<p>U ovoj doktorskoj disertaciji analizirano je brašno strnih žita (pšenice, spelte, ječma,<br />raži, tritikalea, ovsa), prosolikog žita (kukuruza) i pseudocerealija (heljde i<br />amarantusa) primenom gasne hromatografije sa masenom spektrometrijom (GC-MS) u<br />kombinaciji sa multivarijantnom analizom, u cilju ispitivanja mogućnosti za<br />određivanje autentičnosti navedenih biljnih vrsta. U tu svrhu, iz brašna navedenih<br />cerealija i pseudocerealija ekstrahovani su mali molekuli (lipidi i šećeri). Lipidne<br />komponente brašna ekstrahovane su heksanom. Nakon višestrukog obezmašćivanja<br />istih uzoraka brašna heksanom i sušenja, usledila je ekstrakcija šećernih komponenata<br />96%-tnim etanolom. Dobijeni heksanski i etanolni ekstrakti derivatizovani su<br />odgovarajućim reagensima. Za derivatizacaju lipidnih komponenata korišćen je<br />rastvor TMSH (trimetilsulfonijum hidroksida, 0,2 M u metanolu). Time se masne<br />kiseline prevode u odgovarajuće metil-estre. Za derivatizaciju šećernih komponenata<br />korišćen je etanolni rastvor natrijum-hidroksida i hidroksilamin-hidrohlorida u<br />kombinaciji sa BSTFA (bis-(trimetilsilil-trifluoroacetamidom). Na taj način su prosti<br />šećeri prevedeni u odgovarujuće trimetilsilil-oksime. Ovako pripremljeni ekstrakti<br />uzoraka brašna su analizirani na GC–MS uređaju.<br />Dobijeni hromatogrami međusobno pokazuju veliku sličnost, a naročito u okviru<br />uzoraka iste botaničke vrste. U obradi hromatograma i masenih spektara, korišćen je<br />MSD Productivity ChemStation program uz primenu Wiley 275 biblioteke masenih<br />spektara. Dobijeni podaci analizirani su na tri načina. Prvi način podrazumeva<br />kreiranje numeričkih matrica u modu ukupne jonske struje (TIC). Drugi postupak<br />podrazumeva kreiranje numeričkih matrica izolovanjem karakterističnih fragmentnih jona sa hromatograma (kod lipida 74 m/z, a kod šećera 73 m/z u kombinaciji sa bar<br />jednim od sledećih jona: 204 m/z, 217 m/z, i 361 m/z). Kod trećeg načina obrade<br />podataka, analiza je urađena kreiranjem matrica primenom binarnog sistema (1/0), gde<br />„1“ označava prisustvo određene komponente, a „0“ označava njeno odsustvo u<br />posmatranom uzorku. Tako dobijeni podaci podvrgnuti su multivarijantnoj analizi<br />primenom statističkih programa – PAST i STATISTICA. U sva tri slučaja ispitivani<br />uzorci grupisani su u međusobno jasno odvojene grupe, prema odgovarajućoj biljnoj<br />vrsti. Uočeno je jasno razlikovanje pseudocerealija (heljde i amarantusa) i prosolikog<br />žita (kukuruza) od grupe strnih žita (pšenice, spelte, ječma, raži, tritikalea i ovsa).<br />Primenjenim metodama postiže se manje selektivna klasifikacija biljnih vrsta u okviru<br />strnih žita, sa izuzetkom uzoraka ovsa i spelte. Ovi rezultati pokazuju da je novim<br />navedenim postupcima moguće utvrditi autentičnost brašna različitih botaničkih vrsta<br />cerealija i pseudocerealija.<br />Na isti način tretirani su i uzorci proizvedenog hleba (kore i sredine) u kojima je<br />pšenično brašno supstituisano sa 0, 20, 40, 50, 60, 80 i 100% heljdinog brašna.<br />Multivarijantnom analizom GC-MS podataka dobijaju se jasno odvojeni klasteri u<br />skladu sa porastom udela brašna heljde u kori i sredini hleba. Najbolji rezultati<br />postignuti su koreliranjem sastava i sadržaja ugljenohidratnih komponenata u kori<br />hleba.<br />Krajnji ishod razvoja ovih novih originalnih metoda je mogućnost njihove praktične<br />primene u cilju rutinskih kontrola kvaliteta brašna i gotovih pekarskih proizvoda u<br />laboratorijama, proizvodnim pogonima i inspekcijskim službama. Posebna pogodnost<br />primene predloženih metoda je to što su one semi-kvalitativnog i semi-kvantitativnog<br />karaktera, pa se mogu izvoditi bez tačne identifikacije eluirajućih malih molekula</p> / <p>In this doctoral thesis various flour samples of small grains (wheat, spelt, barley, rye,<br />triticale, oats), corn and pseudocereals (buckwheat and amaranth) were analyzed using<br />gas chromatography - mass spectrometry (GC-MS) in combination with multivariate<br />analysis, in order to examine the