Brookfield Engineering

Peanut Butter (creamy style)

Laboratory Viscometer Application Data Sheet

APPLICATION

Creamy Peanut Butter is typically spread onto other foods, such as breads, in making peanut butter and jelly sandwiches, for example, or incorporated into various food products.

Method #1

Test Equipment

  • Spring Torque Range: Various, such as HB
  • Spindle: Various T-bars, such as T-C
  • Accessory: Helipath Stand
  • Speed, rpm: Various, such as 5 rpm

The products were tested in their jars at room temperature.

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 creamy peanut butter. In our example, we used a Brookfield HBDV-II+PRO, with Rheocalc v3.1 software for automated instrument control and data acquisition. Representative data from the analyses are shown in Figure 1, below:


Figure 1: Creamy Style Peanut Butters at room temperature.

Brand B, shown in light brown, is significantly more viscous than Brand A, shown in dark brown. 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 both product data is between approximately 50 and 400 seconds. The decrease in viscosity, at about 225 seconds, occurs as the system first reverses direction. The spindle now travels through material whose structure may have been partially disrupted by the initial portion of the test. Therefore, the "plateau" viscosity from 250 to 400 seconds is somewhat lower than the "plateau" from 50 to 200 seconds. Some users, therefore, prefer to use data from only the first "plateau".

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.

Method #2: Yield Stress Test

Test Equipment

  • Instrument: YR-1 Rheometer or DV3T Rheometer
  • Spring Torque Range: Various, such as HB or 5xHB respectively
  • Spindle: Various vanes, such as V-73; immerse to the primary immersion mark
  • Speed, rpm: 1 rpm

The products were tested in their jars at room temperature.

The choice of Spring Torque Range, spindle and speed may vary widely, depending upon the peanut butter. We used the Brookfield 5XHBDV3T Rheometer, with EZ-YieldTM v1.4 software for automated instrument control and data acquisition. In addition to making viscosity measurements, the DV3T Rheometer also performs yield tests. The yield stress may be defined as the stress that must be applied to make a material flow. The corresponding apparent yield strain is the deformation at which the sample structure breaks down - and at which the sample flows. Representative data from the analyses are shown in Figure 1, below:


Figure 1: Creamy Style Peanut Butters at room temperature.

Figure 1 shows that Brand B has a much higher yield stress than Brand A, at room temperature. The Brand A data are shown in blue, while the Brand B data are in purple. Testing with a 5XHBDV-III Ultra, the V-73 vane spindle at 1 rpm produced on-scale results with both products. Region "1" data is caused by mechanical instrument start-up during testing of this very firm, high-viscosity material. Data from Region "2" and onward are essentially valid test data for behavior of the material. The greater slope of product B data indicate that it is a stiffer or firmer material than product A.