A method for the decrease of phenolic content in commercial canola meal using an enzyme preparation secreted by the white-rot fungus Trametes versicolor

An enzymatic process for upgrading the quality of canola meal (CM) by decre asing its phenolic content was investigated. The new method was based on th e addition of the enzyme preparation from white-rot fungus Trametes versico lor to the meal-buffer slurry. A 98% decrease in the concentration of SAE w as observed after 1 h of the treatment. The following process variables wer e considered for optimizing the process: pH, temperature, enzyme, meal, and oxygen concentrations. It was found that: (1) the natural buffering capaci ty of CM resulted in a negligible effect of the pH of the buffer, which was used as the continuous phase in the process, on the extent of decrease in sinapic acid esters (SAE); (2) the system was saturated with the enzyme whe n its concentration was 4 nkat/ml of the continuous phase; and (3) the opti mum temperature was 50 degrees C. The process could be carried out even at higher temperatures due to the protective action of CM, which resulted in a n increase in the thermal stability of the enzyme. The particle size influe nced the extraction of the SAE from the meal, indicating that, at lower SAE concentrations, the process became diffusion limited. This result, togethe r with those showing no effect of the intensity of agitation, indicated tha t the enzymatic process can be characterized by high Blot numbers. During t he enzymatic process, the molar concentration of available oxygen can becom e a limiting factor when it is more than four times lower than the molar co ncentration of phenolics in the treated meal. The new enzymatic method was compared with other methods reported in the literature for the decrease in the phenolic content of rapeseed meals. It was found that, among the method s tested, the enzymatic treatment was the most effective, followed by the l ime treatment. The enzymatic process did not reduce the quality of the prot ein isolates prepared from the CM. After the addition of a simple acetone-w ashing step, the isolate from the enzymatically treated meal had even bette r properties. (C) 1999 John Wiley & Sons, Inc.