Application of an endo-xylanase from Aspergillus japonicus in the fruit juice clarification and fruit peel waste hydrolysis

Abstract

The endo-xylanase from Aspergillus japonicus (UFMS 48.136) was purified in a single step using carboximethyl-cellulose chromatographic column and applied in fruit juice clarification process and fruit peel waste hydrolysis . This purification procedure resulted in 38.9-fold purification of endo-xylanase with 83.3% final yield. MALDI-TOF analysis confirmed the molecular mass of 32 kDa. The optimal purified endo-xylanase activity was at a range of pH from 5.0 to 6.0 and from 50 to 60 °C, retaining more than 70% of its activity at all pH studied (3.0–8.0) for 24 h at room temperature. The A. japonicus endo-xylanolytic activity stimulation curve was assayed in the presence of different birchwood xylan concentrations (ranging from 0.02 to 0.5% w/v) and the endo-xylanase activity presented a Vmax of 467.4 ± 30.38 μmol/min/mg, with a km of 2.59 ± 0.17 mg/mL, a kcat of 253.95 ± 16.51 s −1 and a kcat/km value of 98.05 ± 4.41 mL s −1 mg −1 . The endo-xylanase was activated by Mn 2+ (34.5%) and inhibited by Cu 2+ (56.9%). The endo-xylanase was activated by β-mercaptoethanol, Triton X-100, Tween-20, Tween-80 and ferulic acid . In the clarification assay, endo-xylanase successfully clarified the juices of mango (51.11%), banana (9.99%) and tangerine (8.54%). Furthermore, the enzyme also hydrolysed all fruit peel wastes that were tested. In summary, A. japonicus endo-xylanase showed potential for applications in fruit juice clarification and in the treatment of fruit peel wastes, and it is a good candidate for the food industry due to its wide pH stability under acidic conditions. • A single step chromatographic procedure was employed for purification of the xylanase . • The MALDI-TOF analysis showed similarity with xylanases in database. • The xylanase could successfully clarify mango, banana and tangerine. • The enzyme hydrolysed all fruit peels wastes tested. • The enzyme was activated by β-mercaptoethanol, triton X-100, tween-20 and 80, and ferulic acid.