SPIRULINA
(ARTHROSPIRA): AN EDIBLE
MICROORGANISM. A REVIEW.
Martha
Sánchez 1, Jaime Bernal-Castillo 1, Camilo Rozo 2, Ignacio Rodríguez 3
1 Departamento
de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Cra. 7 43-88, Bogotá
2 Facultad
de Ingeniería de Alimentos, Universidad de La Salle, Cra. 7 172-85, Bogotá
3 Departamento
de Ingeniería Química, Universidad Nacional de Colombia, Ciudad Universitaria
Cra. 30 Cl 45, Bogotá
E-mail: sanchezgm@tutopia.com; jabernal@javeriana.edu.co; ialimentos@jupiter.lasalle.edu.co;
ignaciorod33@hotmail.com
Spirulina is a photosynthetic, filamentous, spiral-shaped, multicellular and
green-blue microalga. The two most
important species of which are Spirulina maxima and Spirulina
platensis. For these
microorganisms cell division occurs by binary fission. Since this material contains chlorophyll a,
like higher plants, botanists classify it as a microalga belonging to Chyanophyceae
class; but according to bacteriologists it is a bacterium due to its
prokaryotic structure. Before Columbus,
Mexicans (Aztecs) exploited this microorganism as human food; presently,
African tribes (Kanembu) use it for the same purpose. Its chemical composition includes proteins (55%-70%),
carbohydrates (15%-25%), essential fatty acids (18%) vitamins, minerals and
pigments like carotenes, chlorophyll a and phycocyanin. The last one is used in food and cosmetic
industries. Spirulina is
considered as an excellent food, lacking toxicity and having corrective
properties against viral attacks, anemia, tumor growth and malnutrition. It has been reported in literature that the
use of these microalgae as animal food supplement implies enhancement of the
yellow coloration of skin and eggs yolk in poultry and flamingos, growth
acceleration, sexual maturation and increase of fertility in cattle.
Key words: food, microalgae,
nutrition, Spirulina.
Spirulina es una microalga verde-azul, fotosintética, filamentosa, en forma
helicoidal, multicelular. Las dos
especies más importantes son Spirulina máxima y Spirulina
platensis. La división celular se
realiza por fisión binaria. Según los
botánicos es una microalga debido a la presencia de clorofila a al igual
que en plantas superiores. Pertenece a
la división Cianofita y a la clase Cianofícea, pero según los bacteriólogos es
una bacteria debido a su estructura procarionte. Se conoce desde tiempos precolombinos, que este microorganismo
fue utilizado como alimento por tribus mexicanas (Aztecas) y actualmente por
tribus africanas (Kanembu). Su
composición química incluye proteínas (55%-70%), azúcares (15%-25%), ácidos grasos esenciales (18%), vitaminas,
minerales y pigmentos como carotenos, clorofila a y ficocianina; éste
último utilizado en industrias de alimentos y cosméticas. Se le considera excelente alimento, exento
de toxicidad y poseedor de propiedades correctoras de ataques virales, anemia,
crecimiento tumoral y malnutrición. La
literatura ha reportado, que Spirulina, usada como alimento de animales
conlleva al realce de la coloración amarilla de piel y yema de huevos, en
gallináceos y flamencos; aceleración de crecimiento, maduración sexual y
aumento de fertilidad, en bovinos.
Palabras
clave:
alimento, microalga, nutrición, Spirulina.
HISTORY
OF SPIRULINA IN HUMAN CONSUMPTION
It
is not known with accuracy when man began to use microalgae. The current use of these resources has three
precedents: tradition, scientific and technological development, and the
so-called, “green tendency” (Henrikson, 1994). Bernal Díaz del Castillo, a member of Hernán Cortez´s troops, reported
in 1521, that S. maxima was harvested from the Lake Texcoco, dried and
sold for human consumption in a Tenochtitlán (today Mexico City) market,
(Figure 1). This author makes reference
to "..small cakes made of a mud-like algae, which has a cheese-like
flavor, and that natives took out of the lake to make bread,..." (Ciferri,
1983). Years later, the Franciscan
friar Bernardino de Sahagún wrote: “... in certain periods of the year, very
soft things are gathered from Mexican lakes.
They look like curdles, have a clear blue color, and are used to make
bread, that then eaten cooked...” Natives gave this food the name of
Tecuitlalt, which in their language literally means “excrements of stones”. In 1524, friar Toribio of Benavente related
that the Aztecs harvested the Tecuitlalt, using clothes for pressing and the
resulting dough was placed on sand and exposed to the sunshine for its
drying. Once Spanish Conquest was over,
the topic of the Tecuitlalt was not mentioned again, and its elaboration fell
into oblivion, possibly due to contagious disease outbreaks, attributed to the
new customs adopted by the Indians, new foods, and the deep social, political
and religious changes brought by the Europeans (Henrikson, 1994).
