Elimination of toxalbumin in candlenut seed (Aleurites moluccana (L.) Willd) using wet heating at high temperature and identification of compounds in the candlenut glycoprotein

Abstract

Toxalbumin is a toxic glyprotein contained in candlenut seeds. This toxic compound can be removed by heat treatment before the candlenut is used in processed food products. The aim of this study was to determine the effect of wet heating at high temperatures on the toxicity of candlenut toxalbumin by examining protein profiles, amino acid and carbohytrate contens in the candlenut extract. The material used in this study was unbroken candlenut seeds. This research apply Randomize complete design. The wet hight temperature treatment of candlenut seeds in this study was carried out in autoclave followed by drying in an oven. The wet heat tretment was performed at several conditions, namely without heating as control (P0), drying in oven at 70oC for 7 hours (P1), wet heating in autoclave at 121oC for 5 minutes (P2), 10 minutes (P3), 15 minutes (P4), and 20 minutes (P5). The P2, P3, P4 and P5 treatments were respectively followed by oven drying at 70oC for 7 hours. The results showed that treatment P5 reduced toxicity of candlenut toxalbumin as has been shown in other research through hemaglutination assay which indicated the abcence of aglutination of blood cells. The protein profile of candlenut extract revealed four protein bands with molecular weight of about 18-60 kDa. The reduction of toxicity has also been indicated by the lowest intensity of the bright blue color band on the P5 treatment compared the intensities of the other bands from the other treatments. Reduction of toxicity of the toxalbumin of candlenut seeds after 20 minutes of wet heating (P5) was caused by changes in the polarity of the amino acid glycoprotein. The reduction of non polar amino acids in toxalbumin (glycoprotein) occurred during wet heating, in particular, valine and proline. The increase of glucose and fructose contents was due to the breakdown of glycosidic bonds in glycoprotein molecules.