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PubMed2002

Development of a headspace solid-phase microextraction-gas chromatography-mass spectrometry method for the identification of odour-causing volatile compounds in packaging materials.

A method for the identification of volatile organic compounds in packaging materials is presented in this study. These compounds are formed by thermooxidative degradation during the extrusion coating process in the manufacture of packaging. Headspace solid-phase microextraction (HS-SPME) was used as sample preparation technique prior to the determination of the volatile organic compounds by gas chromatography-mass spectrometry (GC-MS). The effects of extraction variables, such as the type of fibre, the incubation temperature, the pre-incubation time, the size of the vial and the extraction time on the amounts of the extracted volatile compounds were studied. The optimal conditions were found to be: carboxen-polydimethylsiloxane 75 microm fibre, 5 min of pre-incubation time, 100 degrees C of incubation temperature, 20-ml vial, and 15 min of extraction time. The chromatograms obtained by HS-SPME and static headspace extraction were compared in order to show that the HS-SPME method surpasses the static headspace method in terms of sensitivity. Twenty-five compounds were identified including carbonyl compounds (such as 3-methyl-butanal, 3-heptanone or octanal), carboxylic acids (such as pentanoic acid or hexanoic acid) known as odour causing compounds and hydrocarbons (such as decane, undecane or dodecane). Finally, the method was applied to different packaging samples (one odour-unacceptable, two odour-acceptable, and three odourless samples) and to the raw materials in order to find out the odour-responsible volatile organic compounds and their source.

Food Packaging↗
PubMed2000

Evaluation of biohazards in dehydrated biofilms on foodstuff packaging.

Plastic materials used for food packaging are clean but not sterile when the food is just packaged. Accidental wet contamination may occur at every moment between packaging and opening by the consumer: on polyethylene (PET), bacteria may adhere strongly and constitute a biofilm in less than 24 h. By rolling on themselves, PET sheets may contaminate food. We tried to show that contact with salted foodstuffs favoured microbial recovery. Four strains were chosen to perform biofilms on PET: Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli. Biofilms were dried up 24 h. Biofilm bacteria were stressed by adhesion, by starvation and by dehydration. However, they were capable of recovery in salted solutions or media, probably because one (or more) stress protected them against another stress. Stress was demonstrated by stress protein production, by mean of electrophoresis, and membrane lesions by mean of flow cytometry. Stress recovery was performed in aqueous salted solutions or salted brain-heart infusion with NaCl 9, 15, 20 and 30 g/l. Staphylococci were more sensitive to these stresses and recovery was a function of salt concentration. Gram-negative bacteria were little affected by stresses; salt effects were less important. If all these biofilms were capable of recovery from stresses in salted media, flexible PET could possibly lead to a health hazard when it is used for wet salt meats, e.g.

Bacterial Adhesion↗
PubMed2001

Effect of high oxygen modified atmosphere packaging on microbial growth and sensorial qualities of fresh-cut produce.

The application of High Oxygen Atmospheres (HOA) (i.e. > 70% O2) for packaging ready-to-eat vegetables was evaluated as an alternative technique for low O2 Equilibrium Modified Atmosphere (EMA) packaging (3% O2-5% CO2-balance N2) for respiring products. Comparative experiments between both techniques were performed in-vitro and in-vivo. Typical spoilage causing microorganisms (Pseudomonas fluorescens, Candida lambica), the moulds Botrytis cinerea, Aspergillus flavus and the opportunistic psychrotrophic human pathogenic microorganism associated with refrigerated minimally processed vegetables. Aeromonas caviae (HG4), showed a retarded growth during the conducted in-vitro studies at 4 degrees C in 70%, 80% and 95% O2 as examples of HOA compared to the in-vitro experiments in 5% O2 (as example of EMA packaging) and the effect was more pronounced in 95% O2. The effect of the high O2-concentrations on the human pathogen Listeria monocytogenes resulted in an extended lag phase (95% O2). The plant pathogen Erwinia carotovora was increasingly stimulated by increasing high O2-concentrations. During a storage experiment of three types of ready-to-eat vegetables (mushroom slices, grated celeriac and shredded chicory endive), which are sensitive to enzymatic browning and microbial spoilage, the effect of EMA and HOA (95% O2-5% N2) on their quality and shelf life was compared. High O2 atmospheres were found to be particularly effective in inhibiting enzymatic browning of the tested vegetables. Also, the microbial quality was better as a reduction in yeast growth was observed. The HOA can be applied as an alternative for low O2 modified atmospheres for some specific types of ready-to-eat vegetables, sensitive to enzymatic browning and spoilage by yeasts.

