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Cilj ovog istraživanja bio je ispitati utjecaj dodatka brašna žutog graška, kiselog tijesta pripremljenog s različitim bakterijama mliječne kiseline, prekursora hlapljivih spojeva arome i proteaza na kvalitetu bezglutenskog kruha. Primjena kombinacije navedenih dodataka doprinijela je poboljšanju profila hlapljivih spojeva arome, senzorskih svojstava, prehrambene vrijednosti i trajnosti kruha. Profil hlapljivih spojeva arome te intenzitet pojedinih atributa mirisa i arome kruha razlikovao se ovisno o dodatku brašna žutog graška, kiselog tijesta i bakterijama mliječne kiseline primijenjenim za kiseljenje, prekursora hlapljivih spojeva arome i proteaza te njihovoj interakciji. Dodatak brašna žutog graška povećao je prehrambenu vrijednost kruha, ali i narušio prihvatljivost njegovog mirisa. Dodatak kiselog tijesta poboljšao je prihvatljivost mirisa sredine kruha s dodatkom brašna žutog graška, a kruh s dodatkom kiselog tijesta pripremljenog s Lactobacillus brevis DSM 20054 pokazao se senzorski najprihvatljivijim. Dodatak većine prekursora hlapljivih spojeva arome, proteaza, kiselog tijesta i njihovih kombinacija pozitivno je utjecao na prihvatljivost mirisa sredine i arome kruha. Pri tome se kruh s dodatkom kiselog tijesta pripremljenog s L. brevis, arginina, proteaza, prolina i fruktoze (KtAEPF) pokazao senzorski najprihvatljivijim. Polupečenom kruhu KtAEPF s 30 % kiselog tijesta zapakiranom u modificiranoj atmosferi produljena je trajnost na 30 dana pri sobnoj temperaturi, u usporedbi s pet dana trajnosti kruha bez navedenih dodataka The aim of this study was to determine the effect of the addition of yellow pea flour, sourdough prepared with various lactic acid bacteria, volatile flavour compounds precursors, and proteases on the quality of gluten free bread. The application of the combination of mentioned improvers enhanced its volatile flavour compounds profile, sensory properties, nutritional value, and shelf life. The volatile flavour compounds profile and the intensity of bread odour and flavour attributes differed depending on the addition of yellow pea flour, sourdough and lactic acid bacteria used for acidification, volatile flavour compounds precursors, proteases, as well as their interaction. The addition of yellow pea flour increased the nutritional value of the bread, but also impaired its odour acceptability. The addition of sourdough improved the odour of the bread crumb containing yellow pea flour, while the most sensory acceptable bread was the one with the Lactobacillus brevis DSM 20054 sourdough. The addition of most volatile flavour compounds precursors, proteases, sourdough, and their combinations positively affected the crumb odour and bread flavour acceptability. Bread with the addition of L. brevis sourdough, arginine, proteases, proline, and fructose (KtAEPF) was the most sensory acceptable. Partially baked KtAEPF bread with 30% sourdough packed in a modified atmosphere had a prolonged shelf life of 30 days at room temperature, compared to five days for bread with no improvers added.

