Lysinoalanine Concentrations in Rapeseed Protein Meals and Isolates

Abstract

Alkaline treatment of proteinaceous materials produces potentially toxic Iysinoalanine. Accordingly, processes involving alkaline extraction of protein to produce isolates could result in increased levels of Iysinoalanine in these products. The Iysinoalanine content of two canola protein isolate fractions, prepared by aqueous alkalineextraction of canola meal, precipitation of one protein fraction at the isoelectric pH and purification of the filtrate bymembrane processing followed by drying, were determined to ensure that the process does not produce excessive quantities of Iysinoalanine. Protein isolates which were prepared under mildly alkaline conditions typical of the process contained <500μg/g Iysinoalanine, concentrations similar to that found in commercially produced casein and soybean protein isolates. The Iysinoalanine content of meals treated with NaOH increased with increasing concentration, treatment temperature and contact time. Canola and soybean meals exposed to O.IN NaOH for 2h at 75°C contained 14,400 and 13,500μg/g Iysinoalanine, while similarly treated casein contained more than 19,500μg/g Iysinoalanine. The Iysinoalanine content of canol a protein isolates from canola meal produced by the methanol/ammoniahexane process will not affect the use of these products as food ingredients