Pullulan-based films and coatings for food packaging : Present applications, emerging opportunities, and future challenges

Societal and industrial demands for lower environmental impact, cost effectiveness, and high-performance goods and services are increasingly impacting the choice of technologies which are developed and deployed in consumer products. Like many other sectors, food packaging is moving to new technologies; the use of biopolymers is one of the most promising strategies toward an optimized use of traditional packaging materials (e.g., oil-based plastics) without impairing the goal of extending shelf life. Among other food packaging materials, pullulan is attracting much attention due to its unique features. The goal of this review is to provide an overview of current and emerging applications of pullulan within the food packaging sector. In particular, the functional properties of interest for the food packaging industry will be discussed in light of the physicochemical attributes of this exopolysaccharide. Future challenges that may dictate the successful penetration of pullulan in the food packaging market are also outlined

New active packaging materials based on propolis

The use of propolis as an active compound, successfully exploited primarily in the pharmaceutical field, was intended in this work to set up natural packaging materials. To achieve this goal, coating techniques were used for the deposition of active layers on plastic films and cellulosic sheets. The stability of the so obtained active coatings was evaluated according to the polyphenols degradation over time

Sviluppo di un nuovo coating anti-fog per applicazioni nel settore dell’imballaggio alimentare

Nel presente lavoro \ue8 descritto lo sviluppo di un nuovo coating anti-fog a base di pullulano. Le propriet\ue0 anti-fog sono discusse in termini di bagnabilit\ue0, chimica e morfologia superficiale e propriet\ue0 ottiche (opacit\ue0 e trasparenza). Vengono inoltre presentati i risultati di test di simulazione in cui sono state riprodotte le condizioni di stoccaggio di tipici prodotti alimentari (esempio IV gamma) che causano la formazione della condensa all\u2019interno dell\u2019imballaggio. In tali test, \ue8 stata messa a confronto l\u2019efficacia del coating anti-fog a base di pullulano con quella di due anti-fog commerciali, utilizzando un film di polietilene a bassa densit\ue0 (LDPE) come riferimento. I risultati ottenuti hanno mostrato come il coating di pullulano determini un marcato aumento della bagnabilit\ue0 del substrato plastico su cui \ue8 stato depositato (LDPE), come dimostrato dai bassi valori di angolo di contatto (~ 24\ub0). Pi\uf9 specificamente, questo effetto \ue8 dovuto alle caratteristiche spiccatamente idrofiliche del biopolimero utilizzato, legate principalmente alla presenza di gruppi idrossilici lungo lo scheletro polisaccaridico. I test di simulazione hanno permesso di evidenziare come, a differenza del riferimento e delle due soluzioni commerciali, il coating a base di pullulano favorisca la formazione di un unico strato di acqua, evitando la presenza di piccole goccioline che rappresentano la causa principale dell\u2019effetto \u2018foggy\u2019 determinato dalla diffusione della radiazione incidente. La presente soluzione pu\uf2 rappresentare un\u2019innovazione nel settore, dove gli anti-fog comunemente utilizzati sono additivi di sintesi inglobati direttamente nel polimero, dal quale migrano verso la superficie a contatto diretto con l\u2019alimento

Self-assembled nanostructured biohybrid coatings by an integrated ‘sol–gel/intercalation’ approach

The combination of sol-gel technology and intercalation was investigated in this study as a strategy to develop bionanocomposite hybrid materials in the form of coatings with specifically intended oxygen barrier properties. To this goal, the exopolysaccharide pullulan was used as the organic phase, whereas tetraethyl orthosilicate (TEOS) and Na+-montmorillonite (MMT) were used as the metal alkoxide precursor and the nanobuilding blocks (NBB) for the sol-gel technology and the intercalation process, respectively. Complementary information from XRD and TEM analyses disclosed a new supramolecular organization arising from the self-assembly of NBB and pullulan, with the latter apparently intercalated between the clay platelets. Although affected by a rise in haze, the hybrid coatings exhibited outstanding oxygen barrier properties, with permeability coefficient values (P\u2032O2) ranging from 0.89 mL \u3bcm m-2 (24 h)-1 atm-1 for a filler volume fraction (\u3c6) = 0.017 to an impressive 0.15 mL \u3bcm m-2 (24 h)-1 atm-1 (\u3c6 = 0.095) under dry conditions. Modeling of P\u2032O2 suggested a very tight structure under dry conditions, which yielded an apparent clays aspect ratio (\u3b1) 3c50, whereas in the hydrated state a more realistic \u3b1 3c 100 was restored. This finding was further supported by SEM analysis, which also highlighted partial embrittlement of the final hybrid coatings. This journal i