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dc.contributor.authorLarsen, Kjersti Westereng
dc.date.accessioned2015-08-06T10:36:47Z
dc.date.available2015-08-06T10:36:47Z
dc.date.copyright2015
dc.date.issued2015-08-06
dc.identifier.urihttp://hdl.handle.net/11250/295173
dc.description.abstractFeta has been produced in Greece since Homer's days and the original Feta cheese is made from sheep's milk mixed with a maximum of 30 % goat`s milk. One aim of this study was to investigate whether goat's milk was suitable as the main ingredient for Feta type cheese. This was done by comparing two types of milk – goat`s milk and cow`s milk – with regard to cheese making properties and cheese quality. The other aim of this study was to investigate whether the concentration of casein would lead to savings in cheese manufacture and if it would have a positive impact on cheese quality. This was done by using microfiltration to separate the casein fraction in the proteins. The concentrated retentate was then used as part of the cheese milk in manufacture of cheese from concentrated milk. Two types of milk – concentrated (microfiltrated) goat milk and non concentrated goat milk – were compared with regard to cheese making properties and cheese quality. 3 types of Feta type cheese were produced and the production took place over a period of 10 weeks. Type 1 cheese was produced with skimmed, non concentrated cow`s milk and cream from cow`s milk, type 2 cheese was produced with skimmed, non concentrated goat's milk mixed with cream from cow`s milk, and type 3 cheese was produced from the retentate from microfiltrated, skimmed goat's milk mixed with cream from cow`s milk. All types of cheese was manufactured in 2 blocks with 2 vats (2 replicates) in every block with exception of one of the blocks with non concentrated goat`s milk - where only one vat (1 replicate) was produced. All of the 3 types of cheese were following the same cheese making procedure. In order to investigate the meaning of the experimental variables cow`s milk / goat's milk and concentrated goat's milk / non concentrated goat`s milk, regarding cheese manufacture and cheese quality, it was performed multiple chemical analysis. The analysis was performed during the cheese making, in fresh cheese and in matured cheese. In the matured cheese there were also conducted texture analysis and a sensory test conducted by a trained taste panel at TINE. The results showed that there were significant differences both between goat- and cow's milk and between concentrated goat's milk and non concentrated goat`s milk when comparing the cheese milk, cheese making process, fresh and mature cheese. Cheese milk from goat proved to have lower pH, the shortest acidification rate and the shortest renneting time compared to cheese milk from cow. It was observed that the coagulum from goat`s milk was very fragile and was more easily broken than cow's milk coagulum. Cheeses that were made of goat's milk had the lowest dry matter content both in fresh and matured cheese. pH levels in fresh and mature cheese of goat`s milk showed no significant differences compared to fresh and mature cheese of cow's milk. The salt content was highest in the matured cheese from cow's milk. When analyzing the carbohydrates it showed that mature cheese from goat had significantly higher content of lactose. Texture analysis regarding hardness and fracture point showed no differences between cheese from cow's milk and goat's milk. The only significant difference that were found in cheese milk from concentrated and non concentrated goat`s milk was the protein concentration and it was highest in the concentrated milk. Observations of the whey and cheese curd in the vat showed that it was clearly less whey after cutting of the curd of the concentrated milk and the coagulum clumped together quickly when the stirring started. There were found no differences between the two types of milk regarding pH of cheese milk, acidification rate or renneting time. Cheese made from the concentrated goat milk had the highest pH and the highest level of total solids. The cheese made from the concentrated goat's milk had the highest values of ash content, fat content, protein content and content of soluble nitrogen in percentage of total nitrogen. The salt content was not significantly different between