Lemon peel in lemon jam is usually mildly bitter , but the bitterness can range from barely noticeable to quite strong depending on how much white pith is left on the peel and whether it’s soaked or boiled first. Recipes often reduce bitterness by removing the white part, then soaking or blanching the peel before cooking the jam.

What affects the bitterness

  • The yellow zest is bright and aromatic, while the white pith is the part that tastes most bitter.
  • Repeated soaking or boiling in fresh water can pull out bitterness before the jam is finished.
  • A little bitterness can actually be pleasant in marmalade-style jam, giving it a more complex citrus flavor.

Practical taste level

  • Low bitterness: thinly peeled skin, no pith, well-soaked.
  • Moderate bitterness: some pith left, typical for marmalade-like texture.
  • High bitterness: thick peel with lots of white pith, not pre-treated enough.

How to keep it pleasant

  1. Use mostly the yellow outer peel.
  2. Remove as much white pith as possible.
  3. Soak or boil the peel in fresh water several times.
  4. Taste before adding the peel to the jam base.

For a lemon jam, the peel should usually taste more zesty than bitter once prepared well. Without prep, it can easily overpower the sweetness.

TL;DR: lemon peels are naturally somewhat bitter, but proper peeling and soaking usually make them only lightly bitter and pleasantly citrusy in jam.