Heat and processing break down vitamin C, so fresh-squeezed orange juice tends to hold more of this nutrient than bottled juice that has sat on a shelf. A vitamin C indicator solution makes that difference visible. It starts blue, and you add drops of juice one at a time until the color disappears. Fewer drops means more vitamin C remains in the sample.

One way to measure vitamin C is to watch for a color change. You use an indicator solution that starts blue, then add drops of orange juice one at a time until the blue disappears. Fewer drops means more vitamin C was present — the indicator's shift from blue to clear reveals how much ascorbic acid each juice contains.

Vitamin C — also called ascorbic acid — breaks down when juice is heated or processed. That means fresh-squeezed orange juice typically holds more of this nutrient than bottled juice that has sat on a shelf. To measure how much remains, you add drops of juice one at a time to a vitamin C indicator solution that starts blue. When the blue color disappears, you stop counting. Fewer drops means a higher concentration of ascorbic acid in that juice. Testing fresh-squeezed, bottled, frozen, and canned juice — three times each — lets you compare the average drop counts and determine which type preserves the most.