The antonyms for the word "more preserving" include "less preserving," "deteriorating," "damaging," and "spoiling." When something is said to be more preserving, it suggests that it can keep things fresh for a longer period of time or maintain their quality over time. However, the opposite of preserving is deteriorating, which means the quality of something is deteriorating or getting worse with time. This could happen with many perishable items like food, medicines, etc. Similarly, another antonym "spoiling" suggests that something has started to decay or rot or has become unfit for consumption due to various reasons. Less preserving is an antonym which suggests that something might not be able to keep things fresh, but it is not necessarily spoiling or deteriorating.