Moeini, Arash (2020) Fungal and plant metabolites formulated into biopolymers, with anti-mold activity for food packaging. [Tesi di dottorato]

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Abstract

The food mold infestation is an extremely dangerous problem for the health of humans and animals. On the other hand, synthetic polymers massive impact on our life results in a serious problem in the term of both environmental issues and economical cost. Consequently, this project focused on the preparation of the smart packaging by incorporating the bioactive metabolites into eco-friendly biodegradable biofilm, a new frontier in the food packaging industry. As a preliminary investigation among 13 metabolites isolated from bacterial, fungal, and plants, three of them (cavoxin, ungeremine, and α-costic acid) showed the highest inhibition against Penicillium roqueforti and Aspergillus niger, the most common mold of bakery products. Besides, the incorporation potential of those three metabolites into a suitable biopolymer has been studied to generate ‘intelligent food packaging’ for the aim of increasing the quality of packaged food, extending the food shelf-life, improving microbiological safety, and preserving food nutritional values. The first metabolite was cavoxin, the HPLC method was developed to quantify the cavoxin. The qualitative and quantitative analysis of Phoma cava culture filtrates proved that cavoxin production in the stirred condition is significantly higher than the static one. The second metabolite was ungeremine (UNG), firstly encapsulated into the chitosan-tripolyphosphate (CH/TPP/UNG) microbeads and then formulated into the Mater-Bi (MBi) polymer matrix (MBi/CH/TPP/UNG) in both forms the microparticles and films showed 72 h of inhibitions against P. roqueforti. Additionally, ungeremine was directly formulated in polylactic acid and polyethylene glycol (PLA/PEG/UNG) nanofibers. The releasing pattern showed an initial burst release of ungeremine presented in the PEG followed by a sustained release, indicated the ungeremine is present in both the PLA and PEG domains of nanofibers. During the Novamot stage, the synthesis of ungeremine was developed in accordance with large scale production. Besides, the CH/TPP microparticles were successfully scaled up and formulated into the starch-based, transparent and polyester-based grades of MBi by film blowing and compression molding methods. The mechanical tests of the sheets and films generally showed that microparticles increased the stiffness and decreased both stress and strain at break. Finally, α-costic acid (α-CA) was incorporated into polylactic acid (PLA). The Films did not have any antifungal activity due to the strong interaction between PLA and α-CA. Despite, α-costic acid could act as a plasticizer and improve both tensile strength and strain at break.

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