Effect of commercial carbohydrases on the hesperetin and narigenin contents of citrus fruits

Abstract

Citrus fruits were treated with commercial carbohydrases to produce hydrolyzed citrus with higher amounts of hesperetin and narigenin. The suitable enzymatic reaction conditions were determined using standard hesperidin and naringin with three carbohydrases (Viscozyme L > AMG 300L > Pectinex Ultra Pulp), varying reaction buffer pH levels (5.0 > 4.0 > 6.0) and reaction times (24 h > 2 h). Viscozyme L produced significantly higher contents of hesperetin and narigenin than the other enzymes (p<0.05), and the contents increased with reaction time. With Viscozyme L, higher contents of hesperetin and narigenin (1.63 and 2.10 times) and higher total phenolic contents (1.69 times) were produced in the hydrolyzed immature citrus relative to those in the hydrolyzed mature citrus (p<0.05). In addition to the minimum inhibitory concentration of the hydrolyzed immature citrus was lower against Staphylococcus aureus than against Escherichia coli. Thus, enzymatic hydrolysis with immature citrus appears to produce much higher contents of hesperetin, narignenin and total phenolic contents than with the mature citrus, and enzymatic hydrolysis could improve the quality of citrus beverages. Hydrolyzed citrus would likely serve as a functional food additive with high added value in the citrus processing industry.