Starch is a naturally occurring carbohydrate that is stored in granular form in many plants as an energy reserve for times of dormancy, germination and growth. Starches in common use are typically found in seeds, tubers, roots and fruits, as well as in plants such as potato, maize and rice.
97% to 99% of starch molecules consist of either amylose or amylopectin. Amylose is a linear molecule consisting of glucose molecules connected by (1,4) glucosidic linkages. Amylopectin is a highly branched molecule consisting of short (1,4) glucose chains connected by (1,6) glucosidic linkages.
Plantic Technology Ltd's primary feedstock is a naturally high amylose starch (up to 70% amylose), derived from corn which has been hybridised over a number generations. When starch is heated, the crystalline structure is disrupted and upon cooling, typically recrystallises in a process called retrogradation. This is commonly known as staling, similar to a loaf of bread hardening several days after being baked. To prevent this from occurring in PLANTIC™ products, the high amylose starch currently used by Plantic Technologies Ltd, undergoes a chemical modification process called hydroxypropylation prior to the manufacture of PLANTIC™. This process retards retrogradation and effectively plasticises the starch, making it behave like a thermoplastic and providing a shelf life of many years.
This hydroxypropylated, high amylose starch forms the base of all of Plantic Technology Ltd products, and its use in packaging applications is protected through a family of patents.