Panagiotis G. Demertzis

The effects of γ-irradiation on compositional changes in plastic packaging films

Sterilization of packaging materials for pharmaceutical or food products with ionizing irradiation can cause chemical and physical changes in polymer materials. The effects of γ-irradiation on the formation of solvent extractable radiolysis products of six flexible packaging materials for foodstuffs and/or pharmaceutical applications were studied after treatment in a 60Co-irradiation plant. The polymer materials polyethylene, polypropylene, poly(ethylene terephthalate), polyamide, polystyrene and poly(vinyl chloride) were investigated after treating with an irradiation dose of 44 kGy. The compositional changes in solvent extractable radiolysis products of each packaging material were quantified. In most cases the radiolysis products formed could be identified using GC/MS. The polyolefine materials (PE and PP) showed an increase of low volatile compounds after irradiation due to an oxidative decomposition of the polymer and typical polymer substances like oligomers and additives. Other packaging materials such as PET, PA and PS did not significantly change their amount of solvent extractable compounds after irradiation with 44 kGy. The PVC packaging material used in this study was not resistant to irradiation treatment at all. Because of the release of HCl during irradiation a large amount of volatile substances could be extracted from the PVC sheet. For consumer protection and also to meet general food packaging legislative requirements for irradiated packaging materials, it is necessary to evaluate the compositional changes in the polymers during irradiation, especially for irradiated polyolefines and PVC. Most attention should be paid to low volatile radiolysis products which are the most likely to migrate into a foodstuff or a pharmaceutical product. Copyright

Migration studies from recycled paper packaging materials: development of an analytical method for rapid testing

Abstract The safe use of recycled paper and board material for food packaging applications is a major area of investigation. Studies on the migration of contaminants into foods and food simulants have been carried out to evaluate the suitability of recycled paperboard for direct food contact applications. In the present study, the kinetics of migration of selected model contaminants (surrogates) from paper packaging samples into an alternative or substitute fatty food simulant (Tenax) was studied with the aim of developing a rapid test method based on solvent extraction, gas chromatography (GC)–mass spectrometry (MS) identification and GC–flame ionization detector (FID) quantification. These tested substances represent a large number of molecular sizes and polarities and are among those that may be present in fiber material. Crucial data about the time needed to reach equilibrium between paper samples and the food simulant were obtained. The results of the study indicate that time and temperature conditions are the most important variables with respect to the actual mass transfer during contact with food simulants. The proposed quick test method seems to be suitable for compliance testing of paper and board samples if migration limits are applied in future legislation.

Isolation of microbial pathogens of subclinical mastitis from raw sheep’s milk of Epirus (Greece) and their role in its hygiene

The natural raw milk microflora is a factor that expresses its sensorial characteristics. The microbial charge into the mammary gland of healthy animal is low and the application of right and healthy conditions during milking and cheese making procedure, prevents from contaminating as well as maintains the natural microflora in order to lend the particular characteristics of milk. The purpose of the present project was the study of the Total Viable Count (T.V.C.) and the count of total psychrotropic bacteria of raw sheep milk from Boutsiko and Karamaniko breeds, collected from healthy animals, as well as the isolation, identification and enumeration of pathogenic bacteria related with the hygiene and the quality of raw sheep milk (with a particular interest in bacteria that may cause human infection). During the experiment we examined two hundred forty (240) samples of raw sheep milk. In these samples a) Staphylococcus aureus, Salmonella sp., Escherichia coli, Clostridium perfringens (vegetative cells and spores) and Bacillus sp. were isolated and identified b) the Total Viable Count and the total number of psychrotropic bacteria were also specified. The sampling, the preparation of samples and decimal dilutions were based on international methods. The Total viable count was determined using the standard methods of the American Public Health Association, 2002. The total number of psychrotropic bacteria was determined using APHA 1976, 1978 rules. The identification of the bacteria was carried out according to the Bergeys manual. Microscopic examination of Gram stained cells, catalase, oxidase and biochemical tests were performed when necessary to further identify. From the 240 milk samples tested, only 5% were E. coli positive, with mean counts ranged from 2 × 10(3) to 2.4 × 10(4) cfu/ml. S. aureus was isolated from 24% of the samples and the mean count per ml was ranged from <10 to 3.4 × 10(2). Meanwhile, Bacillus spp. was also detected in 29% samples. Vegetative forms and spores of C. perfringens were detected in 13% and 63% of the samples respectively. However, microbiological analyses revealed the presence of a small number of selected pathogens in milk samples such as Salmonella, which was only detected in 5% of the samples. Listeria sp., Pseudomonas sp. and Vibrio cholerae were never found. From the experimental results, the Total Viable Count from raw sheep milk samples, fulfils the microbiological criteria of EU Legislation in a percentage of approximately 97%.