In
1940, the French phycologist P. Dangeard mentioned a cake called dihé,
consumed by the people of the Kanembu tribe, near the African Lake Chad, in the
sub-desert area of Kanem. Dihé
is a hardened cake of blue-green algae, collected at the banks of small ponds
surrounding the lake and later on sun-dried.
Dangeard studied the dihé samples and concluded that it was a
purée of a spring form blue algae, main constituent of the phytoplankton in a
large number of the African Valley’s lakes (Ciferri, 1983).
Between 1964 and 1965, the botanist Jean Leonard (Leonard, 1966), who participated
in the Belgian Trans-Saharan Expedition, was impacted when he observed "a
curious bluish green substance, similar to cookies…" Leonard confirmed that dihé was made
up of Spirulina, obtained from alkaline lakes in the Kanem desert,
northeast of Lake Chad. This
investigator and his colleague Cómpere corroborated the previous report by P.
Dangeard, from whose observations the chemical analyses of Spirulina
began. At that time, a group of French
investigators studied some samples of Spirulina (S. maxima) that
grew abundantly in Lake Texcoco, near Mexico City (Ciferri, 1983; Richmond,
1992).
From the scientific point of view, the microalgae cultivation began in
1919 with Warburg’s investigations.
This scientist was well known for his works on dense suspensions of Chlorella,
as a tool to study photosynthesis. The
easy manipulation under controlled conditions and the experimental
reproducibility made the microalgae favorite organisms for biochemical,
vegetable physiology and photosynthetic studies. In 1950, the United States and Japan began the experimental
cultivations of this microorganism to investigate its chemical composition and
industrial applications. Japan was the
first country to produce Chlorella using this microorganism as diet food
or a water-soluble extract, denominated Chlorella Growth Factor (Devlin,
1975).
From
1970, the nutritional and medicinal studies on Spirulina have
proliferated (Chamorro, et al., 1996; Fox, 1993; Hayashi, 1996a;
Richmond, 1992; Saxena, et al., 1983; Schwartz and Shklar, 1987). In 1970, the German Federal Republic
supported investigations on human consumption of Spirulina in India,
Thailand and Peru. In the Asian
countries, the production was focused on nutritious support for the
undernourished population; in Peru, efforts have been made to industrialize the
production of Scenedesmus. In 1970, the massive production of
microalgae, which could be used in protein production and in water treatment,
was projected (Ayala and Vargas, 1987; Cañizares, et al., 1993; Ciferri
and Tiboni, 1985; Oxa and Ríos, 1998).
Spirulina is marketed and consumed in: Germany, Brazil (Lacaz
and Nascimento, 1990), Chile, Spain, France, Canada, Belgium, Egypt, United
States, Ireland, Argentina, Philippines, India, Africa, and other countries,
where public administration, sanitary organisms and associations have approved
human consumption (Henrikson, 1994).
Some of the best worldwide known Spirulina producing companies
are: Earthrise Farms (USA), Cyanotech
(USA), Hainan DIC Microalgae Co., Ltd (China), Marugappa Chettir
Research Center (India), Genix (Cuba) and Solarium Biotechnology
(Chile) (Ayala, et al., 1988; Jourdan, 1993; Belay, 1997).
In 1827, P. J. Turpin isolated Spirulina from a fresh water
sample (Ciferri, 1983). In 1844, near
the city of Montevideo, Wittrock and Nordstedt reported the presence of a
helical, septal and green-blue microalgae named Spirulina jenneri f.
platensis. But it was not until
1852, that the first taxonomic report written by Stizenberger, appeared. He
gave this new genus the name Arthrospira based on the septa presence,
helical form and multicellular structure.
Gomont
confirmed Stizenberger’s studies in 1892.
This author attributed the aseptate form to the Spirulina genus,
and the septal form to the Arthrospira genus. Geitler in 1932, because of the helical morphology, reunified the
members of the two genera under the designation Spirulina without
considering the septum presence only morphological similarity. In 1989, these microorganisms were
classified into two genera, according to a suggestion by Gomont in 1892
(Castenholz and Waterbury, 1989); this classification is currently accepted
(Tomaselli, et al., 1996; Vonshak and Tomaselli, 2000).
