Check sulfite levels on raw, cut potatoes using Indigo® sulfite test strips. Identify surface treatments used to prevent browning. Easy, fast, food-safe testing.
Sulfites are widely used on peeled and cut potatoes to prevent enzymatic browning and extend shelf life. Whether you process potatoes at home, in a commercial kitchen, or in a food-science teaching lab, Indigo® sulfite test strips offer a fast way to check for the presence of free sulfites directly on the potato surface. A color change above ~10 ppm indicates sulfites strong enough to inhibit browning.
You can test raw, peeled, or cut potatoes quickly. Moisten the test strip pad with clean water (distilled or deionized preferred), then press the pad firmly against the potato surface for 1-2 seconds.
If free sulfite is present above approximately 10 ppm, the pad will develop a characteristic color within seconds. Compare the result to the supplied color chart to estimate the sulfite level.
Sulfite Testing on Potatoes EVTF
Concept
Description
Activity
Learning Link
Enzymatic Browning
Cut potatoes rapidly turn brown due to polyphenol oxidase acting on phenolic compounds in the presence of oxygen.
Compare untreated potato slices to sulfite-treated slices and observe color differences over 30-60 minutes.
Food chemistry of browning, culinary quality control.
Sulfites as Anti-Browning Agents
Sulfites inhibit enzymatic browning by reducing quinones back to phenols and blocking oxidation reactions.
Use Indigo® sulfite test strips to detect free sulfites on potato surfaces and correlate results with browning inhibition.
Preservation chemistry, ingredient functionality.
Free vs. Bound Sulfite
Only free sulfite (SO2/HSO3-) is active in browning prevention and detectable by test strips; bound forms are not.
Test potatoes stored for different durations to compare fresh vs. diminished free sulfite readings.
Food additive chemistry, degradation pathways.
Surface Testing Technique
Only a moistened indicator pad is required for detecting free sulfites directly on food surfaces.
Practice pressing a wetted strip against potato surfaces and interpreting the resulting color chart.
Applied food testing, sanitation & safety skills.
Regulatory & Labelling Awareness
Sulfites must be declared when ≥10 ppm in the finished food, a common regulation in many jurisdictions.
Measure a batch of cut potatoes and discuss labeling thresholds relative to strip detection limits.
Food safety compliance, culinary management.
Cut-potato browning is often incorrectly assumed to be the Maillard reaction. See our page on the Maillard reaction, which explains heat-driven, Maillard browning, and how it differs from enzymatic browning (caused by polyphenol oxidase) that sulfites prevent in raw potatoes.
Related information or images
Sulfite Test Strips 100/Vial
Cider Preservative
Dried Fruit
Red Wine
White Wine
Seafood
Specifications
This Indigo® test strip indicates the presence of sulfite ion in increments of 10, 50, 100, 250, and 500ppm after 15 seconds.
The number of strips (100) vial is approximate.
Vial has a built in desiccant and if kept tightly closed, strips can be effective up to 5 years.
Strips test for: sulfite, bisulfite and metabisulfite
Documentation
Test Strip Documentation
Stability Statement
Certificate of Analysis
SDS
Reviews (2)
2023-10-27
Test strips worked as described, including the red wine citric acid method. I first did some comparisons using sulfites in water. Dipping the strips and the citric acid method gave the same result, albeit a little lower than expected. Solution was mixed to 100 ppm and both strips showed about 75. Used a similar technique on red wine, although dipping does not work. Wine with no sulfites showed zero. Added and got similar readings to the water results. Thanks for the great product and the citric acid trick.
2021-01-22
Great place for a hard to find product. Excellent price! Quick shipping.
Thanks for letting us know. This might interest you since you are in quality control: Can 10ppm of Sulfite & Quat Really Mean Zero?