43-10 |
Development of instrumental methods for the textural characterization of low moisture extrudates |
P. V. VEILLARD, C. I. Moraru, and J. L. Kokini. Dept. of Food Science, Rutgers, The State Univ. of New Jersey, 65 Dudley Rd., New Brunswick, NJ 08901-8520 Texture is one of the most important quality attributes in extruded foods, and is considered critical to their overall acceptability. The objective of this work was to establish the most suitable instrumental procedures to assess the texture of dry, slightly expanded extruded foods of different composition and geometry. A large range of methods (uniaxial compression, puncture with conical and cylindrical probes, cutting with blades and fracture-wedge fixtures) was tested using a Texture Analyzer TAXT2i. The variability associated with each type of measurement was assessed for different levels of testing strain (70 to 90%), probe speed (1 to 3 mm/s) and number of replicates (10 to 20). The sensitivity of the different methods was also examined. Force-deformation curves were analyzed in terms of peak force, gradient to peak force, total work, number of peaks and linear distance. In addition, the jaggedness of the curves for selected samples was analyzed by fractal analysis using the Richardson, Minkowski and Kolmogorov algorithms. Results varied for each type of sample, but generally, for the range of products studied, uniaxial compression gave the most reliable and useful information. The lowest testing speed (1mm/s) and the largest strain (90%) consistently produced the lowest coefficient of variation. The minimum number of replicates required was close to twenty for most of the tested methods. Fractal analysis was also used, since the fractal dimension was reported to correlate better with sensory crispness/crunchiness than the other textural parameters. However, for the examined extrudates, fractal analysis was less able to show differences between the samples than the parameters number of peaks and linear distance. Selection of the appropriate testing method and type of data analysis, based on method’s sensitivity and knowledge of consumer eating behavior, can help better characterize the texture of dry and dense extrudates.
Session 43, Food Engineering: Rheology and texture
|