Optimization of processing conditions for cyanide content reduction in fresh bamboo shoot during NaCl treatment by response surface methodology

NaCl treatment was optimized for maximum reduction of cyanide content in raw bamboo (Dendrocalamus strictus) shoot using response surface methodology with 4 independent variables like concentration of NaCl, thickness of bamboo shoot, amount of NaCl solution and duration of treatment at 3 levels of each variable. Box-Behnken design was used to select the levels of variables in experimental runs. Cyanide content ranged between 12.8 and 29.6 mg/kg in bamboo shoot after NaCl treatment. The effect of concentration of NaCl was higher in reducing the cyanide content followed by thickness of bamboo shoot and treatment time in decreasing order. Amount of NaCl solution did not affect the reduction of cyanide content significantly. Optimum condition was 2.4% NaCl concentration, 1.25 cm thickness of bamboo shoot, 216 ml of NaCl solution and 23 min treatment. Corresponding cyanide content was 11.2 mg/kg. Experimental verification at optimum condition gave average cyanide content of 11.3 mg/kg on fresh weight basis, which was in good agreement with predicted and was well below permissible limit (500 mg/kg). The reduction of cyanide content was of 98.3% at optimum level.