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<p>Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR)</p><p>Utvrdeni su sastav i količine nepolarnih i polarnih lipida kao i lipida iz skroba u pojedinim fazama izrade hleba na dva uzorka bra&scaron;na od kvalitetne p&scaron;enice. Takode su odredene promene i prelazi lipidnih sastojaka pod uticajem fizičkih, mehaničkih i toplotnih delovanja tokom tehnolo&scaron;kog postupka.<br />Na osnovu sastava masnih kiselina u lipidnim jedinjenjima razdvojenim tankoslojnom hromatografijom i računa verovatnoće utvrđen je njihov najverovatniji sastav.<br />Iz ekstrakta nepolarnih lipida bra&scaron;na kvantitativno je identifikovano preko 60 %, a iz hleba preko 40 % lipidnih jedinjenja (ASG, MG i TG).<br />U ekstraktima polarnih lipida identifikovano je preko 60 % jedinjenja (DGMG, DGDG, MGMG i MGDG) a u lipidima unutar skroba zastupljeni su samo LPI i NAPE.</p><p>U ekstraktima lipida i u lipidnim jedinjenjima identifikovano je oko 98 % masnih kiselina a najveći udeo je lilinolne kiseline.<br />Takođe je ispitan uticaj načina dodavanja tri vrste komercijalnih emulgatora u pojedinim fazama izrade testa na kvalitet hleba.<br />Delovanje komercijalnih emulgatora u testu i hlebu zavisi od vrste, sastava i i količine emulgatora kao i od kvaliteta bra&scaron;na kome se dodaje. Pobolj&scaron;avajući efekti se mogu postići samo ako se emulgator dozira na početku zamesa ili tokom razvoja testa.<br />Rezultati ovog rada su pomogli da se bliže odredi mesto i uloga lipidnih materija bra&scaron;na u procesu izrade hleba kao i interakcija lipida bra&scaron;na sa komercijalnim emulgatorima.</p> / <p>Abstract was processed by technology for Optical character recognition (OCR).</p><p>Composition and quantities of nonpolar, polar and starch lipids were identified in different stages of bread making process. Changes and translocations of lipid compounds influenced by physical, mechanical and heat treatment during the technological process were determined, too.<br />Based on fatty acid composition in different lipid compounds separated by TLC and on probability calculation, the most probable composition of them was est imated.<br />In nonpolar lipid extracts of flour, over 60 % and in bread over 40 % of lipid compounds were identified (ASG, MG and TG).<br />In polar lipid extracts over 60 % of lipid compounds were identified (DGMG,<br />DGDG, MGMG and MGDG) but in starch lipids only LPI and NAPE were present.<br />In lipid extract and lipid compounds about 98 % of fatty acids were identi- fied with the greatest shane of linoleic acid.<br />The influence of adding three commercial emulsifiers in different stages of dough making on bread quality was also invest igated.<br />Acting of commercial emulsifiers in dough and bread depends on their type, composition and quantity, as well as, on flour quality. Improving effects can be achieved only if emulsifiers ane added at the beginning of mixing stage or during dough development.<br />These results comprise to better understanding of the lipid compounds role, the place of their acting in breadmaking process as well as their interaction with commercial emulsifiers.</p><p>&nbsp;</p>

<p>Seme tikve (Cucurbita pepo) obiluje kako uljem tako i proteinima. Nakon izdvajanja ulja, proteini se koncentri&scaron;u u uljanoj pogači, sekundarnom proizvodu procesa proizvodnje ulja, gde njihov sadrţaj dostiţe do 65%. Proteini semena tikve su primamljiv sastojak za prehrambenu, farmaceutsku i kozmetičku industriju zbog svoje farmakolo&scaron;ke aktivnosti i visoke biolo&scaron;ke vrednosti. Pored toga, budući da su mnogi proizvodi ovih industrija po svojoj koloidnoj prirodi emulzije, proteini semena tikve bi se u njima mogli naći i kao prirodne povr&scaron;inski aktivne materije. Međutim, koloidna funkcionalnost proteina semena tikve se jo&scaron; uvek potcenjuje zbog globularne strukture za koju se vezuju slabija funkcionalna svojstva u odnosu na proteine sa fleksibilnijom strukturom. Prema tome, cilj ove disertacije je ispitivanje funkcionalnih osobina proteinskog izolata semena tikve, pre svega njegovih adsorpcionih i emulgujućih svojstava, kao i ispitivanje uticaja promene proteinske strukture putem enzimske hidrolize na ispitivana svojstva.