GELLING AND COLOR PROPERTIES OF OSTRICH (STRUTHIO CAMELUS) EGG WHITE

The effect of temperature upon the denaturation process of ostrich egg‐white protein was studied, and it compared with that of commercial hen eggs. Turbidity and color properties evolution were used to determine this effect. In addition, egg‐white gels (from both ostrich and hen egg whites) were obtained by heat treatment at 80C, and these were characterized by means of color, textural properties and water‐holding capacity (WHC). Results showed that although 55C was the temperature for the start of coagulation in both types of egg white, only in hen egg white was the process completed at 65C. The gels obtained at 80C (both ostrich and hen egg‐white gels) presented a strong structure that would allow ostrich egg white to be used as a gelling agent in the food industry as it happens with hen egg white.     

GLASS TRANSITION TEMPERATURE (Tg) AND WATER ACTIVITY (aw) OF DEHYDRATED APPLE PRODUCTS

The onset glass transition temperature (T_go) of Granny Smith apple products was evaluated as a function of drying conditions (air drying and freeze-drying) and moisture and water activity (a_w) levels. T_go was determined in the 0–0.75 a_w range, and it was found to have a maximum value at a_w= 0 (T_go= 4.5 ± 1.6C) for freeze-dried apple and a minimum value at a_w= 0.75 (T_go= -81.4 ± 0.1C) for freeze-dried apple juice. A linear relationship between T_go and a_w was obtained in all cases. Theoretical T_go values at a_w= 0 were calculated using these equations, and were within the range of 3.0C (freeze-dried apple) and 10.5C (apple dehydrated at 30C). When Gordon and Taylor's linear model was applied to the experimental data of all the apple products, K values within the range 2.4 (freeze-dried apple juice) and 3.6 (apple dehydrated at 60C), and the theoretical T_g of solids values at a_w= 0 between the range -16.3C (freeze-dried apple juice) and -1.9C (apple dehydrated at 60C) were obtained. No effect of the type of drying on the value of T_g was detected.     

Computerized roundness inspection

Computerized visual inspection systems are increasingly being considered and implemented as an alternative to manual inspection and manual gauging in manufacturing systems. Although computer vision systems and image processing have received much attention in the past, statistically powerful, yet computationally efficiency methods still remain to be developed to process the visual information to make computerized inspection systems cost effective. This study investigates the case of inspecting round production parts for shape and size. The statistical properties of the out-of-roundness measurement procedure are investigated. Real-time implementation considerations are discussed.     

DENSITY and COMPRESSIBILITY of SELECTED FOOD POWDERS MIXTURES1

The density and compressibility of various mixtures of granular and powdered sucrose, granular malic acid, soy protein and cornstarch, at 1:3, 1:1 and 3:1 were determined and compared to those of the pure components. Unless the particles were of similar size and properties (e.g., granular sucrose and malic acid) and density and/or compressibility could not be deduced from those of the pure ingredient, as a result of the formation of new bed structures. This was particularly the case in powders exposed to elevated relative humidity conditions, in this work a_w= 0.65. Because compressibility can reflect changes in the bed structure as well as deformation of the particles themselves, no correlation could be found between loose bulk density and compressibility. Therefore, each mixture ought to be treated as a new powder the bulk properties of which are determined by their particular microstructure and the water moisture of their components.     

Emulsified Milkfat Effects on Rheology of Acid-Induced Milk Gels

Reconstituted skim milk formed by a gel by acidification to < pH 5.2 and heating to 60°C. The gel compressive stress (σ_c) was influenced by the heating process, increased with milk-nonfat-solids (MNFS) and reached a maximum at pH 4.0. The addition of emulsified fat facilitated gelation, increase gel σ_c and shear modulus, and decreased gel deformability. At an equal fat concentration, emulsions containing small-sized fat globules (i.e., more globules) reinforced the gels more markedly than emulsions comprised of large globules reflecting the importance of number of globules in the gels. Electron micrographs revealed crosslinkages between fat globules and casein particles in the gel network, which may have caused reinforcement of milk gels by milkfat.     

Influence of Titanium Dioxide on the Sintering and Microstructural Evolution of Mullite

Addition of TiO₂ under the solubility limit enhances the initial sintering and grain size of mullite; amounts in excess of that limit inhibit sintering and drastically increase the total porosity and mean pore size.     

A METHOD FOR PREDICTING TIME-CURRENT CHARACTERISTICS OF FUSELINKS

ABSTRACT

In this study a model for the calculation of prearcing time-current in fuselinks is presented. This model is based on the solution of the electric potential, current density and heat diffusion equations using the approximation of the partial derivatives by central finite differences. In this model the variation of the different parameters with temperature is taken into account in the equations. Because of the non linearity of the equations, the solution is obtained by means of a Gauss-Seidel iterative method or relaxation process. The model has been applied to the study of a real fuselink, and a perfect coincidence has been obtained between the theoretical results of the model and the experimental values. The consideration of the variability of the parameters with temperature is fundamental for the above mentioned coincidence. The model has been also used to study the behaviour of different metals as fuse elements. For the studied metals, we can conclude that to obtain different characteristic curves it is necessary to use different geometric forms, since for the same geometry there is a thickness for each material which allows to obtain the same characteristic curve. The model can also be applied to the study of geometric influence on fuselinks.     

Use of analytical solutions of groups (ASOG) contribution method to predict water activity in solutions of sugars, polyols and urea

ASOG (Analytical Solutions of Groups) group contribution method was used to predict water activities in solutions of carbohydrates, polyalcohols and urea. Water activities for the systems water-fructose, water-fructose-urea and water-glucose-urea at 25°C were measured with an electric hygrometer. A set of new ASOG groups was considered and their interaction parameters calculated by numerical non-linear regression of published and measured experimental data. a_w Values predicted by the proposed method agree with experimental data within 0.1–0.9%.     

DIFFERENT PROPORTIONS AND TYPES OF MECHANICALLY RECOVERED PORK IN HAMBURGERS

The properties of hamburgers containing 10, 20, and 30% mechanically recovered meat (MRM) from backbones, 20% MRM from leg bones, and 20% MRM from ribs were studied using such parameters as composition, cooking loss, color, sensory analysis, and instrumental texture analysis. Adding more than 10% MRM increased the percentage of water retained during cooking. The presence of MRM caused a significant decrease in the L (lightness) value of the hamburgers and a significant rise in the a (redness) value, in an amount depending on the proportion and type of MRM. When MRM was added, the hardness and firmness of the hamburgers underwent a significant decrease. Sensory analysis indicated that, though adding MRM led to a certain “liver” flavor, a proportion of 10% MRM resulted in organoleptic properties superior to those of hamburgers made exclusively of hand-boned meat.     

COMPUTER VISION INSPECTION OF ELLIPTICAL PROFILES

Abstract

Computer vision is a complex and multidisciplinary field that is still in its early stages of development. Many of the current applications of computer vision are in the field of inspection because of the relatively low cost of these systems and the need for complete inspection in certain high-volume automated manufacturing or assembly processes. The techniques used to inspect the geometric shape and size of an object appear to be application-specific. This article is concerned with the development of a practical method to measure and inspect parts with an elliptical profile. The method is based on the minimization of the sum of the squares of the central norm errors of a given set of boundary points. The central norm error is defined as the Euclidean distance between a boundary point and the point in the best-fit ellipse along the extension line from the center to the boundary point.