Utjecaji tretmana ultrazvukom pri različitim temperaturama i ciklusima na kakvoću sirutke

master's thesis

• Title (english): Effect of ultrasound at different temperatures and duty cycles on whey quality
• Author: Martina Kos
• Mentor: Rajka Božanić (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Technology of Milk and Milk Products); Zagreb
• Defense date and country: 2012-03-09, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Svrha ovog rada je ispitati utjecaj djelovanja ultrazvuka visokog intenziteta na mikrobiološku kvalitetu i senzorska svojstva nativne slatke sirutke. Uzorci sirutke su tretirani ultrazvukom sa ciklusom od 100%, 80% i 50% kroz 5, 6,5 i 8 minuta samostalno, te u kombinaciji s temperaturom od 35 °C, 45 °C i 55 °C. Korišten je ultrazvuk visokog intenziteta konstantne frekvencije 24 kHz te sonde promjera 7 mm. Mikrobiološka kvaliteta sirutke određivana je mjerenjem ukupnog broja bakterija, broja koliformnih bakterija te kvasaca i plijesni. Svi dobiveni rezultati su uspoređivani sa rezultatima nativne sirutke, te sa uzorcima podvrgnutim srednjoj kratkotrajnoj pasterizaciji (72°C/15s) i niskoj dugotrajnoj pasterizaciji (65°C/30min). Rezultati su pokazali visoku djelotvornost ultrazvuka u kombinaciji sa povišenom temperaturom na inaktivaciju mikroorganizama. Svi uzorci tretirani ultrazvukom bili su senzorski bolje ocjenjeni od netretirane i od pasterizirane sirutke. Najbolji rezultati postignuti su kombinacijom ultrazvuka sa ciklusom od 80% i temperature 55 °C kroz 8 minuta.

Abstract (english)

The purpose of this study is to test the effect of high intensity ultrasound on microbiological quality and sensory properties of native sweet whey. Whey samples were treated with ultrasound with duty cycle of 100%, 80% and 50% through 5; 6,5 and 8 min alone, and combined with a temperature at 35°C, 45°C and 55°C. In this work high intensity ultrasound with constant frequency of 24 kHz, with sonotrodes diameter of 7mm was used. Microbiological quality of the whey were observed through measurement of total number of microorganisms, number of coliform bacteria and number of yeast and moulds. All obtained results were compared with the results of native untreated whey, and samples treated with pasteurization, high temperature-short time (72°C/15s) and low temperature-long time (65°C/30min). Results have shown high efficiency of ultrasound combined with high temperature on the inactivation of microorganisms. All samples treated with ultrasound have shown better sensory rate from untreated and pasteurised whey. The best results were obtained by ultrasound with duty cyle of 80% at 55°C through 8 minutes.

• Keywords: ultrazvuk; sirutka; termoprozvučivanje; kakvoća
• Keywords (english): ultrasonic; whey; thermosonication; quality
• Language: croatian
• URN:NBN: urn:nbn:hr:159:524653
• Study programme: Title: Food Technology; specializations in: Food Engineering; Course: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo (diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-18 07:08:18