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Cilj ovog rada je bio pripremiti bioaktivne dodatke hrani na bazi proteina smeđe riže u kombinaciji s fenolima aronije (kompleks proteini/aronija). U tu svrhu se provelo kompleksiranje proteina smeđe riže i soka aronije te kompleksiranje proteina smeđe riže, disaharida (saharoze i trehaloze) i soka aronije. Disaharidi su korišteni s ciljem utvrđivanja da li njihova prisutnost poboljšava adsorpcija fenola na proteine. Pripremljenim kompleksima određen je udio adsorbiranih fenola, proantocijanidina i antocijana. Također je određena i antioksidacijska aktivnost pomoću DPPH, ABTS, FRAP i CUPRAC metode, te parametri boje dobivenih kompleksa. Najveća količinu fenola, proantocijanidina i antocijana određena je u enkapsuliranim uzorcima nastalim kompleksiranjem proteina riže i aronije te proteina riže/trehaloze i aronije. Najveću antioksidacijsku aktivnost pokazali su enkapsulirani uzorci nastali kompleksiranjem proteina riže/aronije i trehaloze. Najmanja ukupna promjena boje uočena je kod uzoraka nastalih kompleksiranjem aronije/saharoze i proteina riže. Strukturne promjene na dobivenim kompleksima u odnosu na čisti protein određene su snimanjem IR spektra. The aim of this study was to prepare bioactive food additives based on brown rice proteins in combination with chokeberry phenols (protein/chokeberry complex). For this purpose, complexation of brown rice proteins and chokeberry juice and complexation of brown rice proteins, disaccharides (sucrose and trehalose) and chokeberry juice was performed. Disaccharides were used to determine whether their presence enhances phenol adsorption on proteins. The content of adsorbed phenols, proanthocyanidins and anthocyanins was determined on the prepared complexes. Antioxidant activity was determined using DPPH, ABTS, FRAP and CUPRAC methods. Color parameters of the obtained complexes were determined as well. The highest amount of phenol, proanthocyanidins and anthocyanins was found on encapsulated samples formed by the complexation of proteins and chokeberry and proteins/trehalose and chokeberry. The highest antioxidant activity was evaluated for encapsulated samples formed by complexation of proteins/chokeberry and trehalose. The lowest total color change was observed in samples formed by complexation of chokeberry/sucrose and rice protein. Structural changes of complexes in comparison to proteins were determined by monitoring of IR spectra.

Cilj rada bio je utvrditi utjecaj tipa šećera (saharoze i trehaloze) i količine šećera (5 %, 10 % i 15 %) na antioksidacijsku aktivnost modelnih otopina eugenola nakon pripreme i tijekom skladištenja. Antioksidacijska aktivnost pripremljenih sustava određena je primjenom DPPH, ABTS i CUPRAC metoda. Primjenom CUPRAC i DPPH metode u modelnim otopinama eugenola s dodatkom trehaloze utvrđeno je linearno smanjenje antioksidacijske aktivnosti, a u otopinama s dodatkom saharoze linearno povećanje s povećanjem udjela dodanog šećera. Primjenom ABTS metode u oba slučaja je utvrđeno da je s povećanjem dodanog šećera došlo do povećanja antioksidacijske aktivnosti. The aim of the study was to determine the effect of the sugar type (sucrose and trehalose) and the amount of sugar (5%, 10% and 15%) on the antioxidant activity of eugenol model solutions after preparation and during storage. The antioxidant activity of the prepared systems was determined using DPPH, ABTS and CUPRAC methods. Using CUPRAC and DPPH method in eugenol model solutions with the addition of trehalose linear decrease of the antioxidant activity occurred while in solutions with addition of sucrose linear increase of antioxidant activity was observed under the same conditions. With application of ABTS method with increase of sugar amount linear increase of antioxidant activity occurred.

