Gas exchange in modified atmosphere packaging. 2: Experimental results with strawberries

Strawberries were used to test a new model describing gas transport through micro-perforated polypropylene films and fruit respiration involved in modified atmosphere packaging. Some experiments were conducted with empty packs initially filled with either 100% N₂ or 100% O₂. Simulations agreed very well with experiments only if we replaced the cross-sectional area of the micro-perforations by areas of approximately half the actual areas in order to account for the resistance of air around the perforations. It is also possible to fit the model to gas concentration changes in packs filled with strawberries, although deviations have been due to the contamination of strawberries by fungi. the model was used to quantify the consequences of the variability of pack properties (number of micro-perforations per pack and cross-sectional area of these perforations) on equilibrium gas concentrations and to define minimum homogeneity requirements for modified atmosphere packaging.     

Valeur d'un test in vitro d'incorporation de glucose marque pour l'estimation de l'activité antiseborrheique

Deux methodes d'estimation de l'activité antiséborrhéique, l'une in vitro , l'autre in vivo , ont été comparées en étudiant l'action de deux produits différents: le metbufen et la N-sébaçoylméthionine. Le test in vitro d'incorporation de glucose marqué est pratiqué sur la glande préputiale de rat isolée. In vivo , sur la peau de rat castré et supplémenté par l'énanthate de testortérone, l'effet de traitement topique est suivi par l'étude histologique des glandes sébacées.
Les résultats obtenus avec les deux produits essayés présentent un parallélisme permettant de conclure à la validité du test in vitro dans le screening de molécules à activité antiséborrhéique.
An in vitro test for the evaluation of antiseborrheic activity     

EFFECT OF SOY PROTEIN ISOLATE AND SOY FIBER ON COLOR, PHYSICAL AND SENSORY CHARACTERISTICS OF BAKED PRODUCTS

Quick breads were formulated to contain 0%, 40%, 50% or 60% Soy Protein Isolate and Fiber (SPI/Fiber), and yeast breads were formulated to contain 0%, 14%, 21% or 28% SPI/Fiber replacement for wheat flour. Physical and sensory data were collected. As SPI/fiber level increased, muffin batter specific gravity, baked product air cell number, Instron peak force to compress by 75%, a value, beany flavor, grain-like flavor, aftertaste, moistness and denseness increased while muffin peak height at the crown, baked volume, L and b values, hue angle, sweetness and crumbliness decreased. There were significant negative correlations between increased level of SPI/fiber in muffins and acceptability of flavor and texture, as well as willingness to purchase or purchase the product at a higher price. As SPI/fiber level increased, bread dough pH after fermentation, air cell number, Instron peak force to compress by 75%, a and b values, beany flavor, grain-like flavor, and aftertaste increased while loaf volume, peak height at the crown, L value, hue angle, cohesiveness and crumbliness decreased. There were significant negative correlation coefficients between level of SPI/fiber and acceptability of flavor and texture, as well as willingness to purchase the product or to purchase it at a higher price.     

Recrystallization in Model Ice Cream Solutions as Affected by Stabilizer Concentration

Ice recrystallization rates in simple aqueous solutions comprising fructose and a hydrocolloid stabilizer were measured. The stabilizers were an enzyme-modified guar and a non-gelling high methoxy pectin. The stabilizer concentration dependence of the recrystallization rates for both materials was similar in that increasing the concentration resulted in decreasing rates until a point is reached where further addition had no additional effect. That recrystallization rates were reduced by both gelling and non-gelling stabilizers was strongly suggestive that gelation was not a requirement for recrystallization inhibition and another more specific mechanism applies, for example a weak interfacial effect such as adsorption or blocking. This behavior was also seen with locust bean gum and guar and provided further empirical evidence to support the hypothesis that stabilizers adsorb to ice crystal surfaces.     

ALPHA-TOCOPHEROL EFFECTS ON COLOR AND SENSORY CHARACTERISTICS OF GROUND PORK DURING RETAIL DISPLAY

To assess the effects of a-tocopherol addition on lipid and pigment oxidation of ground pork, 10, 100 or 1000 ppm was added directly to ground pork in a food grade carrier (2% Medium Chain Triglyceride Oil) then pork was overwrapped with polyvinyl-chloride film and displayed at 4C for three days. Addition of α-tocopherol to ground pork had limited effects on color and sensory characteristics. Display time and light present during display had detrimental effects on a* value, total color, red color contributed by oxymyoglobin, percent of myoglobin, metmyoglobin and oxymyoglobin, visual red and grey colors.     

