Endoxylanases seriously affect the rheological properties of durum wheat (Triticum durum Desf.) semolina spaghetti doughs prepared with, and as evaluated, by the farinograph. Under the experimental conditions, control doughs (34.9% moisture content) made from two semolinas (semA and semB) yielded a maximal consistency of 525 and 517 farinograph units (FU), with, respectively, 19.4 and 16.4% of the total level of arabinoxylans (TOT-AX) being water-extractable (WE-AX). When 75.4 Somogyi units/50 g of semolina of the endoxylanases from Trichoderma viride (XTV), rumen microorganisms (XRM), Bacillus subtilis (XBS), and Aspergillus niger (XAN) were used, the maximal consistencies at 34.9% moisture decreased for semA to 467, 436, 448, and 417 FU, respectively. This was accompanied by increased WE-AX contents of 60.8, 71.2, 70.7, and 73.0%, respectively. Similar results were observed for semB. By reducing the total water content of doughs, it was possible to recover the maximal consistency of the original doughs. Both the decrease in maximal consistency and the amount of water to be omitted were significantly related to the decrease in molecular weight (MW) of the WE-AX and the percentage of WE-AX solubilized as a result of the enzymic action. At the same time, it was clear that endogenous endoxylanase inhibitors were present in the durum wheat semolinas and that they inhibited the endoxylanases used to different degrees. Part of the differences in effects between the different endoxylanases (decrease in maximal consistency, amount of AX solubilized, MWs of the WE-AX, and amount of water that could be omitted) could be ascribed to the differences in inhibition of the endoxylanases by endogenous inhibitors.

As part of a general study aiming to clarify the role of arabinoxylans (AX) in pasta processing and quality, AX were modified by the addition of endoxylanases during pasta processing. The influence on processing parameters and quality were determined. Pasta (800 g) was produced from two commercial semolinas (semA and semB) using dosages of Bacillus subtilis (XBS) and Aspergillus niger (XAN) endoxylanases of 0–0.225 Somogyi units/g of semolina. Increased dosages resulted in a drop of extrusion pressure. The endoxylanase treatments had no great effect on the resulting pasta quality (color of dry products and surface condition, viscoelastic index, and resistance to longitudinal deformations of cooked products). High dosages of XAN and XBS resulted in high levels of solubilized AX (as an extra source of soluble dietary fiber) of low molecular weight which were expected to easily leach out during the cooking process of pasta. Surprisingly, only low levels of AX were found in the cooking water, even with extremely high dosages of endoxylanases used and cooking beyond optimum time. A method is provided to obtain high‐quality pasta with increased levels of soluble fiber.

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Three industrial pasta processing lines for different products (macaroni, capellini and instant noodles) were sampled at three subsequent stages (semolina, extruded, and dried end products) in the process. Arabinoxylans (AX) and arabinogalactan peptides (AGP) were analyzed. Although very low endoxylanase activities were measured, the level of water-extractable AX (WE-AX) increased, probably because of mechanical forces. No change was observed in the level and structural characteristics of AGP. The WE-AX molecular weight (MW) profiles showed a very small shift toward lower MW profiles; those of AGP revealed no changes as a result of the production process. After separation of WE-AX and AGP, (1)H NMR analysis and gas chromatography of the alditol acetates obtained following hydrolysis, reduction, and acetylation revealed no changes in the arabinose substitution profile of the WE-AX samples during pasta processing. At optimal cooking times, WE-AX losses in the cooking water are small (maximally 5.9%). However, the loss of AGP is more pronounced (maximally 25.0%). Overcooking led to more losses of both components.

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