Jose M. Lagaron

Overview of Active Polymer-Based Packaging Technologies for Food Applications

Abstract There has been a growing interest and effort over the last few years in the development of novel food packaging concepts, which can play a proactive role regarding product preservation, shelf-life extension, and even improvement. Several strategies have been devised to exert a positive action over the packaged foodstuff, including retention of desirable molecules (i.e., aldehydes, oxygen) and release of substances (i.e., carbon dioxide, aromas). These new developments have been generally termed active packaging technologies. However, many of these emerging active packaging technologies are finding in the versatility and special properties of plastic materials an efficient vehicle to exploit and enhance their commercial interest. This overview examines the most recent developments and technologies designed to include the active principle within the plastic packaging materials and generally termed active plastics technologies. Due to the novelty of most of these active packaging developments, the s...

Structural characteristics defining high barrier properties in polymeric materials

Abstract The packaging industry has dramatically increased the number of packaging systems and designs made of plastics over recent decades. Plastics, in contrast with more traditional packaging materials such as glass and metals, are permeable systems that permit the exchange of low molecular weight compounds, e.g. gases and vapours, between the inner and the outer atmosphere. Despite this drawback, the availability of shapes and forms in which they can be manufactured, their ease of processing and handling, low price, excellent chemical resistance, etc., have made them very attractive in many packaging fields. Consequently, much industrial and academic research has been devoted to understanding the mechanisms of mass transport in polymers, to enable design of materials with improved barrier properties. The present paper reviews some of these developments, and highlights the structural factors that cause polymers to behave as high barrier materials, taking as benchmark the properties of one of the most widely used family of high barrier materials, the ethylene - vinyl alcohol copolymers.

Novel silver-based nanoclay as an antimicrobial in polylactic acid food packaging coatings

This paper presents a comprehensive performance study of polylactic acid (PLA) biocomposites, obtained by solvent casting, containing a novel silver-based antimicrobial layered silicate additive for use in active food packaging applications. The silver-based nanoclay showed strong antimicrobial activity against Gram-negative Salmonella spp. Despite the fact that no exfoliation of the silver-based nanoclay in PLA was observed, as suggested by transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) experiments, the additive dispersed nicely throughout the PLA matrix to a nanoscale, yielding nanobiocomposites. The films were highly transparent with enhanced water barrier and strong biocidal properties. Silver migration from the films to a slightly acidified water medium, considered an aggressive food simulant, was measured by stripping voltammetry. Silver migration accelerated after 6 days of exposure. Nevertheless, the study suggests that migration levels of silver, within the specific migration levels referenced by the European Food Safety Agency (EFSA), exhibit antimicrobial activity, supporting the potential application of this biocidal additive in active food-packaging applications to improve food quality and safety.

A review of key challenges of electrospun scaffolds for tissue‐engineering applications

Tissue engineering holds great promise to develop functional constructs resembling the structural organization of native tissues to improve or replace biological functions, with the ultimate goal of avoiding organ transplantation. In tissue engineering, cells are often seeded into artificial structures capable of supporting three‐dimensional (3D) tissue formation. An optimal scaffold for tissue‐engineering applications should mimic the mechanical and functional properties of the extracellular matrix (ECM) of those tissues to be regenerated. Amongst the various scaffolding techniques, electrospinning is an outstanding one which is capable of producing non‐woven fibrous structures with dimensional constituents similar to those of ECM fibres. In recent years, electrospinning has gained widespread interest as a potential tissue‐engineering scaffolding technique and has been discussed in detail in many studies. So why this review? Apart from their clear advantages and extensive use, electrospun scaffolds encounter some practical limitations, such as scarce cell infiltration and inadequate mechanical strength for load‐bearing applications. A number of solutions have been offered by different research groups to overcome the above‐mentioned limitations. In this review, we provide an overview of the limitations of electrospinning as a tissue‐engineered scaffolding technique, with emphasis on possible resolutions of those issues. Copyright

Encapsulation of Living Bifidobacteria in Ultrathin PVOH Electrospun Fibers

This study shows the application of the electrospinning technique as a viable method for the encapsulation and stabilization of bifidobacterial strains. Poly(vinyl alcohol) (PVOH) was used as the encapsulating material because it is generally recognized as safe (GRAS), has a high oxygen barrier when dry, and is water soluble, hence allowing easy recovery of the bacteria for viability testing. A coaxial setup was used for encapsulation, and the so-obtained electrospun fibers had a mean diameter of ca. 150 nm. Incorporation of B. animalis Bb12 led to a decrease in melting point and crystallinity of the PVOH fibers and to an increase in the polymer glass transition temperature. The viability tests, carried out at three different temperatures (room temperature and 4 and -20 degrees C) showed that B. animalis Bb12 encapsulated within the electrospun PVOH fibers remained viable for 40 days at room temperature and for 130 days at refrigeration temperature, whereas a significant viability decrease was observed in both cases when bacteria were not encapsulated (p = 0.015 and p = 0.002, respectively).

