Autentičnost cerealija i pseudocerealija - razvoj novih metoda analize brašna i gotovih pekarskih proizvoda / Authenticity of cereals and pseudocereals - development of new methods for the analysis of flour and final bakery products

In this doctoral thesis various flour samples of small grains (wheat, spelt, barley, rye, triticale, oats), corn and pseudocereals (buckwheat and amaranth) were analyzed using gas chromatography - mass spectrometry (GC-MS) in combination with multivariate analysis, in order to examine the possibilities for determining the authenticity of the plant species listed. Small molecules (lipids and sugars) were extracted from flour samples of the above-mentioned cereals and pseudocereals. The lipid components of the flour were extracted with hexane. The extraction of sugar components from the same flour samples was performed with 96% ethanol solution, after multiple defatting with hexane and drying of the samples. The obtained hexane and ethanol extracts were derivatized with appropriate reagents. For the derivatization of the lipid components, a solution of TMSH (trimethylsulfonium hydroxide, 0.2 M in methanol) was used. Thus, the fatty acids were converted into the corresponding methyl esters. For the derivatization of the sugar components, an ethanol solution of sodium hydroxide and hydroxylamine hydrochloride combined with BSTFA (bis- (trimethylsilyl trifluoroacetamide) was used. Thus, the free sugars were converted into the corresponding trimethylsilyl oximes. The derivatized extracts prepared in this manner were analyzed on a GC -MS device. The obtained chromatograms were very similar, and especially within the samples of the same botanical species. In the processing of the chromatograms and mass spectra, MSD Productivity ChemStation program was used with the Wiley 275 Mass Spectra Library. The obtained data were processed in three ways. The first method involves the creation of numerical matrices in the total ion current mode (TIC). The second method involves the creation of numerical matrices by isolating characteristic ion fragments from the TIC chromatograms (74 m/z for the lipid components, and 73 m/z in combination with at least one of the following ions: 204 m/z, 217 m/z, and 361 m/z, for the sugar components). In the third way of data processing, the analysis was done by creating a matrix using a binary system (1/0), where “1” denotes the presence of a particular component, and “0” denotes its absence in the observed sample. The data thus obtained were subjected to multivariate analysis using statistical programs - PAST and STATISTICA. In all three cases, the analyzed samples were grouped in clearly separated groups according to the appropriate plant species. A clear distinction was observed between pseudocereals (buckwheat and amaranth), corn and the group of small grains (wheat, spelt, barley, rye, triticale, oats). The applied methods achieved a less selective classification of plant species within the group of small grains, with the exception of oats and spelt samples. These results show that it is possible to determine the authenticity of flour of various botanical species of cereals and pseudocereals, applying new methods described in this doctoral thesis. The samples of produced bread (crust and crumbs) in which wheat flour was substituted with 0, 20, 40, 50, 60, 80 and 100% of buckwheat flour were treated in the same way. Multivariate analysis of GC-MS data provided clearly separated clusters in accordance with the increase in the share of buckwheat flour in bread crusts and crumbs. The best results were achieved by correlating the composition and content of the carbohydrate components in bread crusts. The ultimate outcome of the development of these new original methods is the possibility of their practical application for the purpose of routine quality control of flour and bakery products in laboratories, production facilities and inspection services. A particular advantage of applying the proposed methods is that they are semiqualitative and semi-quantitative. Therefore, they can be performed without the exact identification of eluting small molecules (lipids and free sugars), nor their quantification using analytical standards.