Bacteria↗
PubMed1998

Mathematical modelling of microbial growth in packaged refrigerated beef stored at different temperatures.

Gompertz and logistic models were fitted to experimental counts of microorganisms growing in beef stored at 0, 4, 7, 9 and 10 degrees C. Samples were packaged in polyethylene (high gaseous permeability) and in EVA/SARAN/EVA (low gaseous permeability) films, being EVA ethyl vinyl acetate and SARAN polyvinyl and polyvinylidene chloride copolymer. Lag phase duration (LPD) and specific growth rate (mu) were obtained as derived parameters for lactic acid bacteria, Enterobacteriaceae, Pseudomonas sp. and psychrotrophic microorganisms. The reciprocal of LPD was fitted to an Arrhenius type equation; LPD of lactic acid bacteria showed a marked dependence on temperature, with activation energy values (ELPD) of 222.2 and 216.9 kJ/mol for polyethylene and ESE respectively. The effect of initial microbial population at different storage temperatures on adaptation period was analyzed. As the initial microbial population increased, adaptation period decreased for all studied microorganisms and for both packaging films. The effect of temperature on specific growth rate was better interpreted by the Arrhenius model than by the linear or the square root equations. Psychrotrophic microorganisms in beef showed the highest activation energy values for specific growth rate (E mu) in both packaging films, being E mu 85.50 and 103.10 KJ/mol for polyethylene and ESE film respectively. In both films, Enterobacteriaceae showed the lowest E mu values, being 15.33 and 59.89 kJ/mol in ESE and polyethylene respectively. The final number of microorganisms (maximum population density) did not show significant changes with storage temperature.

Animals↗
PubMed1999

Using an electronic nose for determining the spoilage of vacuum-packaged beef.

The use of an electronic nose in the quantitative determination of the degree of spoilage of vacuum-packaged beef was evaluated. Beef from four different slaughterhouses was sliced, vacuum-packaged and stored at 4 degrees C for 8 weeks. Samples were withdrawn for bacterial (aerobic bacteria, lactic acid bacteria, Brochothrix thermosphacta, Pseudomonas and Enterobacteriaceae) and sensorial analyses and analysis of the volatile compounds during the storage period. A trained panel was used for the sensorial evaluations. The volatile compounds were analysed using an electronic nose containing a sensory array composed of 10 metal oxide semiconductor field-effect transistors, four Tagushi type sensors and one CO2-sensitive sensor. Four of the 15 sensors were excluded due to lack of response or overloading. Partial least-squares regression was used to define the mathematical relationships between the degree of spoilage of vacuum-packaged beef, as determined by the sensory panel, and the signal magnitudes of the sensors of the electronic nose. The mathematical models were validated after 6 months using a new set of samples. The stability of the sensors during this period was examined and it was shown that the sensitivity of five of the 11 sensors used had changed. Using the six remaining sensors, the signal patterns obtained from the meat from the different slaughterhouses did not change over a period of 6 months. It was shown that the degree of spoilage, as calculated using a model based on two Tagushi sensors, correlated well with the degree of spoilage determined by the sensory panel (r2 = 0.94).

Animals↗
PubMed2003

Comparative assessment of gastrointestinal irritant potency in man of tin(II) chloride and tin migrated from packaging.

