The type of tomato juice would be the starting point hot or cold break juice and the end preserved packaging, hot or cold filled and in glass or can or Aseptic or UHT Tetra packing and if a beverage or sauce as in diagram. . If unpreserved cold filled, is the starting point, the acid of tomato is also acting as a preservative.other acids vinegars in Ketchup plays a role too. Salts come into play as well for water activity. If you add sugar, starch or thickener , you will need to hot fill. Spicing will be one part of preserving and others will be as critical. Cinnamon Celery, Garlic and Onion and Clove even Curry Ketchup play a big role in tomato spicing and other replies give great starting points, herbs are antioxidants and also play a role.(Kalsec have white papers on this topic in Pdf form) Chilli extracts for Tomato Salsa also give some assistance. The strengths of all spices will be different if a juice, sauce or ketchup and if diluted from Paste. For reference go one step further and search Aroma chemicals as preservatives.