Antimicrobial food coatings have been around for decades and synthetic antimicrobials — such as sorbates, nitrates and sulfites applied directly to foods to keep them safe from bacteria — have become commercially popular in the past five years.
The next big step forward is developing food coatings made from natural edible substances, such as polysaccharides, essential oils, enzymes, proteins and lipids.
“Consumers don’t like to see things on ingredient labels they can barely pronounce,” said Carmen Gomes, assistant professor in the biological and agricultural engineering department at Texas A&M University.
Studies are ongoing, but there are manufacturing process challenges to solve before natural edible coatings can hit the market. Because food safety is such a concern to public health and safety, synthetic coatings will remain the industry standard until research and development is further along, said research analyst Aarthi Janakiraman, who recently authored an industry report on the science for Frost & Sullivan.
“Direct antimicrobial coatings act as a barrier to control moisture, oxygen, carbon dioxide, flavor and aroma exchange between food components or with the atmosphere surrounding the food,” Janakiraman says. “These coatings protect the product, extend its shelf life and improve the food quality.”
Gomes’ research is testing edible coatings such as essential oils and polymers, including pectin and chitosan from hardshell crustaceans, on fruits and vegetables that have relatively short shelf lives.
One challenge is layering a polymer coating on food in the proper order. Their polyelectrolyte properties give them different charges so it has to be precise. “The food has to be dipped in a specific order, layer by layer, to get the proper charge sequence so it works,” Gomes said.
Essential oils, such as cinnamon, cloves or thyme, work on vegetables but are not good options for fruit. Essential oils first must be encapsulated in another edible polymer before being applied to the fruit surface.
Gomes said these edible coatings can double the shelf life of food, along with protecting them from bacterial contamination.
“There is no reason not to use natural coatings; it’s the future of food protection,” she said.
Janakiraman said another manufacturing challenge is making sure coatings do not change the characteristics of food, such as sight, smell and taste.
“When a food product is directly coated on to a food surface, it is possible that the active agents in both the food stuff and the coating may interact to bring changes in the sensory characteristics of food,” Janakiraman said.
Another issue is simply the characteristics of the antimicrobials. Some may have strong mechanical and gas barrier properties but poor water vapor barrier properties, while others are just the opposite, Janakiraman said.
Once production challenges are met, the next step is to connect developers with food companies. Janakiraman says technology licensing deals will allow for faster commercialization of edible coatings through marketing agreements.