The
systematic position of cyanobacteria has been a matter of discussion, as these
photosynthetic organisms were first considered algae. In 1962, a distinction between prokaryotes and eukaryotes was
clearly established. The main difference is based upon the presence of cell
organelles enveloped by a phospholipidic membrane in eukaryotes. Stanier and Van Neil (1969) incorporated
green-blue algae into the prokaryote kingdom and proposed to call these
microorganisms cyanobacteria. This designation was accepted and first published
in 1974 in the Bergey`s Manual of Determinative Bacteriology (Guglielmi, et
al., 1993).
Spirulina
and Arthrospira must be admitted as different
genera. The worldwide investigation on microalgae has been carried out under
the name of Spirulina; this common designation between scientist and
consumers has proved difficult to change.
The microalgae exploited as food with excellent health properties
belongs to the genus Arthrospira, but it will probably be called Spirulina
for some time.
Spirulina and Arthrospira morphologies are differentiated fundamentally
by: helix type, distribution of pores in the cell wall, visibility of septos
under light microscopy, diameter and fragmentation type of Trichomes
(filaments) (Guglielmi, et al., 1993; Vonshak and Tomaselli, 2000). As mentioned, S. maxima and S.
platensis are the most important species in this genus and among these
exist taxonomic differences in filaments, vacuoles and external cover or
capsule regularity of each filament (Tomaselli, 1997).
The names cyanobacteria and green-blue algae (Cyanophyceae), are
considered compatible terms. The first
one refers to the phylogenetic / taxonomic relationship, while the second
represents the ecological/biological correlation (Castenholz and Waterbury,
1989).
Transmission
Electron Microscope observations show for Spirulina prokaryotic
organization, capsule, pluri-stratified cell wall, photosynthetic or thylakoid
lamella system, ribosomes and fibrils of DNA region and numerous
inclusions. The capsule has fibrillar
structure and covers each filament protecting it. The irregular presence of capsule around the filaments in S.
platensis is a differentiating morphological characteristic to compare with
S. maxima (Balloni, et al., 1980; Belay, 1997). Trichome width varies from 6 to 12 μm,
and is composed of cylindrical cells.
The helix diameter varies from 30 to 70 μm (Tomaselli, 1997); the
trichome length is about 500 μm, although in some cases when stirring of
culture is deficient the length of filament reaches approximately 1 mm. It is
very important to explain that the helical shape of Spirulina in liquid
culture is changed to spiral shape in solid media (Figure 3). These changes are
due to hydratation or dehydratation of oligopeptides in the peptidoglycan layer
(Ciferri, 1983).
In
this microorganism chlorophyll a, carotenes and phycobilisomes, which
contain phycocyanin (blue pigment) are located in the thylakoid system or
photosynthetic lamellas. The
inter-thylakoid space is limited by the presence of electronically transparent
protein gas vesicles, with the cylindrical form that give Spirulina its
floating capacity (Ciferri, 1983).
Ribosomes
and fibrils of DNA region are generally of central localization (Balloni, et
al., 1980).
Spirulina contains numerous characteristic peripheral
inclusions associated to thylakoids. Those are: cyanophycin granules,
polyhedral bodies, polyglucan granules, lipid granules, and polyphosphate
granules (Balloni, et al., 1980; Ciferri, 1983). The cyanophycin granules, or reserve
granules, are important due to their chemical nature and a series of
pigments. The polyhedral bodies or
carboxysomes mainly contain the enzyme
ribulose 1,5-diphosphate carboxylase that allows the fixation of CO2
in photosynthetic organisms and probably carry out a reserve function. The polyglucan granules or glycogen granules
or a-granules are
glucose polymers, small, circular and widely diffused in the interthylacoidal
space. The lipid granules, b-granules or osmophile
granules form the reservation deposit, constituted by poly-b-hydroxybutyrate (PHB),
found only in prokaryotes. PHB acts as
a carbon and energy reserve (Vincenzini, et al., 1990).
A
fundamental aspect of Spirulina biology is its life cycle (Figure 4) due
to the taxonomic, physiologic and cultivation implications (Ciferri, 1983;
Richmond, 1984). This period is
summarized in three fundamental stages: trichomes fragmentation,
hormogonia cells enlargement and maturation processes, and trichome
elongation. The mature trichomes are
divided into several small filaments or hormogonia through previous formation
of specialized cells, necridium cells, in which the cell material is reabsorbed
allowing fragmentation. The number of
cells in the hormogonias is increased by binary fission. For this process, the trichomes grows
lengthwise and takes their helical form (Balloni, et al., 1980).