Novel Polycaprolactone Nanocomposites Containing Thymol of Interest in Antimicrobial Film and Coating Applications

It is well-known that the nanocomposites technology can significantly enhance, among others, the thermal, mechanical, and barrier properties of plastics. It is also known that most bioplastics, including the thermoplastic biopolymers, have lower than desired levels for certain properties which makes their use in certain packaging applications problematic. The combination of active technologies such as antimicrobials and nanotechnologies such as nanocomposites can synergistically lead to bioplastic formulations with balanced properties and functionalities for their implementation in packaging applications. The present work presents the development and characterization of novel nanocomposites of polycaprolactone with enhanced barrier properties and with controlled-release of the biocide natural extract thymol. The antimicrobial nanocomposites of biodegradable materials were prepared in solution by a casting method. The morphology of the biocomposites was visualized by transmission electron microscopy and by atomic force microscopy, the thermal properties were investigated by differential scanning calorimetry and the relative uptake (solubility) and kinetics (diffusion) of the released biocide were determined by Attenuated Total Reflection Fourier Transformed Infrared spectroscopy. Water, oxygen, and limonene barrier properties were also enhanced in the biocomposites.

Novel PET Nanocomposites of Interest in Food Packaging Applications and Comparative Barrier Performance With Biopolyester Nanocomposites

Poly(ethylene terephthalate) (PET) is one of the polymers most widely used in the packaging industry. However, it is highly desirable to enhance its barrier properties for applications, such as carbonated drinks and other rigid and flexible packaging applications. The nanocomposites route offers unique possibilities to enhance the properties of this material, provided that adequate thermally resistant and legislation complying nanoadditives are used. This study presents novel PET nanocomposites with enhanced barrier properties to oxygen, water, and limonene based on a new specifically developed food-contact-complying highly swollen montmorillonite grade, and, furthermore, presents and discusses morphological data. Moreover, given the current interest in the packaging industry to replace this material by other biopolyesters, a comparative barrier performance of PET nanocomposites versus that of biopolymers, such as poly(lactic acid) (PLA), polyhydroxyalkanoates (PHB, PHBV), and polycaprolactones (PCL) and their corresponding nanocomposites is also reported.

Permeation of water, methanol, fuel and alcohol-containing fuels in high-barrier ethylene-vinyl alcohol copolymer

Abstract A comprehensive study of the permeation rate, and other transport properties, of water, methanol, toluene, fuel C (50/50 toluene and iso-octane) and oxygenated fuels (fuel C+10% ethanol and fuel C+15% methanol) in 32 mol% ethylene–vinyl alcohol (EVOH) copolymer has been carried out by sorption (weight uptake) and/or permeation (weight loss) measurements. Alcohol-containing fuels are aimed at reducing toxic emissions and are envisaged to replace standard fuels. Large-scale water- and methanol-induced polymer plasticization was suggested by large solvent uptakes and confirmed by the observation of a considerable depletion in the glass transition temperature ( T g ) as measured by differential scanning calorimetry and dynamic mechanical analysis. Polymer plasticization is somewhat larger in the presence of methanol. The barrier performance of EVOH to toluene, and consequently to fuel C, is outstanding (better than 0.01 g mm/m 2 day) at 21°C and 40°C under dry conditions, but deteriorates significantly for fuel containing methanol. This is caused by the selective loss of methanol, a severe plasticizing agent, that permeates faster. In spite of this, the barrier performance of EVOH to oxygenated fuels is still outstanding, and only slightly worse than that to fuel C, if ethanol is added to fuel C.

Effects of chitosan films on the growth of Listeria monocytogenes, Staphylococcus aureus and Salmonella spp. in laboratory media and in fish soup

The objective of this study was to assess the antimicrobial effectiveness of chitosonium acetate films on the growth of Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus. The samples were tested in both laboratory conditions using Tryptone Soy Broth (TSB) and in a real food system using fish soup. The study was carried out at different temperatures (4, 12, and 37 degrees C) in order to discern the influence of such variables. Moreover, a sensory evaluation of the final product was performed as a parameter of consumer acceptance. The results showed a significant reduction of the bacterial growth, which greatly depended on the bacteria type, the temperature of incubation and the food substrate. Although the effectiveness of chitosan films decreased in the fish soup, neither the sensory properties nor the pH of the soup was affected upon their addition. The application of chitosonium acetate as an internal coating of the packaging material could be a very suitable means to assure safety of liquid food products such as fish soup at the range of temperatures studied.

Comparative Performance and Barrier Properties of Biodegradable Thermoplastics and Nanobiocomposites versus PET for Food Packaging Applications

This article reports on preliminary studies of several comparative packaging properties between polyethylene terephthalate (PET) packaging films and biodegradable biopolymers such as polycarpolactone (PCL), polylacticacid (PLA), amorphous PLA (aPLA), and polyhydroxyalcanoates copolymer with 8 mol% valeriate (PHBV) and of some nanobiocomposites, in terms of thermal and retorting resistance (thermal humid processes) and oxygen, water vapor, aroma, and solvent barrier by means of time-resolved synchrotron radiation, FT-IR and direct permeation methods. This work suggests that while PHBV can easily withstand retorting and shows excellent water and aroma (limonene and linalool) barriers compared with PET, its solvent resistance (toluene and ethanol) and oxygen barrier properties are poorer. First, trials with compression molded food contact complying nanobiocomposites of PCL and aPLA show enhanced oxygen barrier but are not sufficient, as yet, to outperform high-oxygen-barrier grades of PET film.