RAPID VISCO ANALYZER

RVA

1. RAPID VISCO ANALYZER By Kulwinder Kaur

2. What is a Rapid Visco Analysis? Rapid Visco Analyzer, is a rotational (stirring) rheometer that measures apparent viscosity of starch-containing suspensions, and flour/water mixtures under variable and controlled heating (cooking), cooling, and shear stress conditions.

3. Working principle An aluminum sample container is filled with a certain mass of powdered product and volume of water, and placed to surround the paddle, after which the motor is started. A metal conductor at high temperature (>90°C) rapidly heats the mixture until the sample reaches the gelatinization temperature during which its stability is revealed, then cooled to provide an indication of setback during gelation. Pasting curve of product is recorded and plotted on computer screen.

4. Pasting curve: Plot between temperature (°C), analysis time (min), and apparent viscosity ( cP -Centipoise).).

5. SOP for RVA

6. Benefits

7. Applications Starches and starchy samples Milling and Baking Barley – Malting – Brewing Formulated foods Extruded and Cooked Foods Dairy Ingredients

8. Approved methods that make use of RVA

9. Measurement of α- Amylase Activity with the Rapid Visco Analyser

10. What is the Stirring number method? Measures the effect of the enzymes on wheat quality in flour or meal. Does not measure α-amylase activity directly, but measures the activity indirectly by quantifying the rheological properties of starch hydrolyzed by the enzymes during the test. Uses the starch in flour or meal as a substrate, gelatinizes the suspension rapidly in a boiling water bath, and measures the liquefaction of the starch by α-amylase. After 180 seconds hot, Stirring Number is final viscosity of the heated wheatmeal paste is measured and is correlated with measurements of the Falling Number.

11. Indication of falling number and stirring number Viscosity Stirring number Sprouting indication high final viscosity values (≥ 120 RVU (units) or ≥ 1440 cP ) no pre-germination due to low amylase activity low final viscosity values (< 50 RVU or < 600 cP ) high pregermination due to high amylase activity