Utjecaj dodatka ekstrakta majčine dušice i protektivne kulture na svojstva i trajnost svježeg sira od sirovog mlijeka

master's thesis

• Title (english): The effect of thyme and protective culture addition on the properties and shelf life of fresh cheese from raw milk
• Author: Lucija Hrvatin
• Mentor: Irena Barukčić (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: 2018-11-28, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Trajnost svježeg sira proizvedenog od sirovog mlijeka je vrlo kratka i može se smatrati dnevnim proizvodom. Stoga je cilj ovog rada bio ispitati hoće li dodatak vodenog ekstrakata majčine dušice i protektivne kulture produljiti trajnost svježeg sira. Svježi sir je proizveden od sirovog mlijeka iz mljekomata, a fizikalno-kemijske, mikrobiološke i spektrofotometrijske analize su provedene određene dane čuvanja. Vodeni ekstrakt majčine dušice je dobiven visokotlačnom tekućinskom ekstrakcijom (eng. Pressurized Liquid Extraction, PLE) pri temperaturi od 160 °C, statičkom vremenu od 5 minuta kroz 3 ciklusa, a u mlijeko je dodan u koncentraciji od 2 % (v/v). Temeljem provedenog istraživanja može se zaključiti da dodatak ekstrakta majčine dušice i protektivna kultura produljuju trajnost svježeg sira na 14 dana u odnosu na kontrolni uzorak čija je trajnost bila 10 dana. Kod svježeg sira s protektivnom kulturom i ekstraktom majčine dušice zabilježena je manja promjena boje u odnosu na sir bez protektivne kulture. Najbolji rezultati senzorske analize dobiveni su za svježi sir s protektivnom kulturom koji je postigao 19,1 bodova u odnosu na svježi sir s ekstraktom i protektivnom kulturom koji je ocijenjen s 16,2 bodova.

Abstract (english)

The shelf life of fresh cheese produced from raw milk is very short and it can be said that it is a daily product. Therefore, the aim of this thesis was to examine whether the addition of water extract of thyme and protective culture will extend the shelf life of fresh cheese. Fresh cheese was produced from raw milk purchased at vending machines, and physico-chemical, microbiological and spectrophotometric analysis were determined for certain storage days. The water extracts of thyme were produced by pressurized liquid extraction (PLE) at the temperature of 160 °C, static time of 5 minutes over 3 cycles and were added in milk at the concentration of 2 % (v/v). In conclusion, addition of thyme extract and protective culture prolongs shelf life of fresh cheese, 14 days compared with 10 days of control sample. Fresh cheese with protective culture and thyme extract shows smaller change of color compered with fresh cheese without protective culture. Best score of sensory evaluations was recorded for fresh cheese with protective culture (19,1) compared with fresh cheese with protective culture and thyme extract that scored 16,2 points.

• Keywords: svježi sir; trajnost; PLE; majčina dušica; protektivna kultura
• Keywords (english): fresh cheese; shelf life; PLE; thyme; protective culture
• Language: croatian
• URN:NBN: urn:nbn:hr:159:359918
• Study programme: Title: Food Safety Management; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka upravljanja sigurnošću hrane (magistar/magistra inženjer/inženjerka upravljanja sigurnošću hrane)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2019-11-14 11:07:22