Cilj ovog istraživanja bio je ispitati utjecaj dodatka brašna žutog graška, prekursora aromatskih spojeva, enzima i različitog udjela kiselog tijesta (10, 20 i 30 % KT) na fizikalna i senzorska svojstva bezglutenskog kruha. Kruh s njihovim dodatkom karakterizira tamnija boja kore, smanjena tvrdoća, žvakljivost, kohezivnost i rezilijencija u odnosu na kruh bez njihovog dodatka (0-G). S obzirom na senzorsku analizu sveukupnog doživljaja, potrošači najviše preferiraju kruh 30 % KT. Određena je trajnost polupečenog kruhu 0-G i 30 % KT ohlađenog u vakuumu i pakiranog u modificiranoj atmosferi. Tijekom 30 dana skladištenja kruha pri sobnoj temperaturi nije došlo do značajne promjene specifičnog volumena i teksture kruha. Kruh 0-G bio je mikrobiološki ispravan do 5. dana skladištenja, a kruh 30 % KT do 30. dana skladištenja. Brašno žutog graška ima veliki potencijal za primjenu u proizvodnji bezglutenskog kruha radi povećanja njegove prehrambene vrijednosti, a kiselo tijesto radi poboljšanja teksture, senzorskih svojstava i produljenja trajnosti. The aim of this research was to examine the impact of adding yellow pea flour, precursors of aromatic compunds, enzymes and different quantity of sourdough (10%, 20%, 30% SD) on physical and sensory properties of gluten-free bread. The bread with mentioned improvers was characterized by darker crust colour, reduced hardness, chewiness, cohesivness and resilience in comparison with bread without its addition (0-G). Considering the sensory analysis of overall experience, consumers preferred bread 30 % SD. The shelf life of partially-baked 0-G and 30 % SD bread cooled in a vacuum and packed in a modified atmosphere was determined. During 30 days of storage at room temperature there was no significant change in a specific volume and bread texture. 0-G bread was microbiologically safe until 5th day and 30 % SD bread until 30th day of storage. Yellow pea flour and sourdough have a great potential for the application in gluten-free bread production. Yellow pea flour increases its nutritional value, while sourdough improves its texture and sensory properties and extends its shelf life.

Sensory perception plays a key role in the consumers’ choice of bread. The addition of legume flour in gluten-free bread can improve its usually low nutritional value, but could have a negative effect on its sensory properties. This study aimed to perform descriptive and hedonic analysis of the odour, taste, aroma, texture, and appearance of gluten-free bread prepared without and with pea flour addition (25%, flour basis). Bread with added pea flour was prepared also with addition of potential improvers – sourdough (10%, 20% or 30%, dough basis), proline and fructose (0.1% and 1%, flour basis, respectively). Sourdough was prepared with Lactobacillus brevis DSM 20054 as a starter, with addition of arginine (0.1%, flour basis) and protease (0.25%, protein basis). According to the descriptive analysis (14 panelists), bread without added pea flour was characterized by less pronounced taste, but more pronounced ‘fresh bread-like’ odour and aroma, lighter crumb/crust colour, lower crumb porosity, more moist and sticky texture. In contrast, bread with added pea flour and improvers was characterized by more pronounced ‘burnt-like’ and ‘caramelised sugar- like’ odour, ‘dough-like’ aroma, ‘pea-like’, ‘nut-like’, ‘fat-like’, sour odour and aroma. Higher sourdough addition led to darker crumb/crust colour, higher crumb porosity, less crumbly texture, less pronounced ‘pea-like’ odour and aroma, more pronounced ‘baked-like’ odour, ‘popcorn-like’ and ‘fresh bread-like’ aroma. Bread with 30% sourdough was the most preferred by consumers (n=58), being graded as ‘moderately liked’. Gluten-free bread with pea flour containing improvement agents has enhanced sensory properties compared to gluten- free bread without pea flour.

