Over the past few decades, many new packaging techniques have been introduced in the quest for natural preservation of foods and on-time quality monitoring of packaged food to ensure good product quality and safety for the consumer. This paper discusses scientific, technological, commercial and legislative development, as well as consumer aspects and acceptance of the active and smart food packaging techniques with current or potential commercial value, and the elements that both the manufacturers of these packaging systems and the food industry should take into account before launching products using these techniques.

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The effects of potato variety (Van Gogh, Bintje and Fambo), washing with browning prevention chemicals in place of sodium bisulfite, percentages of CO2, O2, and N2 in the package headspace, and storage time (1, 4, and 7 days) on the sensory and microbiological quality of potato slices were examined. Citric acid and ascorbic acid (at 0.1% each and at 0.5% each) were used as browning prevention chemicals. In the packaging atmosphere the percentage of N2 was 75 or 80%, the percentage of O2 was 5 or 0%, and the percentage of CO2 was 20% at the beginning of storage. Packed potato slices were stored in the dark at 5 degrees C. Darkening was the most important factor limiting the sensory quality of raw potato slices. Darkening occurred quickly with Fambo slices; it seems that Fambo is not a suitable potato variety if slices are to be stored. Water-washed and cooked Van Gogh slices were still acceptable for retailing after a storage period of 7 days. After 7 days of storage the best sensory quality of both raw and cooked Bintje slices was obtained with washing solutions containing 0.1 to 0.5% citric and ascorbic acids and with the gas mixture containing 20% CO2 and 80% N2. The number of microorganisms was higher in samples stored in the atmosphere containing 5% O2 than samples stored in the atmosphere containing 0% O2. Washing of potato slices with browning prevention chemicals decreased the number of microorganisms compared to potato slices not washed or potato slices washed with water after 7 days of storage.

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Marinated chicken breast pieces and sliced rainbow trout were packed in modified atmosphere and stored to measure effects of package leakage. The sensory shelf life of products decreased slowly but linearly as leakage rate increased, with exception of the appearance of sliced rainbow trout, which was not affected by leakage rate. The concentration of ethanol in head space was a potential indicator of spoilage and package leakage for both nroducts. The nresence of dimethvlsulfide indicated spoilage of chicken fillet and acetone indicated leakage in sliced trout packages. A redox leakage color-indicator functioned properly in package lids.

Plasma-activated biaxially oriented polypropylene (BOPP) fi lms and paper substrate have been coated with functional chitosan solutions. Plasma treatment increased the amount of surface peroxide groups and carboxyl groups on the BOPP fi lms. As a result of plasma activation, the surface energy increased from 30 to 50 dynes/cm. The enzyme tyrosinase catalysed the grafting of octyl gallate and dodecyl gallate to amino groups of chitosan polysaccharide. Resulting coatings exhibited strong antimicrobial activity against Gram-positive Staphylococcus aureus and Gram-negative Listeria innocua. After 24 h of incubation, a total reduction in both bacteria cell numbers varied between > 4.9 and 1.4 logarithmic units. Grafted dodecyl gallate and octyl gallate at pH 6 were found to have the lowest reduction values of < 3 logarithmic units for S. aureus, while 1.4 logarithmic reduction value was obtained for grafted dodecyl gallate at pH 6 against L. innocua. Chitosan coatings were also effective barrier layers against oxygen transmission although the transmission rates clearly increased in high-humidity conditions. In dry conditions, however, the transmission rate of 2 cm 3 /(m 2 · 24 h) was obtained with chitosan-coated BOPP. Coatings did not have any effects on water vapour transmission.Both gallates were successfully grafted at pH 6. As increased fl occulation and colour formation indicated, the tyrosinase-catalysed grafting was more powerful with octyl gallate. Dodecyl gallate containing chitosan coatings was more hydrophobic as compared to octyl gallate. Total migration of substances into 95% ethanol was £ 5 mg/dm 2 , thus materials may be exploitable in packaging purposes in direct contact with certain foodstuffs.