Ugotavljanje antioksidativnih in protimikrobnih lastnosti ekstrakta jabolčnih olupkov, ki ga lahko dodajamo hitozanskemu premazu za živila : magistrsko delo

Mavrič, Nina (avtor), Bavcon Kralj, Mojca (mentor), Godič Torkar, Karmen (komentor), Trebše, Polonca (recenzent)

Uvod: Velik del plastične embalaže uporabljamo kot embalažo za živila. S svojimi stranskimi produkti, ki se sproščajo v živilo, plastična embalaža škodljivo vpliva na zdravje ljudi in živali, poleg tega po masi sodi med glavna onesnaževala okolja. Alternativa plastični embalaži so t. i. jedilni premazi za živila, ki so biorazgradljivi, užitni in sestavljeni iz obnovljivih virov, npr. iz beljakovin, lipidov in polisaharidov ter njihovih kombinacij. Hitozan, derivat hitina, je eden izmed polisaharidov, ki ga lahko uporabljamo kot užitni premaz. Zaradi svoje slabe antioksidativne in protimikrobne učinkovitosti hitozanskemu premazu dodajamo razne dodatke, ki te lastnosti izboljšajo, npr. jabolčni ekstrakt. Namen: Namen magistrskega dela je ugotoviti protimikrobno in antioksidativno delovanje jabolčnega ekstrakta, izdelanega iz domačih jabolk. Metode dela: Najprej smo pregledali obstoječo literaturo, na temelju katere smo nadaljevali z laboratorijskim delom. Iz različnih sort jabolk smo z eksperimentiranjem pripravili jabolčni ekstrakt s čim višjo vsebnostjo klorogene kisline, ki je bila modelna spojina z antioksidativnimi lastnostmi. Le-te smo določili z metodo Folin–Ciocalteu in jih preverili še v primeru raztopin, ki so vsebovale hitozan. Protimikrobno delovanje jabolčnega ekstrakta, standardne raztopine klorogene kisline in raztopine hitozana smo preverjali z določanjem občutljivosti na desetih izbranih sevih standardnih mikroorganizmov in nekaj osamljenih sevov iz jabolka. Rezultati: Z eksperimentalno analizo smo določili optimalen način ekstrakcije. Izmed petih ekstraktov vzorcev domačih sort jabolk in enega vzorca kupljenih jabolk je najvišjo vsebnost klorogenske kisline imela domača sorta Jabolka 2, ki je imel 10-krat boljšo antioksidativno učinkovitost od drugih vzorcev, prav tako je imela tudi boljšo antioksidativno učinkovitost od standardne raztopine klorogene kisline. Raztopina hitozana ni prikazala antioksidativne učinkovitosti. Najboljše protimikrobne lastnosti proti preiskovanim mikroorganizmom, predvsem na standardni bakterijski sev B. cereus in na bakterijska seva B. cereus in S. sciuri, ki smo ju osamili iz jabolk, je imela raztopina hitozan in višje koncentracije jabolčnega ekstrakta, medtem ko standardna raztopina klorogene kisline na nobenega izmed preizkušenih sevov ni delovala inhibitorno. Razprava in zaključek: V primerjavi z drugimi avtorji ima naš jabolčni ekstrakt višje koncentracije klorogene kisline. Antioksidativna učinkovitost našega jabolčnega ekstrakta je primerljiva z rezultati študij drugih avtorjev. Jabolčni ekstrakt ima inhibitorne lastnosti na 40 % preiskovanih mikroorganizmov. Na temelju svojih rezultatov lahko trdimo, da ima jabolčni ekstrakt potencial za dodatek hitozanu kot jedilni premaz. Antimikrobne in antioksidativne lastnosti jedilnega premaza na osnovi hitozana in jabolčnega ekstrakta pa bi se dalo z določenimi dodatki še dodatno izboljšati, kar druge študije že potrjujejo.

• Jezik: Slovenski jezik
• Ključne besede: magistrska dela, sanitarno inženirstvo, jedilni premazi, hitozan, jabolčni ekstrakt, antioksidativno delovanje, protimikrobno delovanje
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: ZF - Zdravstvena fakulteta
• Kraj izida: Ljubljana
• Založnik: [N. Mavrič]
• Leto izida: 2021
• Št. strani: 79 str., [7] str. pril.
• PID: 20.500.12556/RUL-129492
• UDK: 614
• COBISS.SI-ID: 75567875
• Datum objave v RUL: 02.09.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Determination of antioxidant and antimicrobial properties of apple peel extract as possible additive for chitosane based edible coating : master thesis

Izvleček

Introduction: Plenty of plastic material is used as food packaging. It can be released in food and consequently it affects human and animal health. Nowadays, plastic material and microplastics pollution represent one of the major issues on planet Earth. An alternative to plastic packaging are the so called edible coatings for foods, which are biodegradable, edible and composed of renewable sources e.g. from proteins, lipids and polysaccharides or/and their combinations. Chitosan, a derivative of chitin, is one of the polysaccharides that can be used as edible coating. Due to its poor antioxidant and antimicrobial efficacy, various additives are added to the chitosan coating, which have the characteristics of improvement, like apple extracts. Purpose: The aim of this study is the determination of antioxidant and antimicrobial potential of an apple extract, made from home-grown apples without any pesticide treatment. Methods: Firstly, we reviewed the existing literature on the basis of which we continued with the laboratory work. From various varieties of apples, we prepared an apple extract with the highest possible chlorogenic acid (a model compound coming from naturally present apple antioxidants) content through experimentation. The antioxidant activity of apple extract, standard chlorogenic acid solution and chitosan solution was tested by the Folin–Ciocalteu method. The antimicrobial activity of apple extract, reference chlorogenic acid solution and chitosan solution were checked by determining the susceptibility of ten strains of microorganisms to their presence. Results: The optimal method of antioxidants extraction from apples was determined by experimental analysis. Among the five samples extracts of home-grown apple varieties and one sample of purchased apples, the highest content of chlorogenic acid showed the domestic variety Jabolka 2, which had 10 times better antioxidant activity than other apple extracts and also had better antioxidant efficiency than standard chlorogenic acid solution. Chitosan solution did not show antioxidant efficacy. The solution of chitosan and higher concentrations of apple extract had the best antimicrobial properties against the investigated microorganisms, while the standard solution of chlorogenic acid did not have an inhibitory effect on any of the analyzed microorganisms. Discussion and conclusion: Compared to other authors, our apple extract had higher concentrations of chlorogenic acid. The antioxidant efficacy of our apple extract was comparable to the results of studies by other authors. Apple extract had inhibitory properties on 40% of the microorganisms tested. Based on our results, we can claim that apple extract has the potential to improve chitosan based edible coating. However, the antimicrobial and antioxidant properties of chitosan could be further improved with the addition of other additives, which would offer an overall protection of food.

• Ključne besede: master's theses, sanitary engineering, edible coatings, chitosan, apple extract, antioxidative properties, antimicrobial properties