Effect of high-dose electron beam irradiation on the migration of DOA and ATBC plasticizers from food-grade PVC and PVDC/PVC films, respectively, into olive oil.

The effect of high-dose irradiation on the migration of dioctyl adipate (DOA) and acetyl tributyl citrate (ATBC) plasticizers from food-grade poly (vinyl chloride) (PVC) and poly (vinylidene chloride/vinyl chloride) (PVDC/PVC) copolymer (Saran) films, respectively, into olive oil was studied. The results showed a significantly higher amount of DOA migrated into olive oil from irradiated versus nonirradiated samples. This difference was more noticeable in oil samples collected during initial periods of contact. The amount of DOA migrating into olive oil was lower for samples irradiated at a dose of 20 kGy in comparison with samples irradiated at a dose of 50 kGy. At a sampling time of 1 h the amount of DOA that migrated into olive oil was 93.9 mg/liter, 141.5 mg/liter, and 183.4 mg/liter for nonirradiated samples, 20-kGy irradiated samples, and 50-kGy irradiated samples, respectively. After 288 hr (12 days) of oil-film contact the respective amounts were 390.8 mg/liter, 409.2 mg/liter, and 430.1 mg/liter. There were no statistically significant differences in migrating amount of ATBC between nonirradiated samples and samples irradiated at a dose of 20 kGy, while in samples irradiated at a dose of 50 kGy the migration of ATBC was increased. After 1 h of oil-film contact no detectable amounts of ATBC had migrated. After 288 h of contact the amounts of ATBC that migrated into olive oil were 3.59 mg/liter, 3.56 mg/liter, and 4.12 mg/liter for nonirradiated samples, 20-kGy irradiated samples, and 50-kGy irradiated samples, respectively. It is suggested that plasticized PVC should not be used in direct contact with high-fat foodstuffs with or without irradiation treatment.

Migration of dioctylphthalate and dioctyladipate plasticizers from polyvinylchloride films into olive oil

Abstract The migration of dioctylphthalate (DOP) and dioctyladipate (DOA) plasticizers from food grade polyvinylchloride (PVC) films into commercial olive oil has been studied. Olive oil was chosen as a fat simulant. Experiments were carried out at 6, 22 and 30°C with and without agitation as a function of time (0–100 h). Two different PVC films were used containing 31·5% DOA and 29·5% DOP, respectively. Results showed a significantly higher amount of plasticizer migration into oil with agitation than without (30% versus 22·2% for DOP after 100 h). The equilibrium amount of DOA migrated was found to be higher than the respective amount of DOP whereas diffusion coefficients determined were slightly higher for DOP than DOA. These findings were related to solubility, compatibility and molecular weight of plasticizer. Data were fitted to the Arrhenius equation and activation energies for diffusion of plasticizers in PVC were calculated.

