Residual sulphur dioxide (SO₂) is one of the most important parameters on a tapioca starch specification, because it is what usually distinguishes a food grade from an industrial grade. If you’re sourcing starch, knowing which SO₂ level your application needs avoids both over-paying and non-compliance.
Why SO₂ is present
Small amounts of sulphur dioxide are used during starch processing to control microbial growth and protect whiteness while the starch is wet. The finished starch retains a residual level, measured in parts per million (ppm). Lower residuals are required for sensitive food uses; higher residuals are acceptable for industrial uses where the starch never enters food.
The three grades
TQ Industry Starch supplies native tapioca starch in three SO₂ grades:
- ≤10 ppm — food grade. The lowest residual, for food applications with the strictest limits and for buyers who want maximum headroom under their market’s regulations.
- ≤30 ppm — food grade. A standard food grade suitable for most food manufacturing.
- ≤100 ppm — industrial grade. For paper, textile, adhesive, and other non-food uses where a higher residual is acceptable.
How to specify the right grade
- Confirm your market’s regulatory limit. Maximum permitted SO₂ in food varies by country and by food category — specify a grade comfortably below your limit.
- Match the grade to the end use. Don’t pay for ≤10 ppm if your industrial process accepts ≤100 ppm; equally, never use an industrial grade in food.
- Ask for the full specification. SO₂ is one parameter among several. Moisture, starch content, whiteness, pH, viscosity, ash, and fineness are all controlled — the typical values are available on request with a Certificate of Analysis.
See the food applications and industrial applications pages for where each grade is typically used.
To get the right grade for your process, tell us your application and destination and we’ll confirm the grade and send a sample on request.