Why can fresh orange juice turn bitter after squeezing?

Some freshly squeezed orange juice develops bitterness after extraction. A naturally occurring, non-bitter precursor can convert to limonin, a bitter compound. The amount and timing vary with the fruit and processing, so there is no universal two-hour bitterness deadline.

Bitterness alone does not prove that juice is spoiled or safe. Refrigerate fresh juice promptly and discard it if it is moldy or has other signs of spoilage; do not taste suspicious juice. Heating is not a guaranteed way to prevent limonin bitterness.

Fresh-squeezed, untreated juice can contain harmful bacteria. FDA warns that children, older adults, pregnant people and people with weakened immune systems face greater risks from untreated juice. For them, choose pasteurized or otherwise treated juice.