Non-starch polysaccharides in the sourdough and their impact on the quality and nutrition value of produced bread

Cilj ove disertacije bio je razviti nutritivno obogaćeni pšenični kruh s dodatkom ječmenog kiselog tijesta s egzopolisaharidima (EPS) i s povećanim udjelom topljivog β-glukana, pripremljenog s L. reuteri i W. cibaria s ili bez dodatka L. plantarum, ksilanaze i saharoze. Istražen je i utjecaj čuvanja proizvedenih kiselih tijesta u hladnjaku i zamrzivaču, a za zamrzavanje su korištene tri metode – zamrzavanje u struji hladnoga zraka, uranjanjem u pothlađenu tekućinu i zamrzavanje visokim hidrostatskim tlakom (VHT). Osim svojstva svježih i čuvanih kiselih tijesta, ispitana su reološka svojstva krušnih tijesta pripremljenih s dodatkom kiselih tijesta, te je određen kemijski sastav i fizikalno-senzorska svojstva kvalitete pšeničnog kruha proizvedenog s dodatkom kiselog tijesta. Zamrzavanje kiselih tijesta u struji hladnoga zraka i uranjanjem u pothlađenu tekućinu se pokazalo kao učinkovit način zamrzavanja kiselih tijesta, dok je primjena tehnologije VHT negativno utjecala na svojstva kiselih tijesta. Kao najstabilnije kiselo tijesto tijekom 8 tjedana čuvanja u zamrzivaču se pokazalo kiselo tijesto kiseljeno s W. cibaria s ili bez dodatka saharoze i ksilanaze. Dodatak saharoze je u svim kiselim tijestima pozitivno utjecao na povećanje sinteze EPS, a sam proces kiseljenja kiselih tijesta je pozitivno utjecao na povećanje relativne molekulske mase topljivih β-glukana. Dodatak ječmenog kiselog tijesta u količini od 20% je pozitivno utjecao na svojstva dizanja krušnog tijesta. Proizvedeni pšenični kruhovi s dodatkom zamrznutog kiselog tijesta su zadovoljili uvjete da ih se navodi kao proizvode „izvor proteina“ i „izvor vlakana“. Dodatak kiselog tijesta u pšenični zamjes je pozitivno utjecao na poboljšanje volumena i teksture sredine proizvedenog kruha, a senzorska analiza je pokazala kako je najpoželjniji pšenični kruh proizveden s dodatkom 20 % zamrznutog ječmenog kiselog tijesta.The aim of this thesis was to produce nutritionally enriched wheat bread with added barley sourdough prepared with L. reuteri and W. cibaria with or without the addition of L. plantarum, xylanase and sucrose, all with the purpose of producing sourdough with higher concentration of exopolysaccharides (EPS) and β-glucan. Also, it was investigated the influence of refrigerated and frozen storage on technological performances on sourdough. For freezing, three methods were used - freezing by air blast freezer, freezing by immersion and freezing with high hydrostatic pressure (HHP). Beside this, the rheological properties of bread dough prepared with the addition of sourdough was observe, together with the chemical composition and physical-sensory properties of quality wheat bread produced with sourdough. Freezing sourdough by air blast freezing and by immersion proved to be an effective way of freezing sourdough, while the application of HHP freezing negative effect on the properties of sourdough. Sourdough prepared with W. cibaria with or without the addition of sucrose and xylanase showed as the most stable sourdough through 8 weeks of storage in the freezer. Addition of sucrose in all produced sourdough showed the positive impact on the EPS synthesis and process of fermentation showed the positively impact on increasing the relative molecular weight of soluble β-glucan. Also, addition of 20 % of barley sourdough had a positive effect on the properties of raising bread dough. Produced mixed wheat bread with frozen sourdough can be cited as the products “source of protein” and “source of fiber”. Sourdough addition have a positive impact on improving the volume and texture of produced mixed wheat bread and sensory analysis showed that the most desirable wheat bread is the one produced with the addition of 20 % of barley sourdough