EVALUATION OF SOME TEXTURAL PROPERTIES OF FOODS WITH THE INSTRON UNIVERSAL TESTING MACHINE

Abstract. Analysis of published chewing force patterns indicates that the 'first bite' involves an approximately linear application of force. The Instron Universal Testing Machine also offers a linear pattern of force application making it possible to obtain information about textural properties identified during the 'first bite' from force-compression tests. However, the data obtained in such tests are influenced not only by the applied force but also by the rate at which it is applied. Both variables must be taken into account when analysing the data, since the applied force in chewing and also the rate of force application depend on the textural characteristics of the food being evaluated. Based on a correlation of sensory responses with instrumental force-compression-rate of force application data, a procedure is described for establishing the mechanical force conditions that should be used in Instron tests so that they simulate those associated with the sensory evaluation.     

RELATIONSHIP BETWEEN THE TEXTURE AND PECTIN CONSTITUENTS OF JAPANESE PEAR

The relationship between texture and pectin constituents and some related compounds of the Japanese pear (Pyrus serotina Render var. culta 'Housui') during fruit enlargement and ripening was studied. The modulus of elasticity, deformation ratio, and relaxation value from the flat plate compression test, and all the properties from the puncture test were affected by the pectin constituents, alcohol insoluble solids, and soluble solids. The hardness and deformation of the fruit obtained from the plate compression test might depend on the combination of the alcohol insoluble solids in fresh weight and weight of the fruit. The oxalate soluble pectin both in alcohol insoluble solids and in fresh weight affected the fruit texture more than the water soluble pectin. The solubitization of nonsoluble pectin to water soluble pectin appeared to influence the textural properties more than that of the nonsoluble pectin to oxalate soluble pectin. The puncture test was superior in analyzing the textural properties of the Japanese pear fruits with regard to changes in the pectin constituents.     

EVALUATION BY INSTRUMENTAL METHODS OF THE TEXTURAL PROPERTIES OF SOME TROPICAL FRUITS1: (A REVIEW)

Published applications to tropical fruits of instrumental methods for texture evaluation are cited and tabulated. The comparability of the results is evaluated in light of the morphological characteristics of the fruits, the types of methods used and the test procedure employed.     

CHARACTERIZATION OF THE TEXTURAL PROPERTIES OF SPREADABLE PEANUT BASED PRODUCTS 1

Textural characteristics of two peanut butter samples and one peanut paste sample were determined using three instrumental methods and a texture profile panel. In Method A, a penetrometer with a cone-shaped probe attachment was used. Method B involved the use of a plunger attached to the crosshead of the Instron Universal Testing Machine. Method C was a modified texture profile analysis (TPA). Instrumental measures show that peanut paste was the hardest, exhibited the greatest adhesive force but the least time to break the peanut column, and was the least cohesive. All instrumental methods were acceptable but TPA provided more information than the two other methods in describing texture. The panel rated the paste as firmest, least adhesive, spread least on the tongue, least smooth, most grainy, and most difficult to swallow. Significant correlations were found between several instrumental measures and sensory characteristics.     

RELATIONSHIPS OF INSTRUMENTAL TEXTURAL PROPERTIES AND MUSCLE FIBER TYPES TO THE SENSORY PROPERTIES OF BEEF

Longissimus muscle steaks from 94 cattle were used to determine the relationship between sensory tenderness ratings and instrumental textural properties of beef and to determine the role of muscle fiber type characteristics to sensory and instrumental textural properties. It was determined that ease of fragmentation, amount of detectable connective tissue, and tenderness ratings were all measurements of the same attribute. Peak load was found to be the best predicator of tenderness and the use of additional instrumental textural properties in regression equations did not substantially improve predictability. White muscle fiber characteristics were found to be positively correlated to sensory tenderness ratings.     

SENSORY EVALUATION OF THE TEXTURE OF 49 COMMERCIAL APPLE AND PEAR PUREES

ABSTRACT

The sensory texture of 49 market samples of pear and apple purees were examined by Flash profile and results were treated by Generalized Procustes Analysis. The product set encompassed grocery products, baby foods and drinking snacks. Four main sensory notions were used to describe the texture of this type of products: graininess, viscosity, moisture and grittiness. Pear and apple purees were discriminated by the gritty perception, carried out on the third component. The other three main characteristics were carried out on the first two axes, where six main groups of products were identified. Pear purees were close to baby foods. Thickened baby foods and pear and apple mixtures constituted additional groups. Finally, apple purees were close sensorially, but three groups could be discriminated by grainy and viscous perceptions. The number of products was not an obstacle and the panel managed the task as required.

