American scientists have developed a new edible antimicrobial coating to extend the shelf-life of strawberries based on cannabidiol (a non-hallucinogenic compound from cannabis known as CBD) and sodium alginate. The findings were reported in ACS Applied Materials & Interfaces.
In previous studies, CBD has been shown to limit the growth of some bacteria and pathogenic fungi, including those that can cause fresh fruit and vegetables to rot. However, the compound needs to be evenly distributed to be incorporated into foods or used for food preservation.
The researchers encapsulated CBD in a biodegradable polymer used in drug delivery, producing 400nm-wide particles. They then mixed the most stable of these nanoparticles (which contained 20% CBD by weight) with sodium alginate in water. Strawberries were then submerged into solutions containing different amounts of nanoparticles before a second dip into a mixture of ascorbic acid and calcium chloride to turn the colourless coating into a gel.
Untreated and treated strawberries were then placed in open plastic containers at refrigerator temperatures. After 15 days, the CBD-treated samples ripened and decayed much more slowly than untreated ones, possibly because of reduced microbial growth. The coating with the most CBD-loaded nanoparticles preserved the berries’ dark red appearance, enhanced their antioxidant activity the most, and exhibited the largest antimicrobial protection over the storage period, suggesting that this version would lead to the longest shelf-life. The researchers say that their results demonstrate how encapsulated CBD could be used to create a colourless antimicrobial coating for active food packaging.