The concept of antimicrobial packaging has received great attention because of its potential to enhance food safety. Several studies have explored its applications and effectiveness to suppress pathogenic microorganisms. However, few studies have analyzed the alterations caused in the engineering properties of food-packaging polymers after the incorporation of antimicrobials. Such information is very important to understand the feasibility of producing antimicrobial packaging films on the industrial scale. This review explores the work done so far to evaluate how the incorporation of antimicrobial substances affects the properties of food-packaging systems. This article also emphasizes diffusion studies on antimicrobial substances through packaging films and the analytical solutions used to characterize this diffusion mechanism. Our review found that although the properties of packaging materials are altered by the addition of antimicrobials such as organic acids, enzymes, and bacteriocins, every packaging material is unique, and these effects cannot be generalized.

Active food packaging involves the packaging of foods with materials that provide an enhanced functionality, such as antimicrobial, antioxidant or biocatalytic functions. This can be achieved through the incorporation of active compounds into the matrix of the commonly used packaging materials, or by the application of coatings with the corresponding functionality through surface modification. The latter option offers the advantage of preserving the packaging materials' bulk properties nearly intact. Herein, different coating technologies like embedding for controlled release, immobilization, layer-by-layer deposition, and photografting are explained and their potential application for active food packaging is explored and discussed.

Biodegradable poly(butylene adipate-co-terephthalate) (PBAT) films incorporated with nisin were prepared with concentrations of 0, 1000, 3000, and 5000 international units per cm(2) (IU/cm(2)). All the films with nisin inhibited Listeria innocua, and generated inhibition zones with diameters ranging from 14 to 17 mm. The water vapor permeability and oxygen permeability after the addition of nisin ranged from 3.05 to 3.61 x 10(11) g m m(-2) s(-1) Pa(-1) and from 4.80 x 10(7) to 11.26 x 10(7) mL.m.m(-2).d(-1).Pa(-1), respectively. The elongation at break (epsilon(b)) was not altered by the incorporation of nisin (P> 0.05). Significant effect was found for the elastic modulus (E) and the tensile strength (sigma(s)) (P < 0.05). The glass transition and melting temperatures with the presence of nisin ranged from -36.3 to -36.6 degrees C and from 122.5 to 124.2 degrees C, respectively. The thermal transition parameters such as the crystallization and melting enthalpies and crystallization temperature were influenced significantly (P < 0.05) by incorporation of nisin into films. The X-ray diffraction patterns exhibited decreasing levels of intensity (counts) as the concentration of nisin increased in a range of 2theta from 8 degrees to 35 degrees . Formation of holes and pores was observed from the environmental scanning electron microscopy images in the films containing nisin, suggesting interaction between PBAT and nisin.

N-halamine modification of materials enables the development of antimicrobial materials whose activity can be regenerated after exposure to halogenated sanitizers. Surface and bulk modification of polymers by N-halamines has shown great success, however, modification of inorganic substrates (e.g., stainless steel) remains an area of research need. Herein, we report the covalent surface modification of stainless steel to possess rechargeably antimicrobial N-halamine moieties. Multilayers of branched polyethyleneimine and poly(acrylic acid) were immobilized onto the surface of stainless steel and the number of N-halamines available to complex chlorine was quantified. Samples were characterized through contact angle, Fourier transform infrared spectroscopy, ellipsometry, dye assay for amine quantification, and X-ray photoelectron spectroscopy. Increasing the number of multilayers from one to six increased the number of N-halamines available to complex chlorine from 0.30 6 0.5 to 36.81 6 5.0 nmol cm À2 . XPS and FTIR confirmed successful covalent layer-by-layer deposition of the N-halamine multilayers. The reported layer-by-layer deposition technique resulted in a greater than seven-fold increase of available N-halamine compared to prior reports of N-halamine surface modifications. The N-halamine modified steel demonstrated antimicrobial activity (99.7% reduction) against the pathogen Listeria monocytogenes. Such surface modified stainless steel with increased N-halamine functionality, and therefore potential for rechargeable antimicrobial activity, supports efforts to reduce cross-contamination by pathogenic organisms in the food and biomedical industries.

Emerging technologies in antimicrobial coatings can help improve the quality and safety of our food supply. The goal of this review is to survey the major classes of antimicrobial agents explored for use in coatings and to describe the principles behind coating processes. Technologies from a range of fields, including biomedical and textiles research, as well as current applications in food contact materials, are addressed, and the technical hurdles that must be overcome to enable commercial adaptation to food processing equipment are critically evaluated.

A method to prepare an antimicrobial coating for food-handling materials is reported. Alternating layers of branched polyethylenimine and styrene maleic anhydride copolymer were applied onto the surface of polypropylene. The resulting coatings had low surface energy and presented enhanced antimicrobial character due to the presence of both cationic and N-halamine forming structures. In its unchlorinated form, the coating inactivated Listeria monocytogenes by ∼3 logarithmic cycles. In the form of N-halamines >5 logarithmic cycles were reached. Microbial inactivation kinetics showed a Weibullian behavior when the coating was unchlorinated and a sigmoidal behavior when chlorinated. Microscopy confirmed that the reduction in the microbial load was due to biocidal effects of the coating and not bacterial adhesion onto the modified surface. The modified surface was able to be repeatedly rechlorinated. Such rechargeable antimicrobial coatings may support improving food safety by reducing cross-contamination of microorganisms from food-processing equipment.

No abstract

No abstract