the two types of cheese. The results also showed that it was most galactose in the cheese from the non concentrated milk. In this cheese it was found lactose, but no lactose was detected in the cheese from the concentrated milk. Texture analysis of hardness and fracture point showed that cheese from the concentrated milk was the hardest one and also the one with the highest fracture point. After sensory evaluation by a trained panel of sensory judges from TINE the cheese from the non concentrated goat milk was considered the best, both regarding taste and consistency. There was consensus among the judges that the use of goat milk has a positive effect on flavour and aroma. Conclusion: Goat`s milk is a suitable raw material for Feta type cheeses; these cheeses received good feedback from the sensory panel regarding the taste and aroma. Goat`s milk has 8 satisfactory cheese making properties for this type of cheese. Microfiltration can be a suitable process for the production of Feta type cheese if some operations of the cheese making process are adjusted. If the stirring time after the cutting of the coagulum is shortened and the stirring done more gently it will lead to a lower dry matter content and the cheese will be less hard and dry. Fetaost har blitt produsert i Hellas siden Homers dager og råstoffet i den originale Fetaosten er sauemelk iblandet maksimum 30 % geitemelk. I dette prosjektet ble det undersøkt om geitemelk var egnet som hovedråstoff til Fetatype ost ved å sammenligne ost og ysteprosess ved bruk av geitemelk og kumelk. Det ble også undersøkt om oppkonsentrering av kaseinene ville være besparende i ysteprosessen og ha en positiv innvirkning på ostekvaliteten. Dette ble gjort ved å benytte mikrofiltrering til proteinfraksjonering for så å sammenligne ost og ysteprosess ved bruk av retentatet fra filtrert geitemelk kontra ufiltrert geitemelk. Det ble produsert 3 typer Fetatype ost og produksjonen foregikk over en periode på 10 uker. Type 1 ble produsert på skummet, ufiltrert kumelk iblandet fløte fra ku, type 2 ble produsert med skummet, ufiltrert geitemelk iblandet fløte fra ku, og type 3 ble produsert av retentatet fra filtrert, skummet geitemelk blandet med fløte fra ku. I alle typene ost ble det ystet i 2 blokker med 2 kar (2 gjentak) i hver blokk med unntak av den ene blokken til ufiltrert geitemelk – hvor det kun ble ystet ett kar (1 gjentak). Alle ystingene fulgte samme ystingsopplegg. For å undersøke betydningen av forsøksfaktorene kumelk/geitemelk og filtrert geitemelk/ufiltrert geitemelk i forhold til ysteprosessen og ostekvaliteten ble det utført flere kjemiske analyser underveis; under selve ystingen, på fersk ost og på lagret ost. På den lagrede osten ble det i tillegg utført teksturanalyser og en sensorisk test utført av et trenet smakspanel hos TINE. Resultatene viste at det var signifikante forskjeller ved sammenligning av ystemelk, ysteprosess, fersk og lagret ost – både mellom geitemelk og kumelk og mellom ukonsentrert geitemelk og konsentrert geitemelk. Ystemelk fra geit viste seg å ha lavere pH, kortere syrningstid og løpningstid enn ystemelk fra ku. Det ble observert at geitemelk-koagelet var skjørere og gikk lettere i stykker enn kumelkkoagelet. Ost som ble ystet av geitemelk hadde lavest tørrstoffinnhold, både i fersk og lagret ost. pH-verdiene i fersk og lagret ost av geitemelk visste ingen signifikante forskjeller i forhold til fersk og lagret ost av kumelk. Saltinnholdet var høyest i den lagrede osten fra kumelk. Målinger av karbohydrater viste at lagret ost fra geit hadde det signifikant høyeste innholdet laktose. Teksturanalyse av hardhet og bruddpunkt viste ingen forskjell mellom ost fra kumelk og geitemelk.nb_NO
dc.language.isonobnb_NO
dc.publisherNorwegian University of Life Sciences, Ås
dc.rightsNavngivelse-Ikkekommersiell-IngenBearbeidelse 3.0 Norge*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/no/*
dc.subjectFetanb_NO
dc.titleFetatype ost av geitemelknb_NO
dc.title.alternativeFetatype cheese from goat milknb_NO
dc.typeMaster thesisnb_NO
dc.subject.nsiVDP::Technology: 500::Food science and technology: 600nb_NO
dc.source.pagenumber73nb_NO
dc.description.localcodeM-MATnb_NO


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Navngivelse-Ikkekommersiell-IngenBearbeidelse 3.0 Norge
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