Prehrambeni proizvodi mogu se okarakterizirati specifičnom bojom, aromom i teksturom, a u ovom radu ispitivana je tekstura modelnih sustava guar/šećeri. U ovom radu ispitivan je utjecaj vrste šećera (saharoze i trehaloze) i količine dodanog šećera (30, 40 i 50 %) na parametre teksture modelnih sustava guar/šećeri. Ispitivani parametri teksture su bili: čvrstoća, konzistencija, kohezija i indeks viskoznosti. Rezultati istraživanja su pokazali da je povećanjem dodane količine šećera (40 % i 50 %) došlo do povećanja svih parametra teksture (čvrstoća, konzistencija, kohezija i indeks viskoznosti). Utvrđeno je da je čvrstoća veća u modelnim sustavima s dodatkom trehaloze u usporedbi s modelnim sustavima s dodatkom saharoze. Rezultati istraživanja pokazali su važanost odabira komponenata, u ovom slučaju šećera, prilikom proizvodnje ili formuliranja nekog prehrambenog proizvoda. Food products can be characterized by its specific colour, flavour and texture, and in this study texture of model systems guar/sugars was evaluated. The aim of this work was to examine the influence of sugars (sucrose and trehalose) and the amount of added sugars (30, 40 and 50%) on the textural parameters of guar gum/sugars model systems. Evaluated textural parameters were firmness, consistency, cohesiveness and index of viscosity. By increasing the added amount of sugar (40% and 50%) all textural parameters increased (firmness, consistency, cohesiveness and viscosity index). Comparison of sugar types, firmness of model systems with addition of trehalose were higher than firmness of model systems with the addition of sucrose. Results of this study showed importance of ingredients choice, in this case sugar, for preparation or formulation of food products.

Uz aromu i boju, tekstura je jedno od senzorskih karakteristika proizvoda. U ovom radu ispitivan je utjecaj vrste šećera (saharoze i trehaloze) i količine dodanog šećera (30 %, 40 % i 50 %) na promjenu parametara teksture ksantan modelnih sustava. Ispitivani parametri teksture bili su čvrstoća, konzistencija, kohezija i indeks viskoznosti. Povećanjem dodane količine šećera došlo je do povećanja svih parametara teksture. Usporedbom utjecaja tipa šećera, utvrđeno je da je čvrstoća i konzistencija veća u modelnim sustavima s dodatkom saharoze u odnosu na modelne sustave s dodatkom trehaloze. Što se tiče koheziji i indeksa viskoznosti nije utvrđena razlika ovisno o tipu šećera pri istoj dodanoj količini šećera. Rezultati istraživanja pokazali su da je povećanjem dodane količine šećera prilikom pripreme modelnih sustava došlo do linearnog povećanja parametara teksture. Next to flavour and colour, texture is one of sensory characteristics of food products. The aim of this work was to examine the influence of sugars (sucrose and trehalose) and the amount of added sugars (30%, 40% and 50%) on the textural parameters xanthan model systems. Investigated parameters were firmness, consistency, cohesiveness and index of viscosity. With increase of sugars amount addition, increase of textural parameters occurred. Comparison of type of sugar revelled that firmness and consistency of model systems with sucrose addition where higher than firmness and consistency of model systems with trehalose addition. There was no difference in the cohesiveness and viscosity index depending on the type of sugar at the same amount of sugar. The results of the study showed that with the increase of the amount of added sugar, during the preparation of the model systems, linear increase of the textural parameters occurred.

U ovom radu ispitivan je utjecaj dodatka različitih količina (5, 10 ili 20 %) disaharida (saharoze i trehaloze) na antioksidacijsku aktivnost vanilina tijekom skladištenja od 12 mjeseci pri sobnoj temperaturi. Rezultati su uspoređivani s rezultatima za kontrolni uzorak odnosno s otopinom vanilina bez dodatka šećera. Antioksidacijska aktivnost je određena primjenom ABTS, DPPH i CUPRAC metoda. Vrijednosti dobivene CUPRAC metodom su niže od vrijednosti dobivenih DPPH i ABTS metodama. Antioksidacijska aktivnost uzoraka tijekom skladištenja povećala se u odnosu na početne uzorke. Modelne otopine s dodatkom šećera imale su manju antioksidacijsku aktivnost od otopine vanilina. Povećanjem udjela dodanog šećera, bez obzira na tip šećera, antioksidacijska aktivnost se linearno povećala primjenom DPPH metode. Primjenom CUPRAC i ABTS metode u otopinama trehaloze utvrđeno je linearno smanjenje antioksidacijske aktivnosti, a u otopinama s dodatkom saharoze linearno povećanje s povećanjem udjela dodanog šećera. Rezultati ovog istraživanja pokazuju važnost odabira sastojaka prilikom formuliranja prehrambenih proizvoda obzirom da njihove interakcije mogu utjecati na antioksidacijsku aktivnost proizvoda. The aim of this research was investigation of the influence of different amounts (5, 10 or 20%) of disaccharides (saccharose and trehalose) on antioxidant activity of vanillin during storage for 12 months at room temperature. The results were compared with the results for the control sample, vanillin solution without the addition of sugar. The antioxidant activity was determined by ABTS, DPPH and CUPRAC methods. Values obtained from CUPRAC were lower than values obtained by DPPH and ABTS methods. Antioxidant activity of the samples increased during storage in regards to the initial sample. The sugar-containing solutions had lower antioxidant activity than the vanillin solution. By increasing amount of added sugar, despite of the type of sugar, antioxidant activity increased when the DPPH method was used. Using the CUPRAC and ABTS method in trehalose solutions, linear decrease of antioxidant activity was determined, while in solutions with saccharose addition linear increase occurred with increase of added sugar. Results of this research indicated importance of formulation of food products, since selected ingredients through interactions could affect antioxidant activity of the product.

