Sprememba arome sirov med skladiščenjem

magistrsko delo

Anja Korošec (Avtor), Irena Kralj Cigić (Mentor), Romana Cerc Korošec (Član komisije za zagovor), Drago Kočar (Član komisije za zagovor)

Povzetek

Aromo živil predstavljajo hlapne organske spojine (HOS). Nekatere izmed njih lahko pomembno vplivajo na profil arome sira, zaradi svoje specifičnosti pa nudijo tudi nedvoumno razlikovanje med njimi. Njihovo določanje je za ugotavljanje kakovosti hrane zelo pomembno. Na profil arome sira lahko vplivajo različni dejavniki, kot so geografski in klimatski pogoji, kvaliteta mleka, tehnološki postopek izdelave, pogoji zorenja sira in pa tudi skladiščenje sira. Pomemben vpliv imajo temperatura, čas, skladiščenje v temi oz. na svetlobi in material, v katerem sir skladiščimo. Razlike v vsebnosti posameznih HOS nastanejo zaradi različnih pretvorb teh spojin in sprememb v samem siru. V siru najdemo prisotne številne skupine HOS, kot so maščobne kisline (MK), ketoni, aldehidi, estri, alkoholi, ogljikovodiki, N-vsebujoče spojine in S-vsebujoče spojine. V glavnem so to produkti procesov, ki se izvajajo med zorenjem sira, kot so lipoliza in proteoliza, ter metabolizem laktoze, laktata in citrata. Pomembna procesa sta tudi metabolizem MK in prostih aminokislin (AK). Na osnovi emisij HOS sem karakterizirala aromo bohinjskih polmehkih sirov Mohant in ugotavljala vpliv skladiščenja sira na prisotne HOS. Spojine sem identificirala in kvantitativno določila s plinsko kromatografijo sklopljeno z masno spektrometrijo. Ekstrakcijo analitov in kromatografsko metodo sem pred meritvijo realnih vzorcev optimizirala. Vzorčenje analitov sem izvajala na dva načina – z direktnim HS vzorčenjem in s kombinacijo HS vzorčenja z mikroekstrakcijo na trdno fazo (HS-SPME). Uporabljala sem sivo trifazno vlakno divinilbenzen-karboksen-polidimetilsiloksan (DVB-CAR-PDMS). Rezultate HS vzorčenja sem uporabila pri preučevanju razmerja analitov v siru, v odvisnosti od časa njihovega skladiščenja. HS-SPME vzorčenje sem uporabila za identifikacijo čim večjega števila spojin. Pomemben faktor pri slednji ekstrakciji je faza, s katero je prevlečeno vlakno, saj neposredno vpliva na vezavo analitov. V siru Mohant sem določila kar precej HOS in s tem okarakterizirala njegovo specifično aromo. Biogenih aminov v vzorcih sira nisem zaznala.

Ključne besede

sir;aroma;hlapne organske spojine;HS-SPME;'Headspace' ekstrakcija;mikroekstrakcija na trdno fazo;plinska kromatografija;magistrska dela;

Podatki

Jezik:	Slovenski jezik
Leto izida:	2023
Tipologija:	2.09 - Magistrsko delo
Organizacija:	UL FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik:	[A. Korošec]
UDK:	543.544.3:637.3(043.2)
COBISS:	159812611
Št. ogledov:	51
Št. prenosov:	11
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	Effect of storage conditions on cheese aroma
Sekundarni povzetek:	The aroma of food is represented by volatile organic compounds (VOCs). Some of them can significantly influence the aroma profile of cheese and due to their specificity also provide a clear unequivocal distinction between them. Their detection is especially important for the determination of food quality. The aroma profile of cheese can be influenced by several factors, e. g. geographical and climatic conditions, milk quality, the technological production process, the ripening conditions of the cheese and also the storage of the cheese. Crucial factors are temperature, time, storage in the dark or in the light and the material in which the cheese is stored. Differences in the content of the individual VOCs result from different transformation of these compounds and from changes in the cheese itself. Many groups of VOCs are present in cheese, such as fatty acids (FA), ketones, aldehydes, esters, alcohols, hydrocarbons, N-containing compounds and S-containing compounds. They are mainly the products of processes that take place during cheese ripening, such as lipolysis and proteolysis, as well as the metabolism of lactose, lactate and citrate. FA and the metabolism of free amino acids (FAA) are also important processes. Based on VOCs emissions, the aroma of Mohant semi-soft cheeses from Bohinj was characterized and the influence of cheese storage on the VOCs present was determined. The compounds were identified and quantified using gas chromatography coupled with mass spectrometry. Before real sample measurements, the extraction of analytes and chromatographic method were optimized. Analytes were sampled in two ways - with direct HS sampling and with a combination of HS sampling and solid phase microextraction (HS-SPME). Grey three-phase fiber divinylbenzene-carboxene-polydimethylsiloxane (DVB-CAR-PDMS) was used. The results of HS sampling were used to investigate the ratio of analytes in cheese as a function of storage time. HS-SPME sampling was used to identify as many compounds as possible. A key factor in the latter extraction is the phase with which the fiber is coated, as it directly affects the binding of the analytes. An entire range of VOCs in Mohant cheese was determined and thus, its specific aroma was characterized. Biogenic amines in the cheese samples were not detected.
Sekundarne ključne besede:	cheese;aroma;HS-SPME;gas chromatography;Univerzitetna in visokošolska dela;
Vrsta dela (COBISS):	Magistrsko delo/naloga
Študijski program:	1000375
Konec prepovedi (OpenAIRE):	1970-01-01
Komentar na gradivo:	Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemija
Strani:	116 str.
ID:	19425920