possibilities for determining the authenticity of the<br />plant species listed. Small molecules (lipids and sugars) were extracted from flour<br />samples of the above-mentioned cereals and pseudocereals. The lipid components of<br />the flour were extracted with hexane. The extraction of sugar components from the<br />same flour samples was performed with 96% ethanol solution, after multiple defatting<br />with hexane and drying of the samples. The obtained hexane and ethanol extracts were<br />derivatized with appropriate reagents. For the derivatization of the lipid components, a<br />solution of TMSH (trimethylsulfonium hydroxide, 0.2 M in methanol) was used. Thus,<br />the fatty acids were converted into the corresponding methyl esters. For the<br />derivatization of the sugar components, an ethanol solution of sodium hydroxide and<br />hydroxylamine hydrochloride combined with BSTFA (bis- (trimethylsilyl<br />trifluoroacetamide) was used. Thus, the free sugars were converted into the<br />corresponding trimethylsilyl oximes. The derivatized extracts prepared in this manner<br />were analyzed on a GC -MS device.<br />The obtained chromatograms were very similar, and especially within the samples of<br />the same botanical species. In the processing of the chromatograms and mass spectra,<br />MSD Productivity ChemStation program was used with the Wiley 275 Mass Spectra<br />Library. The obtained data were processed in three ways. The first method involves the<br />creation of numerical matrices in the total ion current mode (TIC). The second method<br />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<br />combination with at least one of the following ions: 204 m/z, 217 m/z, and 361 m/z, for<br />the sugar components). In the third way of data processing, the analysis was done by<br />creating a matrix using a binary system (1/0), where “1” denotes the presence of a<br />particular component, and “0” denotes its absence in the observed sample. The data<br />thus obtained were subjected to multivariate analysis using statistical programs - PAST<br />and STATISTICA. In all three cases, the analyzed samples were grouped in clearly<br />separated groups according to the appropriate plant species. A clear distinction was<br />observed between pseudocereals (buckwheat and amaranth), corn and the group of<br />small grains (wheat, spelt, barley, rye, triticale, oats). The applied methods achieved a<br />less selective classification of plant species within the group of small grains, with the<br />exception of oats and spelt samples. These results show that it is possible to determine<br />the authenticity of flour of various botanical species of cereals and pseudocereals,<br />applying new methods described in this doctoral thesis.<br />The samples of produced bread (crust and crumbs) in which wheat flour was<br />substituted with 0, 20, 40, 50, 60, 80 and 100% of buckwheat flour were treated in the<br />same way. Multivariate analysis of GC-MS data provided clearly separated clusters in<br />accordance with the increase in the share of buckwheat flour in bread crusts and<br />crumbs. The best results were achieved by correlating the composition and content of<br />the carbohydrate components in bread crusts.<br />The ultimate outcome of the development of these new original methods is the<br />possibility of their practical application for the purpose of routine quality control of<br />flour and bakery products in laboratories, production facilities and inspection services.<br />A particular advantage of applying the proposed methods is that they are semiqualitative<br />and semi-quantitative. Therefore, they can be performed without the exact<br />identification of eluting small molecules (lipids and free sugars), nor their<br />quantification using analytical standards.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)106920 |
| Date | 05 March 2018 |
| Creators | Pastor Kristian |
| Contributors | Ačanski Marijana, Kravić Snežana, Kondić-Špika Ankica |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
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