Promjene stvojstava i kvalitete mlijeka magarice obrađenog različitim režimima toplinske obrade

master's thesis

• Title (english): Changes in the properties and quality of donkey milk processed with different heat treatment regimes
• Author: Valentina Lukenda
• Mentor: Irena Barukčić Jurina (mentor)
• Committee member: Tamara Jurina (predsjednik povjerenstva)
• Committee member: Katarina Lisak Jakopović (član povjerenstva)
• Committee member: Andreja Leboš-Pavunc (član povjerenstva)
• 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: 2022-09-28, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Cilj ovog rada bio je istražiti utjecaj različitih temperaturnih režima na kvalitetu mlijeka magarice; formiranje ukupnog i slobodnog hidroksimetilfurfurala, utjecaj na antioksidacijsku aktivnost (DPPH i FRAP metoda), na količinu ukupnih fenola, kao i na promjene u boji mlijeka magarice, količini ukupnih topljivih tvari i električnoj vodljivosti, te raspodjeli veličine čestica. Istraživanje je provedeno u laboratorijskim uvjetima na sirovom mlijeku magarice, te na uzorcima mlijeka magarice tretiranim različitim temperaturnim režimima (63-65 °C/15 sek, 72 °C/20 sek, 90-95 °C/5 min, 116 °C/15 min). Temeljem dobivenih rezultata može se zaključiti da povećanjem temperature dolazi do povećanja koncentracije ukupnog i slobodnog hidroksimetilfurfurala, koncentracije ukupnih fenola te antioksidacijske aktivnosti mjerene FRAP metodom. Povećava se i količina ukupnih otopljenih tvari i električna vodljivost, a najveće promjene u boji mlijeka izražene su kod uzorka tretiranog pri 116 °C. Također, blisko infracrvena spektroskopija ukazuje na određene kvalitativne promjene strukture pri različitim temperaturnim režimima. Povišenjem temperature dolazi do denaturacije proteina, što pokazuju rezultati SDS elektroforeze.

Abstract (english)

The goal of this paper was to research the influence of different temperature regimes on the quality of donkey milk; formation of total and free Hydroxymethylfurfural, influence on antioxidant activity (DPPH and FRAP method), on the amount of total phenols, as well as on changes in the color of donkey milk, amount of total dissolved solids and electrical conductivity, and particle size distribution. The research was conducted in laboratory conditions on raw donkey milk, and on samples of donkey milk treated at different temperature regimes (63-65 °C/ 15 sec, 72 °C/ 20 sec, 90-95 °C/5 min, 116 °C/15 min. Based on the experimental results, it can be concluded that temperature increase leads to an increase in the concentration of total and free Hydroxymethylfurfural, concentration of total phenols and increase of antioxidant activity measured by the FRAP method. Total dissolved solids and electrical conductivity also increases, and the biggest changes in the color of milk can be seen in samples treated at 116 °C. Likewise, the Near Infrared Spectroscopy shows certain qualitative changes in structure at different temperature regimes. An increase in temperature leads to denaturation of proteins, which has been proven by the results of SDS electrophoresis.

• Keywords: mlijeko magarice; toplinska obrada; hidroksimetilfurfural; antioksidacijska aktivnost; blisko infracrvena spektroskopija
• Keywords (english): donkey milk; heat treatment; Hydroxymethylfurfural; antioxidant activity; Near Infrared Spectrosccopy
• Language: croatian
• URN:NBN: urn:nbn:hr:159:867303
• 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: Open access
• Created on: 2023-02-24 13:53:03