Energy Catabolism in Rabbit Muscle as Affected by Brine Injection: 31P NMR Studies

The energy catabolism in brine-injected muscles was examined by ³¹P Nuclear Magnetic Resonance (NMR) spectroscopy. Immediately after death of rabbits, brines containing NaCl, with or without pyrophosphate, were injected into the arterial system. ³¹P NMR spectra at 4°revealed marked heterogeneity in postmortem catabolism due to brine diffusion. The heterogeneity of the Pi signal for injected muscles reflected the existence of muscle areas with different intracellular pH values. This observation suggested an increase in rate of glycolysis for fibers experiencing brine. The heterogeneity of brine diffusion seemed to be affected by method of injection.     

Effect of Melting History on the Mechanical Properties of Glass: I, Role of Melting Time and Atmosphere

The pristine strength of 0.5Li₂O·0.5K₂O·2SiO₂ glass measured in 3-point bending under liquid nitrogen was studied as a function of melting time and atmosphere at a constant melting temperature. The atmosphere over the melt was one of the most important parameters affecting the pristine strength. The most significant time-dependent melting effects and the highest strengths resulted from melting in a dry atmosphere of O₂ or air. In contrast, vacuum-melted and Ar-melted glasses had the lowest strengths. Melting in N₂ or CO₂ led to intermediate strengths. The presence of water vapor in the atmosphere during melting was detrimental to strength in those cases where very high strengths had been obtained with dry gases. The introduction of water vapor into those gases which in the dry state had led to low-strength glasses did not significantly affect the strength. The effects of the atmosphere in leading to oxygen-deficient or excess-oxygen glasses on the formation or dissolution of microheterogeneous regions were correlated with the pristine strengths of the glasses.     

Swelling Control in Uranium Carbide

Fine particles were dispersed in a fuel structure to trap fission gases as very small bubbles and thereby reduce fuel swelling. The dispersions were made by adding 1.5 to 3.0 wt% W to the UC; the specimens were irradiated to a maximum of ∼2 at.% burnup. Density changes were used as the measure of swelling; there was much scatter in the results. Tungsten reduced the swelling when it was uniformly dispersed. For some samples having excess U and W or a segregated structure, W increased the swelling. The results tentatively confirm that fine particles are of value in reducing fission-gas swelling of carbide fuels.     

Heats of Solution, Density, and Refractive Index Changes in Sodium Borate Glasses Subjected to High Pressure

The densification produced in sodium borate glasses by pressures to 40 kbars at 25° and 250°C was measured. At a constant temperature and pressure, the densification decreased with increasing alkali content. For specimens pressed at 40 kbars and 250°C, the densification ranged from 14.2% for B₂O₃ to 6.3% for the 33.3 mole % Na₂O composition. Under the same conditions, the refractive index increase ranged from 4.8 to 1.1%, and the decrease of the molar refraction of the oxygen ions ranged from 2.5 to 1.5%. The heats of solution of the pressed glasses were more negative than those of the corresponding unpressed glasses. The heats of solution of both the pressed and unpressed glasses pass through a minimum near 20 mole % Na₂O. A decrease in density was observed at room temperature for all pressed specimens. Electron micrographs were made of two of the pressed specimens. The results could be explained on the basis of a repacking of structural units.     

Sensory Detection and Population Thresholds for Sodium Tripolyphosphate in Cooked Ground Turkey Patties

Sodium tripolyphosphate (STP) at levels of 0.1, 0.2, 0.3, 0.4, and 0.5% by weight was added to ground turkey meat to determine if a flavor difference could be detected when STP was present. Detection thresholds for STP in ground turkey meat were determined for 30 female respondents. Two population thresholds were determined using information from the detection thresholds. Two-thirds of the respondents detected a difference between samples with no STP and those with 0.5% STP or less. STP added at less than 0.3% was undetected by more than 50% of the tested population.