Textural instruments

Peleg, M. 1987. The basics of solid food rheology. In Food Texture Instrumental and Sensory Measurement (H.R. Moskowitz, ed.) pp. 3-33. Marcel Dekker, New York. 

Food Texture Instrumental and Sensory Measurement, edited by Howard R. Moskowitz... 

Feeding and texture of food (meeting), Vincent J.F.V, Cambridge UP, 1991, 60 Food texture measurement and perception, Rosenthal A.J, Aspen PubL, 1999, 142 Food texture Instrumental and sensory measurement (meeting), Moskowitz H.R,... 

Campbell (6) was perhaps the first to investigate the relationship between tenderometer values for raw peas and the texture characteristics of collateral samples after freezing and cooking. A high degree of correlation was observed. The investigations of Nielsen and co-workers (31) indicate the usefulness of the instrument for estimation of maturity in peas intended for freezing preservation. In order to secure consistent and reproducible results, the instrument requires standardization and calibration, and the measurements must be made under standardized conditions of temperature and interval after harvest. 

Replication avoids the problem of sample deterioration in the instrument, but it is destructive in that reaction of the material cannot be continued after the replica has been prepared. Transitory features cannot be detected unless a series of preparations are examined corresponding to increasing progress of the reaction considered. The textures of replicas have been shown [220] to be in satisfactory agreement with those of the original surface as viewed in the scanning electron microscope. The uses and interpretations of observations made through sample replication procedures are illustrated in the studies of decomposition of metal carboxyl-ates by Brown and co-workers [97,221—223]. 

Alcohol sulfates are excellent foaming surfactants. According to the Kitchener and Cooper classification [148], alcohol sulfates form metastable foams. However, quantitative values cannot easily be compared because foam largely depends not only on the instrument used to produce and evaluate foam but also on the concentration of surfactant, impurities, temperature, and many other factors. In addition, a complete characterization of the foam capacity should take into account the initial amount of foam, its stability, and its texture. 

In disinfection of instruments, the chemicals used must not adversely affect the instruments, e.g. cause corrosion of metals, affect clarity or integrity of lenses, or change texture of synthetic polymers. Many materials such as fabrics, rubber, plastics are capable of adsorbing certain disinfectants, e.g. quaternary ammonium compounds (QACs), are adsorbed by fabrics, while phenolics are adsorbed by rubber, the consequence ofthis being a reduction in concentration of active compound. A disinfectant can only exert its effect ifit is in contact with the item being treated. Therefore access to all parts of an instrument or piece of equipment is essential. For small items, total immersion in the disinfectant must also be ensured. 

Following previous works on physico-chemical characterisation of sunflower low-methoxyl pectins (Alarc o-Silva, 1990, Leitao at al., 1995) and technological utilisation in the manufacture of low calorie gels (Alarc o-Silva et al., 1992), this investigation was carried out to test the suitability of that pectin to the confection of grape juice reduced calorie jellies in comparison with two types of commercial pectin. Aiming at the optimisation of low-calorie jelly formula, based on consumers preferences, the jellies were submitted to a sensory panel test judgement and instrumental texture-analysis. 

Beilken et al. [ 12] have applied a number of instrumental measuring methods to assess the mechanical strength of 12 different meat patties. In all, 20 different physical/chemical properties were measured. The products were tasted twice by 12 panellists divided over 4 sessions in which 6 products were evaluated for 9 textural attributes (rubberiness, chewiness, juiciness, etc.). Beilken etal. [12] subjected the two sets of data, viz. the instrumental data and the sensory data, to separate principal component analyses. The relation between the two data sets, mechanical measurements versus sensory attributes, was studied by their intercorrelations. Although useful information can be derived from such bivariate indicators, a truly multivariate regression analysis may give a simpler overall picture of the relation. 

Hale, A. B., Carpenter, C. E., and Walsh, M. K. (2002). Instrumental and consumer evaluation of beef patties extended with extrusion-textured whey proteins. /. Food Sci. 67,1267-1270. 

Pons, M., and Fiszman, S. M. (1996). Instrumental texture profile analysis with particular reference to gelled systems. /. Texture Stud. 27,597-624. 

In practice, the application of x-ray measurement techniques to thin films involves some special problems. Typical films are much thinner than the penetration depth of commonly used x-rays, so the diffracted intensity is much lower than that from bulk materials. Thin films are often strongly textured this, on the other hand, results in improved intensity for suitable experimental conditions but complicates the measurement problem. Measurements at other than ambient temperature, not usually attempted with bulk materials, constitutes additional complexity. Since typical strains are on the order of 1 X 10 , measurements of interplanar spacing with a precision of the order of 1 X 10 are needed for reasonably accurate results hence, potential sources of error must be kept to a low level. In particular, the sample displacement error can be a major source of difficulty with a heated sample. The sample surface must remain accurately on the axis of the instrument during heating. 

Texture is an important and complex quality characteristic. It is determined by variety and by structural and biochemical properties of tuber tissue, with some environmental influence. A considerable amount of research has been undertaken to replace subjective sensory evaluation with objective instrumental measurements (Van Dijk et al., 2002). 

Martens, H. J., Thybo, A. K. (2000). An Integrated Microstructural, Sensory and Instrumental Approach to Describe Potato Texture. Lebensmittel-Wissenschaft und-Technologie, 33, 471 82. 

Nitrilotriacetate was used as complexant in the deposition in Ref. 55. Cu-Se could be both electrodeposited and chemically deposited from this solution. The electrodeposited film was Cui.sSe with the berzelianite structure, while the CD one was Cui.iSe with the umangite structure. The XRD pattern of the CD films showed sharp peaks (instrument broadening) with no preferential texture. Electron microscopy of these films (Fig. 6.2) shows large (micron scale) particles that, from their faceted shape and together with the sharp XRD peaks, appear to be single crystals. This is a particularly large crystal size for a CD film from this and... 

Many of the instrumental methods yielding morphological, topological, and textural information of objects are based on microscopy techniques. Although light... 

Diffuse reflectance becomes apparent if one stands in front of a wall and hopes to see his own reflection. He cannot, of course, since the light rays traveling from him to the wall will interact with the wall and are subsequently reflected in all directions. In addition, these light rays now carry information about the wall — its color, its texture, and even its chemical composition. Suitable instrumentation can evaluate the difference between the light before and after diffuse reflectance and provide a route to deducing chemical structure. 

There is no universally good adhesive for food constituents. Proteins that are highly cohesive may not blend well with certain other ingredients. It is necessary to examine the available proteins for optimum properties and to select the most satisfactory ingredient combinations. A number of instruments are available for measurements of textural properties of food ingredients or products, but the final criteria for acceptable performance must be taste-panel evaluations. 

Voisey, P. W. Instrumental Measurement of Food Texture, in "Rheology and Texture in Food Quality," J. M. de Man,... 

Gels for quantitating gel characteristics were prepared In screw capped centrifuge tubes (22 X 100 mm) by heating at 100 C for 15 min C14, l, l, ). Gel strength was determined by a penetration technique using the Instron fitted with a disk probe (6.0 ran diameter) (15.16). Instrumental texture profile analysis on gel sections (1.5 X 1,0 cm) was done on an Instron fitted with a... 

---