Utjecaj tribomehaničke mikronizacije na reološka svojstva proteina sirutke

Investigations with powdered whey protein concentrates containing 60 % (WPC-60) or 80 % (WPC-80) of proteins were carried out. In this work proteins were treated using the laboratory equipment for tribomechanical micronisation with three different rotor speeds. Before and after the tribomechanical treatment, the analyses of the particle size and particle distribution as well as the specific area and scanning microscopy were carried out. The influence of tribomechanical treatment as well as hydrocolloid addition on the rheological properties of model systems of whey protein concentrate (10 % of total solid) was studied. Rheological parameters, flow behavior index (n) and consistency coefficient (k) were determined by the power-law model. The results obtained showed that the tribomechanical treatment involves a significant decrease in particle size, a change in particle distribution and an increase in specific area of powdered whey proteins. Systems without hydrocolloid addition were Newtonian, but those with hydrocolloid addition exhibited pseudoplastic properties. The viscosity of model systems containingn tribomechanically treated whey protein concentrates (TWPC) was greater in comparison with the same systems prepared with untreated WPC. Systems with greater amount of proteins (WPC-80) had higher viscosity than the same systems containing lower amount of proteins. Hydrocolloid addition affected an increase of viscosity of model systems prepared with untreated WPC. The most significant increase of consistency coefficient (k) was observed in systems with carboxymethylcellulose (CMC) and addition of a special type of carboxymethylcellulose (CMC E466) known as DIKO, icecream binder 0911-E. In systems containing tribomechanically treated TWPC hydrocolloids had various effects. In systems with guar gum, carragenan, inulin, pectin or amid pectin, viscosity increased in comparison with those prepared with untreated WPC. CMC and DIKO affected a significant viscosity decrease of TWPC model systems, which is the consequence of the interaction between proteins and (CMC) hydrocolloids. The found effects were pronounced more strongly as the rotor speed of TMA equipment was greater.U ovom su radu istraživanja provedena s praškastim koncentratima proteina sirutke koji su sadržavali 60 % (WPC-60) ili 80 % (WPC-80) proteina. Uzorci su obrađeni u laboratorijskom uređaju za tribomehaničku mikronizaciju i aktivaciju pri trima različitim brzinama okretaja rotora. Prije i nakon tribomehaničke obradbe određena im je veličina i razdioba veličine čestica, te specifična površina, a provedena je i pretražna mikroskopija. Utjecaj tribomehaničke obradbe te dodatka hidrokoloida na reološka svojstva koncentrata proteina sirutke ispitivan je na modelnim sustavima koji su sadržavali 10 % suhe tvari. Reološki parametri, indeks tečenja (n) i koeficijent konzistencije (k), određeni su pomo}u modela potencijalne funkcije. Dobiveni su rezultati pokazali da se tribomehaničkom obradbom bitno smanjuje veličina čestica, mijenja njihova razdioba, te povećava slobodna površina praškastih koncentrata proteina sirutke. Sustavi bez dodatka hidrokoloida imali su newtonski karakter, a oni s dodanim hidrokoloidima uglavnom pseudoplastična svojstva. Utvrđeno je da je viskoznost modelnih sustava s dodatkom tribomehanički obra|enih WPC (TWPC) veća nego istih sustava s dodatkom neobrađenih WPC. Sustavi istog udjela suhe tvari, ali s većim udjelom proteina (WPC-80), imali su veću viskoznost od istih sustava s manjim udjelom proteina (WPC-60). Dodatak hidrokoloida utjecao je na povećanje viskoznosti modelnih sustava pripremljenih s neobrađenim WPC, pri čemu je najznačajnije povećanje viskoznosti izraženo koeficijentom konzistencije (k) utvrđeno u sustavu s dodatkom karboksimetilceluloze (CMC) i dodatka specijalnog tipa karboksimetilceluloze (CMC E466, poznate kao DIKO, vezivo za sladoled). U sustavu s tribomehanički obrađenim proteinima sirutke (TWPC) dodatak je hidrokoloida različito utjecao. U onima s guar gumom, karagenom, inulinom, pektinom i amidiranim pektinom viskoznost se pove}ala u usporedbi sa sustavima s neobrađenim WPC, a u onima s CMC i DIKO viskoznost se smanjila, što je posljedica međudjelovanja između proteina i hidrokoloida. Utvrđeni utjecaji bili su to jače izraženi što je bila veća brzina okretaja rotora pri obradbi WPC-a

