Possible Clues:

• Contents of cellar Neuburger and Claret -- luckily all for opening?
• Bill left on slate possibly for seasoning
• Present for discussion on second key food additive
• State backing included in new lab test to produce food additive
• Condiment
• Sal breaks pill to provide condiment
• Food seasoning at intervals usually going into flattish cake
• This makes more tasteful, oddly small medicine boxes
• NaCl (it's at most meals)