APPLICATION: Spaghetti sauce is a condiment or dressing usually served with various pasta dishes, often consisting of chopped tomatoes, tomato purée and various other ingredients, depending upon the sauce.
* While a particular model/version may be used as an example in this method, any current or past model/version from the same series may also be used. Please consult a sales associate to discuss the most current instrumentation and software available.
The test may be run at room temperature, or at refrigeration temperatures.
Spaghetti sauce is heterogeneous – it consists of a moderate-viscosity liquid filled with deformable solid particles. Therefore, the viscosity or rheology of the mixture as a whole must be evaluated, to properly characterize the material. Furthermore, the more viscous [or less “runny”] the spaghetti sauce, the more desirable the food may be to consumers. Smooth geometries, such as coaxial cylinder, cone-plate, or simple cylindrical/disk spindle [in a jar] may significantly interact only with the liquid. The solids may migrate away from the rotor. The data shown in Figure 1 below was obtained by using a Brookfield HADV-III+ and HA4 (disk)spindle, with Rheocalc v3.1 software for automated instrument control and data acquisition.
Figure 1: Tomato & Basil Spaghetti Sauces at 40°F tested with HA4 Spindle.
We tested Tomato and Basil spaghetti sauces at 40°F. Brand A (shown in red) is more viscous than Brand B (shown in blue). However, the Helipath system is such that the T-bar spindles will turn through a helical path, contacting both the liquid and the solids. The Helipath Stand may be used with various Brookfield Viscometers or rheometers. The choice of Spring Torque Range, spindle and speed may vary widely, depending upon the spaghetti sauce. In our example, we again used a Brookfield HADV-III+, with Rheocalc v3.1 software for automated instrument control and data acquisition. Representative data from the analyses are shown in Figure 2, below:
Figure 2: Tomato & Basil Spaghetti Sauces at 40°F tested with Helipath Stand System.
Brand A (shown in red) was tested with a T-C spindle, while Brand B (shown in blue) was tested with a T-B spindle. We had to use two different spindles – T-B is larger than T-C – to ensure on-scale measurements with two significantly different materials.
Brand A is again more viscous than Brand B. The Helipath data traces progress from "zero" viscosity – before the spindle drills down into the material – to a "plateau" region where the spindle is in the bulk of the sample. The system then reverses direction, and the measured torque – and calculated viscosity – then drops to "zero" as the spindle rises up and out of the sample. The "plateau" for the Brand A product data is between approximately 60 and 370 seconds, and the Brand B "plateau" data lie between approximately 75 and 370 seconds. The “spikes” in the data are caused by the rotating T-bar spindle striking and releasing from pieces of chopped components in the spaghetti sauce. Comparing Figures 1 and 2, we note that the Helipath viscosities are significantly higher than those obtained with the smooth (disk) geometry; the Helipath data more realistically show the influence of the solids on the sauce viscosity.
The Rheocalc data may be exported to a spreadsheet, and the plateau-region data averaged, to give a QC/QA number for viscosity. On the other hand, the Data Averaging feature available in the Rheocalc Wizard may also be used to output averaged data values. Another choice may be to simply have the system “drill” down into the sample for a specified amount of time, say 100 or 120 seconds, and then have the operator record the viscosity value at that time. This last procedure provides a one-point test.