MOISTURE TRANSFER PROPERTIES of WILD RICE

Working isotherms for processed wild rice and desorption isotherms for unprocessed wild rice were determined at temperatures ranging from 10 to 43.5°C. the constants for the Guggenheim-Anderson-DeBoer (GAB), Day and Nelson, Chen and Clayton and modified Halsey equations were determined by using a nonlinear optimization technique. the GAB equation showed extremely good fit to the experimental data (less than 5% error). the diffusion coefficients for moisture transport in both broken and whole processed wild rice and for unprocessed wild rice samples were determined at room temperature. the processed broken wild rice kernels had an effective diffusion coefficient of 2.66 × 10^?9 m²/h, whereas the effective diffusion coefficient was 7.08 × 10^?10m²/h for the processed whole wild rice kernels. Unprocessed wild rice had moderate effective diffusivity (1.4 × 10^?9 m²/h). These results predicted quite well the equilibrium water activities and time to equilibrium of wild rice-white rice mixtures using both analytical methods and the finite element method. the transfer of moisture to or from packaged wild rice was also illustrated for different distribution systems.     

Accelerated Kinetic Study of Aspartame Degradation in the Neutral pH Range

The degradation of aspartame in solution as a function of temperature (70–100°C), buffer concentration (0.01–0.1M phosphate), and pH (6–7) was studied in order to estimate losses during thermal processing and storage of aseptic milk-based drinks. Prior data have been mostly on acid carbonated beverages. First order rate constants were obtained in all the conditions with activation energies in the range 14–20 kcal/ mole. An increase in both pH and buffer concentration caused an increase in rate of loss. These data were used to predict losses that would occur during pasteurization and sterilization conditions. Experiments at 4 and 30°C showed significant losses would occur during 4 and 30°C temperature storage and extrapolation from high temperatures predicted faster degradation rates than those found.     

Solvent Techniques for the Direct Colorimetric Determination of Copper and Iron in Oils

SUMMARY— The standard procedure for determining trace metals in biological materials requires the ashing of the sample to obtain an aqueous solution. Once this sample is prepared, numerous methods may be employed to determine the metal content. With oils the common ashing techniques lead to serious errors because of spattering, foaming, and volatilization of the sample. In the past, several methods have been developed to eliminate the ashing procedure but large samples (20–50 g) or special equipment was necessary. To allow use of very small oil samples (0.5–2 g) for determining iron and copper, solvent procedures which eliminated the ashing step were developed. The iron procedure is based on the standard aqueous 1,10-o-phenanthroline method modified to employ an initial solvent extraction procedure. Comparison of this method with the aqueous ash procedure on oils of known iron content showed the methods to be equivalent in precision. The solvent procedure is capable of determining 0.1 ppm of iron in the oil. The direct solvent copper procedure based on the sodium-diethyldithiocarbamate aqueous method showed similar results. Because of the ease of performance and the small sample size required, these tests would be useful in food and biological research.     

Air Drying Characteristics of Apricots

The optimization of the drying of apricots was studied using four treatments: (1) blanching and drying; (2) sulfiting-blanching and drying; (3) blanching-sulfiting and drying; and (4) sulfiting-drying to 50% moisture-blanching and finish drying. Levels of sulfiting were from 0–2000 ppm SO₂ and drying was done at 50° to 80°C. The quality of dried apricots was judged by extent of browning development and hardness determination. A surface response statistical design was applied to evaluate the optimum drying conditions. Sulfiting-drying, using 80–1000 ppm SO₂ at any temperature in the range 50–80°C, was found to be the best treatment. Thus, sulfite was the major factor in controlling dry apricot quality and would be hard to reduce. Drying time was reduced by 50% when apricots were dried at 80°C compared to 50°C, and blanching reduced the time by 10 to 20%. Loss of SO₂ was greater than 50% for all treatments.     

Influence of Dairy Proteins on Aspartame Stability in the pH 6–7 Range

The effect of three commercial milk protein products on aspartame degradation was studied as a function of temperature (4, 30, 70, 80°C), pH (6 and 7), phosphate buffer concentration (0.01 M/L, 0.1 M/L) and protein (0–3%). Caseinates significantly decreased the pseudo-first order loss rate at low buffer concentration and higher temperature (70–80°C), whereas the rate was faster in the presence of a casein/ whey mixture. At high buffer concentration, the loss rate was not affected by protein. The protective effect may have been due to either a buffering capacity decrease caused by a protein/aspartame interaction that lowered pH or some unknown protein interaction. At 4 and 30°C, the loss rate was not affected by calcium caseinate.