Danas potreba za bezglutenskim proizvodima raste te se stoga sve više obraća pažnja na njihove senzorske karakteristike. Cilj ovog rada bio je razviti deskriptivni test i provesti deskriptivnu i hedonističku senzorsku analizu mirisa bezglutenskih kruhova pripremljenih sa ili bez dodatka brašna graška i kiselog tijesta pripremljenog s različitim bakterijama mliječne kiseline. Dobiveni rezultati ukazuju da sredinu analiziranog bezglutenskog kruha najviše karakterizira miris po grašku, kukuruzu, kiselom tijestu i sirovom tijestu, a koru kruha miris po svježe pečenom kruhu, kikirikiju, pečenom i kukuruzu. Miris kore kruha po svježem kruhu i pečenom je u pozitivnoj, a miris po kukuruzu i kikirikiju u negativnoj korelaciji s rezultatima hedonističke analize. Dodatak brašna graška pojačava miris sredine po grašku i sirovom tijestu te miris kore kruha po grašku i pečenom u kori te negativno utječe na prihvatljivost mirisa. Dodatak kiselog tijesta pozitivno utječe na prihvatljivost mirisa. Miris bezglutenskog kruha pripremljenog bez dodatka brašna graška i s dodatkom kiselog tijesta pripremljenog s Lactobacillus reuteri se pokazao najsličniji mirisu pšeničnog bijelog kruha. The need for gluten-free products increases nowadays, so the attention for their sensory characteristics is growing. The aim of this paper was to develop a descriptive test and to conduct a descriptive and hedonic sensory analysis of the odour of gluten-free bread samples made with or without addition of pea flour and sourdough prepared with different lactic acid bacteria. The obtained results showed that the gluten-free bread crumb of analysed samples was most characterized by the odour attributes peas, corn, sourdough and raw dough like, while crust was characterized by odour attributes freshly baked bread, peanut, roasted and corn like. Fresh bread and baked like odour was positively correlated, while corn and peanut like odour was negatively correlated with hedonic analysis scores for bread crust. The addition of pea flour increased intensity of pea, and raw dough like odour of bread crumb and intensity of pea, baked like odour of bread crust which negatively affected odour acceptability. The sourdough addition positively affected the odour acceptability. The odour of gluten-free bread prepared without pea flour addition and with the addition of sourdough prepared with Lactobacillus reuteri showed to be the most similar to the odour of wheat bread.

Celijakija kao kronična bolest modernog doba zahvaća sve veću populaciju ljudi te se stoga danas teži povećanju nutritivne vrijednosti i kvalitete bezglutenskih proizvoda. Osobe oboljele od celijakije ne podnose gluten, protein koji značajno utječe na kvalitetu pekarskih proizvoda. U proizvodnji bezglutenskog kruha sve je popularniji dodatak brašna mahunarki, a također je i sve veći interes za upotrebu kiselog tijesta, budući da povećava prehrambenu vrijednost, kvalitetu, ali i trajnost takvih proizvoda. Cilj ovog završnog rada bio je pomoću DPPH metode odrediti antioksidativnu aktivnost uzoraka bezglutenskog kiselog tijesta i kruha pripremljenog sa i bez dodatka brašna žutog graška te uz kiseljenje s različitim sojevima bakterija mliječne kiseline. Na temelju dobivenih rezultata, utvrđeno je da proces kiseljenja pomoću bakterija mliječne kiseline povećava antioksidativnu aktivnost tijesta i kruha, dok je dodatak brašna žutog graška smanjuje. Coeliac disease as a modern life chronical disease, affects higher number of today’s population, so there is need to increase nutritive value and quality of gluten-free products. People who suffer from coeliac disease do not tolerate gluten, protein that highly affects the quality of baker’s products. In the production of gluten-free bread, there is increasing popularity of adding legume flours, and there is even more interest in use of sourdough, since it increases nutritional value and sustainability of these products. The main aim of this thesis was to determine antioxidative activity with DPPH method in samples of gluten-free sourdough and bread prepared with or without addition of yellow pea flour with acidification from various types of lactic acid bacteria. Based on obtained results, it is found that acidification with lactic acid bacteria increases antioxidative activity of sourdough and bread, meanwhile addition of yellow pea flour it decreases.

