不同贮藏条件对大杏仁游离脂肪酸含量的影响

由于大杏仁脂肪含量很高,在贮藏过程中极易发生酸败,因此研究了4种包装形式的大杏仁在10种贮藏条件下游离脂肪酸含量的变化规律,为大杏仁的贮藏提供指导。经过360d的贮藏,结果表明:随着贮藏时间的增加,大杏仁中的游离脂肪酸含量逐渐上升,且贮藏的温度、相对湿度越高,杏仁中的游离脂肪酸含量上升的越快。杏仁的最佳贮藏方案为:杏仁采用PE密封包装,带皮整粒杏仁、脱皮整粒杏仁、切片杏仁在低温低湿(40、45%相对湿度)条件下游离脂肪酸含量基本不变;但基于能耗的考虑,建议在中温低湿(70华氏度、45%相对湿度)条件下贮藏。     

High-Temperature Creep of NaCl-KCl Solid-Solution Alloys

The high-temperature creep of polycrystalline NaCl-KCl solid solutions and pure KCI was studied under constant compression stress at 600°C. The creep rate of the ionic solid-solution alloys appeared to obey approximately Weertman's microcreep equation, = KD_S, where D , is taken to be the diffusion coefficient of the cation and G the shear modulus of the material. Transient creep in the ionic alloys was similar to that in metallic solid-solution alloys which depends on the third power of stress. These results support the view that creep in many polycrystalline metallic and nonmetallic alloys is controlled by the same mechanisms. The creep rate of pure KCI depended on stress to the 5.0 power, a dependence similar to that of most pure metals and to that reported for pure NaCl.     

Constraint-based control of flexible flow lines

This paper presents an important framework for controlling a manufacturing system. Within this framework we developed the constraint-based method of controlling a flexible flow line. Constraint-based control (CBC) combines the powerful Theory of Constraints with the advantages of using the hierarchical control algorithm. As a result, CBC is more practical than the hierarchical control algorithm and adds mathematical rigidity to the Theory of Constraints.     

LEVELS OF LEAD, CADMIUM, AND ZINC IN SELECTED CANNED FOODS (1980/1981)

This paper reports the levels of Pb, Cd, and Zn found in 39 individual canned foods and in samples of ground beef and sugar collected throughout the United States in fiscal years (FYs) 1980 and 1981. The foods were collected in conjunction with the Total Diet Studies program of the Food and Drug Administration (FDA), but were analyzed separately from the Total Diet samples at the FDA Kansas City District Laboratory. Before analysis, multiple-can samples of each product type were individually composited and thoroughly homogenized with dilute nitric acid to ensure representative subsamples for analysis. Homogenized subsamples were dry-ashed with sulfuric acid as the ashing aid and analyzed by differential pulse anodic stripping voltammetry for Pb and Cd and by atomic absorption spectroscopy for Zn. Quantitation limits were 0.02 ppm Pb, 0.002 ppm Cd, and 0.1 ppm Zn. The overall mean levels of Pb, Cd, and Zn found in the 19 canned foods that contained sufficient samples for statistical analysis were 0.19 and 0.22 ppm Pb, 0.011 and 0.008 ppm Cd, and 4.3 and 5.0 ppm Zn in FY-80 and FY-81, respectively. These levels are about one-half as high as the levels found for Pb and Cd in an FDA FY-74 survey but are about the same for Zn. The frequency and magnitude of occasionally high levels of Pb in individual samples were considerably diminished in FY-80 and FY-81, compared to those in FY-74. These lower levels are probably due to improvements in canning technology, in quality control by food processors, and in the methods used for analysis. Over the next 3 years the FDA will continue this survey of individual canned foods, focusing on adult canned foods commonly eated by children, to monitor the progress of industry in reducing Pb levels in canned foods.     

Development Aspects of an Integrated Pyroelectric Array Incorporating a Thin PZT Film and Radiation Collectors

Work is being undertaken to produce an uncooled pyroelectric infra-red detector array which incorporates within its structure, an array of radiation collectors made by the bulk micro-machining of silicon. Development aspects of the processing route are presented here.     

