The most abundant organic acid in lemons is citric acid. Lemons and lemon juice are one of the most concentrated sources of natural citric acid. A whole lemon contains about 3 grams of citric acid. Around 140 grams of lemon juice will contain roughly 6 grams of citric acid. Citric Acid in Soap Making ~ What's the Point? When citric acid and sodium hydroxide lye (NaOH) are combined, sodium citrate is created. Sodium citrate works as a chelator in soap. A chelator traps meta