Richa Arya1, Denise I. Skonberg1, Jennifer J. Perry1
1School of Food and Agriculture, University of Maine, 5735 Hitchner Hall, Orono, ME, USA 04469
The volume of aquacultured macroalgae produced in the northeastern USA has increased by nearly 10x since 2018 (Maine DMR). The remoteness of most existing farms and lack of centralized processing infrastructure in the region underlie the need for low-input processes for shelf life extension. We assessed the effects of salting treatments (dry salting [30% NaCl wt/wt] and brining [40% NaCl]) on quality, safety and palatability of Saccharina latissima. Salted algae was stored at 4°C or 22°C for up to 90 days. Physicochemical (water activity, moisture, color, mineral content), and microbial properties (aerobic mesophilic, psychrotrophic, marine bacteria counts) were assessed. Both treatments reduced water activity from 0.98 to ~0.74. Microbial quality remained high (<3.0 logCFU/g) in all treatments through 60 days of storage, regardless of temperature, but psychrotrophic bacteria increased significantly between days 60 and 90 in samples stored at 22°C. Potassium, magnesium and calcium concentrations were significantly higher in dry salted kelp than untreated or brined samples. Subsequently, foodborne pathogens of interest (shigatoxigenic E. coli (STEC), Salmonella, Vibrio spp., Listeria monocytogenes) were inoculated onto kelp before salting and survival during processing and storage was assessed. Salting significantly reduced populations of all four pathogens, with initial reductions ranging from 1.0 (Salmonella) – 2.9 (Vibrio spp.) logCFU/g. L. monocytogenes and Salmonella were significantly more resistant to treatment than STEC or Vibrio spp. Collectively, data illustrate the capability of salting treatments to produce consumer products with enhanced shelf life and safety without requiring significant capital or input cost on the part of the grower/processor.