Abstract: This study investigated the determination of the residual cyanide content of rubber seeds detoxified by different methods by a spectrophotometric method using isonicotinic acid-pyrazolone with and without exogenous β-glucosidase pretreatment. The results showed that cyanide was undetectable or detectable at a level lower than the actual one by the spectrophotometric method without exogenous β-glucosidase pretreatment, while it was detected at a significantly higher level with the sample pretreatment. The optimized pretreatment conditions were 3.35 h soaking at 45.06 ℃ and pH 5.56 with 24.11 U/100 mL of β-glucosidase added, under which, the predicted cyanide content of rubber seeds was 28.79 μg/g. The recovery of spiked samples ranged from 85.02% to 92.04%. The proposed method was accurate and reliable．

Key words: isonicotinic acid-pyrazolone spectrophotometry, β-glucosidase, rubber seed, cyanide, heat treatment