1. Since these salad dressings include flaxseed oil, which is prohibited to heat over 107°, don’t use them for cooking. Use them as salad dressing or add to already cooked dishes before serving.
2. Flaxseed oil is very sensitive to storage conditions. It has quite short shelf life especially if it was stored in warm room and with direct sunlight. Consider that within 3 months after opening the bottle flaxseed oil should be kept in fridge because bitter-off taste develops very fast.
First of all, dont add to much flaxseed oil to your dressing, keep the proportion mentioned above to avoid unpleasant taste. Secondly, taste the oil before you put it in dressing, because it can become bitter very fast and it means shelf life of the oil has been reached. If the bitter-off tastes presents in tolerable level, it doesn’t mean that oil is not usable anymore. Bitter-off taste can appear in the oil after the first day of opening the bottle. This happens due to formation of cyclic octa-peptide containing oxidized amino acid methionine. Slight bitterness is quite specific for this oil, but if it becomes too bitter, I advise you to purchase new one.