So my suggestion can be to buy a different manufacturer of ground poppy seeds, If you're able to. A hint of bitterness is normal, and will be balanced out by including sugar or honey while in the cake batter. But when it’s an unpleasant bitterness, this shouldn’t be the case. https://poppypodsforfloralarrange47898.bleepblogs.com/32613384/how-much-you-need-to-expect-you-ll-pay-for-a-good-buy-dried-poppy-pods