Edible packaging

Edible packaging refers to packaging which is edible and biodegradable.

Several manufacturers are developing or producing food packaging that is edible. One example is made based on the seaweed, Eucheuma cottonii.

About 50 billion single-use plastic water bottles made of polyethylene terephthalate (PET) are produced in the United States each year, and most are discarded. According to the National Association for PET Container Resources, the recycling rate for PET has held steady at 31% since 2013.

Polyesters like PET can be broken down through hydrolytic degradation: the ester linkage is cut by a water molecule. The reaction proceeds differently in acidic or alkaline conditions, but works best at temperatures between 200 and 300 °C. Under environmental conditions the process is undetectably slow.

PET is considered to be essentially non-biodegradable, with plastic bottles estimated to take as long as 450 years to decompose. Because of this, other packaging materials are being sought.

Alginates are the natural product of brown algae and have been used extensively in wound dressing, drug delivery and tissue engineering, as well as food applications. Sodium alginate is an unbranched copolymer of 1,4-linked-β-d-mannuronate (M) and α-l-guluronate (G) sugars.

Sodium alginate (NaAlg) coagulates when exposed to calcium chloride (CaCl₂) and forms calcium alginate (CaAlg₂) and sodium chloride (NaCl), according to the following reaction:

2NaAlg + CaCl₂ → CaAlg₂ + 2NaCl