Formulation of functional edible films enriched with polyphenolic extracts of secondary plant materials

Godišnje se na svjetskoj razini proizvodi velika količina sekundarnih biljnih sirovina, što za prehrambenu industriju predstavlja veliki izazov u smislu kružnog gospodarstva i njihove valorizacije. Cilj ovog rada bio je analizirati polifenolni sastav ekstrakata šest sekundarnih biljnih sirovina (kora banane, ljuska luka, ljuska oraha, ljuska kakovog zrna, mahuna graška, kora cikle) te polifenolne ekstrakte istih primijeniti u formulacijama jestivih filmova uz dodatak biljnih proteina (riža, kikiriki, bundeva). Za karakterizaciju polifenolnog sastava i antioksidacijskog kapaciteta ekstrakata korištene su spektrofotometrijske metode i metoda tekućinske kromatografije visoke učinkovitosti (HPLC-DAD). Kreirano je 28 funkcionalnih jestivih filmova za čiju je karakterizaciju korištena ista metodologija kao i za ekstrakte, a dodatno su određene i njihove fizikalne karakteristike (debljina, boja, tekstura). Najbolja bioaktivna svojstva pokazao je ekstrakt kore banane, kao i jestivi film formuliran s tim ekstraktom. Dodatak proteina kikirikija značajno je povećao udio polifenola i antioksidacijska svojstva filma baziranog na ekstraktu kore cikle. Sve ispitivane sekundarne biljne sirovine pokazale su se kao dobri izvori specifičnih polifenolnih spojeva i kao takve imaju značajan potencijal za širu primjenu u prehrambenoj industriji.Annually, a large amount of secondary plant materials is produced worldwide, which represents a great challenge for the food industry in terms of the circular economy and their valorization. The aim of this work was to analyze the polyphenolic composition of six extracts of secondary plant materials (banana peel, onion peel, walnut shell, cocoa bean shell, pea pod, beetroot peel) and to apply their polyphenolic extracts in the formulations of edible films with the addition of plant proteins (rice, peanuts, pumpkin). Spectrophotometric and high-performance liquid chromatography (HPLC-DAD) methods were used to characterize the polyphenol composition and antioxidant capacity of the extracts. 28 functional edible films were created for the characterization of which the same methodology was used as for the extracts, and their physical characteristics (thickness, color, texture) were also determined. The best bioactive properties were shown by the banana peel extract, as well as the edible film formulated with this extract. The addition of peanut protein significantly increased the content of polyphenols and antioxidant properties of the film based on beetroot extract. All examined secondary plant raw materials proved to be good sources of specific polyphenolic compounds and as such have significant potential for wider application in the food industry