Kajmak je srpski autohtoni mlečni proizvod koji se prevashodno izraĎuje u domaćoj radinosti. Odlikuje se specifičnim sastavom i senzornim svojstvima, na osnovu kojih se može svrstati u grupu delikatesnih mlečnih proizvoda, koji se nalaze izmeĎu sireva i maslaca. MeĎutim, izrazita raznolikost uslova u kojima se proizvodi rezultira u izrazito velikom variranju sastava i kvaliteta kajmaka, koja onemogućavaju njegov organizovan i širi nastup na tržištu. Proces formiranja kajmaka može se podeliti na toplu i hladnu fazu. U toploj fazi, usled površinske aktivnosti masti i proteina, kao i intenzivnog isparavanja vode, dolazi do formiranja početne pokožice, koja predstavlja osnovu i gornji sloj kajmaka, dok u hladnoj fazi dolazi do obogaćivanja pokožice mlečnom mašću, pri čemu se formira donji sloj kajmaka.
Termički tretman mleka zastupljen u proizvodnji kajmaka rezultuje izraženim promenama na proteinskom kompleksu mleka, pri čemu dolazi do denaturacije proteina surutke, stvaranja koagregata p...roteina mleka kao i reakcije denaturisanih proteina surutke sa proteinima iz adsorpcionog sloja globula mlečne masti (MFGM). Usled površinske aktivnosti masti i proteina vrelog mleka dolazi do njihove difuzije i koncentrisanja u graničnom sloju mleko-vazduh. Kazeini se u mleku nalaze u micelarnoj formi i kao takvi pokazuju mali afinitet prema hidrofobnim površinama. Nativni proteini surutke su globularni i sporije se adsorbuju. MeĎutim, nakon termičkog tretmana, na temperaturama od 70 do 75°C, proteini surutke denaturišu, pri čemu dolazi do modifikacije sekunadarne i tercijarne konformacije molekula ovih proteina. Ove modifikacije uzrokuju promene njihovih funkcionalnih svojstava, koje se ogledaju u povećanoj površinskoj aktivnosti, izmenjenoj meĎupovršinskoj reologiji, emulzionim i penivim svojstvima i dr.
Ambijentalni uslovi u kojima se izvodi proces formiranja kajmaka predstavljaju značajan faktor u proizvodnji kajmaka. U toku procesa formiranja pokožice i kajmaka mleko se neprekidno hladi i permanentno je u kontaktu sa okolnim vazduhom. U toku procesa hlaĎenja dolazi do razmene energije, odnosno, procesa predaje toplotnog fluksa sa strane vrelog mleka vazduhu, uz istovremeno isparavanje vode iz mleka.
Istraživanja obuhvaćena ovim radom imaju za cilj detaljnije sagledavanje mehanizama formiranja kajmaka, kao i faktora koji utiču na sastav i svojstva proizvoda, a sve u funkciji stvaranja šire naučne osnove u poznavanju postupka formiranja ovog specifičnog mlečnog proizvoda...
Kajmak is a Serbian autochthonous dairy product which is usually manufactured by the traditional production procedure. Kajmak is characterized by specific composition and unique properties and can be classified into the group of delicious dairy products, which takes place between cheese and butter. However, significant differences in the production conditions often result in a very large variations of the kajmak composition and quality, which prevent its widespread and organized appearance on the market. The process of kajmak formation can be divided into hot and cold phases. In the hot phase, due to the surface activity of proteins and fats, as well as the intense water evaporation, the formation of the initial skin layer occurs, which represents the base and the top layer of the final product (kajmak). In the cold phase, initial skin is being enriched by milk fat, resulting in the formation of the lower layer of the kajmak.
Heat treatment of milk, which is present in the kajmak produ...ction, results in the significant changes in milk protein complex, such as the denaturation of whey proteins, formation of milk protein coaggregates as well as reaction of denatured whey proteins and milk fat globule membrane (MFGM). Due to the strong surface activity, milk fat globule and proteins diffuse to the top layer of milk and concentrate at the air-milk interface. Casein, due to its micellar form, has minor affinity for hydrophobic surfaces compared with individual components of casein micelles or casein preparations. Native whey proteins are globular and hence shows a little surface activity. However, milk heat treatment at temperatures between 70°C to 75°C cause denaturation of whey proteins as well as modification of their secondary and tertiary structure. These modifications cause changes in their functional properties, which result in the increasing of surface activity, altered interfacial rheology, emulsion and foaming properties and others.
Environmental conditions represent an important factor in the overall kajmak production. During the process of the initial skin and kajmak formation, milk is continuously being cooled and permanently is in contact with the surrounding air. During the cooling process there is high energy exchange, i.e. the process of heat flux exchange from the hot milk to the surrounding air. At same time, there is the evaporation of water from milk.
The aim of this research was detailed investigation of the kajmak forming mechanisms, as well as factors that influence the composition and properties of this specific dairy product...
