Utjecaj ultrazvuka visokog intenziteta na fizikalna i reološka svojstva kravljeg i sojinog mlijeka

master's thesis

• Title (english): Influence of high intensity ultrasound of physical and rheological properties of cow’s milk and soymilk
• Author: Dragana Travica
• 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: 2011-02-09, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Cilj ovog istraživanja bio je ispitati utjecaj ultrazvuka visokog intenziteta, nominalne snage od 400 W i konstantne frekvencije od 24 kHz, na fizikalna i reološka svojstva kravljeg i sojinog mlijeka. Praćen je utjecaj sljedećih parametara ultrazvuka: amplitude (A = 37,5; 50; 62,5; 75; 87,5; 100 %), vremena obrade mlijeka (t = 2; 6; 10; 15 minuta) i ciklusa (c = 0,6; 0,8; 1) na promjenu temperature, pH-vrijednosti i gustoće. Promjene prividne viskoznosti, koeficijenta konzistencije, indeksa tečenja i koeficijenta regresije praćene su pri ovim procesnim parametrima: amplituda (A = 37,5; 50; 62,5; 75; 87,5; 100 %), vrijeme obrade (t = 2; 15 minuta), primijenjeni ciklus (c = 1). Dobiveni rezultati statistički su obrađeni pomoću programskog paketa „Statistica 8“. Dobiveni rezultati pokazali su da je nakon obrade ultrazvukom došlo do značajnog povećanja temperature kravljeg i sojinog mlijeka, sniženja pH vrijednosti kravljeg mlijeka i povećanja pH-vrijednosti sojinog mlijeka, pada gustoće kravljeg mlijeka te rasta gustoće sojinog mlijeka. Utjecaj ultrazvuka je najznačajniji na promjenu temperature. Obrada ultrazvukom nije utjecala na promjenu tipa tečenja kravljeg i sojinog mlijeka. Oba mlijeka su zadržala nenewtonski karakter, odnosno karakterizira ih dilatantan tip tečenja.

Abstract (english)

Main purpose of this research was to study the influence of high-intensity ultrasound with nominal power of 400 W and constant frequency of 24 kHz on physical and rheological properties of cow’s milk and soymilk. Changes in temperature, pH and density were measured under following conditions: amplitude (A = 37,5; 50; 62,5; 75; 87,5; 100 %), processing time (t = 2; 6; 10; 15 minutes) and applied cycle (c = 0,6; 0,8; 1), while changes in viscosity, consistency coefficient and flow index were measured under these conditions: amplitude (A = 37,5; 50; 62,5; 75; 87,5; 100 %), processing time (t = 2; 15 minutes), applied cycle (c = 1). Obtained results were processed in the „Statistica 8“ software and indicated that the most significant influence of ultrasound on cow’s milk and soymilk is on the increase of temperature. In addition, ultrasound treatment decreased pH values of cow’s milk and increased pH values of soymilk, decreased density of cow’s milk and increased density of soymilk. Cow’s milk and soymilk displayed non-Newtonian dilatant flow, and it remained dilatant after ultrasound treatment.

• Keywords: ultrazvuk; kravlje mlijeko; sojino mlijeko; fizikalna svojstva; reološka svojstva
• Keywords (english): ultrasound; cow's milk; soymilk; physical properties; rheological properties
• Language: croatian
• URN:NBN: urn:nbn:hr:159:069654
• Study programme: Title: Biotechnology; specializations in: Biochemical Engineering; Course: Biochemical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer biotehnologije; smjer biokemijsko inženjerstvo (diplomirani inženjer biotehnologije; smjer biokemijsko inženjerstvo)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-30 10:10:53