Traditional polymers made from petroleum-based materials are gradually being replaced by plastics made from renewable sources such as corn in some food and grocery applications.
To date Wild Oats Markets are the first grocery stores to use Cargill Dow’s NatureWorks PLA plastic containers derived from corn. They have substituted them for traditional plastic containers in some of their stores, with plans for more widespread use throughout their organisation to follow. They have even installed in-store bins for customers to return used containers. The containers are then taken to an industrial composter and turned into garden compost.
NatureWorks ™ PLA is a biopolymer and is based on corn, making them 100% natural. They are claimed to be the equivalent to traditional plastic containers in terms of strength, clarity and their ability to seal in flavours.
NatureWorks ™ PLA uses carbon that has been removed from the air (as carbon dioxide) by corn plants during photosynthesis. The carbon is stored in grain starches which are broken down by fermentation processes to yield carbon and other plant sugars. These are further refined using condensation and vacuum distillation used to make the lactide monomer, from which polylactide is derived.
The advantages of this polylactide material are that is comes from a renewable resource and it uses 20-50% less fossil fuels to produce compared to petroleum-derived polymers. Furthermore, if incinerated it does not produce toxic fumes.