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In this research a new antioxidant active food packaging has been developed and evaluated. It consists of an innovative system in which several natural antioxidants from rosemary ( Rosmarinus officinalis L.) have been immobilized in a polypropylene film. The influence of concentration of the active compounds in the polymer and the contact system between the active film and simple food simulants have been studied. l -ascorbic acid, iron (II) and fatty acids from flax seed oil have been used as model compounds, being representative of the behaviour of different foodstuffs with respect to oxidation. Whereas ascorbic acid has proven to be not adequate for antioxidant quantitation purposes due to its prooxidant properties, increased protection of up to 30.1% for iron (II) and 62.0% for fatty acids were found. Among the advantages of this developed system, which extends the shelf life of packaged food, the non contact plastic-food requirements can be emphasized.

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.

Both specific and overall migration tests have been applied to new experimental food packaging-active plastic films with antioxidant properties, including in its composition a natural rosemary extract. Determination of volatile and semivolatile compounds migrating from plastic to the four established simulants showed that both specific and overall migration was very low. The results obtained gave values 20 times lower than the established limits in the worst case. So, from the point of view of health risk, the new active packaging can be considered as safe. Analytical procedure used provided the necessary information about the migration behavior, with good analytical characteristics and detection limits in the sub μg kg-1 range. Besides, no significant difference was found between laboratory and factory-made samples, which is an important issue for industrial production, the next step in the development of the new antioxidant active film. Keywords: Active packaging; migration; antioxidant; rosemary; polyp...

The presence of antibodies against antigens of K. pneumoniae in HLA-B27 positive patients with ankylosing spondylitis (AS), has been well documented. We have previously reported that sera from HLA-B27 positive subjects react with the K. pneumoniae GroEL-like protein (HSP60Kp) and have higher titers than HLA-B27 negative individuals. We cloned the gene that codes for this protein, determined hydrophilic regions by computer analysis of the predicted amino acid sequence and found that residues 389-397, 360-368 and 282-290, were possible B cell epitopes. To test this prediction, and to determine if the HLA-B27 positive and negative AS patients recognize the same or different epitopes, we truncated the hsp60Kp gene, from the 3; terminal nucleotide, to obtain fragments having or not the predicted epitopes. Four polypeptides of 40, 37, 30 and 18 kDa were obtained and analysed, by ELISA and inhibition of ELISA, for their reactivity with IgG antibodies from three high responders HLA-B27 positive AS patients and three HLA-B27 negative subjects who recognized the rHSP60Kp. Sera from both HLA-B27 positive and negative subjects reacted equally well with rHSP60Kp or with the 40 and 37 kDa peptides, which do not have residues 389-397 and 360-368, respectively, but reactivity was lost with the 30 kDa peptide, which also lacks residues 282-290. Contrary to what we expected, antibodies from HLA-B27 negative and positive individuals recognized the same epitope of the HSP60Kp. Our results indicate that the important epitope for B cells could be the 282-290 region and that the contribution of the two other predicted regions is minimal. We also conclude that the differences in response to the HSP60Kp in HLA-B27 positive AS patients and HLA-B27 negative individuals is not qualitative, but only quantitative.