<br />Pripremljeni su izolat proteina semena tikve (IPST) i dva enzimska hidrolizata, H1 i H2. IPST, H1 i H2 su okarakterisani određivanjem sadržaja vlage, proteina i pepela, zatim, određivanjem prinosa, molekulske mase i zeta potencijala. Ispitan je uticaj koncentracije proteina/peptida (0,0001&ndash;1 g/100 cm³), pH (3&ndash;8) i jonske jačine (0&ndash;1 mol/dm³ NaCl) na rastvorljivost i adsorpciona svojstva: dinamički međupovr&scaron;inski pritisak (ulje/voda), statički povr&scaron;inski (vazduh/voda) i međupovr&scaron;inski (ulje/voda) pritisak, kinetiku adsorpcije i dilatacionu reologiju proteinskih adsorpcionih filmova. Nakon toga, ispitan je i uticaj pomenutih parametara na emulziona svojstva IPST, H1 i H2. Emulgujuća svojstva IPST, H1 i H2 su okarakterisana na osnovu prosečnog prečnika kapljica emulzija, raspodele veličina kapljica i stabilnosti emulzija.<br />Utvrđeno je da je prinos IPST veći od prinosa oba hidrolizata za oko 65 %. IPST ima najniţu rastvorljivost na pH=5, &scaron;to ujedno predstavlja i njegovu izoelektričnu tačku. Enzimskom hidrolizom IPST značajno se povećava rastvorljivost, posebno na pI=5. Povećanje jonske jačine je izazvalo salting&ndash;in ili salting&ndash;out efekat rastvorljivosti kod svih uzoraka u zavisnosti od pH. IPST, H1 i H2 poseduju povr&scaron;insku aktivnost pri čemu je povr&scaron;inski/međupovr&scaron;inski pritisak H1 i H2 manje zavistan od promene pH i jonske jačine u poređenju sa povr&scaron;inskim/međupovr&scaron;inskim pritiskom IPST. Adsorpcijom na granicu faza IPST i oba hidrolizata obrazuju adsorpcione filmove sa dominantnom elastičnom komponentom. Emulgujuća svojstva IPST, H1 i H2 zavise od koncentracije uzorka, pH vrednosti i jonske jačine kontinualne faze. Pri koncentraciji od 1 g/100 cm³ i Ic=0 mol/dm³ pripremljene emulzije su stabilne na svim pH osim emulzije IPST na pH 5. Sve emulzije podležu gravitacionoj nestabilnosti.</p> / <p>Pumpkin (Cucurbita pepo) seed is rich source of both, oil and proteins. Once the oil has been extracted, proteins concentrate in oil cake, a by&ndash;product of the oil<br />extraction process, where their content can reach up to 65%. Pumpkin seed proteins are desirable ingredient in food, pharmaceutical and cosmetic industry due to their pharmacological activities and high biological value. Moreover, since many of products of these industries are, in colloidal terms, emulsions, pumpkin seed proteins could serve as surface active materies. However, colloidal functionality of pumpkin seed proteins is still underestimated for their globular structure which entails inferior functional properties to functional properties of proteins with more flexible structure. Based on that, the aim of this dissertation is to investigate functional properties of pumpkin seed protein isolate, adsorption and emulsifying properties, in the first place, and then to investigate the influence of modification of the protein structure, by means of enzymatic hydrolysis, on the aforementioned properties.<br />Pumpkin seed protein isolate, IPST, and two enzymatic hydrolysates, H1 and H2, were prepared. IPST, H1 and H2 were characterized by determination of moisture, ash and protein content, then, by determination of protein recovery, molecular mass and zeta potential. Influence of the protein/peptide concentration (0.0001&ndash;1 g/100 cm³), pH (3&ndash;8) i ionic strength (0&ndash;1 mol/dm³ NaCl) on the solubility and adsorption properties: dynamic interfacial (oil/water) pressure, static surface (air/water) and interfacial (oil/water) pressure, adsorption kinetics and interfacial dilatational properties, was<br />investigated next. In the end, influence of the aforementioned pharameters on the emulsifying properties of IPST, H1 and H2 was investigated. Emulsifying properties of IPST, H1 and H2 were discussed in terms of mean droplet diameter, droplet size distribution and emulsion stability.<br />Protein recovery of IPST was determined to be 65 % higher than recovery of H1 and H2. Solubility of IPST was the lowest at pH 5, what presents the isoelectric point. The enzymatic hydrolysis of IPST significantly increased solubility, especialy at the isoelectric point. Increase in the ionic strenght led to salting&ndash;in or salting&ndash;out effect depending on pH of the sample. Three investigated samples, IPST, H1 and H2 exhibited surface activity, however, sufrace/interfacial pressure of H1 and H2 were found to be less influenced by change in pH or ionic strenght of the solution in comparison to the IPST. Once adsorbed to the interface IPST and both hydrolysates form interfacial film with dominant elastic component. Emulsifying properties of IPST, H1 and H2 depend on the concentration, pH and ionic strength of the continuous phase. Stabile emulsions were formed at concentration of 1 g/100 cm3 and Ic=0 mol/dm³ regardless of pH, with the exception of the IPST at pH 5. All emulsions were susceptibile to gravitational separation.</p>