Tin is present in low concentrations in most canned foods and beverages, the highest levels being found in products packaged in unlacquered or partially lacquered tinplate cans. A limited number of case-reports of acute gastrointestinal disorders after consumption of food containing 100-500 mg/kg tin have been reported, but these reports suffer many insufficiencies. Controlled clinical studies on acute effects of tin migrated from packaging suggest a threshold concentration for adverse effects (AEs) of >730 mg/kg. Two separate randomised, single-centre, double-blind, crossover studies, enabling comparison of the tolerability of tin added as tin(II) chloride at concentrations of <0.5, 161, 264 and 529 mg/kg in 250 ml tomato juice in 20 volunteers (Study 1) and tin migrated from packaging at concentrations of <0.5, 201 and 267 mg/kg in 250 ml tomato soup in 24 volunteers (Study 2) were carried out. Distribution studies were conducted to get insight in the acute AEs of low molecular weight (<1000 Da) tin species in the soluble fraction of food products. Results show that the chemical form of tin and not the elemental concentration per se determines the severity of AEs. A clear dose-response relationship was only observed when tin was added as tin(II) chloride in tomato juice. No clinically significant AEs were reported in Study 2 and comparison of the incidence of tin-related AEs showed no difference between the dose levels (including control). Tin species of low molecular weight in supernatant represented 31-32% of total tin in canned tomato soup versus 56-61% in juice freshly spiked with tin(II) chloride. Differences in the incidence of AEs following administration of tomato juice with 161 and 264 mg of tin per kg and tomato soup with 201 and 267 mg of tin per kg likely results from differences in the concentration of low molecular weight tin species and in the nature of tin complexes formed. The results of this work demonstrate that tin levels up to 267 mg/kg in canned food cause no AEs in healthy adults and support the currently proposed tin levels of 200 mg/kg and 250 mg/kg for canned beverages and canned foods, respectively, as safe levels for adults in the general population.

Adolescent↗
PubMed2001

Application of sorption--desorption moisture transfer modeling to the study of chemical stability of a moisture sensitive drug product in different packaging configurations.

The sorption--desorption moisture transfer (SDMT) model was used to predict the effect of desiccant quantity, tablet quantity and tablet initial moisture content on the relative humidity inside high density polyethylene (HDPE) bottles containing a moisture sensitive drug product, roxifiban tablets. The effect of these variables on the stability of roxifiban tablets in the HDPE bottles was also evaluated. There was a good correlation between the calculated relative humidity values inside the package and stability results. Tablet degradant concentration increased with the increase in the relative humidity calculated by the SDMT model. Desiccant quantity was the most important factor in controlling degradation rate, which decreased as the quantity of desiccant in the bottle was increased. For a given desiccant quantity, degradation rate increased with an increase in the weight of tablets in the bottle. The inclusion of a desiccant in the package significantly reduced the effect of initial tablet moisture content on stability. Nevertheless, the effect of initial moisture content was still discernible. This study demonstrated the practical utility of the SDMT model in understanding the correlation between packaging variables and the stability of a moisture sensitive product.

Adsorption↗
PubMed2001

Flavor, color, and vitamin C retention of pulsed electric field processed orange juice in different packaging materials.

Effects of packaging materials, storage temperature, and time on the stability of pulsed electric field (PEF) processed orange juice were investigated. Single-strength orange juice was treated with PEF at an electric field strength of 35 kV/cm for 59 micros using an integrated pilot plant scale PEF processing and glovebox packaging system. The retention of eight orange juice aroma compounds, color, and vitamin C in glass, polyethylene terephthalate (PET), high-density polyethylene, and low-density polyethylene were evaluated at 4 and 22 degrees C for 112 days. Packaging material had a significant effect (p < or = 0.05) on the retention of orange juice aroma compounds, color, and vitamin C. PEF-treated orange juice had a shelf life of >16 weeks in glass and PET at 4 degrees C.

Ascorbic Acid↗
PubMed2001

Modified atmosphere packaged cheddar cheese shreds: influence of fluorescent light exposure and gas type on color and production of volatile compounds.

