There are conventional methods which are followed at every home like heating the food as per its suitability, drying certain types of food categories, ignoring the best-before dates in certain cases like Rice, sugar, honey etc, controlling fridge temperature, freezing just about everything, keeping food covered airtight etc. These are home practices and are followed at the  customer-end to deal with small portions of food for a relatively shorter period of time. However, at the industrial level, more scientific and advanced methods are followed for food preservation in the context of packaging. As earlier discussed, there are many different types of plastic polymers like Polyester, Nylon, Ethylene, propylene coupled with special material like foil which have barrier properties of varying degrees and are used for shelf life extension of food products during the industrial processes. This purpose-built packaging generally is a combination of two or more such polymers along with a foil (coating or film) fused together to make a seamless structure. This more complex packaging thus acts as a barrier between oxygen & moisture and the food contents ensuring longer life for the products to be available to consumers in the supermarkets.