Smart bump / Milk packaging

During shelf life of milk when it closes to expiration date or some days after opening the lid, the milk freshness is questionable ,so some people heat it or there are other methods that shows the level of milk freshness. But the story differs for blinds and visual impaired people since they have problem in seeing colors or heating the milk.
Smart bump is a packaging which benefits from smart materials that react to milk’s PH. Whenever the PH decreases below 6.5 small bumps on the packaging’s surface will be grown and indicate spoiling process by being touched. In more advanced type spoiled level can be determined by amount of bumps.