Struktura i funkcija proteina mleka modifikovanih u Majarovoj reakciji

Abstract

Majarova reakcija (MR) je spontana reakcija izmeĊu karbonilne i amino grupe i od velikog je znaĉaja u hemiji hrane. Proteini modifikovani u MR imaju poboljšane tehno-funkcionalne osobine i nalaze primenu u prehrambenoj industriji. TakoĊe, strukture Majarovih proizvoda modifikovanih proteina imaju brojne efekte na alergenost proteina hrane. Predmet rada ove disertacije bilo je ispitivanje efekata MR indukovane ultrazvukom ili sušenjem raspršivanjem na fiziĉko-hemijske i tehno-funkcionalne osobine kravlje surutke i kamiljeg mleka, kao i efekata intenzivnog glikovanja u MR na imunološke osobine glavnog alergena kravljeg mleka, β-laktoglobulina (BLG). Kombinovana primena ultrazvuka i makromolekulskog nagomilavanja je znaĉajnije ubrzala MR i glikovanje proteina nego sam ultrazvuĉni tretman. Makromolekulsko nagomilavanje, preko ubrzavanja MR, povećava oksidativne promene na proteinima i formiranje struktura sliĉnih amiloidima. Visoko glikovani proteini surutke su pokazali poboljšanu rastvorljivost u širokom pH i temperaturnom opsegu, kao i povećanu antioksidativnu moć. U kamiljem mleku u prahu sušenom raspršivanjem više temperature (230 °C – 250 °C) su rezultirale većim stepenom MR u odnosu na niže temperature sušenja (190 °C – 210 °C). Poboljšanje tehno-funkcionalnih osobina proteina kamiljeg mleka u prahu, kao što su antioksidativna moć i rastvorljivost, je pozitivno koreliralo sa stepenom MR. Glikovanje BLG u MR, dovelo je do njegovog smanjenog transporta kroz model sistem intestinalne barijere, povećanog preuzimanja od strane dendritskih ćelija, smanjenog luĉenja citokina u mešovitoj kulturi dendritskih ćelija sa CD4+ T-ćelijama, i do smanjene aktivacije bazofila, ukazujući da modifikovanje BLG u MR znaĉajno menja njegovu sudbinu u procesima koji odreĊuju alergenost proteina mleka.

Maillard reaction (MR) is a spontaneous reaction between carbonil and amino group, and it is of high importance in food chemistry. Proteins modified in MR possess improved techno-functional properties and they have application in food industry. MR products of food proteins exert numerous effects on food proteins allergenicity. The subject of this doctoral dissertation was to examine the effects of MR induced by ultrasound or spray-drying on phisyco-chemical and techno-functional properties of cow whey proteins and camel milk proteins, as well as the effects of MR on immunologic properties of major cow milk allergen, β-lactoglobulin (BLG). Combined application of ultrasound and macromolecular crowding enhanced MR to a greater extent than ultrasound treatment alone. Macromolecular crowding indirectly, by enhancing MR, intensified oxidative modifications of whey proteins and formation of amyloid-like structures. Highly glycated proteins exhibited improved solubility in wide pH range, thermal stability and antioxidative power. Upon spray-drying treatment of camel milk, higher temperatures (230 °C – 250 °C) induced higher degree of MR compared to lower drying temperatures (190 °C – 210 °C). Improvement of techno-functional properties of camel milk proteins, such as antioxidative power and solubility, strongly correlated with the degree of MR. Intensive glycation of BLG in MR reduced its transport through the model system of intestinal barrier, increased uptake by dendritic cells and decreased cytokine production in dendritic cells/CD4+ T-cells coculture, as well as reduced basophil activation, indicating that modification of BLG in MR alters its fate in processes crucially involved in allergenicity of milk proteins.