PRACTICAL APPLICATIONS

Flash profile seems to be a powerful tool to provide a statement of the sensory diversity of a specific market very quickly even when the number of products is quite large.

     

EFFECTS OF CHITOOLIGOSACCHARIDE ON THE PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF TOFU

Chitinous polymers have been experimented with for the purpose of shelf-life extension of foods due to their antimicrobial activity. Food additives, however, may impair the taste, color or texture of foods. Therefore, it is necessary to evaluate the effect of a food additive on foods before it is used. In this study, we investigated how the physicochemical properties, microstructure, textural properties and sensory characteristics of tofu are affected by the addition of chitooligosaccharide during its preparation. The addition of chitooligosaccharide to tofu did not significantly affect its physicochemical properties including moisture content, yield, turbidity and color. The chitooligosaccharide tofu, however, had lower hardness and smaller protein aggregates than the control tofu. The chitooligosaccharide did not influence most sensory attributes of tofu except for imparting a bitter taste.     

INSTRUMENTAL AND SENSORY TEXTURAL PROPERTIES OF FURA

ABSTRACT

A uniaxial compression test and sensory textural analysis was conducted of fura samples made from millet flour. Significant differences (p<0.05) existed among the samples for hardness (the force to compress the sample between molar teeth), cohesiveness (extent to which sample falls apart during chewing) and gumminess (denseness and cohesion persisting during mastication). Correlations between sensory and instrumental tests revealed that a significant relationship exists between modulus of deformability and cohesiveness (r=?0.93, p<0.05); gradient and springiness (r=?0.90, p<0.05); deformation at failure and chewiness (r=0.98, p<0.05); energy per unit mass and gumminess (r=?0.95, p<0.05). A fura quality scale was established based on the peak force; soft and poor quality fura have a peak force of <19 kN; acceptable fura has a peak force of 19–24 kN; a firm and good quality fura, 24–25 kN; very hard and very poor quality fura have a peak force of >25 kN.     

TEXTURAL PROPERTIES OF DEHYDRATED FOODS. RELATIONSHIPS WITH THE THERMODYNAMICS OF WATER VAPOR SORPTION

Abstract Textural properties of pre-cooked, freeze-dried beef and of special bite-size space foods, all of which were designed for consumption without prior rehydration, were determined by instrumental and sensory methods at different relative humidity points of the moisture sorption isotherm. Supplemental instrumental measurements were also made on completely rehydrated pre-cooked, freeze-dried beef.
In general, as the relative humidity increased, the mechanical properties of hardness and cohesive-ness (Szczesniak) increased, whereas the mechanical property called the crushability index (Drake) and the sensory property 'ease of biting' decreased. Close relationships were found between the heat of sorption and the sensory rating of heat evolved in the mouth during chewing of initially dry meat samples. Good correlations were also obtained between other thermodynamic functions and textural properties.     

SENSORY AND TEXTURAL EVALUATION OF MAINE WILD BLUEBERRIES FOR THE FRESH PACK MARKET

Maine wild blueberries were sized according to berry diameter into three size classes; ≤ 8 mm, 9–10 mm and 11–12 mm. A consumer sensory panel was asked to indicate their opinion of flavor, texture and overall attributes using a 9-point hedonic scale. Subsamples of berries were subjected to a compression test using an Instron Materials testing machine, measuring force and deformation to point of rupture of individual blueberries. Berries ≤ 8 mm were significantly lower in sensory acceptability for all three attributes evaluated. No significant difference was found between 9–10 mm and 11–12 mm samples. Both were rated "like moderately". Ranked preference data indicated a significant preference for the larger 11–12 mm berries. The results of the compression tests revealed significant differences among all size classes with respect to the apparent modulus. A linear relationship was found between the "texture" sensory attribute and the elastic modulus.     

STRUCTURAL, RHEOLOGICAL AND TEXTURAL PROPERTIES OF SOFT PARAFFINS

Abstract Various aspects of soft paraffins, with the main emphasis on their rheological properties, are considered in a review of 119 references. Rheological test methods currently used are critically appraised in sections on penetrometry, continuous shear viscometry, oscillatory testing and creep analysis. The chemical nature, microscopic structure, miscellaneous methods of standardisation, formulation and work softening of petrolatums are reviewed. The textural properties of soft paraffins are discussed; a master curve of the rheological conditions operative during spreading on the skin is presented.