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Razvoj aktivnega pakiranja je posledica potreb sodobnega časa. Koncept aktivne embalaže vključuje interakcijo le-te z živilom preko aktivne spojine v ali na površini embalaže za izboljšanje obstojnosti in kakovosti živila. Cilj dela je bil izboljšati funkcionalnost inertne polipropilenske folije z dvoslojnimi premazi, s prvim slojem na osnovi primarnega ali kvartarnega hitozana in drugim slojem na osnovi naravnih izvlečkov, bodisi rjave alge (Padina pavonica), iglic brina ali listov robide. Pripravili smo folije z različnimi kombinacijami premazov za pridobitev podatkov o vplivu posameznih nanosov ter njihovem učinku pri dvoslojni aplikaciji. Vezavo premazov na folije smo potrdili s tehtanjem folij in z XPS analizo. Določili smo fizikalno-kemijske lastnosti folij, ki so pomembne z vidika pakiranja živil (omočljivost, prepustnost kisika), ter testirali antioksidativni potencial in protimikrobno aktivnost proti S. aureus in E. coli. Prisotnost hitozana ter izvlečkov listov robide in iglic brina je izboljšala antioksidativni potencial folij, medtem ko so veliko slabši antioksidativni potencial izkazale folije s slojem izvlečka alge. Kvartarni hitozan in izvlečka listov robide in iglic brina so izkazali odlično protimikrobno delovanje proti bakteriji S. aureus, proti bakteriji E. coli pa le folija s samostojnim slojem kvartarnega hitozana. Prisotnost tako hitozana kot izvlečkov je pomembna, saj v dvosloju vpelje dobre bioaktivne lastnosti, ključne za koncept aktivne embalaže, prav tako izboljša omočljivost folije oz. zmanjša stični, kot tudi prepustnost kisika, kar je pomembno z vidika funkcionalnosti živilske embalaže. The development of active packaging is a result of the needs of modern times. The concept of active packaging involves its interaction with food through an active compound in or on the surface of the packaging material to improve the shelf-life and quality of food. The goal was to improve the functionality of an inert polypropylene (PP) film with two-layer coatings, with the first layer based on primary or quaternary chitosan and the second layer based on natural extracts, either brown algae (Padina pavonica), juniper needles or blackberry leaves. We prepared films with different combinations of coatings to obtain data on the impact of individual coatings and their effect in a two-layer application. We confirmed the presence of coatings on the films by weighing and by an XPS analysis. We determined the physico-chemical properties of foils, important for food packaging (wettability, oxygen permeability), and tested the antioxidant potential and antimicrobial activity against S. aureus and E. coli. Chitosan and the blackberry leaves and juniper needles extracts improved the antioxidant potential of films, while foils with a layer of algae extract showed a much lower antioxidant potential. Quaternary chitosan and extracts proved excellent antimicrobial activity against S. aureus. Only films with an individual layer of quaternary chitosan proved good antimicrobial activity against E. coli. The presence of both chitosan and extracts is important, as it not only introduces good bioactive properties into the bilayer and is key for the concept of active packaging, but it also improves wettability, i.e. reduces the contact angle, as also oxygen permeability, which are important for the functionality of food packaging. |
