I flew from LAX to SYD in April and my book bag contained a banana. I had declared the banana on my form. It was confiscated. On the way to customs I searched for a sign to guide me - could I keep it or not. In most European countries I find a list on the wall telling what is forbidden (religious propaganda, fruit, veggies, meat).
Returning to the U.S. I get to keep unopened packages of mixed nuts and perhaps a packet of dried miso soup I took overseas but did not use.
Before landing in YVR the last time a FA told us not to take the little packet of sugar into Canada without declaring it. She said a colleague got stung with a $200CN fine for not declaring that food item. Sugar has no nutritional value so I don't think of it as food.
Bottom line: if you have any food item, declare it.