Utjecaj djelovanja ultrazvuka visokog intenziteta na fizikalna svojstva suspenzija kukuruznog škroba

master's thesis

• Title (english): Influence effect of high intensity ultrasound on physical properties of corn starch suspension
• Author: Tomislav Zalar
• Mentor: Mladen Brnčić (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Process Engineering); (Laboratory for Unit Operations); Zagreb
• Defense date and country: 2009-05-29, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Svrha ovoga rada bila je ispitati utjecaj djelovanja ultrazvuka visokog intenziteta pri frekvenciji od 24 kHz u ultrazvučnoj kupelji intenziteta (2-3 W/cm 2 ), te ultrazvukom sa direktno uronjenom sondom nominalne izlazne snage (100, 300 i 400 W) u vremenu od 15 i 30 minuta na reološka, teksturalna, termofizička i neka fizikalna svojstva kukuruznog škroba. Praćeni su reološki parametri: koeficijent konzistencije, indeks tečenja, prividna viskoznost te maksimalna viskoznost i početak želatinizacije; termofizikalni parametri- temperatura početka i završetka želatinizacije te entalpija želatinizacije; teksturalni parametri-čvrstoća, adhezivnost kohezivnost, elastičnost i gumastost. Također su određeni i kapacitet bubrenja, indeks topljivosti škrobova te mutnoća pripremljenih suspenzija. Vrijednosti prividne viskoznosti su znatno veće kod modelnih suspenzija, pripremljenih sa nativnim škrobom, u odnosu na modelne otopine kukuruznog škroba tretirane ultrazvukom visokog intenziteta. Povećanjem nominalne snage ultrazvuka kojim su obrađene suspenzije kukuruznog škroba, povećava se kapacitet bubrenja u odnosu na nativne suspenzije. Čvrstoća kukuruznih škrobnih gelova raste nakon obrade suspenzija kukuruznog škroba ultrazvučnom sondom. Mikrografijom 10%-tnih suspenzija nativnog i ultrazvukom modificiranog kukuruznog škroba, utvrđene su promjene u morfološkoj strukturi škroba nakon tretmana ultrazvukom.

Abstract (english)

The aim of this study was to observe the influence effect of ultrasound frequency of 24kHz in ultrasound bath intensity (2-3 W/cm 2 ) and direct immersed probe of nominal power (100, 300 i 400 W) in duration of 15 and 30 minutes on rheological, textural, thermophiysical and some physical properties of corn starch. Observed rheological parameters: consistency coefficient, flow behaviour index, apparent viscosity, maximum viscosity and beginning of gelatination; termophysical parameters: start and ending temperatures with enthalpy of gelatination; textural parameters: hardness, adhesiveness, cohesiveness, springiness and gumminess. Also measured: swelling capacity, starch melting index and abstruseness of prepared suspensions. Apparent viscosity of model suspensions prepared with native starch is much higher than model solution of corn starch treated with ultrasound of high intensity. Corn starch suspensions treated with higher ultrasound intensity shows higher values of swelling capacity than native suspensions. Hardness of corn starch gel grows after suspensions of corn starch have been treated with ultrasound sond. Micrography of 10% suspensions native and with ultrasound modified corn starch shows changes in morphological structure of starch after treatment with ultrasound.

• Keywords: škrob; ultrazvuk; reološka svojstva; želatinizacija
• Keywords (english): starch; ultrasound; rheological properties; gelatination
• Language: croatian
• URN:NBN: urn:nbn:hr:159:950986
• Study programme: Title: Food Technology; specializations in: Nutrition; Course: Nutrition; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer prehrambene tehnologije; smjer nutricionizam (diplomirani inženjer prehrambene tehnologije; smjer nutricionizam)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-08-31 07:20:50