The influences of fluorescent light exposure and packaging atmosphere on the headspace volatiles and color of Cheddar cheese shreds were evaluated using gas chromatography-mass spectrometry and spectrocolorimetry, respectively. Cheddar cheeses were packaged under atmospheres of 100% carbon dioxide or 100% nitrogen and stored at 4 degrees C under fluorescent light for 6 weeks. Cheeses stored under carbon dioxide contained higher concentrations of aldehydes and fatty acids and lower concentrations of alcohols and esters than cheeses stored under nitrogen. Carbon dioxide atmospheres potentiated light-induced oxidation in shredded Cheddar cheeses, as evidenced by aldehyde and fatty acid headspace volatiles measured following storage. Color bleaching occurred only in cheeses packaged under carbon dioxide and exposed to light. The shift in color is proposed to be due to an interaction between carbon dioxide and high-intensity light, leading to the oxidation of the pigment molecule, bixin. The results have significant implications for procedures used to handle and store pigmented cheeses to ensure desirable flavor and consumer acceptability.

Carbon Dioxide↗
PubMed2002

The effect of post-harvest and packaging treatments on glucoraphanin concentration in broccoli (Brassica oleracea var. italica).

The effects of post-harvest and packaging treatments on glucoraphanin (4-methylsulfinylbutyl glucosinolate), the glucosinolate precursor of anticancer isothiocyanate sulforaphane [4-methylsulfinylbutyl isothiocyanate], were examined in broccoli (Brassica oleracea var. italica) during storage times. The results showed that at 20 degrees C, 55% loss of glucoraphanin concentration occurred in broccoli stored in open boxes during the first 3 days of the treatment and 56% loss was found in broccoli stored in plastic bags by day 7. Under both air and controlled atmosphere (CA) storage, glucoraphanin concentration appeared to fluctuate slightly during 25 days of storage and the concentrations under CA was significantly higher than those stored under air treatment. In modified atmosphere packaging (MAP) treatments, glucoraphanin concentration in air control packaging decreased significantly whereas there were no significant changes in glucoraphanin concentration in MAP with no holes at 4 degrees C and two microholes at 20 degrees C for up to 10 days. Decreases in glucoraphanin concentration occurred when the broccoli heads deteriorated. In the present study, the best method for preserving glucoraphanin concentration in broccoli heads after harvest was storage of broccoli in MAP and refrigeration at 4 degrees C. This condition maintained the glucoraphanin concentration for at least 10 days and also maintained the visual quality of the broccoli heads.

Brassica↗
PubMed2004

Influence of temperature, modified atmosphere packaging, and heat treatment on aroma compounds in broccoli.

The aroma compounds in broccoli stored in different modified atmospheres were studied. The packaging materials used were oriented polypropylene (OPP), poly(vinyl chloride) (PVC), and low-density polyethylene (LDPE) containing an ethylene-absorbing sachet. All samples were stored for either 1 week at a constant temperature of 10 degrees C or for 3 days at 4 degrees C, followed by 4 days at 10 degrees C. The atmospheres that developed inside the packaging materials differed significantly. The broccoli samples were analyzed raw and after cooking, with regard to volatile compounds, using gas-phase (headspace) extraction followed by gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), hexanal, 3-cis-hexen-1-ol, nonanal, ethanol, and a group of thiocyanates were selected for a detailed study because these compounds cause off-odor and can be used as indicators of stress. Significant differences were found in the aroma profiles of the broccoli samples relative to the packaging materials used for storage. Storage in OPP (14% O(2), 10.5% CO(2)) resulted in most of the off-odors, while storage in LDPE (6% O(2), 7% CO(2)) and PVC (17.9% O(2), 4% CO(2)) was found to maintain the concentration of DMS, DMDS, and DMTS during storage. Heat treatment of the broccoli increased the content of aroma compounds as well as the number of compounds containing sulfur.

Brassica↗
PubMed2004

Representativeness of extracts of offset paper packaging and analysis of the main odor-active compounds.

