Enzymatic wheat conditioning

This work was aimed to the preliminary development of an enzymatic wheat conditioning process in order to partly hydrolyse the fibre fraction to increase both milling yield and antioxidant capacity of whole flour. Two different commercially available food grade enzyme preparations were selected and used: Viscozyme® L (a complex including several carbohydrase activities) and a 50:50 mixture of Celluclast® BG and Fungamyl® Super AX (a mixture of purified 1, 4-β-xylanase and a fungal a-amylase). Lab-scale conditioning trials were carried at 16 % final grain moisture, under stirred conditions for 24 h. The investigated process variables were: working temperature (25 °C and 40 °C) and enzyme addition (3 % w/w based on dry weight of wheat, at 25 °C). All the samples and a control (not conditioned grain), were ground in a domestic mill and the flours were analysed to evaluate the influence of the treatment on: friability of bran fraction (flour weight fraction with particle size < 0.5 mm); free glucose and xylose content; total dietary fibre content; total free phenols (expressed as equivalents of ferulic acid based on Folin's assay) and antioxidant capacity (according to different in vitro test: ABTS, FRAP and ORAC assay). Use of enzymes significantly increased the bran friability since the % of flours with particle size < 0.5 mm was 14 % higher than in the samples conditioned only with water. The free glucose content was 350 % higher in the enzymatically treated flours, while free xylose was detected only in the flour treated with the Celluclast®-Fungamyl® mixture. The total dietary fibre content was decreased by the Viscozyme® treatment. Both the enzymatic treatments improved the antioxidant capacity of flour based on ORAC and FRAP assays, but not the total phenols content and the ABTS-antioxidant capacity. The results showed an effect of the enzymes on the cell wall components, suggesting interesting potential for the development of an enzymatic wheat conditioning process.