Interlaboratory Measurement of Rheological Properties of Tomato Salad Dressing

Abstract

Rheological properties of food materials are important as they influence food texture, processing properties, and stability. Rotational rheometry has been widely used for measuring rheological properties. However, the measurements obtained using different geometries and rheometers are generally not compared for precision and accuracy, so it is difficult to compare data across different studies. In this study, nine rheometers from seven laboratories were used to measure the viscosity and viscoelastic properties of a commercial salad dressing. The measurements were obtained at three temperatures (8, 25, and 60 °C) using different diameter parallel plates (20, 40, 50, and 60 mm). Generally, the viscosity measurements among rheometers differed significantly (P<0.05). For larger geometry diameter (40, 50, and 60 mm) and at lower temperatures (8 °C), viscosity measurements at lower shear rate (0.01, 0.1, and 1.0 s−1) were significantly different. Rheometer brand significantly affected storage modulus only at low (0.01%) and high levels (10% and 100%) of strain. Temperature was an influencing factor on viscoelastic behaviors only at high strain (>10%). Storage moduli values obtained by frequency sweeps were not affected by rheometer or plate diameter. Overall, rheometer, geometry, and temperature can influence rheological measurements and care should be taken when comparing data across laboratories or published works. Higher shear rates (≥10 s−1) and moderate strains (0.1% to 10%) generally provide more repeatable data among different laboratories. Practical Application This study provides information on what factors may potentially influence rheological measurements conducted across different laboratories. It is useful for rheometer users who want to compare their experimental data to published data or compare two sets of published data. It is better to compare data collected at shear rates 10 s−1 and strains between 0.1% and 1.0%.

The effect of high‐pressure processing or thermosonication in combination with nisin on microbial inactivation and quality of green juice

“…Since some researchers indicated that the efficacy of HPP on rheological properties may vary based on the ingredients of food products (Dumay, Lambert, Funtenberger, & Cheftel, 1996). As seen in Table 3, viscosity measurements of juice samples obtained at 5°C were significantly higher than those obtained at 25°C when the shear rate was 100/s ( p < .05) This result agreed with previous studies (Hosseini‐Parvar, Matia‐Merino, Goh, Razavi, & Mortazavi, 2010; Tan et al., 2019), indicating green juice viscosity decreased with increased product temperature, because the elevated temperature might cause an increase in molecular mobility and weakness in intermolecular bonds. Furthermore, under the same temperature conditions, combining HPP with 100 mg/L of nisin did not change the viscosity of green juice samples ( p > .05).…”

Effect of ultrasound processing on rheological properties and color of green food products

“…As shown in Table 1, there was a significant difference between the viscosity of avocado dressing samples at 5 °C and 25 °C at the shear rate of 0.1/s (p < 0.05). The reason of higher viscosity in samples at 5 °C than 25 °C might be due to the fat droplets are in liquid form at high temperature (Tan et al, 2019). Additionally, results indicated efficacy of product temperature on viscosity was only observed in longer US treatment times when compared at the shear rate between 1 and 100/s.…”

Research on the Rheological Properties of the Plant Oil Pitch

“…e study in [7] proposed that the rheological properties of vegetable oil pitch are very important, because they affect the texture, processing performance, and stability of food.…”