Packagings often carry odors due to the support and printing inks. The aim of the investigation was to define a representative solvent-free extract of paper-based packaging materials printed by the offset process, for the identification of the odor-causing volatile compounds. Static headspace and solid-phase microextraction were the two applied extraction methods. Representativeness tests showed that the odor of the PDMS fiber extract gave satisfying odor similarities with the original packaging. The sample incubation was performed at 40 degrees C for 30 min, whereas the extraction time was 3 min at 40 degrees C. Extracts of both the nonprinted and printed papers of different batches were analyzed by gas chromatography-olfactometry. 4-Phenylcyclohexene was identified as the most potent compound contributing to the latex-like odor of the nonprinted paper. Among the 13 major odorants identified by mass spectrometry, 10 were aldehydes and ketones generated by oxidation of the printing ink resins. The ratio of odorants to interferences was too low for a possible detection of the key odorants by nonseparative techniques such as sensor arrays.

Aldehydes↗
PubMed2006

Stabilization of beef meat by a new active packaging containing natural antioxidants.

A new antioxidant active packaging material for food has been designed and developed, consisting of a polypropylene film in which some natural antioxidants have been immobilized. The antioxidant properties of the new material have been tested by using both pure myoglobin and fresh beef steaks. Two different cell configurations (glass vial and Petri dish) and four different myoglobin concentrations-according to the common content of this compound in fresh meat and meat derivatives (1080, 1995, 3332, and 4414 microg g(-1), respectively)-have been evaluated in oxidation studies. Furthermore, three different concentrations of natural antioxidants in the film (designated as PR1, PR2, and PR3) were evaluated. Once myoglobin samples and the active films were introduced in the cell, they were exposed to cool white fluorescent light to accelerate oxidation for a period of time ranging from 5 to 30 days. Remaining myoglobin concentration was measured by molecular absorption UV-vis spectrophotometry at 409 nm. Organoleptic properties and color, texture, and physical characteristics of fresh meat packaged with the new active film have also been measured to evaluate the shelf life of the packaged meat. Results showed that, compared to normal polypropylene, the active film containing natural antioxidants efficiently enhanced the stability of both myoglobin and fresh meat against oxidation processes, thus being a promising way to extend the shelf life of fresh meat.

Adult↗
PubMed2000

Maintaining quality of fresh-cut mangoes using antibrowning agents and modified atmosphere packaging.

Treatments to inhibit browning and decay and prolong shelf life of fresh-cut mangoes were investigated. Combinations of antibrowning agents and modified atmosphere packaging (MAP) resulted in a reduction of browning and deterioration of fresh-cut mangoes stored at 10 degrees C. Combinations of several browning inhibitors were more effective than those applied individually. Among these treatments, solutions containing 4-hexylresorcinol (0.001 M) (HR) plus potassium sorbate (0.05 M) (KS) and HR plus KS plus D-isoascorbic acid (0.5 M) (ER) reduced changes in color (L, a, and b) and microbial growth and did not affect sensory characteristics of fresh-cut mangoes. In general, these treatments did not affect significantly the changes in organic acids and sugar content of slices during the 14 days of storage at 10 degrees C. High humidity created in the in-package atmosphere alleviated tissue dryness and was an important factor in the ability of the antibrowning solutions to prevent browning and decay. It appears that the maintenance of quality of fresh-cut mangoes is more related to particular combinations of the antibrowning agents used rather than the modified atmosphere created inside the package. HR + ER + KS treatment in combination with MAP could be used to inhibit browning, decay, and deterioration of fresh-cut mangoes.

Atmosphere↗
PubMed1997

Spoilage microflora in fresh chicken breast stored at 4 degrees C: influence of packaging methods.

