20.500.12556/DKUM-46613 Manipulation of chitosan binding on the polyethylene terephthalate (PET) surface and study of coatings on poultry meat shelf life-time Manipulacija vezave hitozana na površino polietilen tereftalata (PET) in vpliv premazov na podaljšanje roka trajanja piščančjega mesa The aim of this study was to activate inert PET surfaces in order to introduce the surfaces’ carboxyl groups and to obtain its hydrophilic character, which was important for the chitosan bonding to it. Films where chitosan was attached to the PET could be used as active packaging material for food like fresh poultry meat. For PET activation two advanced and environmentally friendly techniques were used: 1) O2 plasma activation; and 2) CO2 plasma activation. Differently treated PET foils deposited on Au quartz crystals (model studies - adsorption and desorption) and real films were characterized. Later on, real films were studied in the terms of carboxylic/amino group content, hydrophobic/hydrophilic character, surface composition and adsorption/desorption of chitosan onto/from the surface. Results clearly showed that the use of both surfaces’ activation processes increased the ability of PET foils to adsorb chitosan, but CO2 plasma gave a higher concentration of carboxyl groups on the PET surface and consequently, due to the chemical bonding the chitosan layers were more stable. Even though CO2 plasma pre-treated PET foils gave better results during the experimental work, we could not avoid layer by layer adhesion of chitosan which resulted in non-bound molecules. Pre-treated foils and with chitosan functionalized foils were tested preliminarily with ASTME E1 (2002) microbiological tests. Functionalized CO2 plasma pre-treated foils gave the broadest spectra of antimicrobial activity, and therefore they were chosen for further microbiological analyses, where chitosan`s influence on inoculated poultry models towards selected standard strains, typical for poultry meat, was being tested. By determining the MIC (minimal inhibitory concentration) for selected microorganisms we have proven, that chitosan possesses antimicrobial properties at low concentrations. During the transfer of the experiment to a larger scale (food models, which are a very complex environment), it has been shown that on PET bonded chitosan did not have the inhibitory effect to that extent, with the exception of Staphylococcus aureus, as was expected. Similar results were expressed using both these methods: Colony count technique and real-time PCR. In the end, the organoleptic properties of the chicken models exposed to foils have shown that chitosan changes the color and taste of meat immediately after exposure, but samples were staying edible longer. Therefore, functionalized PET, which has an inhibitory influence towards variety of microorganisms, may be applied as an active packaging system for poultry meat after some optimization of the coating procedure in binding chitosan onto the PET surfaces. Cilj raziskave je bil aktivirati inertno PET površino, s čemer smo posledično na njej pridobili karboksilne funkcionalne skupine, ki pomembno prispevajo k hidrofilnosti folije. Karboksilne skupine na površini predstavljajo vezavna mesta za hitozan, ki predstavlja osnovno komponento premaza s protimikrobnim učinkom. PET z vezanim polimerom bi se zaradi svojih lastnosti, tako lahko uporabil za izdelavo aktivne embalaže za pakiranje svežega perutninskega mesa. PET površino smo aktivirali z dvema naprednima in okolju prijaznima tehnologijama: i) O2 plazma in ii) CO2 plazma. Pri raziskavah smo se osredotočili na dve skupini filmov in sicer na model (študija adsorpcije in desorpcije) ter realne filme. Slednje smo proučili z vidika: vsebnost karboksilnih / amino skupin, hidrofoben / hidrofilen značaj, površinsko sestavo in adsorpcijo / desorpcijo hitozana na / iz PET. Rezultati kažejo, da se z uporabo pred- obdelovalnih procesov (plazma) povečuje sposobnost PET folij za absorpcijo hitozana na njihovo površino. Ugotovili smo, da CO2 plazme daje več karboksilnih skupin na površini PET in posledično hitozan močneje veže nanjo. Le-tega je pri spremljanju desorpcije z različnimi metodami, možno dlje časa detektirati. Pred testiranjem na modelih smo določili MIK (minimalna inhibitorna koncentracija), za vsak izbran mikroorganizem, s čemer smo dokazali protimikrobno aktivnost hitozana. Vse predobdelane in funkcionalizirane folije so bile s testom ASTM E1 (2002) preliminarno ovrednotene z vidika protimikrobnega učinka na izbranih standardnih sevih. Ugotovili smo, da ima s CO2 plazmo predobdelana in funkcionalizirana folija najširši spekter protimikrobne aktivnosti in smo jo zato uporabili za vsa nadaljnja in vivo testiranja. Pri tem smo uporabili klasične mikrobiološke gojitvene metode in PCR v realnem času. Med prenosom poskusa na živilski model, ki predstavlja zelo kompleksno okolje, se je izkazalo, da hitozan z izjemo bakterij vrste Staph. aureus, ni imel pričakovanega protimikrobnega učinka. Ugotovili smo tudi, da je meso spremenilo barvo in okus v stiku s hitozanom, vendar so kljub vsemu vzorci so ostali dlje časa uporabni. Na podlagi rezultatov sklepamo, da bi lahko funkcionalizirani PET s skrbnim načrtovanjem formiranja ovojnine in vezave hitozana nanjo, morebiti v prihodnosti uporabljali kot aktivno embalažo za pakiranje perutninskega mesa. PET/chitosan/antimicrobial packaging/adsorption-desorption kinetics/microbiological tests PET/hitozan/protimikrobna embalaža/kinetika adsorpcije/desorpcije/mikrobiološko testiranje true true false [T. Tkavc] Angleški jezik Slovenski jezik Doktorska disertacija 2014-10-14 23:13:45 2014-10-22 10:52:41 2022-05-18 03:07:21 2021-05-05 03:34:57 2014 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 [544.72.023.2:678.742.2.06]:664(043.3) 18180374 URN:SI:UM:DK:FVNF55TU DR_Tkavc_Tina_2014.pdf DR_Tkavc_Tina_2014.pdf 1 E01E168ADFE747E0501E194772AABE49 4e8cc46791f889152bbb022102dbef45e937c71d86394fcd1e4a834870059ae0 5f75db2d-7c0b-11eb-bb7a-00155d0001ca https://dk.um.si/Dokument.php?lang=slv&id=68367 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0