Food technologies have played a crucial role since the beginning of human civilization. The evolution of food processing and packaging have led to an increase of food quality and safety, improving the quality of human life. Recently, academic research and industries have gained awareness about the economic and environmental impact of conventional technologies. This consciousness oriented the efforts towards more sustainable techniques and materials, paving the way to a new “green era” of food technology. This PhD project is an example of multidisciplinary approach in which food microbiology, biomaterial science, extraction techniques, and statistic tools are synergistically applied to develop and test sustainable protocols and active packaging materials with promising applications in food sector. An outline of the thesis chapters is provided below. Chapter 1 introduces sustainable non-thermal technologies as promising substitutes of conventional thermal treatments to ensure food safety and quality. A focus is dedicated to biodegradable polymers from renewable sources (e.g., agri-food by-products) and their application to produce active packaging films with antimicrobial and antioxidant properties. Moreover, this chapter gives to the readers an overview about the concept of “hurdle technology”. Chapter 2 aims to evaluate cold storage coupled with gaseous ozone as a prospective strategy to inhibit pathogenic and spoilage bacteria growth in food storage cold chambers. The research investigated the impact of gaseous ozone (0.05 ppm, different exposures) on the bacterial contamination of internal surfaces and air in a cold chamber (3°C). The effectiveness of this combination of technologies was also tested in vitro against E. coli, L. monocytogenes, S. enterica Typhimurium, C. jejuni, and P. fluorescens. Chapter 3 focuses on the complex interaction between the properties of biodegradable films and the manufacturing parameters, leading the need for statistical models to describe and predict this interdependence. This study analysed the impact of 8 compositional and drying factors on microstructural and functional properties of films based on chitosan and pectin through a multivariate approach. 32 formulations were developed and the results were analysed through principal component analysis (PCA). An in-depth discussion of the results was provided, highlighting the suitability of multivariate data analysis to predict the technical behaviour of films related to the manufacture process. Chapter 4 explores the use of plant leaf extracts to produce active biodegradable films with antioxidant properties. This research aimed to set up an optimised protocol to extract polyphenols from sage and nettle leaves and to incorporate them into films based on chitosan/hydroxypropyl methylcellulose (CS/HPMC) blend, hence characterising their structural, technical, and antioxidant performances. The results showed that the obtained natural films could be employed as valuable alternative to synthetic plastics with antioxidant activity to prolong the shelf-life of food products. In Chapter 5, cellulose nanocrystals (CNCs) were isolated from orange peel discarded by orange juice industry using an alkaline/H2O2 bleaching followed by sulfuric acid hydrolysis. Extracted CNCs were added as reinforcing agent into CS/HPMC films enriched with lauroyl arginate ethyl (LAE) to produce nanocomposite antimicrobial films. The biocidal activity of the films against E. coli, S. enterica, L. monocytogenes, and P. fluorescens was tested. Overall, nanocomposite films enriched with LAE showed potentiality as a suitable strategy to replace antimicrobial petroleum-derived materials and to valorise discarded orange peels, using food waste to reduce food loss.

Le tecnologie alimentari giocano un ruolo fondamentale fin dall’inizio della civiltà umana. L’evoluzione dei processi e del packaging hanno determinato un aumento della sicurezza e della qualità alimentare, migliorando la vita delle persone. Attualmente, il mondo accademico e l’industria sono divenuti consapevoli dell’impatto ecologico ed economico delle tecnologie convenzionali, spingendoli ad orientarsi verso tecniche e materiali sostenibili e inaugurando l’era “green” delle tecnologie alimentari. Questo progetto di PhD ha avuto lo scopo di sviluppare e testare protocolli e biomateriali attivi sostenibili per applicazioni alimentari attraverso un approccio multidisciplinare comprendente microbiologia alimentare, scienza dei materiali, tecniche estrattive e strumenti statistici. Si riporta una descrizione dei capitoli della tesi. Il Capitolo 1 introduce le tecnologie non termiche come alternativa ai trattamenti convenzionali per garantire la sicurezza degli alimenti. Un particolare focus è dedicato ai polimeri biodegradabili da fonti rinnovabili (sottoprodotti alimentari), impiegati per la produzione di packaging attivo con funzione antimicrobica e antiossidante. Il capitolo introduce inoltre il concetto di “teoria degli ostacoli”. Il Capitolo 2 valuta l’impiego sinergico della refrigerazione e dell’ozono gassoso come strumento per inibire la crescita di batteri ambientali e patogeni all’interno di celle frigo per lo stoccaggio di alimenti. La ricerca ha valutato l’impatto dell’ozono a bassa concentrazione (0.05 ppm, diversi periodi) sulla popolazione batterica presente sulle pareti e nell’aria interna a una cella appositamente costruita. L’efficacia del trattamento è stata testata sulla crescita in vitro di E. coli, L. monocytogenes, S. Typhimurium, C. jejuni, and P. fluorescens. Il Capitolo 3 mette in luce la complessa interazione tra proprietà dei film biodegradabili e parametri di produzione, e quindi la necessità di strumenti statistici che descrivano e predicano in modo efficace tale interdipendenza. La ricerca ha analizzato l’influenza di 8 fattori compositivi e di essiccazione sulle proprietà strutturali e tecniche di film in chitosano e pectina attraverso un approccio statistico multivariato. Sono state sviluppate 32 formulazioni di packaging in base alla variazione dei suddetti parametri e i risultati sono stati analizzati mediante PCA. La discussione dei risultati ha confermato l’idoneità degli strumenti di analisi multivariata per lo studio del comportamento tecnico dei film biodegradabili sulla base del processo produttivo. Il Capitolo 4 esplora il mondo degli estratti vegetali applicati alla produzione di biofilm attivi con funzione antiossidante. E’ stato messo a punto un protocollo ottimizzato per l’estrazione di polifenoli da foglie di salvia e ortica, i quali sono stati incorporati all’interno di film in chitosano e idrossipropil metilcellulosa (CS/HPMC). Le proprietà tecniche e antiossidanti dei film sono state discusse, mettendo in luce la possibilità di impiegare questi film in sostituzione a packaging sintetico per il confezionamento di alimenti sensibili all’ossidazione. Nel Capitolo 5, sono stati isolati nano-cristalli di cellulosa da bucce di arancia di scarto mediante un processo di bleaching alcalino seguito da idrolisi acida. I nano-cristalli sono stati impiegati per la produzione di biofilm nano-rinforzati in CS/HPMC, ai quali è stato aggiunto lauroil etil arginanto con funzione antimicrobica. Le proprietà tecniche e battericide dei film sono state misurate. I film prodotti si sono dimostrati promettenti sostituti di film antimicrobici sintetici. Inoltre, l’utilizzo di bucce di arancia di scarto ha dimostrato come i sottoprodotti alimentari possano impiegati per ridurre lo spreco alimentare.

