No abstract

Due to an increasing incidence of celiac disease (CD) and other gluten-related disorders, different gluten-free breads have been developed using starches and additives as a substitute for gluten. Thus, patients miss not only the taste and aroma of wheat bread but also risk their sensitive intestines. Therefore, modifying gluten to avoid an immune response in CD and its application to baking is in progress. The aim of the study was to enzymatically modify gluten on wheat flour, during bread-making avoiding the use of additives, to reduce immunoreactivity, preserving its properties. Microbial transglutaminase (mTG) or chymotrypsin (ChT) was used to bind lysine or valine to gluten proteins in a model system. The best conditions were directly applied to wheat flour for bread-making with and without punching at 45 min. Subsequently, the rheological properties of the doughs, specific volume of the loaves, immunoreactive gluten content and modification of the extracted proteins were evaluated. ChT-treated breads presented a better appearance with a more homogeneous crumb, higher specific volume values (3.34-4.25 cm(3) g(-1)) and higher reactive gluten reduction (up to 71%) than the mTG-treated ones (1.23-2.66 cm(3) g(-1)) with only a 42% reactive gluten reduction. Thus, transpeptidation during bread-making is a promising technology, although it is necessary to improve the modification process to obtain the reactive gluten reduction required in breads for the treatment of CD patients and other gluten-related disorders.

Gluten-related diseases are a range of inflammatory disorders of the small intestine, characterized by an adverse response to gluten ingestion; therefore, the treatment is a gluten withdrawal. In spite of the increased market of gluten-free products, widely available breads with high acceptability are still missing due to the technological challenge of substituting the special gluten properties. Instead of using alternative ingredients for baking, some attempts have been done to decrease gluten immunogenicity by its enzymatic degradation with microbial proteases. Although the gluten immunogenicity reduction has been reached to an acceptable level, some quality parameters of the products are affected. This review focus on the use of microbial peptidases to prepare less immunogenic baked goods and their effect on product quality.

Consumers with gluten-related disorders require gluten-free (GF) foods to avoid an immune response. Alternative to the use of non-gluten containing grains to prepare GF bread, the gluten reactivity has been greatly reduced using a proline specific cleavage enzyme, however, the gluten functionality was lost. The aim of this study was to evaluate the effect of adding an amaranth flour blend (AFB) to enzymatically modified wheat-flour proteins on dough functionality and to evaluate the immunoreactivity and acceptability of the prepared bread. First, wheat flour (20% w/v, substrate) was hydrolyzed using 8.4 U mg protein Aspergillus niger prolyl-endopeptidase (AnPEP) for 8 h at 40 °C under constant agitation. Four types of breads were prepared with the same formulation except for the type of flour (14% w.b.): wheat flour (WF), WF-AFB unmodified not incubated, WF-AFB unmodified incubated and WF-AFB modified. The protein composition and free thiols were analyzed before and after amaranth addition, and the flour and bread proteins were run using SDS-PAGE and immune-detected in blots with IgA from celiac disease patients. The immunoreactive gluten content, specific volume and bread acceptability were evaluated. The polymeric proteins and free thiol groups of WF decreased after AnPEP treatment. The electrophoretic patterns of the modified flour and bread proteins were different and the IgA-immunodetection in blots was highly reduced, particularly for the higher molecular weight subunits. The addition of AFB to the modified wheat flour prepared using AnPEP improved the dough functionality by increasing the thiol groups and allowed the preparation of a sensorially acceptable bread with only 60 mg kg immunoreactive gluten.