The Analysis of Stress Relaxation Data of Some Viscoelastic Foods Using a Texture Analyzer*

Abstract

Uniaxial compression test for dough and several commercial products like jello, mozzarella cheese, cheddar cheese, tofu and sausage (cooked and uncooked) was performed using a texture analyzer (TA). Percent stress relaxation (%SR ), k1 (initial rate of relaxation), k2 (extent of relaxation) and relaxation time (RT) were calculated and compared for different products. The TA software was used to convert the raw SR data into a linear form. Constants k1 and k2 were determined from the intercept and slope of the linear data. Higher values of %SR and k2 (90 and 9, respectively) indicated higher elasticity for jello, whereas wheat flour dough samples showed the lowest values (20–30) for %SR and 1 to 2 for k2. The RT and k1 values were not good indicators for differentiating different products based on their viscoelastic behavior. Measurement of RT was limited by the maximum time for which the data were collected, whereas k1, because of its mathematical form, needed careful interpretation. In this study, %SR was found to be a good measure to interpret viscoelasticity of different food samples.

Improvement of maize bread quality through modification of dough rheological properties by lactic acid bacteria fermentation

“…Relaxation time was calculated as the time required for the maximum force of compression to drop to 36.8% of its value, as described by Singh et al (2006). paraffin oil was added to the edges because it caused a bubbling effect at higher temperatures.…”

“…They also required a shorter relaxation time [the time required for the maximum force of compression to drop to 36.8% of its value (Singh et al, 2006)] than the chemically acidified maize dough or the straight maize dough. The lower amount of force required and shorter relaxation time required by maize sourdoughs compared to that required by the chemically acidified maize dough and straight dough indicates that the sourdoughs were softer, and less elastic.…”

Texture and stress relaxation of spelt-amaranth composite breads

“…The k 1 values in composite spelt amaranth breads ranged from 51 to 65. So far, this constant has not been considered as a reliable parameter to discern viscoelastic properties as it is surmised to depend on numerous other factors such as sample shape, and experimental errors (Buňka et al, 2013;Peleg, 1979Peleg, , 1980Singh et al, 2006). Relaxation times were strongly inter correlated showing that they carry the same type of information.…”

The Effects of Ovine Whey Powders on Durum Wheat-Based Doughs

“…The TA.XT2i Texture Analyser (Stable Micro Systems Ltd., Surrey, UK) equipped with a 30 kg load cell and a P50 probe was used for the stress relaxation test on the dough [15] and force (N) versus time (s) curves were recorded using Texture Expert Exceed software, version 2.64. The test speed was 1 mm s −1 .…”