Dispersion of inorganic fillers in polymeric matrices for food packaging applications

2010 - 2011The objective of this PhD project regards the formulation, preparation and characterization of polymeric materials in which lamellar inorganic solids containing potentially active molecules are dispersed. In particular the present work was aimed at the preparation and characterization of "Active Food Packaging Materials" using inorganic fillers modified with active molecules (antimicrobials, antioxidants) dispersed in polymeric matrices for the realization of: 1) Materials with improved barrier properties to gases and vapors 2) Systems for controlled release of active molecules, act to protect and extend the shelf life of food products. Two techniques of dispersion of active inorganic fillers in polymer matrices have been used, generating: 1) polymeric nanocomposites 2) coatings of polymeric surfaces. A screening of different polymers, from biodegradable and thermoplastic to natural, was done to compare the effect of the fillers and of the dispersion technique on the properties mentioned above.[edited by author]X n.s

Valorization of tomato processing residues through the production of active bio-composites for packaging applications

The present work reports a study aimed at investigating the recovery and the upgrade of tomato processing residues through the preparation of innovative green composites based on tomato peels (TPs) and natural halloysite nanotubes (HNTs) loaded with carvacrol, as a natural antibacterial agent. The loading of carvacrol into HNTs was successfully achieved through a simple procedure that does not involve any chemical modifications of HNTs. Composite films with different amount of HNTs (i.e., 2.5, 5, 10, 20%wt) were prepared using mechanical milling in presence of water, followed by solvent casting method. The structural organization and the main physical properties of the obtained bio-based active composites have been deeply investigated. In particular, thermal and mechanical properties along with the films' interaction with water vapor were assessed and then correlated to the filler loading. Results show that the thermal behaviour of bio-composites improves with the filler loading. Conversely, the mechanical properties get worse, especially at higher loading, due to the poor interaction between HNTs and matrix. The presence of hydrophilic HNTs was found to not dramatically increase the degree of hydrophilicity of the of the materials, most likely due to the presence of hydrophobic carvacrol that acts as an hydrophobic coating for HNTs. The release of carvacrol was also analyzed. Results show that the obtained composites exhibit a long-term release of the antimicrobial agent, which suggests them to be promising candidate materials for food packaging application

Active packaging for table grapes: Evaluation of antimicrobial performances of packaging for shelf life of the grapes under thermal stress

Abstract The paper reports the formulation of an active packaging based on PET coated with a Layered Double Hydroxide (LDH) hosting 2-acetoxybenzoic anion (salicylate) as antimicrobial molecule. The release of the molecule anchored to the LDH, compared to the molecule free dispersed into the coating, appeared much slower. Permeability of carbon dioxide and oxygen through the packaging at different temperatures was evaluated, as well as the capability of the active material to inhibit Pseudomonas, Listeria and Lactobacillus. Table grape was stored in thermal stress conditions (i.e. 10 °C) into the active packaging and the total mesophilic aerobic count and yeasts and moulds population was evaluated up to 14 days of storage. The experimental results were used for a theoretical prediction of shelf life of the packed grapes and compared with the same fruit packed into untreated material. Global and specific migration of salicylic acid from the active packaging demonstrated, in compliance with the migration limits of the EU regulation, the suitability of the considered material for food contact

The AGMA1 poly(amidoamine) inhibits the infectivity of herpes simplex virus in cell lines, in human cervicovaginal histocultures, and in vaginally infected mice

The development of topical microbicides is a valid approach to protect the genital mucosa from sexually transmitted infections that cannot be contained with effective vaccination, like HSV and HIV infections. A suitable target of microbicides is the interaction between viral proteins and cell surface heparan sulfate proteoglycans (HSPGs). AGMA1 is a prevailingly cationic agmatine-containing polyamidoamine polymer previously shown to inhibit HSPGs dependent viruses, including HSV-1, HSV-2, and HPV-16. The aim of this study was to elucidate the mechanism of action of AGMA1 against HSV infection and assess its antiviral efficacy and biocompatibility in preclinical models. The results show AGMA1 to be a non-toxic inhibitor of HSV infectivity in cell cultures and human cervicovaginal histocultures. Moreover, it significantly reduced the burden of infection of HSV-2 genital infection in mice. The investigation of the mechanism of action revealed that AGMA1 reduces cells susceptibility to virus infection by binding to cell surface HSPGs thereby preventing HSV attachment. This study indicates that AGMA1 is a promising candidate for the development of a topical microbicide to prevent sexually transmitted HSV infections

