In the past, food that was deemed expensive were seen as precious to waste. Items such as salt and oil were therefore seem as bad luck to spill. Salt in particular requires the person guilty of spilling it to throw some of it over their shoulder to counterbalance that luck.
I looked into items of food produced that had gone up in price that year (2013), which would increase the value of wasting such foods for the buyer, to throw over ones shoulder. Updating what would be considered to be lucky. By creating each food in such a way, I still wanted to maintain the disposable, supermarket type feel to the foods. That even though the price had risen, that did not mean that the quality of food had too.