Complex sentence: This seal is extremely important to the safe preservation of the food product, and is why most preserved screw-top food products used a domed metal cover that emits an audible popping sound as the container is opened.
Split into simpler sentences: This seal is extremely important to the safe preservation of the food product. That is why most preserved screw-top food products used a domed metal cover that emits an audible popping sound as the container is opened.