U radu su ispitivani modelni sustavi ksantan/saharoza i ksantan/trehaloza s dodatkom eugenola. Cilj rada bio je odrediti antioksidacijsku aktivnost modelnih sustava i utvrditi utjecaj tipa šećera na antioksidacijsku aktivnost eugenola u modelnim sustavima te odrediti parametre teksture. Osim toga, ispitivan je i utjecaj skladištenja na antioksidacijsku aktivnost eugenola u modelnim sustavima. Antioksidacijska aktivnost određena je DPPH, ABTS i CUPRAC metodom. Najveće vrijednosti antioksidacijske aktivnosti otopine eugenola dobivene su ABTS metodom, a najmanje CUPRAC metodom. Tip šećera, ali i metoda utjecali su na dobivene vrijednosti antioksidacijske aktivnosti. Od parametara teksture određeni su čvrstoća, elastičnost i adhezija. Vrsta šećera imala je utjecaj na parametre teksture. This paper examined the model systems of xanthan/sucrose and xanthan/trehalose with the addition of eugenol. The aim of the work was to determine the antioxidant activity of the model systems and influence of sugars on the eugenol antioxidant activity in the model systems. Also, textural parameters were determined. Antioxidant activity was determined using DPPH, ABTS and CUPRAC method. The highest values of eugenol antioxidant activity were obtained by ABTS method and the lowest by CUPRAC method. Sugar type as well as method for evaluation of antioxidant activity affected results. Hardness, elasticity and adhesion were determined as textural parameters. Textural parameters were dependent on the type of sugar.

U radu su ispitivani modelni sustavi ksantan/saharoza i ksantan/trehaloza s dodatkom vanilina. Ispitivana je antioksidacijska aktivnost modelnih sustava te utjecaj tipa šećera na antioksidativnu aktivnost vanilina u modelnim sustavima te parametri teksture. Osim toga, ispitivan je i utjecaj skladištenja na antioksidativnu aktivnost vanilina u modelnim sustavima. Antioksidativna aktivnost određena je DPPH, ABTS i CUPRAC metodom. Utvrđeno je da modelni sustav ksantan/trehaloza ima veću antioksidativnu aktivnost. DPPH metodom utvrđena je najveća antioksidacijska aktivnost, a CUPRAC metodom najmanja. Tijekom skladištenja antioksidativna aktivnost sustava se je smanjila. Od parametara teksture određeni su čvrstoća, elastičnost i adhezija. Modelni sustav ksantan/saharoza imao je veće vrijednosti ispitivanih parametara u odnosu na sustav ksantan/trehaloza. Tijekom skladištenja od 12 mjeseci utvrđeno je smanjenje parametara u oba sustava. The model system xanthan/saccharose and xanthan/trehalose with the addition of vanillin were investigated in this work. The antioxidant activity of model system has been tested alongside with testing the influence of various types of sugar on the antioxidant activity of vanillin in model systems. Furthermore, texture parameters and the influence of the system's storage have also been evaluated. Antioxidant activity was evaluated by DPPH, ABTS and CUPRAC method. It has been noted that the model system xanthan/trehalose had higher antioxidant activity. The highest antioxidant activity has been found using the DPPH method and the lowest has been found using the CUPRAC method. During the storage, antioxidant activity decreased. Hardness, elasticity and adhesion were evaluated among textural parameters. Model system xanthan/saccharose had higher values of all parameters in comparison to xanthan/trehalose system. During 12 months storage all parameters decreased in both model systems.

Trehalose is an important disaccharide which takes a major role of a stress protector in many organisms, including green algae and lower plants. It has long been thought that trehalose functions in higher plants are marginal and that they have been overtaken by sucrose. In the last years it has been discovered that trehalose takes on a lot of important physiological roles in vascular plants metabolism. It is an important signal metabolite of sucrose availability and maintains sucrose concentrations within an appropriate range. It also contributes to starch synthesis and degradation and to synthesis of organic acids. Trehalose-sucrose nexus was found to be very important in plant interactions with pathogenic organisms and herbivorous insects. Furthermore, trehalose is involved in response of plant to abiotic stressors such as drought, cold, salinity and hypoxia. It contributes in regulation of stomatal conductivity where it interacts with abscisic acid. All this makes trehalose an important primary metabolite which significantly influences plant growth and development such as induction of flowering and stimulation of photosynthesis.

