Modified atmosphere packaging (MAP) is commercially used to increase the shelf life of packaged produce by reducing the produce respiration rate, delaying senescence, and inhibiting the growth of many spoilage organisms, ultimately increasing product shelf life. MAP systems typically optimize O(2) levels to achieve these effects while preventing anaerobic fermentation but fail to optimize CO(2) concentrations. Altering film permselectivity (i.e., beta, which is the ratio of CO(2)/O(2) permeation coefficients) could be utilized to concurrently optimize levels of both CO(2) and O(2) in MAP systems. We investigated the effect of modifying film permselectivity on the equilibrium gas composition of a model MAP produce system packaged in containers incorporating modified poly(ethylene) ionomer films with CO(2)/O(2) permselectivites between 4-5 and 0.8-1.3. To compare empirical to calculated data of the effect of permselectivity on the equilibrium gas composition of the MAP produce system, a mathematical model commonly used to optimize MAP of respiring produce was applied. The calculated gas composition agreed with observed values, using empirical respiration data from fresh cut apples as a test system and permeability data from tested and theoretical films. The results suggest that packaging films with CO(2)/O(2) permselectivities lower than those commercially available (<3) would further optimize O(2) and CO(2) concentration in MAP of respiring produce, particularly highly respiring and minimally processed produce.

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Objective:The 2 H dilution technique is the reference method to estimate total body water for body composition assessment. The aims of the present study were to establish the total body water technique at the Kuwait Institute for Scientific Research and assess body composition of Kuwaiti children. Design: The isotope ratio mass spectrometer was calibrated with defined international reference water standards. A non-random sampling approach was used to recruit a convenience sample of Kuwaiti children. A dose of 2 H 2 O, 1-3 g, was consumed after an overnight fast and 2 H enrichment in baseline and post-dose urine samples was measured. Total body water was calculated and used to estimate fat-free mass. Fat mass was estimated as body weight minus fat-free mass. Setting: The total body water study was implemented in primary schools. Subjects: Seventy-five boys and eighty-three girls (7-9 years). Results: Measurements of the isotope ratio mass spectrometer were confirmed to be accurate and precise. Children were classified as normal weight, overweight or obese according to the WHO based on BMI-for-age Z-scores. Normal-weight and overweight girls had significantly higher percentage body fat (median (range): 32?4 % (24?7-39?3 %) and 38?3 % (29?3-44?2 %), respectively) compared with boys (median (range): 26?5 % (14?2-37?1 %) and 34?6 % (29?9-40?2 %), respectively). No gender difference was found in obese children (median 46?5 % v. 45?6 %). Conclusions: The establishment of a state-of-the-art stable isotope laboratory for assessment of body composition provides an opportunity to explore a wide range of applications to better understand the relationship between body size, body composition and risk of developing non-communicable diseases in Kuwait.

The aim of this pilot study was to assess body composition and total energy expenditure (TEE) in 35 obese 7–9 years old Kuwaiti children (18 girls and 17 boys). Total body water (TBW) and TEE were assessed by doubly-labeled water technique. TBW was derived from the intercept of the elimination rate of deuterium and TEE from the difference in elimination rates of 18O and deuterium. TBW was used to estimate fat-free mass (FFM), using hydration factors for different ages and gender. Fat mass (FM) was calculated as the difference between body weight and FFM. Body weight was not statistically different but TBW was significantly higher (p = 0.018) in boys (44.9% ± 3.3%) than girls (42.4% ± 3.0%), while girls had significantly higher estimated FM (45.2 ± 3.9 weight % versus 41.6% ± 4.3%; p = 0.014). TEE was significantly higher in boys (2395 ± 349 kcal/day) compared with girls (1978 ± 169 kcal/day); p = 0.001. Estimated physical activity level (PAL) was significantly higher in boys; 1.61 ± 0.167 versus 1.51 ± 0.870; p = 0.034. Our results provide the first dataset of TEE in 7–9 years old obese Kuwaiti children and highlight important gender differences to be considered during the development of school based interventions targeted to combat childhood obesity.

ABSTRACT:Ionomers have been studied in detail and have gained widespread commercial use. Interested in altering the ratio of CO 2 /O 2 permeability (i.e., permselectivity) of films for use in packaging respiring produce, we pressed sodium-neutralized poly(ethylene methacrylic acid) ionomers into films at 120 -160°C and investigated their thermal, morphological, and permeability properties. The heat treatment of the ionomers at 160°C increased the gas permeability for O 2 more than for CO 2 and reduced the CO 2 /O 2 permselectivity ratio from 4.1 to 1.6. The reasons for these changes in the permeability characteristics of the ionomers are not understood but could be related to a reduction in the polyethylene (PE) crystallinity and the destruction of the aggregates into smaller, dispersed clusters. These results were supported by differential scanning calorimetry data and scanning electron micrographs. This suggests that the heat treatment of ethylene-methacyrlic ionomers may improve their potential for applications as selective barriers for modified-atmosphere packaging of respiring produce.