Patrizia Fava

Water transport properties of cellophane flexible films intended for food packaging applications

Abstract In the present paper, a mathematical model able to predict the water barrier properties of cellophane film as a function of the water activity at the upstream and downstream side of the film is presented. To validate the model water sorption, and permeation tests were performed at 30 °C and at several water vapor activities. Despite the approximations involved in deriving the model, its ability to predict the water permeability of the investigated film is quite satisfactory. The proposed model was then applied to hypothetical measuring conditions in which the water activity at one side of the film was set equal to zero (like in a permeation test) or equal to 0.6 (like in the real working conditions), while the water activity of the other side changes between 0 and 0.6. A substantial difference has been observed between the two examined cases, showing the need for a more accurate analysis of the transport phenomena in the case of water sensitive packaging films like cellophane.

Poly(vinyl alcohol)-Based Film Potentially Suitable for Antimicrobial Packaging Applications

This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 μm in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances.

Study of diffusion through LDPE film of Di-n-butyl phthalate

The apparent diffusion coefficients (D) across a PE-LD film of Di-n-butyl phthalate (DnBP) dissolved in isooctane and ethanol, were calculated in different ways and compared. DnBP, a common plasticizer of plastics and printing inks, may be a possible contaminant of flexible packaging and PE-LD is the most common food-contacting polymer. To perform diffusion measurements, small plastic sachets filled with solutions of the contaminant were used at three different temperatures. The D coefficients of the two solvents and dissolved DnBP were calculated using the lag time method, a formula taking into account the molar weight and absolute temperature, and an equation based on the initial concentration and the amounts migrated after subsequent times. The results demonstrated great solvent interference in the plasticizer diffusion across polyethylene; in particular as far as isooctane is concerned, a remarkable co-diffusion of both the plasticizer and the non-polar solvent must be assumed. Isooctane quickly penetrates PE-LD but ethanol also diffuses across PE-LD, although at a greatly reduced speed. These facts must be considered for realistic prediction of migration or effectiveness of the functional barrier.

Identification Of Geographical Origin Of Coffee Before And After Roasting By Electronic Noses

Geographical origin traceability of food is a relevant issue for both producers’ business protection and customers’ rights safeguard. Differentiation of coffees on the basis of geographical origin is still a challenging issue, though possible by means of chemical techniques [1]. Between the most widely consumed beverage, coffee is a valuable one, with an aroma constituted by hundreds of volatiles [2]. Since the final global volatile composition is also determined by the cultivation climatic conditions, Electronic Noses (ENs) could be interesting candidates for distinguishing the geographical provenience by exploiting differences in chemical volatile profile. The present investigation is directed toward the characterization of green and roasted coffees samples according to their geographical origin.

Design of a functional box for take-away pizza

Pizza is one of the world-famous Italian dishes because of its simplicity, taste, nutritional value and low cost. It is usually consumed at specialized vending points, which also offer a take-away service. The packaging must guarantee adequate protection against rapid temperature decrease and water vapour elimination, to maintain quality. In this paper the performance of a traditional corrugated cardboard container is compared with that of a new package, realized with expanded polystyrene and a water-absorbing polymer. The tests performed (water absorption, WVTR, thermal insulation and sensory profile) showed that the new packaging was better than the traditional one. The ‘consumption life’ of take-away pizza was increased, allowing the product to reach consumers nearly in the same condition in which it left the oven: warm and not softened. Copyright

Early detection of fungal contamination on green coffee by a MOX sensors based Electronic Nose

Fungal growth can occur on green coffee beans along all the distribution chain, eventually bringing on health hazards to consumers, because of the production of toxic metabolites (mycotoxins) [1]. Besides, the sensorial contamination due to volatiles by‐products of fungal metabolism could cause defects on coffee also after roasting. Therefore, it is necessary to devise strategies to detect and quantify fungal infection and toxin production at early stages of the food chain. One of the most promising techniques is the analysis of volatile compounds in the headspace gas surrounding the samples. The aim of this work was to verify the ability of the Electronic Nose (EN EOS835) to early detect the microbial contamination of Arabica green coffee. This EN is equipped with Metal Oxide Semiconductor sensor array. Gas chromatography coupled to mass spectrometry (GC‐MS) analysis of the static headspace of non‐contaminated Arabica green coffee samples was carried out to confirm the EN ability to provide satisfactory ...

Discrimination Between Different Types of Coffee According to Their Country of Origin

Geographical origin traceability of food is a relevant issue for both producers’ business protection and customers’ rights safeguard. Between the most widely consumed beverage, coffee is a valuable one, with an aroma constituted by hundreds of volatiles. Differentiation of coffee on the basis of geographical origin still a challenging issue, tough possible by means of chemical techniques. Nonetheless, producer companies need cheaper and simpler tools, able to give a yes/no response in a short time and possibly in a non destructive way. Since the final global volatile composition is also determined by the cultivation climatic conditions, it is in principle possible to distinguish geographical proveniences by exploiting the differences in chemical volatile profile. The present investigation is direct toward the characterization by EN of green and roasted coffees samples according with their geographical origin. The analyzes have been carried out in parallel with chemical classical techniques like GC-MS with SPME. The GC-MS analyses were in good agree with EN results, without sample treatment performed before the analysis.