Functional properties of whey proteins after tribomechanical treatment and enzyme hydrolysis

U ovom radu ispitan je utjecaj tribomehaničke obrade i enzimske hidrolize sirutkinih proteina na sposobnost pjenjenja i emulgirajuća svojstva istih. 10%-tnim suspenzijama određeni su čvrstoća pjene, povećanje volumena i stabilnost pjene. Emulgirajuća svojstva ispitana su na modelnim otopinama pri različitim pH-vrijednostima (3, 5 i 7). Praškastim uzorcima određena je veličina čestica, razdioba veličine čestica i specifična površina. Rezultati ispitivanja sposobnosti stvaranja pjene pokazuju da tretirani uzorci izolata stvaraju pjenu većeg volumena i veće stabilnosti u odnosu na netretirane uzorke. Modelne otopine koje pokazuju veću stabilnost pjene pokazuju i veću čvrstoću pjene. Rezultati ispitivanja emulgirajućih svojstava pokazuju da hidrolizati sirutkinih proteina imaju veći indeks aktiviteta emulzije u usporedbi sa netretiranim i tribomehanički tretiranim izolatima pri svim pH-vrijednostima. Hidrolizati također stvaraju stabilnije emulzije u odnosu na tretirane izolate dok stupanj hidrolize iznad 20% ima negativan učinak na emulgirajuća svojstva sirutkinih proteina. Tribomehanička obrada dovodi do značajnog smanjenja veličine čestica i povećanja specifične površine. Sličan učinak ima i enzimska hidroliza, ali u znatno manjoj mjeri.In this work, the influence of tribomechanical treatment and enzyme hydrolysis of whey proteins was examined on their foamability and emulsifying properties. The foam solidity, volume increase and foam stability of 10% suspensions were determined. Emulsifying properties were examined on model suspensions at various pH-values (3, 5 and 7). Particle size as well as their distribution and specific area were determined in powdered samples. The results of examination on the ability of foam production show that treated samples of isolates create a foam with greater volume and stability as compared to untreated samples. Model solutions that show greater foam stability also show greater foam solidity. The results of examination of emulsifying properties show that whey protein hydrolysates have greater emulsion activity index than untreated and tribomechanically treated isolates at all pH-values. Hydrolysates also form emulsions that are more stable as compared to treated isolates while hydrolysis degree above 20% has a negative effect on the emulsificational properties of whey proteins. Tribomechanical treatment leads to significant decrease of particle size and increase of specific area. Enzyme hydrolysis has the similar effect but in a considerable less scale