Influence of different heat treatments on goat milk quality

Kozje mlijeko ima visoko antioksidativno djelovanje koje štiti potrošače od izloženosti oksidacijskom stresu. Također, bogato je brojnim fenolnim spojevima koji su zaslužni za niz metaboličkih aktivnosti. Cilj ovog rada bio je ispitati utjecaj različitih toplinskih tretmana na tvorbu spojeva nastalih u kozjem mlijeku uslijed toplinske obrade (ukupni i slobodni hidroksimetilfurfural), odrediti utjecaj toplinske obrade na antioksidacijski potencijal pomoću DPPH i FRAP metoda te odrediti utjecaj toplinske obrade na udjel ukupnih fenola Folin-Ciocalteu metodom. Osim toga, pomoću SDS- PAGE elektroforeze je određivan stupanj denaturacije proteina pri različitim toplinskim tretmanima mlijeka. Na temelju provedenog istraživanja može se zaključiti da uslijed povećanja intenziteta toplinske obrade dolazi do povećanja koncentracije hidroksimetilfurfurala. Također, uslijed toplinske obrade nastaju spojevi slične strukture kao fenoli i ulaze u reakciju s Folin-Ciocalteu regensom i FRAP reagensom. Dok s druge strane, aktivnost mjerena DPPH metodom je padala što je vezano uz antioksidacijsku aktivnost sastojaka koji su prisutni od početka i dolazi do očekivanog – povećanjem intenziteta toplinske obrade smanjuje se antioksidacijska aktivnost svojstvena mlijeku. Ono što je i bilo za očekivati jest da uslijed toplinske obrade dolazi do denaturacije proteinaGoat's milk has a high antioxidant effect that protects consumers from exposure to oxidative stress. It is also rich in numerous phenolic compounds that are responsible for a number of metabolic activities. The aim of this study was to examine the effect of different heat treatments on the formation of compounds formed in goat milk due to heat treatment (total and free hydroxymethylfurfural), to determine the effect of heat treatment on antioxidant potential using DPPH and FRAP methods and to determine the effect of heat treatment on total Ciocalteu method. In addition, the degree of protein denaturation in various heat treatments of milk was determined by SDS-PAGE electrophoresis. Based on the conducted research, it can be concluded that due to the increase in the heat treatment intensity, the concentration of hydroxymethylfurfural increases. Also, due to heat treatment, compounds with a similar structure as phenols are formed and react with Folin-Ciocalteu reagent and FRAP reagent. While on the other hand, the activity measured by the DPPH method decreased, which is related to the antioxidant activity of the ingredients that are present from the beginning and comes to the expected - increasing the intensity of heat treatment reduces the antioxidant activity inherent in milk. Expectations were that due to heat treatment, protein denaturation occurs