recovery of dry matter and protein was largely dependent on sample pre-treatment and filter porosity. Prior heating increased dry matter recovery from around 50 to 80%, and crude protein from 45 to about 90%. The palatability of the crambe meals was tested in piglets (20–38 kg liveweight) during a 4 week period, in which the proportion of crambe meal in the diet was increased by 1% daily. A minimum dietary inclusion (3%) of untreated crambe meal made the diet unpalatable and led to poor growth of the piglets (44 g day −1). However, the intake of diets containing up to 20% toasted crambe meal was equal to the control, resulting in the same growth rate (570 g day −1) as on a commercial diet. The results suggest that adequate treatment of crambe meal can result in a product with good property as an ingredient in pig diets.