Ricerca e sviluppo di tecnologie e protocolli innovativi atti a migliorare la sicurezza alimentare e ridurre lo spreco di alimenti / Francesco Bigi , 2022 Apr 22. 34. ciclo, Anno Accademico 2020/2021.

Ricerca e sviluppo di tecnologie e protocolli innovativi atti a migliorare la sicurezza alimentare e ridurre lo spreco di alimenti

BIGI, FRANCESCO
2022

Abstract

Food technologies have played a crucial role since the beginning of human civilization. The evolution of food processing and packaging have led to an increase of food quality and safety, improving the quality of human life. Recently, academic research and industries have gained awareness about the economic and environmental impact of conventional technologies. This consciousness oriented the efforts towards more sustainable techniques and materials, paving the way to a new “green era” of food technology. This PhD project is an example of multidisciplinary approach in which food microbiology, biomaterial science, extraction techniques, and statistic tools are synergistically applied to develop and test sustainable protocols and active packaging materials with promising applications in food sector. An outline of the thesis chapters is provided below. Chapter 1 introduces sustainable non-thermal technologies as promising substitutes of conventional thermal treatments to ensure food safety and quality. A focus is dedicated to biodegradable polymers from renewable sources (e.g., agri-food by-products) and their application to produce active packaging films with antimicrobial and antioxidant properties. Moreover, this chapter gives to the readers an overview about the concept of “hurdle technology”. Chapter 2 aims to evaluate cold storage coupled with gaseous ozone as a prospective strategy to inhibit pathogenic and spoilage bacteria growth in food storage cold chambers. The research investigated the impact of gaseous ozone (0.05 ppm, different exposures) on the bacterial contamination of internal surfaces and air in a cold chamber (3°C). The effectiveness of this combination of technologies was also tested in vitro against E. coli, L. monocytogenes, S. enterica Typhimurium, C. jejuni, and P. fluorescens. Chapter 3 focuses on the complex interaction between the properties of biodegradable films and the manufacturing parameters, leading the need for statistical models to describe and predict this interdependence. This study analysed the impact of 8 compositional and drying factors on microstructural and functional properties of films based on chitosan and pectin through a multivariate approach. 32 formulations were developed and the results were analysed through principal component analysis (PCA). An in-depth discussion of the results was provided, highlighting the suitability of multivariate data analysis to predict the technical behaviour of films related to the manufacture process. Chapter 4 explores the use of plant leaf extracts to produce active biodegradable films with antioxidant properties. This research aimed to set up an optimised protocol to extract polyphenols from sage and nettle leaves and to incorporate them into films based on chitosan/hydroxypropyl methylcellulose (CS/HPMC) blend, hence characterising their structural, technical, and antioxidant performances. The results showed that the obtained natural films could be employed as valuable alternative to synthetic plastics with antioxidant activity to prolong the shelf-life of food products. In Chapter 5, cellulose nanocrystals (CNCs) were isolated from orange peel discarded by orange juice industry using an alkaline/H2O2 bleaching followed by sulfuric acid hydrolysis. Extracted CNCs were added as reinforcing agent into CS/HPMC films enriched with lauroyl arginate ethyl (LAE) to produce nanocomposite antimicrobial films. The biocidal activity of the films against E. coli, S. enterica, L. monocytogenes, and P. fluorescens was tested. Overall, nanocomposite films enriched with LAE showed potentiality as a suitable strategy to replace antimicrobial petroleum-derived materials and to valorise discarded orange peels, using food waste to reduce food loss.
Investigation and development of innovative protocols and technologies to enhance the safety of food and to reduce the food loss
22-apr-2022
PULVIRENTI, Andrea
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