U današnjem modernom svijetu sve je više ljudi izloženo svakodnevnom stresu zbog čega se javljaju različite bolesti, a time i potreba za pravilnom i nutritivno kvalitetnijom prehranom. Broj oboljelih od celijakije je sve veći pa je i potražnja za bezglutenskim proizvodima u svakodnevnom porastu. S obzirom da je bezglutenski kruh nutritivno siromašan, potrebno ga je obogatiti različitim dodacima. Također, moderne metode proizvodnje kruha upotrebom pekarskog kvasca S. cerevisiae i kratkotrajna fermentacija daju kruh lošije kvalitete i trajnosti zbog čega se sve više pribjegava proizvodnji kruha uz dodatak kiselog tijesta. Stoga je cilj ovog rada bio utvrditi utjecaj brašna žutog graška i kiseljenja tijesta pomoću bakterija mliječne kiseline (BMK) na antioksidativnu aktivnost bezglutenskog kiselog tijesta i kruha. Utvrđeno je da kiseljenje s različitim kulturama BMK povećava antioksidacijsku aktivnost, dok je dodatak brašna žutog graška smanjuje. In today's modern world, more and more people are exposed to daily stress, which is why there is even more different illnesses and need for healthy and nutritious nutrition grows. The number of celiac patients is increasing, so demand for gluten-free products is daily growing. Since the gluten-free bread is nutritiously poor, it is necessary to enrich it with various supplements. Also, modern methods of bread making using baker's yeast S. cerevisiae and short-therm fermentation negativelly affect breads quality and durability which is why bakery industry is increasingly using the addition of sourdough. The aim of this study was to determine the influence of addition of yellow pea flour and sourdough prepared with different lactic acid bacteria (LAB) on the antioxidant activity of gluten-free sourdough and bread. It was found that fermentation with different LAB cultures increases antioxidant activity, while the addition of yellow pea flour reduces it.

U današnjem ubrzanom tempu života, upotreba tradicijskih metoda kiseljenja tijesta u pekarskoj proizvodnji je gotovo iščeznula. Moderne metode upotrebe monokulture kvasca S. cerevisiae i kratkotrajna fermentacija se nisu pokazali prikladnim za postizanje sigurnosti, kvalitete i trajnosti pekarskih proizvoda. Sve je veća svijest o utjecaju antinutrijenata i alergena žitarica na zdravlje modernog čovjeka. Stoga je cilj ovoga rada ukazati na kvalitetnije, nutritivnije i zdravstveno ispravnije pekarske proizvode koji nastaju uporabom tradicijskih kiselih tijesta s brašnom od cjelovitih žitarica bez dodanog kvasca i aditiva. In today fast paced life, usage of traditional methods with sourdoughs in bakery production is almost perished. Modern methods of using yeast monoculture S. cerevisiae with short fermentation haven¨t proven suitable for achiving safety, quality and shelf life of baked goods. There is growing awareness of decremental effects of cereal antinutrients and allergens on health of a modern man. Thus the goal of this work is to indicate on higher quality, nutrient rich and healthier baked produce which are made with traditional sour dough and flower from wholesome cereals without added yeast or additive.

U ovom radu provedeni su razvoj i validacija HS-SPME/GC-MS metode za određivanje akroleina u kiselom tijestu. Pri optimizaciji mikroekstrakcije na čvrstoj fazi analiziran je utjecaj dva parametra – temperature (40 i 50 °C) i vremena ekstrakcije (10, 15 i 20 minuta). Najveći odziv akroleina dobiven je pri 40 °C i 20 minuta te je stoga validacija metode provedena pri tim uvjetima. Ključni parametri validacije bili su selektivnost, linearnost i područje, preciznost, točnost, stabilnost te granice detekcije i kvantifikacije. Ispitivanjem točnosti utvrđeno je da matriks uzorka značajno utječe na odziv dodanog standarda akroleina te je stoga metoda dodatka standarda u uzorak primijenjena za izradu baždarnog dijagrama. Rezultati su pokazali da je metoda selektivna, linearna i precizna unutar ispitivanog područja. S obzirom da su zadovoljeni kriteriji prihvatljivosti svih validacijskih parametara, može se zaključiti da je razvijena HS-SPME/GC-MS metoda prikladna za određivanje akroleina u kiselom tijestu. In this thesis, HS-SPME/GC-MS method for determination of acrolein in sourdough was developed and validated. Two parameters were analyzed for SPME optimization, temperature (40 and 50°C) and extraction time (10, 15 and 20 minutes). The best results were obtained at 40 °C and 20 minutes of extraction so the validation process was conducted under these conditions. Key validation parameters were selectivity, linearity and range, precision, accuracy, stability, and limits of detection and quantification. During the accuracy experiments, significant influence of sample matrix on the acrolein response was determined, so the calibration curve was created by standard addition method. Results of validation experiments confirmed that this method is selective, linear in working range and precise. It can be concluded that developed HS-SPME/GC-MS method for the determination of acrolein in sourdough is suitable for its intended purpose.

