Acid preservation of the brown seaweed Saccharina latissima for food applications

Abstract

Acidification of the brown seaweed species Saccharina latissima using lactic or citric acid was investigated as a preservation method to increase the shelf life prior to further processing for use in food applications. Cut seaweed biomass was mixed with seawater or acid solution prepared using seawater and stored at ambient temperature for a period of up to 56 days. The samples were assessed through compositional analysis, recording of biomass loss and calculation of compound retentions. In addition, the sensory properties of selected samples were assessed through descriptive analysis. Acid addition resulted in a drop in pH to the range 3.6 to 4.1 for all treatments where the pH remained stable throughout the storage period. For the sample preserved in seawater only, pH dropped from 7.3 to 4.3 during the storage period due to production of lactic acid by naturally occurring bacteria. All treatments resulted in biomass and loss of minerals (mainly K) and carbohydrates, which correlated positively with acid concentration with the exception for mannitol where the highest loss was found in the seawater-preserved sample. Samples with low concentration of lactic or citric acid had the lowest total mass loss and highest retention of dry matter. Increasing concentrations of lactic acid led to lower total remaining dry matter and lower compound retention. Finally, the sensory evaluation showed that the intensity of sour taste significantly differed between treatments which were otherwise characterized by high saltiness. Higher acid dose resulted in a more sour taste and lactic acid was perceived as less sour than citric acid. In addition, lower sourness correlated with a more intense saltiness. The sensory profiles were not significantly affected by storage time.