Nutritional profile of edible red marine seaweeds

Marine biodiversity represents an exceptional source of natural resources. Their use in a sustainable way may ensure alternative food sources for human consumption, which scarcity is anticipated. Macroalgae, also known as seaweed, are an outstanding example of this biodiversity and are considered an excellent source of a wide number of chemical compounds with beneficial health effects [1]. According to their pigmentation, they can be distinguished in green (Chlorophytaea), brown (Phaeophytaea) and red (Rhodophytaea), showing differences in nutritional and chemical compositions [1]. Some macroalgae are widely used as food ingredients in oriental countries as a good source of fiber and protein. Alternatively, they are also considered a source of nutraceuticals, providing health benefits such as anti-inflamatory, anti-allergic, antimutagenic, antitumor, antidiabetic, antioxidant, antihyperthensive and neuroprotective properties [2]. Indeed, macroalgae are a very attractive material for the food, pharmaceutical and cosmetic industries. According to some studies red seaweeds seem to be the most suitable source of proteins for human nutrition [3]. The aim of this study was to evaluate the nutritional profile of the most consumed species of red seaweed that are commercially available in the market. Red species as Palmaria palmata (Dulse), Porphyra tenera (Nori) and Eisenia bicyclis (Arame), were analyzed. Moisture determination was performed using a Scaltec SMO01 moisture analyzer. The ashes were obtained by incineration at 500ºC. The protein content was determined using the Kjeldahl procedure and total fat was measured through Soxhlet method. The carbohydrates were calculated indirectly by difference. In addition, chlorides were volumetrically determined and vitamin E profile was analysed by HPLC/DAD/FLD. The algae samples are commercialized dry, so the moisture content was very low, around 10%. The ash content was around 10-17%. Protein levels ranged from 12 to 34% and the highest content was found in red species, especially in Porphyra tenera. The fat content was less than 1% in all species. The carbohydrate content, which includes the dietary fiber, ranged from 50 to 67%. Significant differences (p<0.05) were found between chloride contents and vitamin E profiles of the analysed samples. In western countries, the use of seaweeds for human consumption is not a very common practice. In the other hand, deficient nutrition mainly in underdeveloped countries drive research on cheaper plant sources rich in the main macronutrients for a balanced diet with potential health benefits for population. The results of this work show that the analysed macroalgae can be interesting sources of alternative protein, minerals, and, eventually, fiber. Further studies are being conducted in order to better characterize these species in what concerns to their chemical composition and potential health effects.