Cilj ovog rada je bio odrediti optimalni udio smrznuto skladištenog ječmenog kiselog tijesta u miješanom kruhu i ispitati utjecaj vremena skladištenja smrznutog kiselog tijesta na kvalitetu kruha. Kiselo tijesto je fermentirano s inokulumom bakterije mliječne kiseline Weissella cibaria i dodano je u krušno tijesto u količini od 10, 20 i 30%. Na temelju kiselog analiza tijesta, krušnog tijesta i kruha određeno je da je optimalni udio kiselog tijesta u kruhu 20%. Kiselo tijesto je skladišteno zamrznuto 4, 8 ili 12 tjedana. Tijekom skladištenja broj živih stanica se u tijestu značajno smanjivao s vremenom, titracijska kiselost je rasla, no vrijeme skladištenja nije negativno utjecalo na fermentacijsku sposobnost krušnog tijesta i nije bilo značajne razlike u kvaliteti kruha u odnosu na kruh sa svježim kiselim tijestom. Rezultati ovog rada pokazuju mogućnost industrijske primjene smrznutog kiselog tijesta za poboljšanje kvalitete miješanog ječmenog kruha. The goal of this study was to determine the optimal proportion of frozen barley sourdough in a composite bread and examine the impact of sourdough frozen storage on bread quality. Sourdough was fermented with lactic acid bacteria Weissella cibaria and added to bread dough in quantity of 10, 20 or 30%. The results of testing sourdough, bread dough and bread features showed that the optimum sourdough addition in bread is 20%. Sourdough was frozen and stored for 4, 8, and 12 weeks. During storage the number of viable cells in the sourdough declined over time, titratable acidity was slightly increasing. Sourdough storage time did not negatively affect the ability of the dough fermentation and there was no differences in the quality of bread with stored sourdough compared to the bread with fresh sourdough. Results of this study demostrate the possibility of industrial application of frozen barley sourdough since it can improve the quality of bread compared native barley flour.

Kako raste potreba za funkcionalnim pekarskim proizvodima, tako je od iznimne važnosti razvitak tehnologije proizvodnje i čuvanja ječmenog kiselog tijesta. U ovom radu je ispitan utjecaj čuvanja ječmenog kiselog tijesta u uvjetima hladnjaka i zamrzivača na preţivljavanje starter kultura. Zamrzavanje je provedeno primjenog visokog tlaka, imerzijom ili strujom brzog zraka u šokeru. Kao starter kultura je korištena heterofermentativna bakterija mliječne kiseline Lactobacillus reuteri. Određen je broj živih stanica laktobacila u svježem kiselom tijestu te nakon čuvanja 7, 14 i 28 dana na +4 ili -18oC. Dobiveni rezultati upućuju na to na nije došlo do značajnih promjena u broju živih laktobacila kod zamrzavanja imerzijom i šokerom, dok se zamrzavanjem visokim tlakom značajno smanjio broj živih stanica u kiselom tijestu.U hladnjaku se nije značajno promijenio broj živih stanica laktobacila te nije došlo do pojave plijesni na kiselom tijestu. As the need for functional bakery products grows, it is extremely important to develop production technology and methods of preserving barley sourdough. In this study, it is interrogated how cooling and freezing of sourdough will effect on survival of starter culture. Freezing is performed by applying a high pressure, immersion and with cold air in shocker. As a starter culture is used heterofermentative lactic acid bacterium Lactobacillus reuteri. Is determined by the number of living cells of lactobacillus in fresh sourdough and after saving 7, 14 and 28 days at +4 or -18 ° C. The results suggest that the there has been no significant change in the number of live lactobacilli in immersion freezing and shocker, while freezing with high pressure significantly reduce the number of viable cells in sourdough. In refrigerator the number of viable cells of lactobacillus did not change significantly and there was no mold on sourdough.

