Reflecting the importance of food packaging, the number of peer-reviewed papers is huge, to such an extent that it is frequently difficult for those working in the field to keep up with the literature. As a special service to our readers, FEI presents a selection of literature abstracts, chosen by our editorial board as being particularly worthy of attention.
Reducing the brittleness of zein films through chemical modification.
Zein protein is a major coproduct of biofuel from corn. To reduce the brittleness of zein films, a new type of zein-based biomaterial was synthesised by chemical modification of zein with lauryl chloride through an acylation reaction. The final products were confirmed by H NMR, FT-IR analysis and SDS-PAGE. Thermal analysis did not detect any microphase separation in the synthesised polymer matrix. As the content of the lauryl moiety increased, the glass transition temperatures of modified zein decreased by as much as 25.8 °C due to the plasticisation effect of the lauryl moiety. In addition, the mechanical and surface properties of cast films from acylated zein were investigated. The elongation at breakpoint of the modified zein sheet was increased by about 7-fold at the high modification level, with some loss of mechanical strength. The surfaces of modified zein films were as uniform as unmodified zein film but more hydrophobic, further suggesting that no microphase separation happened during the film formation process. This work indicates the potential of these new biomaterials in the development of biodegradable food packaging materials and delivery systems.
Shi K, Huang Y, Yu H, Lee TC, Huang Q. J Agric Food Chem. 2010 Dec 2.
Effect of novel food processing methods on packaging: structure, composition and migration properties.
Classical stabilisation techniques (e.g. thermal treatments) usually involve food being packed after processing. However increasingly novel food processing methods, such as high pressure or microwaves, me4an that both packaging and foodstuff undergo stabilisation treatment. Moreover, novel treatments — UV light, irradiation, ozone, cold plasma — are specifically used for disinfection and sterilisation of the packaging material itself. In recent years a number of papers have therefore focused on the effects of these new treatments on food-packaging interactions, with a special emphasis on chemical migration and safety concerns. New packaging materials are being developed that are environmentally friendly, (e.g. bio-sourced materials) or have mechanical and barrier properties (e.g. nanocomposite packaging materials). It is important to evaluate the knowledge about how these in-package food technologies affect food/packaging interactions, especially in the case of novel biodegradable and/or active materials. This article presents the effect of high pressure treatment, microwave heating, irradiation, UV-light, ozone and cold plasma treatment on food/packaging interactions.
Guillard V, Mauricio-Iglesias M, Gontard N. Crit Rev Food Sci Nutr 2010 Nov;50(10):969-88.
Endocrine disrupting chemicals and other substances of concern in food contact materials: an updated review of exposure, effect and risk assessment.
Food contact materials (FCM) are an underestimated source of chemical food contaminants and a potentially relevant route of human exposure to endocrine-disrupting chemicals (EDCs). Quantifying the exposure of the general population to substances from FCM relies on estimates both of food consumption and leaching into food. Recent studies using polycarbonate plastics show that food simulants do not always predict worst-case leaching of bisphenol A, a common FCM substance. In addition, exposure of children to FCM substances is not always realistically predicted using the common conventions and thus it is possibly misjudged. Furthermore, the exposure of the whole population to substances leaching into dry foods is underestimated. Consumers are exposed to low levels of substances from FCM throughout their entire lives. The effects of these compounds are currently assessed with a focus on mutagenicity and genotoxicity. This approach, however, neglects recent new toxicological findings such as endocrine disruption, mixture toxicity and developmental toxicity. According to these new toxicology paradigms, pregnant women or those of childbearing age and during pregnancy are a new sensitive population group requiring more attention. Furthermore, in overweight and obese persons a change in the metabolism of xenobiotics is observed, possibly implying that this group of consumers is insufficiently protected by current risk assessment practice. Innovations in FCM risk assessment should therefore include routine testing for EDCs and an assessment of the whole migration toxicity of food packaging, taking into account all sensitive population groups. This article focuses on recent issues of interest concerning either exposure to, or effects of, FCM-related substances. The use of benzophenones and organotins, two groups of known or suspected Endocrine Disrupting Chemicals in Food Contact Materials authorised in the US and EU, are also reviewed.
Muncke J.J Steroid Biochem Mol Biol. 2010 Nov 10.
Morphology and water barrier properties of nanobiocomposites of κhybrid carrageenan and cellulose nanowhiskers.
