CHEMICAL ENGINEERING TRANSACTIONS VOL. 57, 2017 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Sauro Pierucci, Jiří Jaromír Klemeš, Laura Piazza, Serafim Bakalis Copyright © 2017, AIDIC Servizi S.r.l. ISBN 978-88-95608- 48-8; ISSN 2283-9216 Enzymatic Wheat Conditioning Alice Gruppi, Guillermo Duserm Garrido, Roberta Dordoni, Dante M. De Faveri, Giorgia Spigno* Istituto di Enologia e Ingegneria Agro-Alimentare, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy giorgia.spigno@unicatt.it 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 -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. 1. Introduction Over the last years, the market demand for high fibre foods has been constantly increasing following the overall new challenge for the society to promote a long, healthy, and active life span (Minuti et al., 2014). “Source of fibre” and “High fibre” are permitted EU nutrition claims (EU Reg. No 1047/2012) for products containing, respectively, at least 3 g or 6 g of fibre per 100 g or 1,5 g or 3 g of fibre per 100 kcal. That is why the industry has focused on the development of high fibre products of typical large daily consumption, such as cereal based products where, on the other hand, the use of a whole flour with a high fibre content may typically impair technological (such as machinability and leavening strength) and sensorial problems (such as off-flavors) (Delcour et al., 2012). Another potential negative aspect of whole flour use is the average higher content of unhealthy compounds, such as heavy metals, toxins and residues of pesticides (Moncalvo et al., 2016). Cereal milling processes have in fact been developed to remove the external layers (the bran) of the grains to improve both the technological quality and safety profile of flours. On the other hand, besides the already cited fibre nutrition claim, the external layers contain other healthy compounds, such as lignans, tocotrienols, minerals and phenols (Oghbaei and Prakash, 2016). In wheat milling, conditioning is traditionally applied before grinding to enhance the separation of the germ and of the external layers from the starchy and proteinaceous endosperm which constitute the refined flour. Conditioning (also referred to as tempering) is the process of adding small amount of water to wheat (to increase the water content to an average 15.5-16.5 %) to toughen the bran and mellow the endosperm and thus improve the efficiency of flour extraction. This step is fundamental also for the technological quality of the