Utjecaj ultrazvuka visokog intenziteta na fizikalna i teksturalna svojstva suspenzija škroba pšenice

Svrha ovog rada je ispitati utjecaj ultrazvuka visokog intenziteta na fi zikalna i teksturalna svojstava suspenzija škroba pšenice. Ispitivane suspenzije pripremljene su sa 10 % pšeničnog škroba te su neposredno nakon pripreme tretirane ultrazvukom. Sva ispitivanja provedena su prije i nakon ultrazvučne obrade u ultrazvučnoj kupelji frekvencije 22 kHz, nominalne snage 150 W te ultrazvučnom sondom frekvencije 24 kHz, nominalne snage 100, 300 i 400 W. Vrijeme ultrazvučne obrade svih uzoraka bilo je 15 i 30 minuta. Određena su teksturalna svojstava suspenzija pšeničnog škroba, kapacitet bubrenja (KB) i indeks topljivosti škrobova (IT). Tretman ultrazvukom uzrokovao je značajne promjene teksturalnih svojstava škrobnih gelova (elastičnosti, kohezivnosti, adhezivnosti i gumenosti), pri čemu je povećanje vremena ultrazvučne obrade modelnih suspenzija pšeničnog škroba dovelo do povećanja čvrstoće nastalih gelova. Kapacitet bubrenja i indeks topljivosti nakon obrade ultrazvukom visokog intenziteta povećavao se primjenom veće nominalne snage ultrazvuka i duljim vremenom obrade ultrazvukom. Najveći kapacitet bubrenja i indeks topljivosti pšeničnog škroba uočen je kod nominalne snage ultrazvuka od 300 W. Mikrografija modelnih suspenzija je pokazala narušavanje strukture i smanjenje veličine promatranih škrobnih granula primjenom ultrazvučne obrade.
The aim of this paper was to examine the influence and effect of high power ultrasound on some physical and textural properties of wheat starch suspensions. Suspensions containing ten percent of wheat starch have been treated with ultrasound. All analysis has been carried out before and after power ultrasound treatment. Ultrasound bath of 22 kHz frequency and nominal power of 150 W has been used, as well as ultrasound probe of 24 kHz frequency and nominal power of 100, 300 and 400 W for 15 and 30 minute treatments. The effect of ultrasound on texture profile of wheat starch gels was observed by measuring their textural properties. The swelling power and solubility of wheat starch before and after ultrasonic treatment were also determined. The ultrasound treatment induced changes in springiness, cohesiveness, adhesiveness and gumminess of starch gels, with increase in starch gel hardness by applying longer treatment times. The swelling power and solubility index of wheat starch have risen by applying longer treatment times and higher nominal power of ultrasound, while maximum swelling power and solubility index was achieved by applying nominal power of ultrasound probe treatment at 300 W. Micrographs of model suspensions showed that the use of ultrasound treatment degraded the structure and reduced the size of observed starch granules.