14E-6

Fresh asparagus deteriorates and lignifies after harvest becoming less edible. Asparagus can be processed into juice and other products to increase total utilization and increase net value. Asparagus juice contains antioxidants, such as rutin, ferulic acid and ascorbic acid. However, little work has been done on antioxidant activity of asparagus juice. Our objective was to test the antioxidant activity of asparagus juice as affected by selected enzymes and to compare the antioxidant activity of asparagus juice with broccoli juice. Asparagus juice was produced from fresh asparagus.  Total phenolics were determined using Folin-Ciocalteu reagent. Total flavonoids were measured using (2-aminoethyl)diphenylborate. Antioxidant activity of asparagus juice was determined by DPPH, ABTS and b-carotene bleaching methods. Rutin and ascorbic acid were analyzed by HPLC. To test for rutin cleavage, selected enzymes were incubated with asparagus juice. Rutin, quercetin, total phenolics and antioxidant activity of asparagus juice were analyzed. Total phenolics and total flavonoids of asparagus juice was 0.5±0.2 mg/ml (catechin equivalent) and 0.3±0.01 mg/ml (rutin equivalent), respectively, compared to 0.6±0.1mg/ml and 0.1±0.04 mg/ml, respectively, in broccoli juice.  Asparagus juice contained 0.32±0.01mg/ml rutin and 0.3±0.01 mg/ml ascorbic acid.   The antioxidant activity by DPPH and ABTS were 1.2±0.1 and 2.3±0.3mmol/ml Trolox equivalent, respectively. The antioxidant activity coefficient (AAC) was 311±90. Broccoli juice had the value of 0.4±0.2, 2.0±0.03mmol/ml and AAC value of 328±55. Enzyme treatment decreased ruitn and increased quercetin with variable results for each enzyme.  While cleavage of rutin to produce quercetin was observed, antioxidant activity and total phenolics were not changed systematically. Asparagus has similar antioxidant activity compared to broccoli juice according to ABTS and b-carotene bleaching methods while by the DPPH method, the antioxidant activity of asparagus juice was greater. Commercial pectinase enzymes had glucosidase activity without greatly affecting the antioxidant activity of asparagus juice.