Migration of dioctylphthalate and dioctyladipate plasticizers from food-grade PVC films into ground-meat products

Abstract The migration of dioctylphthalate (DOP) and dioctyladipate (DOA) plasticizers from polyvinyl chloride (PVC) films into ground meat of varying fat contents was studied at 4°C and −20°C. The amount of migrating plasticizer was determined indirectly after the extraction, saponification and quantification of the alcoholic constituent of the ester plasticizer using gas chromatography. The amount that had migrated ranged from approximately 2 to 80 mg per kilogram of meat (0.12–4.8 mg/dm2) after 8 days at 4°C and from 2 to 60 mg (0.13–4 mg/dm2) after 2 1 2 months at −20°C. The amount of migrating DOA was (under similar experimental conditions) higher than the respective amount of DOP. The migration to samples of lower fat content was proportionally lower. Mathematical treatment of the migration of both DOA and DOP showed that the rate-determining step in the migration process is that of the diffusion of the plasticizer from the bulk of the PVC film to its surface.

Gas chromatographic studies on polymer-plasticizer compatibility: Interactions between food-grade PVC and epoxidized soybean oil

Abstract The technique of inverse gas chromatography was applied to study the miscibility (compatibility) of the system of PVC with epoxidized soybean oil (ESO). The PVC-ESO thermodynamic interaction parameters, χ + 23 , were determined from the measured retention data for various vapour-phase “probes” in stationary phase mixtures of the components covering the entire composition range. Experiments were run in the range 90–110°C. In accordance with previous studies on polymer-polymer and polymer-plasticizer blends, the interaction parameters were found to be dependent on the temperature, the chemical nature of the probe and the blend composition. χ + 23 values were mostly negative or slightly positive up to 0.40 weight fraction of ESO, indicating relatively high compatibility of PVC and ESO for this range of compositions. They then increased with increasing plasticizer content and, at ca 0.70 weight fraction of ESO, exceeded 0.5 which is considered as the “compatibility limit value”.

Study of compatibility of PVC and polyester-type plasticizer blends by inverse gas chromatography

The technique of inverse gas chromatography has been applied to a thermodynamic study of the miscibility (compatibility) of PVC and a polymeric (polyadipate ester) plasticizer. A number of organic solvents (probes) were used to evaluate the Flory-Huggins parameters for the PVC-plasticizer interaction in stationary phase mixtures of the two components covering the entire composition range for each component (0–100%). Experiments were carried out in the range 90–120°. The interaction parameter values were found to be dependent on the chemical nature of the probes, the temperature and the composition of the mixed (binary) phase. The results predict good polymer-plasticizer compatibility for a wide range of the above mixture (up to ca 0.55 weight fraction of plasticizer).

Physical, chemical and microbiological quality of ice used to cool drinks and foods in Greece and its public health implications.

Ice used for direct human consumption or to preserve foods and cool down drinks can be contaminated with pathogenic microorganisms and may potentially become a vehicle for consumers infection. To evaluate physical, chemical and microbiological quality of commercial ice and ice used for fish and seafood, 100 ice samples collected at 10 different retail points in the region of Epirus were studied. The following microbiological parameters were determined: Total coliforms, fecal coliforms, Salmonella spp., Shigella spp., Yersinia spp., Escherichia coli, Campylobacter sp., Vibrio cholerae, Aeromonas spp., Pseudomonas aeruginosa and Clostridium perfringens. E. coli was detected in 22% and coliforms were detected in 31% of samples. Samples in which coliforms were detected fail to meet the microbiological criteria specified by the drinking water legislation. Aeromonas spp., Shigella spp., Campylobacter sp. and V. cholerae were not detected. Spore forms of C. perfringens were prevalent at 35% and the psychotropic bacteriums P. aeruginosa and Yersinia spp. were found only at three samples each. The presence of large numbers of coliforms as well as of other pathogenic strains suggested that commercial ice and ice used to make cool drinks or in preservation of fish and seafood may represent a potential hazard to the consumer. In view of the results reported herein, it is highly recommended that national regulatory guidelines should be established for the production of ice as long as regular inspections.

Gas chromatographic study of water sorption by wheat flour

Water sorption by wheat flour was studied using inverse gas chromatography. Sorption isotherms were constructed at temperatures between 25 °C and 55 °C in the range of water activity (aw) values 0