CHEMICAL
COMPOSITION
Since
1970, Spirulina has been analyzed chemically. It has been shown to be an excellent source of proteins, vitamins
and minerals (Switzer, 1980).
Proteins. Spirulina has
a high protein concentration (60%-70% of its dry weight), (Table 1) (Ciferri,
1983). Spirulina is useful in
human nutrition, due to the high quality and quantity of its protein. The nutritive value of a protein is related
to the quality of amino acids, digestibility coefficient, as well as by its
biological value (Dillon and Phan, 1993; Richmond, 1992). Spirulina contains essential amino
acids; the highest values are leucine (10.9% of total amino acids), valine
(7.5%), and isoleucine (6.8%), (Cohen, 1997).
Denaturation of Spirulina protein is observed when algae are
heated above 67 ºC, at neutral aqueous solution. Hydrophobic regions interaction during heating and hydrogen bonds
formation during cooling are aggregation and gelation factors of Spirulina
protein (Chronakis, 2001).
Vitamins. Among food, Spirulina
has a relative high provitamin A concentration (Belay, 1997), (Table 2). An excessive dose of b-carotene may be toxic, but when the b-carotene is ingested from the Spirulina or another vegetable it
is usually harmless since the human organism only converts into vitamin A the
quantity it needs (Henrikson R., 1994).
Spirulina is a very rich source in vitamin B12, and
that is a reason why these cyanobacteria is of great value for people needing
supplements in the treatment of pernicious anemia (Richmond, 1992; Becker,
1984; Belay, 1997).
Lipids. Spirulina
contains 4-7% lipids. Spirulina
has essential fatty acids: linoleic acid (LA) (C18:2)D9,12 and g-linolenic
acid (C18:3)D9,12,15 (GLA) (Othes and Pire, 2001), (Table 3). The latter is claimed to have medicinal properties and is
required for arachidonic acid and prostaglandin synthesis (Dubacq and Pham-Quoc,
1993). GLA lowers low-density
lipoprotein, being 170-fold more effective than LA (Cohen, 1997).
Minerals. Iron in some nutritional
complements is not appropriately absorbed.
Iron in Spirulina is 60% better absorbed than ferrous sulfate and
other complements. Consequently, it
could represent an adequate source of iron in anemic pregnant women
(Pyufoulhoux, et al., 2001) (Table 4).
Carbohydrates. Spirulina platensis
contains about 13.6% carbohydrates; some of these are glucose, rhamnose,
mannose, xylose and galactose (Shekharam, et al., 1987). Spirulina does not have cellulose in
its cell wall, a feature that makes it an appropriate and important foodstuff
for people with problems of poor intestinal absorption, and geriatric patients
(Richmond, 1992). A new high molecular
weight polysaccharide, with immunostimulatory activity has been isolated from Spirulina
and is called “Immulina”. This
highly water-soluble polysaccharide represents between 0.5% and 2.0% (w/w) of
the dry microalgae (Pugh, et al., 2001).
Nucleic
acids content. One
of the main concerns about the consumption of microorganisms is their high
content of nucleic acids that may cause disease such as gout. Spirulina contains 2.2%-3.5% of RNA
and 0.6 %-1% of DNA, which represents less than 5% of these acids, based on dry
weight. These values are smaller than
those of other microalgae like Chlorella and Scenedesmus
(Ciferri, 1983).
Pigments. Some natural pigments are found in Spirulina, (Table 5). These pigments are responsible for the
characteristic colors of certain flamingo species that consume these
cyanobacteria in the African Valley.
This knowledge has promoted the use of this microorganism as source of
pigmentation for fish, eggs (Ciferri, 1983; Saxena, et al., 1983;
Henrikson, 1994) and chicken. Spirulina
also increases the yellowness and redness of broiled chicken due to
accumulation of zeaxanthin (Toyomizu, et al., 2001).
SOME
Spirulina CONSUMPTION BENEFITS
Studies
have shown that Spirulina consumption during 4 weeks reduces serum
cholesterol levels in human beings by 4.5% (Henrikson, 1994) and significantly
reduces body weight by 1.4 +/- 0.4 Kg after four weeks (Becker, et al.,
1986). These reports indicated no
changes in clinical parameters (blood pressure) or in biochemical variables
(hematocrite, hemoglobin, white blood cells, sedimentation rate) and absence of
adverse effects. The reduction of
cholesterol is partly owed to the g-linolenic
acid cyanobacteria high content (Henrikson, 1994).
