Milk in aluminum pouch and box combo. Manufactured February 2012 and expires August 2013. Total of 17 months shelf life. In case a customer bought it immediately after manufacture, he can still store it for almost 17 months before consumption. Because the buyer consume it immediately after buying, such long time frame is more than enough for manufacturer’s dispatch, wholesalers temporary storage and distribution and display on groceries shelf.
Do you think 17 months is long? Think again! The same milk packed in lacquered tin can has a declared shelf life of 24 months. Manufactured May 2012 and expires May 2014. It is seven months longer than same product packed in aluminum pouch and box combo. More time for product’s travel, storage, display on grocery shelves and safe keeping at consumer’s home.
Let us make things clear. The product declared shelf life is true only under ambient conditions. It will last significantly longer when placed in cold storage. May become shorter or too short when handled and stored in rough manner. Upon opening , the declared shelf life is null and void. Length of product safety now depends on consumer handling.
Going back to seven months shelf life difference. Why do milk in can has relatively long life?
The answer and explanation relies on packaging difference.
The aluminum pouch or multi-layered film provides a good barrier against moisture and atmospheric oxygen. The carton box is just a secondary packaging, an aesthetic. However, lacquered tin can provide better protection. Imagine a dried product hermetically sealed in a metal packaging many times thicker and stronger than pouches. It makes sense. It provides protection against moisture, oxygen, physical dents, rodents and cockroaches.
This great advantage also comes with two drawbacks. Tin cans are more expensive and prone to rust.