By-products of the dairy farming as raw material for the biotechnology production of polyhydroxyalkanoates

I Poliidrossialcanoati (PHA) sono poliesteri completamente biodegradabili, prodotti da microrganismi come fonte di energia e di carbonio per la sintesi di nuovo materiale cellulare, utilizzando come substrato materie prime rinnovabili. Questi poliesteri sono considerati potenziali candidati per la sostituzione delle materie plastiche convenzionali. Tuttavia, i più alti costi di produzione dei PHA in confronto a quelli delle materie plastiche derivanti dal petrolio, rappresentano il principale ostacolo per la parziale sostituzione di questi ultimi con i biopolimeri. Gli alti costi sono principalmente dovuti all'utilizzo di colture microbiche pure (in cui sia presente un solo ceppo batterico) e substrati puri e costosi. Nell'ultimo decennio è stato sviluppato un processo di produzione a tre stadi alternativo e potenzialmente a minor costo, basato sull'utilizzo di colture microbiche miste (Mixed Microbials Culture, MMC) e una varietà di substrati organici a costo contenuto o nullo, quali alcuni rifiuti dell’industria agro-alimentare. Il presente studio si è concentrato sulla prima fase del processo di produzione dei PHA da colture miste, la fermentazione acidogenica, utilizzando siero di latte come fonte di carbonio per produrre acidi organici. In particolare questo lavoro ha avuto come obiettivo quello di studiare come diverse condizioni operative utilizzate nella fase di fermentazione acidogenica possono influenzare la concentrazione e il profilo degli acidi organici prodotti. Sono stati valutati anche gli effetti dei diversi profili degli acidi organici sulla fase di selezione della coltura microbica, in termini di capacità di stoccaggio di PHA e composizione polimerica.

Shelf Life Assessment of Fresh Poultry Meat Packaged in Novel Bionanocomposite of Chitosan Incorporated with ZnO nanoparticles synthesized using food industry by-products

Nel settore alimentare viene utilizzata un’elevata quantità di materie plastiche per conservare i prodotti e facilitarne la distribuzione. L’utilizzo di questi polimeri ha un costo ambientale piuttosto elevato, per questo trovare surrogati ecosostenibili diventa sempre più importante. In questa tesi abbiamo testato l’efficacia del confezionamento di un prodotto altamente deperibile, quale carne di pollo, con un biofilm a base di chitosano. Il chitosano è polisaccaride largamente presente in natura, dotato di caratteristiche chimico-fisiche che permettono l’ottenimento di un film con proprietà meccaniche e di barriera simili ai polimeri tradizionali, oltre a possedere attività antibatterica. Abbiamo realizzato film contenenti chitosano e altri biocomposti, quali montmorillonite, nanoparticelle di ossido di zinco e olio essenziale di rosmarino, per un totale di 6 film con diversa composizione. Tramite analisi microbiologiche e chimico-fisiche abbiamo confrontato l’efficacia dei diversi film prodotti rispetto ad un controllo (carne conservata in un contenitore asettico). Le analisi sono state svolte in doppio, a 0, 3, 7, 10, 15 giorni di conservazione ad una temperatura di 4°C. In diversi film abbiamo ottenuto una riduzione significativa rispetto al controllo (p<0,05) della conta totale dei microrganismi mesofili aerobici (TMAM) e delle Enterobacteriaceae. La rilevazione del pH e dell’acidità titolabile ha fornito risultati in linea a quelli microbiologici. I campioni nel biofilm hanno spesso subito una variazione significativa (p<0,05) dell’umidità rispetto al controllo, a causa dell’elevata permeabilità al vapore acqueo. L’analisi dei TBARS non ha spesso riportato differenze significative rispetto al controllo (p>0,05), e quando presenti, è perché il campione era più ossidato del controllo (p<0,05). Invece, è stato ottenuto un miglioramento significativo (p<0,05) dello Hue angle tra i film e il controllo. I risultati ottenuti forniscono le basi per studi aggiuntivi.

Extraction of antioxidants from corn by-products for applications in bio-based polymer matrices

The objective of this dissertation is the evaluation of the exploitability of corn cobs as natural additives for bio-based polymer matrices, in order to hone their properties while keeping the fundamental quality of being fully bio-derived. The first part of the project has the purpose of finding the best solvent and conditions to extract antioxidants and anti-degrading molecules from corn cobs, exploiting room and high-temperature processes, traditional and advanced extraction methods, as well as polar and nonpolar solvents. The extracts in their entirety are then analysed to evaluate their antioxidant content, in order to select the conditions able to maximise their anti-degrading properties. The second part of the project, instead, focuses on assessing chemical and physical properties of the best-behaving extract when inserted in a polymeric matrix. To achieve this, low-density polyethylene (LDPE) and poly (butylene succinate – co – adipate) (PBSA) are employed. These samples are obtained through extrusion and are subsequently characterised exploiting the DSC equipment and a sinusoidally oscillating rheometer. In addition, extruded polymeric matrices are subjected to thermal and photo ageing, in order to identify their behaviour after different forms of degradation and to assess their performances with respect to synthetically produced anti-degrading additives.

