| Abstract | Boja meda je karakteristično svojstvo svakog meda, a može se pripisati prisutnosti različitih sastavnih molekula meda poput melanoidina, Maillardovih produkata, proteina, polifenola, flavonoida, slobodnih aminokiselina, mineralnih tvari, vitamina i šećera. Međutim koja od gore navedenih klasa molekula ima glavnu ulogu u formiranju boje meda, i u kojoj mjeri joj doprinosi, za sada nije poznato. Upravo iz tog razloga, u ovom završnom radu provedeno je razdvajanje boje i molekula meda primjenom gel filtracije na Sephadexu G-25. Ukupno je analizirano 14 različitih uzoraka meda (3 meda kadulje, 3 lipe, 3 medljikovca, 3 meda bagrema i 2 meda kestena), a prikupljene frakcije analizirane su na boju te sadržaj proteina, reaktivnih amino skupina i ukupnih polifenola. Analizom elucijskih profila ustanovljeno je da se boja meda skuplja od treće do čak 18-te frakcije, pri čemu se uočava dominantni oštri vrh elucije boje centriran u petoj frakciji, dok je dodatni vrh boje nižeg intenziteta raširen u području od sedme do 18-te frakcije. Na temelju podataka o eluciji proteina, reaktivnih amino skupina i ukupnih polifenola, te izračuna površina ispod krivulja, može se zaključiti da glavnina molekula koje doprinose boji meda pripada skupini molekula molekulske mase veće od 5000 Da što uključuje proteine, melanoidine i Maillardove produkte. Međutim, ključno je za naglasiti da na boju meda isto tako značajno utječu i molekule niske molekulske mase, poput polifenola, flavonoida i slobodnih aminokiselina, dok se utjecaj mineralnih tvari i vitamina na boju meda također ne smije isključiti. Nadalje, na temelju izračuna površina ispod krivulje može se zaključiti da boji svjetlijih vrsta meda, poput meda od bagrema, lipe i kadulje, najviše doprinose proteini, melanoidini i Maillardovi produkti, koji čine od 50 do 79 % ukupne boje meda. S druge strane, u slučaju tamnijih vrsta meda, poput meda od kestena i medljikovca, glavni doprinos boji meda dolazi od niskomolekularnih komponenti poput polifenola, flavonoida i slobodnih aminokiselina, dok proteini, melanoidini i Maillardovi produkti doprinose ukupnoj boji meda od 22 do 43 %. |
| Abstract (english) | Honey colour is unique property of each honey, attributed to the presence of various endogenous molecules including melanoidins, Maillard products, proteins, polyphenols, flavonoids, furosine, free amino acids, minerals, vitamins, and sugars. However, which of aforementioned class of molecules plays major role in honey colour, and to what extent it contributes to colour, is still unknown. In this respect, we have separated 14 different honey samples (3 of sage, 3 of lime, 3 of black locust, 3 of honeydew honey, and 2 of chestnut honey) using gel filtration on Sephadex G-25 and analysed for colour, protein, total polyphenol and reactive amino group content. Elution profiles of colour of examined honeys revealed that colour-contributing molecules were spread between third up to 18th fraction, with dominant sharp peak centred at fifth fraction, and additional wide spread peak of quite lower intensity between seventh up to eighteen fraction. On the basis of area under the curve calculation (AUC), and data on protein, total polyphenol and reactive amino group content in fractions, it can be concluded that the great amount of honey colour-contributing molecules belongs to group of molecules with molecular mass greater than 5000 Da, what includes proteins, melanoidins and Maillard products. However, honey colour seems also significantly affected by the amount of low molecular weight compounds such as polyphenols, flavonoids, and free amino acids, while the effect of mineral and vitamins also can not be neglected. Moreover, on the basis of AUC it can be concluded that majority of colour of light honeys, such as black locust, sage and lime honeys, can be attributed to protein, melanoidin and Maillard products fraction which comprise from 50 up to 79% of total honey colour. On the contrary, in the case of dark honeys, such as honeydew and chestnut honey, colour is more dependent on low molecular weight compounds such as polyphenols, flavonoids and free amino acids, where proteins, melanoidins and Maillard products comprise from 22 up to 43% of total honey colour. |
