Carotenoids: importance of stability in food products

Karotenoidi su pigmenti topljivi u uljima i organskim otapalima, a boja im varira od žute, preko narančaste pa do crvene. Razlikuju se dvije strukturne grupe karotenoida: karoteni i ksantofili. Osnovnu strukturu karotenoida čine kovalentno povezane izoprenske jedinice, a na kraju lanca se nalaze prsten ili otvoreni lanac. Najzastupljeniji karotenoid je β-karoten, a ostali poznatiji karotenoidi su likopen, lutein, zeaksantin. Karotenoidi imaju raznoliku ulogu u prirodi, koriste se za apsorpciju svijetlosti, fotosintezu, fotoprotekciju, opskrbu bojim, zatim kao prekursori vitamina A, te kao bojila za hranu. Neki karotenoidi, bez obzira da li se radi o biljkama ili životinjama, vezani su na proteine i tada dolazi do promjene boje. Karotenoidi lako oksidiraju zbog velikog broja konjugiranih dvostrukih veza, te to dovodi do gubitka boje karotenoida. S obzirom da karotenoidi podlijžu oksidaciji, imaju antioksidativna svojstva, a pri visokom parcijalnom tlaku β-karoten ima prooksidativna svojstva. Karotenoidi su relativno stabilni tijekom skladištenja i rukovanja voćem i povrćem, a tijekom procesiranja su stabilni na toplinu, promjenu pH, te na tretiranje vodom.Carotenoids are pigments soluble in oils and organic solvents, and the they color variate from yellow through orange to red. There are two structural groups of carotenoids: the carotens and xantophyls. The basic structure of carotenoids is covalently linked isoprene units, and at the end of the chain is ring or open chain. The most common caroetnoid is β-carotene, and other important carotenoids are lycopene, lutein, zeaxanthin. Carotenoids have a diverse role in the nature. They absorb light, they are involved in photosynthesis, photoprotection, colour, they are precursors of vitamin A, as well as colorants for food. Some carotenoids, are bonded to protein and than colour changes. Carotenoids are easily oxidized due to large number of conjugated double bonds, and this leads to a loss o colour of carotenoids. Carotenoids have antioxidant properties, but at high partial pressure, β-carotene has prooxidant properties. Carotenoids are relatively stable over the storage and handling of fruits and vegetables, and during processing they are stable to heat, changes in pH, and water treatment