D.E. Smith

Effect of water content and molecular weight on the moisture isotherms and glass transition properties of inulin

Abstract Inulin is being used more and more in foods due to its ability to add functionality either as a sweetener or fat replacer and also for its nutritional benefits. In this research, moisture sorption isotherms and glass transition temperature (Tg) as a function of moisture content and molecular weight for four inulins were determined. The Tg of the inulins was related to moisture content and also molecular weight. As with maltodextrins, the extent of lowering Tg was directly related to the average chain length (lower Tg with lower chain length). The sorption properties are also similar to maltodextrins, thus inulin may be useful in providing similar functionality as maltodextrins with almost no calories (1.5 kcal/g).

Water vapor permeability, mechanical, and structural properties of edible β-casein films.

Abstract Edible films were made using glycerol and β-casein that had been stored for 16 months at −29 and +22.5°C. Water vapor permeability at 22.5°C was determined for two relative humidity gradients. Stress–strain curves for mechanical property evaluation were obtained by dynamic mechanical analysis. Film structure was observed by scanning electron microscopy and Fourier transform infrared spectroscopy. Protein storage temperature did not significantly affect water vapor permeability, elongation, or observed structure; however, differences in yield strength, modulus of elasticity, and tensile strength were detected.

Effect of water content, temperature and storage on the glass transition, moisture sorption characteristics and stickiness of β‐casein 1

Abstract Moisture sorption isotherms at +4 °C and +22.5 °C were obtained for β‐casein after isolation and after 9 months of storage at ‐29 °C and +22.5 °C. Glass transition state diagrams (Tg vs. moisture) were determined for β‐casein after storage. The results showed that effects of storage temperature on moisture sorption isotherms were varied; however, at any aw differences in moisture content were small (< 0.03g H2O/g solids at high aw). β‐casein stored at ‐29°C had lower mo and Tg values than that of β‐casein stored at +22.5°C. The glass transition temperatures for β‐casein were above room temperature, even at aw = 0.76. Onset of stickiness occurred above aw = 0.76.

Agility Metric Robustness Using Linear Error Theory

The robustness of agility metrics has been studied to determine the sensitivity of selected metrics to variations in initial conditions and uncertainties in physical characteristics and coefe cients. The selected metrics are time to roll through bank angle metric, time-averaged integral of pitch rate metric, and power onset/loss parameter. Each metric was evaluated with initial condition errors and parametric uncertainties of physical constants using linear error theory to validate the use of linear approximations to propagate the errors.

Adsorption of proteins at the lipid-serum interface in milk systems with various lipids

Abstract The effect of lipid type on the amount and profile of proteins adsorbed at the lipid-serum interface in homogenized milk systems was studied. Lipid sources were milkfat, butter oil, corn oil and a commercial system used for vitamin A and D milk fortification. Protein adsorption with the commercial system was significantly lower than with the other systems, which exhibited similar protein concentrations. Inclusion of vitamin A (all- trans retinyl palmitate) alone or in combination with Tween 80 or distilled monoglycerides in corn oil decreased significantly the amount of proteins adsorbed. Both casein and whey proteins were adsorbed at the lipid-serum interface. Casein composed more than 96% of the total milk proteins adsorbed. Among whey proteins, β-lactoglobulin was the dominant protein. The ratios for the three caseins in the adsorbed film were different from their proportions in the serum phase; β-casein was present in higher concentrations, followed by α s and κ-casein, respectively.

Effect of β-carotene on vitamin A light stability in fortified milk

Abstract The effect of incorporation of β-carotene into the carrier system on the light stability of all- trans retinyl palmitate in fortified skim milk was investigated. Skim milk was fortified with all- trans retinyl palmitate using corn oil with and without added β-carotene as the vitamin carrier. Two levels of β-carotene were used, one similar to, the other half the concentration of vitamin A in the carrier system. After homogenization and pasteurization, fortified milk samples were exposed to fluorescent light (1614 lx) at 4°C in glass tubes. Less light degradation of all- trans retinyl palmitate occurred in samples containing added β-carotene in the carrier systems compared to samples without added β-carotene. The β-carotene content of fortified milk samples showed only a slight decrease over the four-day period of exposure.

Determining the kinetic reaction rate order for the thermal denaturation of β-lactoglobulin using two statistical approaches ☆

Abstract Literature data, reporting the kinetic reaction rate order of the thermal denaturation of β -lactoglobulin ( β -lg), were reviewed using two statistical approaches including R 2 and the Box–Cox transformation. Although R 2 , the coefficient of determination, has been used by many researchers as a criterion to compare the fit of data to various kinetic reaction rate orders, this statistic should not be considered appropriate for transformations of the same data set. The Box–Cox transformation, however, was constructed to systematically approach the problem of choosing a data transformation, which is the basis for the different reaction rate orders. The results of the analysis showed that, for some data sets, the reaction rate order determined using R 2 was not in agreement with the Box–Cox determination. Just as importantly, the Box–Cox transformation resolved that for most data sets analyzed, the reaction rate order was indeterminate and that more than one reaction rate order could represent the data. The conflicting results reported in the literature on the thermal denaturation of β -lg could result from the statistical approach used to analyze the data and determine a reaction rate order.

COMPARISON OF TRADITIONAL AGILITY METRICS TO BECK PERFORMANCE AND AGILITY METRICS USING LINEAR ERROR THEORY

Previous investigations have studied the robustness of agility metrics to variations in initial conditions and uncertainties in physical characteristics and coefficients. In each of these investigations, the selected agility metrics were evaluated in a Cartesian coordinate system. It is known that values of calculated parameters can be sensitive to the particular form of the equation used, which in turn results from the choice of coordinate system. Although simple and intuitive for quantifying agility, Cartesian coordinates are not necessarily the best coordinate system for studying agility. Best is defined here as the form of agility equation, resulting from choice of coordinate system, which is most robust to variations in initial conditions and uncertainties in physical characteristics and coefficients. This paper seeks to establish the relationship between form of agility equations, choice of coordinate system, and the measured agility of high performance aircraft. Cartesian based agility metrics consisting of time to roll through bank angle metric, average pitch rate metric, and power onset/loss parameter metric, are compared to the Beck metrics which are based in the Frenet coordinate system. Each group of metrics is evaluated with initial condition errors and parametric uncertainties of physical constants using linear error theory to validate the use of linear approximations to propagate the errors, l^. is shown that the Beck metrics are less sensitive to initial condition errors and parametric uncertainties for the longitudinal and axial axes. The time to roll through bank angle metric is less sensitive to these variations than the Beck metrics for evaluating agility in the lateral axis.