MadSci Network: Chemistry |
While it is possible to extract citric acid from fruit, the chemistry of the fruits is complicated enough that I'd suggest a much easier way to measure the relative acid content. Do you have a pH meter? The best kind for this test would be one that has a flat sensor surface (something like this). If you don't have one like that available, the next best thing would be to test the pH of the juice from each fruit. For either method, that will be a relative indicator -- the lower the pH, the greater the acidity. I would suspect, based on the taste (citric acid tastes sour), that the order you listed them in (lemon, grapefruit, orange) is also the order from greater to lesser acidity. It will vary somewhat within individual fruit types; for example, a Seville orange would generally be more acidic than a navel orange. You might even be able, for example, to find a "sweet" grapefruit with lower acidity than a "bitter" orange.
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