Impact of food processing and interactions with other food components on the structure and function of food allergens

β-laktoglobulin (BLG) je glavni protein surutke mleka preživara, ali je prisutan i u mleku mnogih drugih vrsta sisara. Poznato je da BLG poseduje niz funkcionalnih osobina (npr. geliranje, stvaranje pene, emulzifikacija) važnih za industriju hrane kao i veliku nutritivnu vrednost zbog visokog sadržaja esencijalnih aminokiselina. Iz tog razloga se često koristi kao aditiv u prehrambenoj industriji. Međutim, BLG je jedan od glavnih alergena mleka; 45% pacijenata alergičnih na mleko reaguje na BLG. Stoga se sve više nameće potreba za razvijanje metoda za modifikaciju BLG-a u cilju smanjenja alergenosti i poboljšanja funkcionalnih osobina. Takođe, sva istraživanja u oblasti hrane ne smeju isključiti prisustvo drugih komponenti u matriksu hrane. Predmet rada ove teze je bio ispitivanje uticaja interakcija komponenti matriksa hrane (protein-polifenolna jedinjenja) i odabranih tehnika za obradu hrane (ultrazvuk i enzimsko umrežavanje) na strukturu i funkciju BLG-a. U okviru rada su okarakterisane nekovalentne interakcije između polifenolnih jedinjenja iz ekstrakata kafe, kakaoa, zelenog i crnog čaja i BLG-a. Pokazano je da se usled formiranja nekovalentnih interakcija između polifenolnih jedinjenja i BLG-a smanjuje digestibilnost proteina i da dolazi do maskiranja ukupnog antioksidativnog kapaciteta. Tretiranjem BLG-a ultrazvukom visokog intenziteta generisani su stabilni modifikati sa različitim promenama u sekundarnoj i tercijarnoj strukturi. Kontrolisanje temperature u toku tretmana je imalo odlučujući efekat na vrstu modifikacije. Izrazite promene u tercijarnoj strukturi BLG-a su dovele do formiranja polimera, gubitka afiniteta za vezivanje retinola i brže degradacije pepsinom. Promene u sekundarnoj strukturi nisu uslovile promene u digestibilnosti i vezivanju retinola. Afinitet sonifikovanih formi za vezivanje IgE antitela i indukciju IgE posredovane aktivacije bazofila i mastocita nije bio narušen...β-lactoglobulin (BLG) is the major whey protein of ruminant species, but is also present in the milk of many other species. It is well known that BLG has many benefitial functional properties such as gelling, foaming and emulsifying properties. Although, BLG is considered to be a valuable protein in view of nutritional science, and is frequently used as an additive in food industry, BLG is known to be a potent allergen responsible for milk allergy; around 45% of patients allergic to milk are sensitive to BLG. Hence, it is strongly desirable to develop new methods that would decrease the allergenicity and enhance the functional properties of BLG. Also, all the research in the field of food science can not exclude the presence of other components in the food matrix. The subject of this thesis was to examine the impact of the interactions formed between food matrix components (protein-polyphenol compounds) and selected food processing techniques (ultrasound and enzyme cross-linking) on the structure and function of BLG. In the paper, non-covalent interactions between polyphenolic compounds from extracts of coffee, cocoa, green and black tea and BLG are characterized. It is shown that due to the formation of non-covalent interactions between polyphenolic compounds and BLG, protein digestibility is reduced and total antioxidant capacity is masked. Treatment of BLG by high intensity ultrasound generated stable modified protein forms with marked changes in the secondary and tertiary structure. Temperature control during treatment had a determining effect on the type of modification. Striking changes in the tertiary structure of BLG led to the formation of polymers, the loss of affinity for retinol binding and degradation by pepsin. Alterations in the secondary structure did not cause changes in digestability and retinol binding..