Promjene kemijsko-fizikalnih svojstava mlijeka nakon obiranja i pasterizacije

master's thesis

• Title (english): Changes in chemical-physical parameters of milk after purification and pasteurization
• Author: Nives Kalit
• Mentor: Nataša Mikulec (mentor)
• Committee member: Nataša Mikulec (predsjednik povjerenstva)
• Committee member: Neven Antunac (član povjerenstva)
• Committee member: Krešimir Salajpal (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Dairy Science); Zagreb
• Defense date and country: 2018-02-26, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Cilj rada bio je utvrditi utjecaj obiranja i pasterizacije na promjene kemijsko-fizikalnih svojstava mlijeka. Specifični cilj bio je utvrditi razlike za točku ledišta sirovog (ishodišnog), pasteriziranog punomasnog te pasteriziranog obranog mlijeka. Ukupno je analizirano 15 uzoraka mlijeka. Uzorci su analizirani primjenom standardnih i referentnih metoda za određivanje točke ledišta mlijeka i osnovnog kemijskog sastava (udio mliječne masti, laktoze, proteina i suhe tvari, suhe tvari bez masti). U istraživanju sirovo mlijeko imalo je najnižu vrijednost točke ledišta (-0,5226 °C), dok su vrijednosti točke ledišta punomasnog pasteriziranog i punosmasnog obranog mlijeka bile nešto više. Došlo je do porasta vrijednosti točke ledišta u pasteriziranom mlijeku za 0,0019 °C, ali zbog premalog broja analiza (n = 15) taj porast vrijednosti točke ledišta nije bio statistički značajan. Obiranje je također uvjetovalo porast vrijednosti točke ledišta i to za 0,0021 °C. Povrh toga, kao posljedica tehnološkog postupka obiranja utvrđene su značajne (P<0,005) promjene u sastavu obranog mlijeka. Značajno je povećan udio laktoze, proteina te suhe tvari bez masti, dok je udio mliječne masti i suhe tvari značajno (P<0,005) smanjen u obranom mlijeku u odnosu na sirovo i pasterizirano mlijeko. Na temelju rezultata istraživanja može se zaključiti da pasterizacija nije značajno utjecala na promjene osnovnog kemijskog sastava i točke ledišta mlijeka, dok je obiranje utjecalo na promjenu osnovnog kemijskog sastava mlijeka te je neznatno utjecalo na porast vrijednosti točke ledišta.

Abstract (english)

The aim of this paper was to determine the influence of skimming and pasteurization on changes in the chemical-physical parameters of milk. The specific aim was to determine the differences between the freezing point of the initial raw milk, the pasteurized whole milk and the skimmed pasteurized milk. A total of 15 milk samples were analyzed. Samples were analyzed using standard, reference methods for determination of the freezing point of milk and it’s basic chemical composition (milk fat content, lactose, protein and dry matter, non-fat dry matter). In this study, raw milk had the lowest value of the freezing point (-0.5226 °C), while the values of the freezing point of pasteurized and skimmed milk were higher. There was a rise in the value of freezing point in pasteurized milk at 0.0019 °C, but due to the low number of analyzes (n = 15), the increase of the freezing point value was not statistically significant. Skimming also caused an increase of the freezing point value for 0.0021 °C. Moreover, as a consequence of the technological process of skimming, there have been significant (P<0.005) changes in skimmed milk composition. Comparing to fresh raw and pasteurized milk, in skimmed milk lactose, protein and non-fat dry matter has significantly increased, while the milk fat and dry matter has significantly decreased (P<0.005). Based on the results of this research it can be concluded that pasteurization does not have a significant effect on the changes in the basic chemical composition and freezing point of milk, whereas the skimming affects the changes in the basic chemical composition of the milk and can slightly affect the increase in the value of the freezing point.

• Keywords: mlijeko; točka ledišta; kemijski sastav; pasterizacija; obiranje
• Keywords (english): milk; freezing point; chemical composition; pasteurization; separation
• Language: croatian
• URN:NBN: urn:nbn:hr:204:134269
• Study programme: Title: Production and Processing of Milk; Study programme type: university; Study level: graduate; Academic / professional title: magistar / magistra inženjer/inženjerka proizvodnje i prerade mlijeka (magistar / magistra inženjer/inženjerka proizvodnje i prerade mlijeka)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2018-05-08 12:07:43