It's a good question, Chai. I don't think it's incorrect to say 罐头食物, but 罐头食品 does sound more correct. 《食品工业基本术语》对食品的定义：可供人类食用或饮用的物质，包括加工食品，半成品和未加工食品，不包括烟草或只作药品用的物质。 《食品卫生法》对“食品”的法律定义：各种供人食用或者饮用的成品和原料以及按照传统既是食品又是药品的物品，但是不包括以治疗为目的的物品。 食品 —— [＋食物][＋产品] 食品 refers to the things we eat and drink, including the processed food, semi-processed food and unprocessed food. It excludes tobacoo and the drugs for medical use or healing the illness. The word 食品 usually appears in government's files or the wrapper of food to define the products, such as 罐头食品，绿色食品，保健食品… 食物 refers to the things we eat. As a word, it is more widely used in people's daily talk.