Amination of naringinase to improve citrus juice debittering using a catalyst immobilized on glyoxyl-agarose

A naringinase complex was chemically aminated prior to its immobilization on glyoxyl-agarose to develop a robust biocatalyst for juice debittering. The effects of amination on the optimal pH and temperature, thermal stability, and debittering performance were analyzed. Concentration of amino groups on catalysts surface increased in 36 %. Amination reduced the β-glucosidase activity of naringinase complex; however, did not affect optimal pH and temperature of the enzyme and it favored immobilization, obtaining α-l-rhamnosidase and β-d-glucosidase activities of 1.7 and 4.2 times the values obtained when the unmodified enzymes were immobilized. Amination favored the stability of the immobilized biocatalyst, retaining 100 % of both activities after 190 h at 30 °C and pH 3, while its non-aminated counterpart retained 80 and 52 % of α-rhamnosidase and β-glucosidase activities, respectively. The immobilized catalyst showed a better performance in grapefruit juice debittering, obtaining a naringin conversion of 7 times the value obtained with the non-aminated catalyst.