Cilj rada bio je ispitati termofizička svojstva modelnih sustava hidrokoloida (guara, ksantana) i šećera (saharoze, trehaloze) u temperaturnom području od -60 °C do 140 °C. Termička analiza uzoraka provedena je pomoću diferencijalnog motridbenog kalorimetra, a praćeni su parametri staklastog prijelaza, kristalizacije i taljenja. Iz rezultata se može zaključiti da su temperature faznih prijelaza kod istovrsnih sustava bile niže, što je viši udio suhe tvari. U modelnim sustavima ksantan-trehaloza razlika u srednjoj (midpoint) temperaturi staklastog prijelaza između sustava (0,6 % ksantana + 30 % trehaloze) i (0,6 % ksantana + 50 % trehaloze) iznosila je 2 °C, a u sustavima guar-trehaloza pri istim koncentracijama i manja (1,3 °C). U modelnim sustavima ksantan-saharoza pad srednje temperature staklastog prijelaza kod spomenutih koncentracija bio je 6,2 °C, odnosno 6,7 °C u sustavu guar-saharoza. Povećanjem udjela suhe tvari (dodavanjem šećera) došlo je do sniženja vrijednosti entalpija faznih prijelaza u svim uzorcima, a vrijednosti su niže u sustavima sa saharozom. U ispitivanim modelnim sustavima nije bilo značajne razlike u DSC parametrima između hidrokoloida. The aim of this study was to investigate the thermophysical properties of model systems of hydrocolloids (guar, xanthan) and sugars (sucrose, trehalose) in a temperature range from -60 °C to 140 °C. Thermal analysis of samples was performed using a differential scanning calorimeter, and the parameters of the glass transition, crystallization and melting were studied. The findings of this study indicate that the temperatures of phase transitions at the same systems were lower, with the higher the proportion of dry matter. In model systems of xanthan and trehalose difference in the midpoint glass transition temperature between the system (0.6% of xanthan + 30% trehalose) and (0.6% of xanthan + 50% trehalose) was 2 °C, and in the systems guar- trehalose at the same concentrations and lower (1.3 °C). In model systems of xanthan-sucrose drop of midpoint glass transition temperature in the mentioned concentration was 6.2 °C, and 6.7 °C in the system guar-sucrose. By increasing the content of dry substance (addition of sugars) values of the enthalpy of phase transitions in all samples were decreased. The values are lower in the system with sucrose. In the tested model systems there were no significant differences in the DSC parameters between hydrocolloids.

U ovom radu ispitivan je utjecaj dodatka različitih količina (5, 10 ili 20%) disaharida (saharoza, maltoza ili trehaloza) na udio fenola, antocijana i antioksidativnu aktivnost liofiliziranih kaša od višanja. Rezultati su uspoređivani s rezultatima za kontrolni uzorak odnosno s liofiliziranom kašom od višanja bez dodatka šećera. Najveći udio antocijana imao je kontrolni uzorak. S povećanjem udjela šećera došlo je do smanjenja udjela antocijana, osim u uzorku s dodatkom 20% maltoze koji je imao najveći udio antocijana od svih uzoraka s dodanim šećerom. Udio fenola je također bio najveći u kontrolnom uzorku a najmanji u uzorku s dodatkom 20% trehaloze. Antioksidativna aktivnost je određena primjenom ABTS, DPPH i FRAP metode. Vrijednosti dobivene primjenom ABTS metode su niže od vrijednosti dobivenih DPPH i FRAP metodama. Najveću antioksidativnu aktivnost primjenom navedenih metoda imao je uzorak s dodatkom 20% maltoze. Rezultati ovog istraživanja pokazuju da interakcije unutar kompleksnog matriksa proizvoda utječu na udio fenolnih tvari i antioksidativnu aktivnost proizvoda. The aim of this research was investigation of the influence of different amounts (5, 10 or 20%) of dissacharides (sucrose, maltose or trehalose) on phenolics, anthocyanins and antioxidant activity of freeze-dried sour cherry puree. Results were compared with control sample, freeze-dried sour cherry puree without addition of sugars. The highest anthocyanin content had control sample. With increase of sugar addition, increase of anthocyanin content was observed except in the case of addition of 20% of maltose. That sample had the highest anthocyanin content among samples with sugar addition. The highest phenol content was also determined in control sample, while the sample with 20% of trehalose addition had the lowest content. Antioxidant activity was determined by ABTS, DPPH I FRAP methods. Values of antioxidant activity determined by ABTS were lower in comparison to values obtained by FRAP and DPPH method. The highest antioxidant activity (determined with all methods) had sample with addition of 20% of maltose. Results of this research showed that interactions among food component play important part on phenolics and antioxidant activity.