Kiselo tijesto dobiveno je prirodnom fermentacijom pšeničnog brašna uz dodatak tipičnih bakterija mliječno-kiselog vrenja. Kruh s takvim tijestom je bolje kvalitete, dulje trajnosti i povećane prehrambene vrijednosti, te ga je poželjno dodavati u proizvodnji kruha bogatog vlaknima kao što su integralni i raženi. Sve veći zahtjevi tržišta za poboljšavanjem kakvoće, trajnosti i funkcionalnosti proizvoda na bazi pšenica postavljaju veliku zadaću pekarskoj industriji. Kiselo tijesto pomaže kod eliminacije fitinske kiseline i usporava razgradnju ugljikohidrata u probavnom sustavu, pa jedući takav kruh zadržavamo osjećaj sitosti, jer je on lakše probavljiv. Bakterije mliječno kiselog vrenja su dominantni mikroorganizmi u kiselom tijestu. Okus, miris, te nutritivne karakteristike kruha uvelike ovise o njihovoj djelatnosti, jer u zajedničkom djelovanju s raznim sojevima kvasaca čine cjelinu potrebnu za dobivanje kiselog tijesta. Današnja istraživanja pokazuju važnost u povezivanju hrane i zdravlja, budući da sve veći broj ljudi pokazuje zanimanje za korištenjem namirnica bogatih vlaknima te njihovog utjecaja na ljudsko zdravlje. Sourdough is made of natural fermentation of wheat flour with the addition of typical lactic-acid fermentation bakteria. Bread with souch kind of dough is better quality, has longer shelf-life and higher nutriitional value. It is desirable in manufacturing of fiber-rich bread souch as wholemeal and rye bread. The baking industry have great challenge because of increasing demands of market for improving the qouality, durability and functionality of wheat based products. Sourdough helps with elimination of pyhtic acid and slows degradation of the carbohydrates in the digestive tract. When we are eating of this type of bread we feel satiety because it is easily degistable. Lactic-acid fermentation bacteria are the dominant microorganisms in sourdough. Flavour, aroma and nutritional characteristics of bread depend on their activities because of joint activity with different strains of yeast are needed to get the sourdough. Today's research demonstrates the importance of linking food and health because an increasing number of people are showing interest in the use of foods rich in fiber and their impact on human health.

Bread has been an essential part of human nutrition and culture for thousands of years. Every step of it’s production, from careful raw material selection to dough preparation, processing and baking, could be considered as art that ensure unlimited abundance of color, taste and aroma. Diversity of bakery products is result of the diversities in tradition, culture and geographic origin. All around the world alluring and aromatic bakery products always contain sourdough. Sourdough is a complex microbial ecosystem that is composed of lactic acid bacteria and yeasts. The use of lactic acid bacteria in the bread production has long tradition, from spontaneous fermentations (leavening the dough only), to the development and use of defi ned and functional starter cultures. This review covers the sourdough technology, with major emphasis on production of wheat bread with enhanced nutritional value, prolonged shelf life, better taste and aroma., Kruh je od pamtivijeka neizostavni dio ljudske prehrane i kulture. Svaki korak u njegovoj proizvodnji, od pažljivog izbora sirovina do pripreme i obrade tijesta te procesa pečenja, predstavlja dio umjetnosti koja u konačnici osigurava neograničeno bogatstvo boje, okusa i arome kruha. Raznolikost pekarskih proizvoda rezultat je različitosti tradicije, kulture te geografskog podrijetla. Međutim, san svakog pekara, primamljivi i mirisni pekarski proizvodi diljem svijeta, uvijek sadržavaju kiselo tijesto. Kiselo tijesto je kompleksni mikrobni ekosustav kojeg čine bakterije mliječne kiseline i kvasci. Upotreba bakterija mliječne kiseline u pripremi kruha ima dugu tradiciju, od spontanih fermentacija gdje je njihova uloga bila samo dizanje tijesta, preko defi niranih starter kultura, do razvoja i primjene funkcionalnih starter kultura. U ovom radu dat je prikaz tehnologije proizvodnje kiselog tijesta s naglaskom na proizvodnju pšeničnog kruha povećane nutritivne vrijednosti i trajnosti, bogatijeg okusa i arome.

