Because hydrosols are produced at high temperatures and are somewhat acidic, they tend to inhibit bacterial growth but not fungal growth. They are not sterile, and should be kept refrigerated to preserve freshness.[7] Herbal distillates degrade over time and will degrade faster than essential oils, which are more stable and will degrade slower.[8] Small-scale producers of hydrosols must be particularly aware of the risk of bacterial contamination and take steps to prevent it.