1. Depends on the situation. Keep it at room temperature for 3-4 days and refrigerate it at about 5℃ for a shelf life of about 1 month. Want to protect the taste of homemade ketchup, storage can not be stained with oil and raw water, or prone to quality change, in addition to sealing should also be done well, can effectively prevent the oxidation of ketchup deterioration and flavor. In addition, you can add a few drops of lemon juice when making ketchup to extend the preservation time of ketchup.

2, modern ketchup from the early 20th century. The immediate cause of its emergence was the discussion about the use of sodium benzoate. The father of the FDA, Harvey Wiley, questioned the safety of benzoic acid. As a result entrepreneurs, notably H.J. Heinz (founder of Heinz Foods), began looking for substances that could be used to replace benzoic acid. Previous ketchups had been very dilute, and the reason for this was the use of unripe tomatoes with a low pectin content. Ketchup then also contained less vinegar than it does today. By selecting ripe tomatoes as an ingredient, the use of benzoic acid in ketchup was eliminated, and the flavor was no worse than that of earlier ketchups. Some experts believe that this change in ingredients not only eliminated the use of benzoic acid, but also led to the change in flavor that has made it the widely used condiment it is today.