Utjecaj dodataka stabilizatora na reološka svojstva modelnih sladolednih smjesa

The quality of ice cream is in great extent determined by its sensoric properties. Therefore, it is important to know and to predict the effect of the hydrocolloid and emulsifier addition on the consistency of the ice cream mixtures. In this work, the influence of several carboxymetylcellulose hydrocolloids (DIKO, YO-EH, HVEP) and emulsifier E-420 (mixture of sorbitol, monoglicerids and diglicerids) on the rheological properties of the model ice cream mixture as well as their ability to prevent crystallization and recrystallization were examined. The rheological properties as well as electroconductivity before and after pasteurization were measured at 20 °C. The results of these investigations have shown that the viscosity of all ice cream mixtures significantly increased after pasteurization. All investigated systems exhibited non-Newtonian characteristics. Hydrocolloid YO-EH showed the greatest influence on the rheological properties of the model systems. After pasteurization conductivity increased for all investigated samples. Sensory evaluation have shown that the most acceptable product was that prepared with emulsifier E-420.Kakvoću sladoleda u velikoj mjeri određuju njegova senzorska svojstva, te je važno znati kakav će utjecaj na njih, posebno na konzistenciju, imati dodatak hidrokoloida odnosno emulgatora. U ovom radu ispitan je utjecaj hidrokoloida na bazi karboksimetilceluloze (DIKO, YO-EH, HVEP) i emulgatora (smjesa sorbitola, monoglicerida i diglicerida, E-420) na reološka svojstva modelnih sladolednih smjesa kao i njihova sposobnost da spriječe kristalizaciju i rekristalizaciju vode te u vodi otopljenih tvari. Reološka svojstva određena su u rotacionom reometru Brookßeld DV-IIl kod temperature od 20 °C prije i poslije pasterizacije. Nakon provedene pasterizacije i smrzavanja izmjerena je provodljivost na konduktometru "Iskra " Kranj pri temperaturi od 20 °C. Rezultati ispitivanja su pokazali da je nakon provedene pasterizacije došlo do značajnog povećanja viskoznosti svih modelnih smjesa. Svi sastavi su pokazali nenewtonski karakter. Najveći utjecaj na reološka svojstva modelnih sustava imao je hidrokoloid YO-EH. Mjerenje elektroprovodljivosti pokazalo je da tijekom pasterizacije te smrzavanja dolazi do kontinuiranog rasta provodljivosti. Ocjena senzorskih svojstava pokazala je da se upotrebom emulgatora E-420 dobiva senzorski najprihvatljiviji proizvod

Influence of Tribomechanical Micronisation on the Rheological Properties of Whey Proteins

Investigations with powdered whey protein concentrates containing 60 % (WPC-60) or 80 % (WPC-80) of proteins were carried out. In this work proteins were treated using the laboratory equipment for tribomechanical micronisation with three different rotor speeds. Before and after the tribomechanical treatment, the analyses of the particle size and particle distribution as well as the specific area and scanning microscopy were carried out. The influence of tribomechanical treatment as well as hydrocolloid addition on the rheological properties of model systems of whey protein concentrate (10 % of total solid) was studied. Rheological parameters, flow behavior index (n) and consistency coefficient (k) were determined by the power-law model. The results obtained showed that the tribomechanical treatment involves a significant decrease in particle size, a change in particle distribution and an increase in specific area of powdered whey proteins. Systems without hydrocolloid addition were Newtonian, but those with hydrocolloid addition exhibited pseudoplastic properties. The viscosity of model systems containingn tribomechanically treated whey protein concentrates (TWPC) was greater in comparison with the same systems prepared with untreated WPC. Systems with greater amount of proteins (WPC-80) had higher viscosity than the same systems containing lower amount of proteins. Hydrocolloid addition affected an increase of viscosity of model systems prepared with untreated WPC. The most significant increase of consistency coefficient (k) was observed in systems with carboxymethylcellulose (CMC) and addition of a special type of carboxymethylcellulose (CMC E466) known as DIKO, icecream binder 0911-E. In systems containing tribomechanically treated TWPC hydrocolloids had various effects. In systems with guar gum, carragenan, inulin, pectin or amid pectin, viscosity increased in comparison with those prepared with untreated WPC. CMC and DIKO affected a significant viscosity decrease of TWPC model systems, which is the consequence of the interaction between proteins and (CMC) hydrocolloids. The found effects were pronounced more strongly as the rotor speed of TMA equipment was greater