Graph-based Vision-Language Model for Multi-Modal Retrieval of Fashion Products

Artificial Intelligence is reshaping the field of fashion industry in different ways. E-commerce retailers exploit their data through AI to enhance their search engines, make outfit suggestions and forecast the success of a specific fashion product. However, it is a challenging endeavour as the data they possess is huge, complex and multi-modal. The most common way to search for fashion products online is by matching keywords with phrases in the product's description which are often cluttered, inadequate and differ across collections and sellers. A customer may also browse an online store's taxonomy, although this is time-consuming and doesn't guarantee relevant items. With the advent of Deep Learning architectures, particularly Vision-Language models, ad-hoc solutions have been proposed to model both the product image and description to solve this problems. However, the suggested solutions do not exploit effectively the semantic or syntactic information of these modalities, and the unique qualities and relations of clothing items. In this work of thesis, a novel approach is proposed to address this issues, which aims to model and process images and text descriptions as graphs in order to exploit the relations inside and between each modality and employs specific techniques to extract syntactic and semantic information. The results obtained show promising performances on different tasks when compared to the present state-of-the-art deep learning architectures.

Oxidative properties of the Iron - Thymine-1-acetic acid - Hydrogen peroxide catalytic system

The oxidation of alcohols and olefins is a pivotal reaction in organic synthesis. However, traditional oxidants are toxic and they often release a considerable amounts of by-products. Here, two IronIII-based systems are shown as oxidative catalyst, working in mild conditions with hydrogen peroxide as primary oxidant. An efficient catalytic system for the selective oxidation of several alcohols to their corresponding aldehydes and ketones was developed and characterized, [Fe(phen)2Cl2]NO3 (phen=1,10-Phenantroline). It was demonstrated that the adoption of a buffered aqueous solution is of crucial importance to ensure both considerable activity and selectivity.The Iron - Thymine-1-acetic acid in-situ complex was studied as catalyst in alcohol oxidations and C-H oxidative functionalization, involving hydrogen peroxide as primary oxidant in mild reaction conditions. The catalytic ability in alcohol oxidations was investigated by Density Functional Theory calculations, however the catalyst still has uncertain structure. The system shows satisfactory activity in alcohol oxidation and aliphatic rings functionalization. The Fe-THA system was studied in cyclohexene oxidation and oxidative halogenations. Halide salts such as NBu4X and NH4X were introduced in the catalytic system as halogens source to obtain cyclohexene derivatives such as halohydrins, important synthetic intermediates.The purpose of this dissertation is to contribute in testing new catalytic systems for alcohol oxidations and C-H functionalization. In particular, most of the efforts in this work focus on studying the Iron - Thymine-1-acetic acid (THA) systems as non-heme oxidative model, which present: •an iron metal centre(s) as a coordinative active site, •hydrogen peroxide as a primary oxidant, •THA as an eco-friendly, biocompatible, low cost coordinating ligand.

Characterization Of Single Use Reactor Used For The Manufacturing Of Formulated Products Within The Pharmaceutical Industry

Mixing is a fundamental unit operation in the pharmaceutical industry to ensure consistent product quality across different batches. It is usually carried out in mechanically stirred tanks, with a large variety of designs according to the process requirements. A key aspect of pharmaceutical manufacturing is the extensive and meticulous cleaning of the vessels between runs to prevent the risk of contamination. Single-use reactors represent an increasing trend in the industry since they do not require cleaning and sterilization, reducing the need for utilities such as steam to sterilize equipment and the time between production batches. In contrast to traditional stainless steel vessels, single-use reactors consist of a plastic bag used as a vessel and disposed of after use. This thesis aims to characterize the fluid dynamics features and the mixing performance of a commercially available single-use reactor. The characterization employs a combination of various experimental techniques. The analysis starts with the visual observation of the liquid behavior inside the vessel, focusing on the vortex shape evolution at different impeller speeds. The power consumption is then measured using a torque meter to quantify the power number. Particle Image Velocimetry (PIV) is employed to investigate local fluid dynamics properties such as mean flow field and mean and rms velocity profiles. The same experimental setup of PIV is exploited for another optical measurement technique, the Planar Laser-Induced Fluorescence (PLIF). The PLIF measurements complete the characterization of the reactor with the qualitative visualization of the turbulent flow and the quantitative assessment of the system performance through the mixing time. The results confirm good mixing performances for the single-use reactor over the investigated impeller speeds and reveal that the filling volume plays a significant role in the fluid dynamics of the system.