UNE researchers studying food safety aspects of edible seaweed

Most food harvested from the sea is contaminated by some level of pathogenic bacteria, and edible seaweed is no exception.

What level of pathogens are found on edible seaweed and what can be done to keep levels low are the focus of a study now underway involving researchers and students at UNE.

“Edible seaweed, including sugar kelp, is really a burgeoning industry in Maine,” explained Kristin Burkholder, Ph.D., associate professor in the School of Biological Sciences. “Our recent work has shown that, not surprisingly, kelp harvested from the Gulf of Maine is subject to occasional low levels of contamination by bacterial pathogens. However, the Food and Drug Administration (FDA) has not been keeping pace with potential safety issues around consuming this product as food. Since seaweed is not considered seafood or a crop, it is not regulated by the FDA.”

“So, there really is no guidance out there for the industry on how to keep the risk low,” stated Carrie Byron, Ph.D., associate professor in the School of Marine and Environmental Programs.  “Our goal is to work with industry members to produce best management practices and set some standards. We are now in the beginning stages of trying to gather data.”

With $150,000 worth of funding from a Maine Sea Grant, Byron, Burkholder, and their students are examining ways that the industry can minimize the food safety risk.

“We are thinking about how people in the industry are handling and processing the seaweed before it gets to the consumer,” Burkholder said. “We are specifically looking at post-harvest storage temperature and drying methods applied to the seaweed.”

The most commonly used drying method in the industry now is air drying. The researchers will be comparing that to freeze drying the seaweed, a method used in some other countries, to see if one way is better than the other at keeping pathogen load low.

Master of Marine Sciences student Jessica Vorse is conducting the experiments for the study.

“This spring, I will be running storage temperature trials on freshy harvested farmed sugar kelp,” she stated. “I will be taking kelp samples, inoculating them with six common food pathogens, then storing them in one of three temperatures, all relevant for food storage. I will then analyze their pathogen load post storage treatment to determine the best storage temperature for the product.”

Vorse will follow the temperature study with experiments that examine the effects of seaweed drying methods on pathogen levels.

An important element of the study is working with industry members to inform the project goals.

“The industry really sees the need for this research,” Byron said. “Very rarely do you see diverse industry members all coming together in the same place at the same time on a topic, but we were able to do that with representation across species, across farming, and across harvesting methods on a topic that can be really scary for them.”

Byron says the project is giving the students involved real-world, hands-on experience that they can take with them after graduation.

“We have had a couple of teams of undergraduate students who've been involved in this, which I think great for them,” she stated. “It gives them some solid material to put in their resumes and in future applications to graduate schools. It really is a pretty incredible skillset that these students will be walking away with.”

Vorse says part of the experience she is receiving is learning how to work independently.

“I have a lot of independence with this project, which comes with more responsibility than I have had before in a working environment,” Vorse explained. “The protocols for the experiments I am running are designed with huge amounts of input from my advisors, but I am responsible for getting that work done in a timely fashion. I also have two undergraduates who assist me with lab work, so I make their lab schedules and train them in new techniques.”

The team is now about halfway through the two-year project. The research is expected to really ramp up this month now that we are in the seaweed harvesting season in Maine.