Assessment of food quality and microbial safety of brown macroalgae (Alaria esculenta and Saccharina latissima)

Background There has been a rapid increase in the number of seaweed farms in the Western world, and it is crucial for these companies and their customers to have standardized methods for quality assessment and optimization. The aim of this study was to adapt known methods for food-quality determination for the analysis of seaweed quality, including color, texture, and microbiology, and to discuss optimal heat treatments for the popular macroalgae Saccharina latissima and Alaria esculenta. Results The development of an attractive, green color during heating was highly specific to species, freezing history, and part of the thallus. Resilience and thermostability were also species dependent. Low microbial numbers (1-3 log cfu/g) for total aerobic count, psychrotrophic bacteria, and spore-forming bacteria were found, but Bacillus spp. were isolated. No enterococci, coliforms, pathogenic vibrios, or Listeria monocytogenes were detected. Conclusion The methods employed were able to describe clearly the physical and microbial qualities of A. esculenta and S. latissima, and quality changes during processing. Based on the results, optimal cooking for a minimum of 15 min at 95 degrees C was suggested for S. latissima. Fresh and frozen A. esculenta showed the greenest color after heating for 5-9 s at a high temperature (> 85 degrees C). If a higher heat load is needed to achieve safe and stable food products, using fresh and not frozen A. esculenta is highly recommended, as fresh specimens remain green even after 15 min at 95 degrees C. (c) 2018 Society of Chemical Industry