Page 273 - Algae Anatomy, Biochemistry, and Biotechnology

256 Algae: Anatomy, Biochemistry, and Biotechnology

Arthrospira biomass has a high content of protein, about 55–60% of the dry matter, with
respect to other foods such as milk, eggs, etc.; the proteins are low in lysine and sulfured
aminoacids such as methionine and cystein, but their amount is much higher than in other veg-
etables, including legumina. Phycobiliproteins represent a major portion of proteins, and among
them phycocyanin can reach 7–13% of the dry matter; carbohydrates reach 10–20% of the dry
weight, and consist mainly of reserve products, while lipids account for 9–14% of the dry
weight. The mineral fraction represents 6–9% of the dry biomass, rich in K, P, Na, Ca, Mn, and
Fe. Group A, B, and C vitamins are also present, with an average b-carotene content of
1.5 mg g 21 of Arthrospira, corresponding to 0.25 mg of vitamin A. Considering a recommended
dietary allowance (RDA) of vitamin A of about 800 mg, and taking into account a natural
20–30% decrease in b-carotene level due to dihe ´ storing conditions, we can say that a daily con-
sumption of 5 g of dihe ´ would provide about 100% of RDA.

Rhodophyta

Porphyra (Bangiophyceae) is popularly known as Nori in Japan, Kim in Korea, and Zicai in China,
(see Chapter 1, Figure 1.24). It is among the most nutritious macroalgae, with a protein content of
25–50%, and about 75% of which is digestible. This alga is an excellent source of iodine, other
trace minerals, and dietary fibers. Sugars are low (0.1%), and the vitamin content very high,
with significant amounts of vitamins A, complex B, and C, but the shelf life of vitamin C can be
short in the dried product. During processing to produce the sheets of nori, most salt is washed
away, so the sodium content is low. The characteristic taste of nori is caused by the large
amounts of three amino acids: alanine, glutamic acid, and glycine. It also contains taurine,
which controls blood cholesterol levels. The alga is a preferred source of the red pigment r-phycoer-
ythrin, which is utilized as a fluorescent “tag” in the medical diagnostic industry.
Porphyra has been cultivated in Japan and the Republic of Korea since the 17th century,
because even at that time natural stocks were insufficient to meet demand. Today Porphyra is
one of the largest aquaculture industries in Japan, Korea, and China. Because of its economic
importance and other health benefits, Porphyra cultivation is now being expanded to other
countries.
Porphyra species are primarily intertidal, occurring mainly in temperate zones around the
world, but also in subtropical and sub-Artic regions, as confirmed by its history of being eaten
by the indigenous peoples of northwest America (Alaska) and Canada, Hawaii, New Zealand,
and parts of the British Isles. Porphyra abbottae Krishnamurthy is a nutritionally and culturally
important species of red alga used by First Peoples of coastal British Columbia and neighboring
areas, down to northern California. This species, along with Porphyra torta and possibly others,
is a highly nutritious food, still gathered in quantity today by the Coast Tsimshian, Haida, Heiltsuk,
Kwakwaka’wakw, and other coastal peoples from wild populations in large quantities, dried and
processed, and served in a variety of ways: toasted as a snack, cooked with clams, salmon eggs,
or fish in soup, or sprinkled on other foods as a condiment. Common linguistic origin of the
majority of names for this species among some 16 language groups in five language families indi-
cates widespread exchange of knowledge about this seaweed from southern Vancouver Island north
to Alaska. The harvesting and preparation of this seaweed is exacting and time-intensive. It necessi-
tates a wide range of knowledge and skills, including an understanding of weather patterns, tides,
and currents; an appreciation of the growth and usable life stages of the seaweed; and a knowledge
of the optimum drying locations and techniques and of the procedures for secondary moistening,
chopping, and drying to achieve the best flavors and greatest nutritional value. P. abbottae is gen-
erally harvested in May. Though formerly a women’s activity, as for dihe ´ harvesting by Kanembu
women, both genders now participate in seaweed gathering. The postharvest preparation and hand-
ling of the seaweed is fairly labor-intensive and detailed. Once processed, seaweed is considered
“an expensive and prestigious food” and is valued as a gift or trade item that is often exchanged