Decomposition of Oxalic Acid in Ginger Juice by Adding the Roots of Barley Seedlings Containing Oxalate Oxidase

Abstract

The decomposition of oxalic acid was performed in 0.1 M succinate buffer (pH 3.5) and in the diluted ginger juice (adjusted to pH 3.5 by the addition of citric acid) by adding the roots of barley seedlings containing oxalate oxidase, using stirred tank and packed-bed reactors. When oxalic acid was oxidized by oxalate oxidase of the barley seedlings roots under 1-atm oxygen pressure in the stirred tank reactor, the decomposition rate of oxalic acid during the initial 15-min reaction reached to 452 mg/h·g-dry roots in the buffer solution containing oxalic acid of 378 mg/l and to 104 mg/h·g-dry roots in the ginger juice (diluted by ten times with deionized water) containing oxalic acid of 90 mg/l. Repeated batch decomposition of oxalic acid resulted in a rapid decline of the initial decomposition rate with increasing time of repitition, and the decomposition rate fell to a half of the initial rate after repitition of more than 3 times. When the decomposition of oxalic acid was carried out in the packed - bed reactor and by continuous addition of the reacting solution with oxygen from the upper side of the reactor, the decomposition remained at the rate of 77 and 28 mg/h·g-dry roots at SV of 41.7 11^-1 for the buffer solution and the diluted ginger juice, respectively.