| Popis: |
U novije je vrijeme prehrambena industrija fokusirana na iskorištavanje agro-otpada u svrhu razvoja novih funkcionalnih proizvoda. Ljuska crvenog luka predstavlja značajan udio takvog otpada, koji je ujedno i bogat izvor različitih funkcionalnih sastojaka, kao što su pektin i polifenolni spojevi. Nastojeći iskoristiti taj bogati sastav, cilj ovog rada bio je ekstrahirati i karakterizirati pektin i polifenolni ekstrakt ljuske crvenog luka (Allium cepa L.) te ispitati njihov inkapsulacijski potencijal metodom ionskog geliranja. Kao nosači za inkapsulaciju korišteni su alginat i kombinacije alginata s pektinom ljuske crvenog luka (u omjeru 80:20, 70:30 i 60:40). Formiranim hidrogel česticama određeni su fizikalno-kemijski parametri, inkapsulacijska učinkovitost te kinetika otpuštanja ukupnih polifenola i antioksidacijskog kapaciteta u simuliranim gastrointestinalnim uvjetima. Dobiveni rezultati potvrdili su da su glavni polifenolni sastojci ljuske crvenog luka kvercetin i derivati kvercetina. Ekstrahirani pektin je visokometilirajući (DE = 53,8 %) i kao takav ne može samostalno formirati stabilne hidrogel čestice. Najveći udjel pektina u stabilnim alginatno-pektinskim inkapsuliranim sustavima je 40 %. U odnosu na hidrogel čestice formirane s čistim alginatom kao nosačem, iste formirane s alginatno-pektinskim nosačima pokazale su bolja svojstva zadržavanja vode, manju elastičnost i tvrdoću, manje su veličine, tamnije boje i pokazuju brži profil otpuštanja polifenola i antioksidacijskog kapaciteta u simuliranim gastrointestinalnim uvjetima. Recently, food industry has focused on exploiting agro-waste for the development of new functional products. Onion peel represents a significant part of all agro-waste, which is also a rich source of various functional ingredients, such as pectin and polyphenol compounds. In order to exploit that rich composition, the aim of this paper was to extract and characterize pectin and polyphenol extract of the onion peel (Allium cepa, L.) and examine their encapsulation potential by using ionotropic gelation method. Pure alginate and alginate-pectin combinations (in proportions of 80:20, 70:30 and 60:40) were used as matrices for encapsulation. Formed hydrogel particles were tested for physical properties, encapsulation efficiency and release kinetics of total polyphenols and antioxidant capacity in simulated gastrointestinal conditions. The obtained results confirmed that the main polyphenol compounds of red onion peel are quercetin and quercetin derivatives and that extracted pectin is high methoxyl pectin with DE = 53.8 % which is not suitable for making stable hydrogel particles. The biggest share of pectin in alginate-pectin matrices that is still able to make stabile hydrogel particle is 40 %. Compared to hydrogel particles formed with pure alginate as matrix, the same form with alginate-pectin matrices showed better water retention properties, lower elasticity and hardness, were smaller and darker. Also, those particles showed faster release profiles of polyphenols and antioxidant capacity in simulated gastrointestinal conditions. |