The study described in this paper presents the development and characterisation of novel carrageenan nanobiocomposites showing an enhanced water barrier due to incorporation of cellulose nanowhiskers (CNW). Prepared by acid hydrolysis of highly purified α cellulose microfibres, CNW were seen to have a length of around 25-50 nm and a cross section of ca. 5 nm when dispersed in the matrix. The nanobiocomposites were prepared by incorporating 1, 3, and 5 wt % of the CNW into a carrageenan matrix using a solution casting method. Morphological data (TEM and optical microscopy) of the nanocomposites containing CNW were compared with the morphology of the corresponding biocomposites containing the original cellulose microfibres and the differences discussed. Thermal stability by TGA, water vapour permeability and percent water uptake were also determined. The main conclusion arising from the analysis of the results is that the nanobiocomposites containing 3 wt % of CNW exhibited the lowest reduction in water vapour permeability, namely approximately 71%, and that this reduction was largely attributed to a filler-induced water solubility reduction. This fully biobased nanoreinforced carrageenan can open new opportunities for the application of this biopolymer in food-packaging and food-coating applications.
Sánchez-García MD et al. J Agric Food Chem. 2010 Nov 12.
Evaluation of the genotoxicity of chitosan nanoparticles for use in food packaging films.
The use of nanoparticles in food packaging has been proposed on the basis that it could improve protection of foods by, for example, reducing permeation of gases, minimising odour loss and increasing mechanical strength and thermal stability. Consequently the impacts of such nanoparticles on organisms and on the environment need to be investigated to ensure their safe use. In an earlier study, the effect of the addition of chitosan (CS) and poly(methacrylic acid) (PMAA) nanoparticles on the mechanical properties, water vapour and oxygen permeability of hydroxypropyl methylcellulose films used in food packaging was described. In this study the genotoxicity of different polymeric CS/PMAA nanoparticles (size 60, 82, and 111 nm) was evaluated at different concentration levels, using the Allium cepa chromosome damage test as well as cytogenetic tests employing human lymphocyte cultures. Test substrates were exposed to solutions containing nanoparticles at polymer mass concentrations of 1.8, 18, and 180 mg/L. Results showed no evidence of DNA damage caused by the nanoparticles (no significant numerical or structural changes were observed), however the 82 and 111 nm nanoparticles reduced mitotic index values at the highest concentration tested (180 mg/L), indicating that the nanoparticles were toxic to the cells used at this concentration. In the case of the 60 nm CS/PMAA nanoparticles, no significant changes were observed in the mitotic index at the concentration levels tested, indicating that these particles were not toxic. The techniques used show promising potential for application in tests of nanoparticle safety envisaging the future use of these materials in food packaging.
De Lima R et al. J Food Sci 2010 Aug 1;75(6):N89-96.
Saturated and aromatic mineral oil hydrocarbons from paperboard food packaging: estimation of long-term migration from contents in the paperboard and data on boxes from the market.
In the absence of a functional barrier, mineral oil hydrocarbons from printing inks and recycled fibres tend to migrate from paper-based food-packaging materials through the gas phase into dry food. Concentrations far exceed the limit derived from the acceptable daily intake (ADI) of the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Since the estimation of long-term migration into the food by testing at 40°C for 10 days is difficult, it seems preferable (and easier) to use the mineral oil content in the paperboard. Evaporation experiments showed that hydrocarbons eluted up to about n-C₂₄ are sufficiently volatile for relevant migration into dry food: in worst-case situations, about 80% migrate into the packed food. The extraction of the paperboard was optimised to give good recovery of the relevant hydrocarbons, but to discriminate against those of high molecular mass which tend to disturb gas chromatographic analysis in on-line coupled normal phase HPLC-GC-FID. Even though some of the relevant hydrocarbons had already evaporated, the average concentration of <C₂₄ mineral oil saturated hydrocarbons (MOSH) in the paperboard boxes of 102 products on the Swiss and Italian market was 626 mg kg¹. Nearly 15% of investigated boxes still contained more than 1000 mg/kg < C₂₄ MOSH up to over 3000 mg/kg (maximum = 3500 mg/kg). This amount of MOSH in the board has the potential of contaminating the packed food at a level several hundred timesmore than the limit derived from <br />the JECFA ADI.
Lorenzini R et al. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2010 Dec;27(12):1765-74.