Impaired activation of plasmacytoid dendritic cells via toll-like receptor 7/9 and STING is mediated by melanoma-derived immunosuppressive cytokines and metabolic drift

IntroductionPlasmacytoid dendritic cells (pDCs) infiltrate a large set of human cancers. Interferon alpha (IFN-α) produced by pDCs induces growth arrest and apoptosis in tumor cells and modulates innate and adaptive immune cells involved in anti-cancer immunity. Moreover, effector molecules exert tumor cell killing. However, the activation state and clinical relevance of pDCs infiltration in cancer is still largely controversial. In Primary Cutaneous Melanoma (PCM), pDCs density decreases over disease progression and collapses in metastatic melanoma (MM). Moreover, the residual circulating pDC compartment is defective in IFN-α production.MethodsThe activation of tumor-associated pDCs was evaluated by in silico and microscopic analysis. The expression of human myxovirus resistant protein 1 (MxA), as surrogate of IFN-α production, and proximity ligation assay (PLA) to test dsDNA-cGAS activation were performed on human melanoma biopsies. Moreover, IFN-α and CXCL10 production by in vitro stimulated (i.e. with R848, CpG-A, ADU-S100) pDCs exposed to melanoma cell lines supernatants (SN-mel) was tested by intracellular flow cytometry and ELISA. We also performed a bulk RNA-sequencing on SN-mel-exposed pDCs, resting or stimulated with R848. Glycolytic rate assay was performed on SN-mel-exposed pDCs using the Seahorse XFe24 Extracellular Flux Analyzer.ResultsBased on a set of microscopic, functional and in silico analyses, we demonstrated that the melanoma milieu directly impairs IFN-α and CXCL10 production by pDCs via TLR-7/9 and cGAS-STING signaling pathways. Melanoma-derived immunosuppressive cytokines and a metabolic drift represent relevant mechanisms enforcing pDC-mediated melanoma escape.DiscussionThese findings propose a new window of intervention for novel immunotherapy approaches to amplify the antitumor innate immune response in cutaneous melanoma (CM)

Combined Effect of Active Packaging of Polyethylene Filled with a Nano-Carrier of Salicylate and Modified Atmosphere to Improve the Shelf Life of Fresh Blueberries

Blueberries are popular among consumers for their high nutritional value but are highly perishable due to the microbial decay. The use of active packaging that is able to interact with the food through releasing or absorbing substances can be a valid approach to preserve the quality and increase the fruit’s shelf-life. In this paper, an active packaging based on polyethylene (PE) filled with a nano-carrier of salicylate was prepared and characterized. Fresh blueberries were packaged in passive modified atmosphere packaging (pMA) for 13 days at 8 °C. The combination of the active filler in bulk and pMA showed a significant inhibition of mold development and a reduction of the respiration rate of fruits. Moreover, the release of salicylate on blueberries did not alter the fruits’ sensory traits and preserved the firmness and the nutritional quality. Finally, the combination of active packaging and pMA resulted a valid solution to extend blueberries’ shelf-life up to 13 days

PET and Active Coating Based on a LDH Nanofiller Hosting p-Hydroxybenzoate and Food-Grade Zeolites: Evaluation of Antimicrobial Activity of Packaging and Shelf Life of Red Meat

Layered double hydroxide (LDH) nanofillers were considered as hosts of p-hydroxybenzoate as an antimicrobial molecule for active coating. A food grade resin with LDH-p-hydroxybenzoate and two different types of food grade zeolites was used to prepare active coatings for Polyethylene terephthalate (PET) trays. The release kinetics of the active molecule were followed using UV spectrophotometry and the experimental results were analyzed with the Gallagher–Corrigan model. The thermal properties of the coating mixtures and the PET coating were analyzed and found to be dependent on the coating’s composition. On the basis of CO2 transmission rate and off-odors tests, the best coating composition was selected. Global migration in ethanol (10% v/v), acetic acid (3% w/v), and vegetable oil, and specific migration of p-hydroxybenzoic acid revealed the suitability of the material for food contact. Antimicrobial tests on the packaging demonstrated a good inhibition against Salmonella spp. and Campylobacter jejuni. Red meat was packed into the selected active materials and results were compared to uncoated PET packaging. Color tests (browning of the meat) and analysis of Enterobacteriaceae spp. and total viable count evolution up to 10 days of storage demonstrated the capability of the considered active packaging in prolonging the shelf life of red meat

Un esperimento riuscito di sintesi tra Architettura e Urbanistica

none2A. Bugatti; V. ErbaA., Bugatti; Erba, MARIA VALERI