Céline Rebours a *, Janne Stangeland a, Wenche Emblem Larssen a, Pierrick Stévant a
a Møreforsking AS, PO Box 5075, 6021 Ålesund, Norway
Kelp products have challenges related to production (epiphytes, short harvest period) and food safety (iodine, arsenic). The Norwegian industry is therefore looking at other species and fresh sea lettuce presented to the restaurant market generated great interest. However, restrictions are associated with the sale of fresh seafood (limited shelf life) and conservation methods need to ensure high-quality product delivered year-round. Little information is available about the effect of freezing on the quality of sea lettuce in relation to food safety, nutritional content and sensory characteristics. U. fenestrata grown under standard culture conditions were frozen under different methods and thawed with two different methods (room temperature vs. refrigerator) after 1, 5 and 10 months of frozen storage. Appearance, smell and flavor were evaluated and the combination of the two freezing methods (blast vs. normal) and thawing methods did not results any significant differences. Each sample was analyzed for fluid loss, dry matter, nutrient and microbiological contents. No coliform, mold or yeast had been detected. Drip loss was around 5 to 6%. Dry matter and nutritional contents were similar between treatments and the literature on Ulva species. Iodine (32 mg.kg-1) and arsenic (< 3 mg.kg-1), including inorganic arsenic (< 0.06 mg.kg-1) were similar between treatments and much lower than those reported in kelp. Temperature registration provided a basis for calculating thermal conductivity, capacity and energy consumption. The energy´s costs (freezing process and frozen storage) for 10 months was estimated at 10 Euro t – 1.