Утицај хладне атмосферске плазме на технолошки квалитет и безбедност пшеничног брашна

The main aim of this doctoral dissertation was to examine the impact of cold atmospheric plasma treatment on the quality and safety of wheat flour. The first phase of research conducted in this doctoral dissertation was aimed at comparing the SRC method with empirical rheological methods on samples of wheat flour mill streams. The method showed good power to describe very different properties of wheat flour mill streams. By comparing the parameters of the Solvent Retention Capacity method (SRC) with empirical rheological parameters, the division of SRC parameters into two groups is noticed. The first group of SRC, lactic acid and glutenin performance index (SRCLa and GPI) is sensitive to the dough strengths, and the second group, SRC of sodium carbonate, sucrose and water (SRCSо, SRCSu and SRCw) is sensitive to flour hydration potential. Through multivariate analysis, the relationships between the parameters of the SRC method and the rheological parameters were determined. Based on the experimental data of the SRC parameters, models were developed with partial least squares regression (PLSR) to predict the most important rheological parameters. PLSR models with high values of coefficient of determination, R2 = 0.93 for farinographic water absorption (FWA) and R2 = 0.92 for energy and model with multiple responses R2 = 0.89 were developed. In the second phase of the research, the influence of different conditions of cold atmospheric plasma treatment (time, distance, degree of cover utilization) on flour quality indicators determined by the SRC method, as well as the content of free sulfhydryl groups, wet gluten, gluten index, rheological properties and ultraviolet and infrared spectra were analyzed. The electrical characterization of the plasma source indicates that the electrodes are homogeneously covered with plasma at the RMS voltage of 2400 V and current of 0.1 A. Optical emission spectroscopy shows the most intense emission lines are in the N2 second positive system band, as expected for the atmospheric air plasma. Relatively lower intensities of peaks associated with atomic oxygen (triplet at 777 nm) are due to the involvement of O in the creation of O3, and quenching by N2 and O2 molecules. All observed parameters changed with the conditions of cold atmospheric plasma treatment. The prolonged treatment time of wheat flour leads to an increase in the modulus of elasticity G’, SRCSu and SRCw parameter. The values of the wet gluten (WG) and gluten index (GI) parameters vary in a narrow interval and the content of free sulfhydryl groups and SRCL and GPI parameters show a decreasing trend. As the SRC method showed a good ability to monitor changes in flour caused by atmospheric cold plasma treatment. Based on the parameters of the SRC method, with the application of the response surface methodology, the procedure of modeling and optimization of the treatment was performed. Developed models of all SRC parameters indicated significant treatment conditions and were characterized by high values of R² SRCL (0.92), SRCSu (0.84), SRCSo (0.75), SRCw (0.91) and GPI (0, 92) respectively. Analysis of secondary structures indicated that the treatment leads to an increase in the proportion of α-helix secondary structure and to a decrease in the proportion of β-plane as well as β-turn + β-sheet. In the third phase, the influence of two directions of optimization of cold atmospheric plasma treatment on the quality indicators of three groups of products (wheat bread, whole grain bread and bread with bran) was observed. The aim of the first optimization was to minimize SRCL and maximize SRCSu parameters and of the second to maximize both SRCLa and SRCSu parameters. The influence of cold atmospheric plasma treatment, of both directions of optimization, on the quality indicators of all three groups of products, was analyzed through the analysis of volume, physical and sensory properties of bread. Results indicate that the treatment of flour with cold atmospheric plasma leads to changes in all baking properties of wheat flour. Treatments affect texture parameters as well as color parameters. Shorter treatment time had a more favorable effect on the course of colloidal processes during mixing and the volume of finished products. Sensory analysis showed that the substitution of 10% flour with flour treated with Shorter treatment time has a positive effect on the volume, appearance of the crumb, taste and smell of bread. The results indicate that the optimization of flour treatment should be carried out according to the appropriate purpose, quantity as well as the quality of the flour which is substituted by the treated flour. In the fourth phase, investigations of the impact of cold atmospheric plasma treatment on the safety of flour were conducted. The possibility of reduction of Alternaria toxins in the wheat flour matrix and the influence of treatment conditions (time and distance) were investigated. The examinations were focused on three Alternaria toxins: alternariol (AOH), alternariol monomethyl ether (AME), and tentoxin (TEN). The extent of reduction of three Alternaria toxins were determined in "spiked" samples of wheat flour depending on the treatment conditions. The modeling of the treatment was performed by applying the response surfaces methodology and the significance of the treatment conditions on the extent of the reduction rate of the Alternaria toxins were determined. The optimization was performed by calculating the standard scores and testing of the optimal treatment was performed on naturally contaminated samples of wheat mill products. The results showed that it is possible to achieve a significant degree of reduction of all tested Alternaria toxins with relatively short treatment times (180 s) in both "spiked" and naturally contaminated samples. The best results of the reduction of all three Alternaria toxins were obtained for treatment with a sample placed at a distance of 6 mm, with a treatment time of 180 s. Under these treatments, a reduction of 60.6%, 73.8% and 54.5%, for AOH, AME and TEN, respectively, was achieved. Results also showed that the extent of the reduction of Alternaria toxins in naturally contaminated samples also depended on the initial Alternaria toxins concentrations. All research indicates that the treatment of wheat flour with cold atmospheric plasma can be successfully used to modify the technological quality but also to improve the safety of wheat flour and it is justified to continue further research.