Effects of ozone treatment on the molecular properties of wheat grain proteins

Abstract

Ozone is a powerful and highly reactive oxidizing agent, which has found increasing applications in the field of grain processing. However, in some cases, O3 can potentially promote oxidation and/or degradation of the chemical constituents of grains. Experiments were carried out to evaluate the specific effects of gaseous ozone on the molecular properties of wheat grain proteins and their consequences on the bread-making quality of the resulting flours.Ozonation causes a significant reduction in the SDS solubility of the wheat prolamins, which can reasonably be attributed to conjugate effects of an increase in molecular dimensions and an increase in the compactness of the protein polymers initially present. In fact, our results demonstrate that this general reinforcement of the aggregative status of prolamins due to ozonation of wheat grains results from (i) the formation of new intermolecular S-S bonds, (ii) to a lesser extent, the formation of other types of intermolecular covalent cross-links (dityrosine cross-links) and finally, (iii) significant changes in secondary structure. By significantly affecting the molecular properties of wheat grain prolamins, ozone leads to profound changes in the rheological properties (i.e. increase in the tenacity and a great limitation of the extensibility) of the flours and/or doughs obtained.

Disinfestation of stored wheat grain infested with Rhyzopertha dominica by ozone treatment: process optimization and impact on grain properties

“…Prolonged high‐concentration ozone exposure led to the degradation of the gluten structure through oxidation, which might explain the lower protein content in treated wheat grain. The causative role of protein oxidation is supported by previous studies . After ozone treatment with 2.44 g m −3 for up to 7.79 h, it was observed that the 1000‐kernel weight of treated grain, as compared to untreated grain, was reduced and that the hardness was increased.…”

“…22,23 Trombete et al 24 reported the effect of ozone on chemical properties, mineral profile and rheological properties of wheat at an ozone concentration of 60 mg L −1 and found no significant alteration due to treatment. Gozé et al 25 observed no significant changes in wheat starch when treated with ozone gas at a flow rate of 33.34 L min −1 for up to 60 min, but in their previous study, 26 changes in rheological properties in flour samples were reported, implying oxidation of protein and non-starch polysaccharides as possible reasons. Gozé et al 27 studied the effect on the molecular structure of wheat protein after exposure to ozone at concentrations varying from 60 to 180 g m −3 Normal temperature and pressure and noticed a decrease in the amount of -helix and -pleated structures.…”

“…Gozé et al 25 observed no significant changes in wheat starch when treated with ozone gas at a flow rate of 33.34 L min −1 for up to 60 min, but in their previous study, 26 changes in rheological properties in flour samples were reported, implying oxidation of protein and non-starch polysaccharides as possible reasons. Gozé et al 27 studied the effect on the molecular structure of wheat protein after exposure to ozone at concentrations varying from 60 to 180 g m −3 Normal temperature and pressure and noticed a decrease in the amount of -helix and -pleated structures. The possible cause of this decrease is the oxidation of amino acid residues or their cross-linking.…”

“…The causative role of protein oxidation is supported by previous studies. 27,39 After ozone treatment with 2.44 g m −3 for up to 7.79 h, it was observed that the 1000-kernel weight of treated grain, as compared to untreated grain, was reduced and that the hardness was increased. Reduction of surface moisture as a result of kernel oxidation due to ozone treatment might harden the grain.…”

Ozone technology as an alternative for reducing mycotoxin contamination in wheat products

“…However, due to its oxidizing properties, ozone can promote changes in the constituents of wheat (GOZÉ et al, 2017). Ozone can partially demolish the cell structure (ZOU et al, 2015) and oxidize carotenes, tannins, ascorbates, flavoproteins or polyphenols and other constituents (OBADI et al, 2017).…”