Zadatak ovog rada je bio ispitivanje utjecaja dodatka kiselog tijesta pripravljenog s različitim udjelima vode i pri različitim temperaturama fermentacije na parametre kvalitete kruha. Kisela tijesta su pripremljena s različitim tipovima brašna (T-400 i T-1100), različitim udjelima vode (omjer voda:brašno 1:1, 2:1) te fermentirana pri različitim temperaturama (25, 30 i 35 °C) s Lactobacillus brevis L-63 tijekom 20 sati. Rezultati ispitivanja su pokazali da je dodatak kiselog tijesta imao utjecaj na smanjenje aktiviteta vode, pH vrijednosti, povećanje ukupne titracijske kiselosti krušnog tijesta i kruha te povećanje specifičnog volumena kruha, a najizraženije promjene su se dogodile pri udjelu vode 2:1 i povišenim temperaturama fermentacije. Ispitivanja viskoamilografskih svojstava kruha su pokazala utjecaj dodatka kiselog tijesta na sve parametre kod oba tipa brašna. Dodatak kiselog tijesta nije imao statistički značajan ujecaj na čvstoću svih uzoraka (p < 0,05). Kohezivnost se pokazala različitom pri različitim uvjetima pripreme kiseog tijesta, dok je otpor žvakanju bio manji kod svih uzorka od brašna T-400. Do statistički značajnog porasta elastičnosti (p < 0,05) je došlo kod uzorka od brašna T-400 (omjer voda:brašno 1:2, tempratura fermentacije 35 °C) te kod uzorka od brašna T-1100 (omjer voda:brašno 1:1, temperatura fermentacije 25 °C). The aim of this thesis was to determine the influence of sourdough addition prepared with different water contents, fermented at different temperatures on bread quality parameters. Sourdough was prepared with different types of flour (T-400 and T-1100), different water contents (water:flour ratio 1:1, 2:1) and fermented at different temperatures (25, 30 and 35 °C) with Lactobacillus brevis L-62 during 20 hours. The results indicate that the addition of sourdough had an influence on decrease of water activity, pH value, increase of total titrable acidity of bread and dough as well as increase in bread specific volume, while the most expressed changes occur at water content 2:1 and higher fermentation temperatures. Viscoamylograph tests pointed out the influence of sourdough addition on both flour types samples parameters. The sourdough addition had no statistically meaningful impact on hardness of all samples (p < 0.05). Cohesiveness was changed with different sourdough preparation conditions, while the chewiness was lower at samples made of flour T-400. Statistically meaningful increase in resilience (p < 0.05) was perceived at samples made of flour T-400 (water:flour ratio 2:1, fermentation temperature 35 °C) as well as at samples made of flour T-1100 (water:flour ratio 2:1, fermentation temperature 25 °C).

