Utjecaj ultrazvuka na fermentaciju sirutke acidofilnom i jogurtnom kulturom

master's thesis

• Title (english): The effect of ultrasound on whey fermentation with acidophilus and yogurt culture
• Author: Anja Knežević
• 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: 2014-07-15, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Sirutka je nutritivno visokovrijedan sporedni proizvod u sirarstvu i upravo joj se zbog sastava pridaje sve veće značenje. Cilj ovoga rada bio je odrediti utjecaj ultrazvuka na aktivaciju kulture Lactobacillus acidophilus (La-5) i jogurtne kulture (YC-380); na trajanje fermentacije sirutke te udio proteina i svojstva sirutke – električnu vodljivost, titracijsku kiselost, reološka svojstva i viskoznost. Ultrazvučni tretman ulazne snage 84 W u trajanju od 150 sekundi imao je najbolji učinak na porast broja živih mikroorganizama kultura La-5 i YC- 380. Fermentacija pasteriziranih ili termosonificiranih uzoraka sirutke provedena s La-5 kulturom aktiviranom ultrazvukom skraćena je za pola sata u odnosu na kontrolu (pasterizirana sirutka inokulirana sa netretiranom kulturom), dok kod fermentacije s ultrazvučno aktiviranom YC-380 kulturom nije došlo do skraćenja. Značajnije promjene u svojstvima sirutke nisu uočene, a došlo je do poboljšane topljivosti proteina. Određivanjem reoloških svojstava utvrđeno je da sirutka ima nenewtonski karakter odnosno da ju karakterizira dilatantan tip tečenja. Svi uzorci su senzorski ocjenjeni kao prihvatljivi.

Abstract (english)

Whey is a high-quality nutritional byproduct of cheese production and because of its properties whey is gaining importance. The aim of this study was to determine the effect of ultrasound on activation of cultures Lactobacillus acidophilus (La-5) and yoghurt culture (YC-380); on the fermentation of whey; protein content and properties of whey - electrical conductivity, titratable acidity, viscosity and rheology. Ultrasonic treatment of input power 84 W for 150 seconds had the best effect on the increase in the number of viable microbial cultures La-5 and YC-380. Fermentation of pasteurized or thermo-sonicated whey samples conducted with La-5 culture activated by ultrasound is shortened for half an hour, as compared to control (pasteurized whey was inoculated with untreated culture), while fermentation with ultrasonically activated YC-380 culture didn't affect the duration. Significant changes in the properties of whey were not noticed but improvement of the protein solubilization was detected. Assessement of rheological properties showed that whey has a non-Newtonian character and that it is characterized by the dilatantan type of flow. All samples were organoleptically evaluated as acceptable.

• Keywords: sirutka; fermentacija; ultrazvuk; Lactobacillus acidophilus; jogurtna kultura
• Keywords (english): whey; fermentation; ultrasound; Lactobacillus acidophilus; yogurt culture
• Language: croatian
• URN:NBN: urn:nbn:hr:159:158305
• 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 11:27:41