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Vpliv sirišča na kakovost sirov
Pušnik, Anja (Author), Čanžek Majhenič, Andreja (Mentor) More about this mentor... This link opens in a new window, Perko, Bogdan (Co-mentor)

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Abstract
Za mleko, ki ga želimo predelati v sir, veljajo glede kakovosti še ostrejše zahteve kot za mleko, ki ga predelujemo v konzumno mleko. Sestavine mleka morajo oblikovati takšne fizikalno-kemijske lastnosti, ki dopuščajo normalno usirjanje, hkrati pa omogočajo tehnološko koristnim mikroorganizmom (MO) ustrezno življenjsko okolje. Pri izdelavi sira pogosto uporabljamo industrijska sirišča, pridobljena iz siriščnikov telet (živalskega izvora), poznamo pa tudi rastlinske koagulante in mikrobiološka sirišča, kakršna smo uporabili tudi v našem poskusu. Po tehnološkem postopku za edamski sir smo izdelali 50 sirov, od tega polovico z obstoječim siriščem v prahu in polovico z novim, tekočim siriščem. Kakovost izdelanih sirov smo primerjali z vidika senzoričnih parametrov, kjer smo ocenjevali zunanji videz, barvo, testo, prerez, vonj in okus sirov ter z vidika fizikalno-kemijskih parametrov, kjer smo spremljali vsebnost maščob, beljakovin, suhe snovi, vlage, soli in maščobe v suhi snovi. Fizikalno-kemijske analize sirov smo izvedli v 4-ih časovnih intervalih, in sicer na svežem siru takoj po izdelavi ter po 10-ih, po 20-ih in po 150-ih dneh zorenja. Ne glede na uporabljeno sirišče so rezultati fizikalno-kemijskih analiz sirov pokazali zelo podobne vrednosti posameznih parametrov v vseh štirih časovnih intervalih. Siri so namreč zoreli v foliji, ki preprečuje izhajanje vlage iz sira ter v glavnem ohranja konstantne fizikalno-kemijske parametre v celotnem časovnem obdobju. Po drugi strani pa uporaba novega sirišča ni pozitivno vplivala na senzorično kakovost sirov, saj so bile povprečne ocene senzorične analize sirov, izdelanih z novim siriščem, v vseh štirih časovnih intervalih nižje od ocen senzorične analize sirov, izdelanih z obstoječim siriščem.

Language:Slovenian
Keywords:mleko, analize mleka, sirišče, mikrobiološko sirišče, tekoče sirišče, sirišče v prahu, koagulacija, tehnološki postopki, sir, edamec, fizikalno-kemijske analize, senzorične analize, senzorične lastnosti
Work type:Master's thesis/paper (mb22)
Tipology:2.09 - Master's Thesis
Organization:BF - Biotechnical Faculty
Year:2017
Publisher:[A. Pušnik]
UDC:637.334.2:543.2/.9
COBISS.SI-ID:4822904 Link is opened in a new window
Views:692
Downloads:330
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Secondary language

Language:English
Title:The effect of rennet on cheese quality
Abstract:
Quality demands for cheese milk are more rigorous then demands for drinking milk. Milk components should provide such physicochemical characteristics that allow normal coagulation and provide proper environmental conditions for technologically important microorganisms (MO). During the cheese production industrial rennet, obtained from calf rennet (animal origin) is usually used. On the other hand vegetable coagulants and microbial coagulants are also known, and the latest were used in our study. According to technological process of making the Edam cheese, we made 50 cheeses, half of which were made by the use of the existing powder rennet and half of them by the use of new liquid rennet. The quality of cheeses were than evaluated in terms of sensory parameters, where we scored appearance, color, consistency, cross section, smell and flavor; and in terms of physicochemical parameters, where we analyzed content of fats, proteins, dry matter, moisture, salt and fats in dry matter. Physicochemical analyses of cheeses were performed in four time intervals. First analysis was made on freshly made cheese and then after 10, 20 and 150 days of ripening. Regardless on the rennet used, the results of the physicochemical analyses showed very similar contents of the individual parameters in all four time intervals. All cheeses have been ripening in foil, which is known to prevent the loss of moisture from the cheese and maintains constant physicochemical parameters in the entire time period of cheese ripening. On the other hand, there was no positive effect of the use of new rennet on the sensory quality of the cheeses. The average scores of the sensory analysis of cheeses made with new rennet were lower than ratings of the sensory analysis of cheeses made with existing rennet in all four time intervals.

Keywords:milk, milk analysis, rennet, microbial rennet, liquid rennet, powder rennet, coagulation, cheese-making technology, cheese, Edam, physicochemical analysis, sensory analysis, sensory properties

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