Ispitivan je utjecaj karboksimetilceluloze (CMC) te biološkog i kemijskog zakiseljavanja na svojstva tijesta od dva tipa pšeničnog brašna i kvalitetu kruha. Kao biološka sredstva zakiseljavanja korištena su svježe pripravljena kisela tijesta od dva soja mliječno-kiselih bakterija (Lactobacillus plantarum i Lactobacillus brevis) i kiselo tijesto u prahu, a kao kemijsko sredstvo zakiseljavanja korištena je mliječna kiselina. Praćena su reološka svojstva tijesta primjenom osnovnih reoloških metoda, promjene ukupne titracijske kiselosti (TTA) i pH vrijednosti tijekom fermentacije, promjene na HMW gluteninima nakon fermentacije SDSPAGE elektroforezom, te toplinska promjena pšeničnog škroba tijekom pećenja upotrebom diferencijalnog motridbenog kalorimetra (DSC) za simulaciju procesa pećenja. Uzorcima svježih kruhova i kruhova podvrgnutih zamrzavanju i čuvanju u smrznutom stanju (1, 5 i 9 tjedana) te odmrzavanju zagrijavanjem mikrovalovima određen je specifični volumen, dubina prodiranja penetrometrom, udjel vode, te vrijednost pH i TTA. Rezultati reoloških ispitivanja pokazali su da svaki od ispitivanih dodataka različito djeluje na pojedine reološke parametre, a opseg tog djelovanja ovisi o kemijskom sastavu upotrijebljenog brašna. Utvrđen je puferski učinak CMC bez obzira na način zakiseljavanja i tip brašna, te visoka korelacija izmedu parametara kiselosti tijesta (pH i TTA) i pojedinih reoloških parametara (farinografskog razvoja tijesta, stabilnosti, rezistencije i stupnja omekšanja, ekstenzografske rastezljivosti, amilografske maksimalne viskoznosti i broja padanja). Elektroforetska analiza je pokazala da kemijsko i biološko zakiseljavanje tijesta utječe na degradaciju određenih proteina, što značajno mijenja strukturu glutena nakon fermentacije. Simulacija procesa pečenja kruha na DSC-u pokazala je da parametri želatinizacije pšeničnog škroba u sustavu tijesta nakon fermentacije značajno ovise o kemijskom sastavu upotrijebljenog brašna te da kiselost tijesta može značajno utjecati na želatinizacijska svojstava škroba kao i na taljenje znatno stabilnije kristalne strukture škroba. Dodatak CMC pozitivno utječe na specifični volumen, tvrdoću i udjel vode kod kruhova. Primijećeno je značajno smanjenje specifičnog volumena i udjela vode, te povećanje tvrdoće svih ispitivanih uzorka kruha nakon primjene postupka zamrzavanja/odmrzavanja mikrovalovima. Kod svih provedenih ispitivanja, izuzev elektroforetske analize, utvrđene su razlike obzirom na dva tipa upotrijebljenog brašna. Effect of biological and chemical acidification and carboxymethylcellulose (CMC) on dough properties, and bread quality was examined, the dough being made of two wheat flour types. Biological acidification was done with freshly prepared sourdoughs from two strains of lacticacid bacteria (Lactobacillus plantarum and Lactobacillus brevis) and dry sourdough. On the other hand, chemical acidification process involved lactic acid. Rheological properties of dough were monitored by the basic rheological methods. Changes of total titration acidity (TTA) and pH values during fermentation were also examined, as well as, changes of HMW glutenins after fermentation by SDS-PAGE electrophoresis. Thermal changes of wheat starch during baking were tested by differential scanning calorimeter (DSC) as an oven. Specific volume, penetration depth, water share, pH value and TTA were determined in fresh bread samples and bread that had undergone freezing and frozen storage (one, five and nine weeks), and subsequently microwave reheating. Rheological examination results showed that each of the examined additions had various effects on certain rheological parameters. The effect extent depended on chemical composition of flour. CMC buffer effect was proved regardless of acidification or flour type. There was a high correlation between the parameters of dough acidity (pH and TTA) and specific rheological parameters (pharinographic dough development, stability, resistance and softening degree, dough extensibility, amylographic maximum viscosity and Falling number). Electrophoretic analysis proved that chemical and biological dough acidification had an effect on specific protein degradation, which significantly changed gluten structure after fermentation. Simulation of bread baking on DSC showed that parameters of wheat starch gelatinization in dough after fermentation depended significantly on chemical composition of flour. Besides, dough acidity significantly influenced gelatinization capacity of starch, as well as melting of the more stable crystalline structure of starch. CMC addition had a positive influence on specific volume, hardness and water share in bread. On the other hand, lactic acid did not change specific volume of breads with regard to the control sample. While outstanding decrease of specific volume and water share occurred, there was an increase of hardness of all examined bread samples after freezing and microwave reheating. All research, apart from electrophoretic analysis, showed differences regarding two flour types.