Some observations on the bowl phenomenon

Previous studies suggest that performance of a series system may be enhanced if those station(s) having smallest mean operation time requirement(s) and/or smallest variability are placed in the middle of the line. There has been considerable confusion relative to whether this ‘bowl phenomenon’ has to do with the placement of means, variances, or some combination of the two. The results of the current study show that the phenomenon observed is not related to an imbalance in means. Rather, it is associated with an imbalance in absolute variability. Furthermore, it is suggested that the bowl effect vanishes altogether in cases where a minimal level of in-process buffer stock is provided.     

Effect of Sodium Nitrite Concentration, Sodium Erythorbate and Storage Time on the Quality of Franks Manufactured from Mechanically Deboned Turkey

The effects of sodium nitrite (0-156 ppm), sodium erythorbate (0 or 550 ppm) and storage time (up to 10 wk at 4°C) were measured on the chemical and sensory properties of turkey franks formulated largely from mechanically deboned turkey (MDT), Residual nitrite in the finished product was proportional to that incorporated at time of formulation and was reduced by using small initial amounts in combination with the maximum allowable erythorbate (550 ppm). Acceptable cured color in turkey franks was achieved with the incorporation of 50 ppm of nitrite. Erythorbate effectively increased cured color development and stability, particularly with smaller amounts of nitrite. Rancidity development in turkey franks was not of major significance. Even so, the presence of erythorbate imposed further control of oxidative changes in lipids. Maximum cured flavor development occurred with 50–100 ppm nitrite.     

CITIZEN REACTIONS TO URBAN GROWTH: ATITUDES TOWARD QUALITY OF LIFE AND LOCAL PUBLIC SERVICES IN AN EXPANDING SUNBELT COMMUNITY

This paper reports the results of a survey of citizen attitudes toward growth, and the quality of life in an expanding Sunbelt community. We find considerable continuity in our results with those of earlier research on “community satisfaction” in more stable metropolitan areas. A t the same time there are unusual findings here—in particular regarding how evaluations of certain kinds of local public services and of public sector efforts to control growth—influence perceptions of quality of life. These and other results in the paper suggest directions for future research on Sunbelt communities. They point, as well, to the importance of both population and community dynamics and local political reactions to such changes for a general understanding of perceptions of quality of life.     

SIMULTANEOUS INSTRUMENTAL MEASUREMENT OF FIRMNESS AND JUICINESS OF APPLE TISSUE DISCS

Discs of apple tissue were compressed to 75% of their original height. Throughout compression, the force-distance curve was collected and the electrical impedance of the discs was measured at two frequencies of alternating current—1 kHz and 1 MHz. Electrical impedance was separated into its resistive and reactive components, and at these particular frequencies changes in resistance predominated. Measurements at 1 kHz indicate the resistance of extracellular regions of the discs (ruptured cells as well as those regions external to the plasma membrane), while measurements at 1 MHz indicate the resistance of the entire disc (combined intracellular and extracellular regions). Juice was released from the discs as a result of damage to cells and the extrusion of cellular fluid into intercellular air spaces. This resulted in a decline in electrical resistance at 1 kHz, but little change to the resistance at 1 MHz. Changes in juice release as determined by electrical measurement were related to the mechanical properties of the discs. Generally, the release of juice occurred after the inflection point on the force-distance curves, but much earlier than mechanical failure (indicated by maximum force). The extent of tissue damage was determined from the relative decrease in resistance at 1 kHz, and was found to vary among apple cultivars and in response to fruit ripening.     

Mass-Spectrometric and Electrochemical Studies of Thermodynamic Properties of Liquid and Solid Phases in the System CaO-Al2O3

The activities of CaO and Al₂O₃ in lime-alumina melts were studied by Knudsen cell-mass spectrometry at 2060 K. Emf of solid state cells, with CaF₂ as the electrolyte, was measured from 923 to 1223 K to obtain the free energies of formation of the interoxide compounds. The results are critically evaluated in the light of data reported in the literature on phase equilibria, activities in melts, and stabilities of compounds. A coherent set of data is presented, including the previously unknown free energy of formation of CaO.6Al₂O₃ and the temperature dependence of activities in the liquid phase.