The Rapid Visco Analyzer (RVA) is a cooking stirring viscometer that features ramped temperature and variable shear profiles. It has been optimized for testing a range of viscous properties.
Image Credit: PerkinElmer Food Safety and Quality
The instrument incorporates several international standard methods while offering full flexibility to utilize custom-made profiles.
The RVA’s robust combination of precision, speed, automation and flexibility make it an ideal solution for product development, quality assurance and process control. It is also well suited to the rapid assessment of wheat gluten vitality.
Description
Wheat gluten is primarily employed as an additive to improve leavened bread’s baking quality. It is also a popular choice for use in a range of other products, including pet foods.
Wheat gluten can be partially denatured by heat during commercial preparation, typically reducing its vitality. The RVA can be used to assess the functionality of wheat gluten via heating and cooling in aqueous ethanol.
Figure 1. RVA curves showing the large differences between vital and heat damaged gluten samples. Heat damaged samples lack the second peak. Image Credit: PerkinElmer Food Safety and Quality
Method
A 30-minute pasting profile was used for this study.
Sample Preparation
A total of 6.00 g gluten (12% mb) and 3.5 g ethanol (98%) were mixed. These were then stirred until the mixture was like breadcrumbs.
A total of 20.5 g distilled water was then added, bringing the total amount of water + flour to 26.5 g. The sample was then covered using a rubber stopper and vigorously shaken to disperse.
Profile
Source: PerkinElmer Food Safety and Quality
| Time |
Type |
Value |
| 00:00:00 |
Temp |
50 °C |
| 00:00:00 |
Speed |
960 rpm |
| 00:00:30 |
Speed |
160 rpm |
| 00:02:00 |
Temp |
50 °C |
| 00:06:30 |
Temp |
85 °C |
| 00:08:30 |
Temp |
85 °C |
| 00:24:00 |
Temp |
20 °C |
| 00:30:00 |
End |
|
Idle Temperature: 50 ± 1 °C
Time Between Readings: 4 s |
Measure
Measurements were performed as follows:
- P1V: Peak 1 viscosity (cP)
- P2V: Peak 2 viscosity (cP)
- P1T: Peak 1 temperature (°C)
- P2T: Peak 2 temperature (°C)
- T1V: Trough 1 viscosity (cP)
- T2V: Trough 2 viscosity (cP)
- T1T: Trough 1 temperature (°C)
- T2T: Trough 2 temperature (°C)
- FV: Final viscosity (cP)
The viscosity of the second peak can be understood to be the RVA Wheat Gluten Ethanol Index.
This information has been sourced, reviewed and adapted from materials provided by PerkinElmer Food Safety and Quality.
For more information on this source, please visit PerkinElmer Food Safety and Quality.