magistrsko delo
Nika Horvat (Author), Ilja Gasan Osojnik Črnivec (Reviewer), Sonja Smole Možina (Mentor), Lidija Fras Zemljič (Co-mentor)

Abstract

V magistrski nalogi smo preučevali protimikrobno delovanje funkcionaliziranih folij v in vitro pogojih s pomočjo standardne metode ISO 22196 in poskušali optimizirati izbrani protokol s poudarkom na ponazarjanju realnih pogojev shranjevanja živil. Pripravili smo funkcionalizirane folije na osnovi polimlečne kisline (PLA) s premazi na osnovi hitozana, izvlečka brina in njune kombinacije v dvoslojnem premazu. Prav tako smo določali omočljivost folij z merjenjem površinsko proste energije (SFE) in stičnega kota z vodo. Funkcionalizirane folije PLA so pokazale dobro protimikrobno delovanje proti gram-pozitivni bakteriji S. aureus in gram-negativni P. fragi ter kvasovki S. cerevisiae, ter šibko delovanje proti gram-negativni E. coli. Optimiziran protokol, kjer smo vzorce inkubirali pri nizki temperaturi, je izrazil šibko oz. ni pokazal nobene aktivnosti proti S. aureus v gojiščih in na modelnem živilu (piščančja salama). Najboljše protimikrobno delovanje sta izkazali foliji PLA s premazom z izvlečkom brina ter kombinacije izvlečka brina in hitozana. Prav tako smo ugotovili, da dodatek izvlečka brina poveča hidrofilnost površine folij, kar nakazuje na to, da bolj hidrofilne folije izkazujejo učinkovitejšo inhibicijo rasti bakterij in imajo izboljšano protimikrobno delovanje. Najbolj jasna je zveza v primeru testnih bakterij S. aureus in P. fragi. Zaključili smo, da je potrebno razviti protokol za ocenjevanje protimikrobnega delovanja folij v prisotnosti živila pri realnih pogojih shranjevanja. Tako bomo dobili še bolj zanesljiv vpogled v protimikrobno delovanje funkcionaliziranih folij za pakiranje živil.

Keywords

aktivna embalaža;funkcionalizirane folije;PLA;hitozan;brin;protimikrobna aktivnost;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [N. Horvat]
UDC: 621.798.1:664.0:579.67:579.24
COBISS: 163102467 Link will open in a new window
Views: 71
Downloads: 21
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Other data

Secondary language: English
Secondary title: Comparison of antimicrobial testing procedures for active food packaging materials
Secondary abstract: In this work, we studied the antimicrobial activity of functionalized foils in in vitro conditions using the ISO 22196 standard method and tried to optimize the chosen protocol with an emphasis on approaching real food storage conditions. We prepared functionalized films based on polylactic acid (PLA) with coatings based on chitosan, juniper extract and their combinations in a two-layer coating. We also determined the wettability of the foils by measuring the surface free energy (SFE) and contact angle with water. The functionalized PLA films showed good antimicrobial activity against gram-positive bacteria S. aureus and gram-negative P. fragis and yeast S. cerevisiae, with a poor activity against gram-negative E. coli. The optimized protocol, where the samples were incubated at a low temperature, exhibited weak or no activity against S. aureus in various media and on the model food product (chicken salami). The best antimicrobial performance was demonstrated by PLA films with a juniper extract coating and a combination of juniper extract and chitosan. We also found that the addition of juniper extract increases the hydrophilicity of the film surface, which suggests that more hydrophilic films exhibit more effective inhibition of bacterial growth and have improved antimicrobial activity. The correlation is most clear in the case of test bacteria S. aureus and P. fragi. We conclude, that it is further necessary to develop a testing protocol for evaluating the antimicrobial activity of films in the presence of food products and in realistic storage conditions. In this way, we can anticipate an even more reliable insight into the antimicrobial action of functionalized foils for food packaging.
Secondary keywords: active packaging;functionalized films;PLA;chitosan;juniper;antimicrobial activity;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages: 1 spletni vir (1 datoteka PDF (XI, 56 str.)
ID: 19884031