Chicken breasts with skin were packaged either in air, under vacuum or in modified atmospheres of (i) 30% CO2/70% N2 and (ii) 70% CO2/30% N2. After 3, 7, 14 and 21 days of storage at 4 degrees C, the samples were evaluated for spoilage microbial growth, odour and overall aspect. As expected, pseudomonads grew well in air or under vacuum, but growth was suppressed in both types of modified atmosphere packaging (MAP). However, growth of lactobacilli, Enterobacteriaceae and Brochothrix thermosphacta was not inhibited in MAPs. Modified atmosphere packaging (ii) extended shelf-life up to 21 days compared to 5 days for air-packed samples.

Animals↗
PubMed1999

Combined use of acetic acid treatment and modified atmosphere packaging for extending the shelf-life of chilled chicken breast portions.

Samples of chicken breasts with skin were treated with a 1% acetic acid solution or untreated and packaged in a 70% CO2/30% N2 modified atmosphere. Two different types of films were studied to establish their usefulness within the above pre-determined conditions. After 3, 7, 14 and 21 d of storage at 4 degrees C, the samples were evaluated for spoilage microbial growth, odour and slime, as well as the gas composition in the headspace volume in the package. As a result of this, it was found that both films were adequate for using them as barriers. Samples treated with the acetic acid solution smelt slightly acidic and pleasant, while the untreated ones had 'off' odours at the end of the storage periods. However, all samples showed acceptable overall aspect by that time. Acetic acid treatment produced decreases in counts in all genera studied. Results of this study indicate that using modified atmosphere packaging (MAP) on chicken breasts previously decontaminated with acetic acid is a worthwhile technology to extend samples shelf-life.

Acetic Acid↗
PubMed2000

Behaviour of Listeria monocytogenes and autochthonous flora on meat stored under aerobic, vacuum and modified atmosphere packaging conditions with or without the presence of oregano essential oil at 5 degrees C.

The effect of aerobic, modified atmosphere packaging (MAP; 40% CO2/30% O2/30% N2) and vacuum packaging (VP) on the growth/survival of Listeria monocytogenes on sterile and naturally contaminated beef meat fillets was studied in relation to film permeability and oregano essential oil. The dominant micro-organism(s) and the effect of the endogenous flora on the growth/survival of L. monocytogenes were dependent on the type of packaging film. The fact that L. monocytogenes increased whenever pseudomonads dominated, i.e. aerobic storage and MAP/VP in high-permeability film, and even earlier than on sterile tissue, suggests that this spoilage group enhanced growth of the pathogen. Brochothrix thermosphacta constituted the major proportion of the total microflora in MAP/VP within the low-permeability film, where no growth of L. monocytogenes was detected either on naturally contaminated or sterile meat fillets. The addition of 0.8% (v/w) oregano essential oil resulted in: (i) an initial reduction of 2-3 log10 of the majority of the bacterial population, with lactic acid bacteria and L. monocytogenes indicating the most apparent decrease in all gaseous environments, and (ii) limited growth aerobically and survival/death of L. monocytogenes in MAP/VP, regardless of film permeability.

Aerobiosis↗
PubMed2006

Modulation of the viral ATPase activity by the portal protein correlates with DNA packaging efficiency.

DNA packaging in tailed bacteriophages and herpesviruses requires assembly of a complex molecular machine at a specific vertex of a preformed procapsid. As in all these viruses, the DNA translocation motor of bacteriophage SPP1 is composed of the portal protein (gp6) that provides a tunnel for DNA entry into the procapsid and of the viral ATPase (gp1-gp2 complex) that fuels DNA translocation. Here we studied the cross-talk between the components of the motor to control its ATP consumption and DNA encapsidation. We showed that gp6 embedded in the procapsid structure stimulated more than 10-fold the gp2 ATPase activity. This stimulation, which was significantly higher than the one conferred by isolated gp6, depended on the presence of gp1. Mutations in different regions of gp6 abolished or decreased the gp6-induced stimulation of the ATPase. This effect on gp2 activity was observed both in the presence and in the absence of DNA and showed a strict correlation with the efficiency of DNA packaging into procapsids containing the mutant portals. Our results demonstrated that the portal protein has an active control over the viral ATPase activity that correlates with the performance of the DNA packaging motor.

Adenosine Triphosphatases↗