Effect of low-intensity ultrasound treatment on functional properties of whey proteins isolate

Svrha ovog istraživanja je ispitati utjecaj ultrazvuka niskog inteziteta na proteine sirutke kako bi se poboljšala njihova funkcionalna svojstva. Utjecaj ultrazvuka na fizikalno- kemijska i funkcionalna svojstva proučavao se preko mjerenja temperature, svojstva pjenjenja i emulgiranja. Upotrebljen je ultrazvuk niskog inteziteta (1 W/ cm²). 10 %-tne modelne suspenzije izolata proteina sirutke tretirane su ultrazvučnom kupelji (20 kHz, 15 i 30 minuta). Vrijednosti temperature povećale su se kod svih tretiranja modelnih suspenzija. Ultrazvuk je utjecao na funkcionalna svojstva proteina sirutke, kao što su svojstvo pjenjenja i stvaranja emulzije. Koristeći ultrazvuk frekvencije 20 kHz postignuti su bolji rezultati djelovanjem od 15 minuta nego djelovanjem od 30 minuta. Na reološka svojstva hrane utječu temperatura, procesni parametri, kemijski sastav, te posebno udio i vrsta suhe tvari. Ispitivan je utjecaj izolata proteina sirutke na reološka svojstva 10 %-tnih modelnih suspenzija proteina. Određivanje viskoznosti ispitivanih modelnih sustava provedena su na rotacionom reometru Rheometric Scientific RM- 180. Reološka svojstva ispitivanih suspenzija proteina izražena su reološkim parametrima pomoću Ostwald de Waele- ovog zakona.The aim of this study was to observe the effect of low- intensity ultrasound on whey proteins in order to improve their functional properties. Effect of ultrasound treatment on physicochemical and functional properties was examined by temperature, foaming and emulsifying properties. In this work low- intensity ultrasound (1 W/ cm²) were used. 10 % wt. protein model suspensions of whey protein isolate were treated with ultrasound baths (20 kHz, 15 and 30 minutes). Temperatures incresaed for all whey proteins samples upon ultrasound treatments. Ultrasound affeected functional properties of whey proteins like foaming and emulsion ability. Using ultrasound of 20 kHz frequency had better results were obtained with 15 minute treatment than with 39 minute treatment. Temperature, process parameters, chemical composition, especially the content and the type of solid matteer have a significant influence on the rheological properties of food. The influence of whey proteins isolate on rheological parameters was tested on 10 % whey protein- starch model suspensions. All rheological properties of our suspensions were determinated usinag a rotational viscosimeter, Rheometric Scientific RM- 180. Rheological parameters were determined by Ostwald de Waele power- law model