Note. Behaviour of packaging materials during high pressure thawing Nota. Comportamiento del material para el envase durante la descongelación con altas presiones

This paper focuses on the resistance of packaging materials to piercing during high pressure thawing and delamination due to residual air. Six different packaging materials were tested, the influence of temperature, different depressurization rates and freezing were studied. Among the packaging ma terials tested, only one, BB4L®, containing EVA copolymer, was found to be resistant to piercing.

Interactions between water and EVOH food packaging films / Interacciones entre el agua y películas de EVOH para el envasado de alimentos

The transport of water in four EVOH copolymers commonly used in high barrier food packages was characterized through permeation (continuous flow) and gravimetric experiments at different rela tive humidities and 23 ± 2°C. Water sorption isotherms were fitted with the D'Arcy and Watts' equa tion. From these data, the value of the solubility coefficient (S, as defined by Henry's law) was deter mined and was found constant within a 0.2-0.75 water activity ( aw) range. Water uptake at the same aw increased as the EVOH ethylene content decreased. The permeability coefficient ( P) for water through EVOH was determined as a function of water activity. The permeability was constant within the range of 0.3-0.75 aw and decreased with EVOH ethylene content. At high relative humidities ( aw > 0.75) the value of permeability increased by up to two orders of magnitude. In this range, the higher the ethylene content the lesser the value of P.

Prediction and Determination of Water Uptake in Packaged Yerba Mate

Permeability of different packaging materials and the water uptake were studied in stored yerba mate at different conditions of humidity and temperature. Water vapour transmission rate (WVTR) was evaluated using the quasi-isostatic method. During storage at high relative humidity conditions, WVTR values were of 500 gm2/day for paper and ranged from 16 to 22 gm2/day for laminated films. Values of package permeability and data of food isotherms were used to calculate the variation of internal water vapour activity and to predict the yerba mate water uptake. The predicted and experimental values were in good agreement. For similar high humidity storage conditions, yerba mate packaged with paper reached critical humidity content (9.5% d.b.) at the second day of storage whereas for the laminate films the humidity content stood below the critical value until a month of exposure.

Food aroma partition between packaging materials and fatty food simulants

By means of thermal desorption experiments, the partition equilibrium (partition coefficient, K) was analysed for six food aroma components (d-limonene, n-decane, ethyl caproate, phenylethanol, n-hexanol and hexanal) between three sealable pollymer films suitable for direct food contact (ultra-low density polyethylene, ULDPE; ionomer, ION; and polyester, PET) and four fatty food simulants (ethanol 95%, EtOH; sunflower oil, Oil; n-heptane, HEP, and iso-octane, OCT). The results showed that aroma scalping is highly dependent on the fatty food simulant utilized. Polar aroma components were more sorbed into polymers in the presence of a non-polar fatty food simulant, and vice versa. K values in the presence of Oil were always between those in EtOH and in HEP or OCT. In general, PET was the packaging film which showed the lowest partition coeffecient for non-polar components while ULDPE showed the lowest partition for polar aromas. The partition equilibrium of mixed d-limonene, ethyl caproate, and n-hexanol was also determined. The differences in K values between isolated aromas and mixed aromas were small. In general, the most sorbed aroma showed increased partition by mixture while the partition of the least sorbed was reduced.