Struktura i svojstva ultrazvukom modificiranog pšeničnog škroba

master's thesis

• Title (english): Structure and properties of ultrasound modified wheat starch
• Author: Tamara Milinković
• Mentor: Suzana Rimac Brnčić (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Food Processes Engineering); Zagreb
• Defense date and country: 2014-06-13, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

U ovom radu ultrazvukom su obrađene vodene suspenzije pšeničnog škroba (10%) (ultrazvučna kupelj, 30 kHz, snaga 170W, vrijeme obrade 30 minuta te s ultrazvučnom sondom , snage 400 W, vrijeme obrade 15 minuta). Proučavan je utjecaj ultrazvučne obrade na morfološke i funkcionalne promjene pšeničnog škroba. Škrobne granule promatrane su skenirajućim transmisijskim mikroskopom (SEM). Određeni su reološki parametri, kristaličnost te raspodjela veličina čestica. SEM mikrofotografije škrobnih granula nakon ultrazvučne obrade su pokazale mala površinska udubljenja i pukotine. Utjecaj ultrazvuka na reološke parametre je jače izražen kod uzoraka obrađenih ultrazvučnom sondom u odnosu na obrađene u ultrazvučnoj kupelji. Takvi efekti su posljedica fizikalnog djelovanja ultrazvuka visokog intenziteta koji se zasniva na fenomenu kavitacije. Nakon ultrazvučne obrade i stupanj kristaličnosti se smanjio. Ultrazvučna obrada predstavlja korisnu metodu za modificiranje svojstava pšeničnog škroba.

Abstract (english)

In this work, aqueous wheat starch suspensions (10.0%) were sonicated (ultrasound bath 30 kHz, power of 170 W, propagation time of 30 min and a 24 kHz ultrasound probe, nominal power of 400 W propagation time of 15 minutes). The effect of sonication on morphological and functional changes of wheat starh were examined. Starch granules were observed under scanning transmission electron microscopes (SEM). Rheological parameters, cristalinity and particle size have been also determined. SEM micrographs of starch granules after modification with ultrasounds in water showed small fissures and depressions on the surface. Influence of ultrasounds on rheological parameters were much more evident in the case of ultrasound treatment with sonotrode than ultrasonic bath. Such effects are caused due to the physical effects of high intensity ultrasound that relies on cavitation phenomenon. After the sonication treatment crystallinity degree were decreased. Sonication presents a useful method to modify properties of wheat starch.

• Keywords: kristaličnost; morfologija; ultrazvuk; pšenični škrob; reološka svojstva
• Keywords (english): cristalinity; morphology; rheological properties; sonication; wheat starch
• Language: croatian
• URN:NBN: urn:nbn:hr:159:497143
• Study programme: Title: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka prehrambenog inženjerstva (magistar/magistra inženjer/inženjerka prehrambenog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-04-28 12:16:16