Here’s another great science experiment question from a student who is trying to test for Protein and Vitamin C in foods using our test strips. Follow our example below to see how best to perform this test, and various methods you can try.

I purchased your Protein test strips to test the protein in foods for a science fair project. How would I prepare the solution so it’s not diluted? Can these strips be used for that application? I also have your Ascorbic Acid test strips. – Danielle

Test Methods

Both test strips were developed to test water samples (not urine). As such, both can be used to test solutions or extracts from food. The trick is how to extract the protein or vitamin C from the food. The usual way to do this is to take a certain amount of the food under study and chop, crush or grind it into a given amount of water.

For example, broccoli should have about 89.2mg of vitamin C in a 100-gram serving (this information is available online from sites like livestrong.org). Since the color chart for the vitamin C test strips ranges from 0 to 0.1%, if you were to take 50 grams of broccoli and use 100 mL of water as the extract, provided all the vitamin C goes into the extract, the test result should be about 0.44%, which is in the middle of the test strip color scale.

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For the best accuracy, you want to try and have the test result land in the middle of the color chart. To do this, adjust the amount of the food placed into the 100mL extract solution based on the expected amount of vitamin C present. By taking the result and knowing the amount of the food used, you can calculate the percent in the original food item.

Another possibility is to settle on a standard amount of food to be used with the 100mL extract, and then qualitatively rank the various foods from low to high vitamin C content.

The technique can be evaluated by conducting some standard addition experiments using vitamin C tables (ground up) or BSA (bovine serum albumin) for the protein test. The extractions are not 100%, so a standard addition test can help determine the efficiency of the extraction.

There are, however, a couple of caveats to consider:

  1. The vitamin C test has some interferences. Citric acid is the worst. Foods high in citric acid will yield a more lavender test result instead of the blue shown on the color chart.
  2. The protein strip was developed to work with BSA. The test strips are not sensitive to other proteins.

Science experiments are just that – experiments! Have fun with it, and keep working to reach your conclusion.