The b-carotene is one of the most effective
substances to counteract those free radicals that alter cells causing cancer
(Fedkovic, et al., 1993; Schwartz, et al., 1990). Studies at the Harvard University School of Dental Medicine found
a reduction in mouth cancer when b-carotene extracts, obtained from Spirulina,
are consumed. The b-carotene solution applied to oral cancer
tumors in hamsters reduced the tumor number and size and in some cases these
disappeared (Schwartz and Shklar, 1987; Schwartz, et al., 1988). Spirulina
extract induces the tumor necrosis factor in macrophages, suggesting a possible
tumor destruction mechanism (Shklar and Schwartz, 1988).
An
extract of sulfated polysaccharides, called Calcium-Spirulan (Ca-SP), made up
of rhamnose, ribose, mannose, fructose, galactose, xylose, glucose, glucuronic
acid, galacturonic acid, and calcium sulfate, obtained from Spirulina, showed activity against HIV,
Herpes Simplex Virus, Human Cytomegalovirus, Influenza A Virus, Mumps Virus and
Measles Virus (Henrikson R, 1994; Hayashi, 1996b). Current investigation in this field is
searching for extracts that inhibit the AIDS virus replication (Ayehunie, et
al., 1998) and allows these patients to improve their health.
Spirulina
excretes variable quantities of products from its metabolism
such as: organic acids, vitamins, and phytohormones. Cell extract of S. maxima
has shown antimicrobial activity against Bacillus
subtillis, Streptococcus aureus, Saccharomyces cerevisiae, and Candida
albicans. The presence of high quantities of acrylic acid in Spirulina was substantiated at the end
of the seventies. This substance shows
anti-microbial activity, in a 2 mg/L of biomass concentration. Propionic, benzoic and mandelic organic acids
were also found (Balloni W. et al.,
1980).
Lactobacillus
population in human gastrointestinal tract is increased by Spirulina
consumption. This means: food digestion
and absorption improvement, intestinal protection against bacterial infections
and immune system stimulation (Henrikson, 1994; Schiffrin, et al., 1997). Immune
system modulation is due to interference on production and NK cytotoxicity
(Hirahashi, et al., 2002).
Spirulina
reduces:
hepatic damage due to drug abuse and heavy metal exposure, inflammatory
response (Richmond, 1984; González, et al.,
1999), cells degeneration (Bulik, 1993), anaphylactic reaction (Yang, et al., 1997), Bitot’s spots, and
Cesium-137 and Strontium-90 radiation in Chernobyl children (Henrikson,
1994).
Spirulina contains vitamin A, important in preventing eye diseases; iron and
vitamin B12, useful in treating hypoferric anemia and pernicious
anemia, respectively; g-linolenic acid, appropriate in treatment of atopic child eczema
therapy; to alleviate premenstrual syndrome, and in immune system stimulation
(Pascaud, 1993). Spirulina also has a positive effect on cardiac disease,
Parkinson`s disease, malnutrition, sclerosis (Richmond A, 1992; Fox, 1993, Fox,
1998; Thein, 1993) and wounds cure (Richmond, 1992).
Other
benefits are attributed to Spirulina: anti-arthritic effect due to the anti-inflammatory and
antioxidative properties of phycocyanin (Ramirez, et al., 2002);
anti-atherogenic property (Kaji, et al., 2002), tumor burden inhibition
(Dasgupta, et al., 2001); chemo protective and radio-protective effect
(Zhang, et al., 2001); and antioxidant activity on lead-induced toxicity
in rats (Upasani, et al., 2001).
In
Mexico, Spirulina is used in to enrich candies. In Australia and New Zealand beverages of
this substance are marketed. In Japan,
India, and Singapore Spirulina-enriched appetizers are sold specially to
pregnant women, children and elderly. Spirulina is not only food, but also a
natural coloring in Japanese chewing gums.
Countries like Chile, France, Cuba, Germany, Switzerland, Spain,
Portugal, Sweden, Holland, Belgium, Denmark, United Kingdom, Australia, and New
Zealand market food complements, which include Spirulina as the main component.
Internationally, skin care products, shampoos, dyes, masks, creams and
tonics containing this microorganism are marketed. In Sweden low calorie bread enriched with Spirulina is
sold, and in France a vegetable pâté, made of Spirulina, is sold as bread spread (Henrikson, 1994).
Many
agricultural and industrial materials are being prepared from cyanobacteria.
These include: biomass (Ciferri, 1983; Richmond and Becker, 1984; Shang-Hao,
1988; Thein, 1993), restriction nucleases (Kawamura, et al., 1986), antifungal, antineoplastic (Moore, et al., 1984; Clardy, et al., 1990), antimicrobial (Gerwick, et al., 1987), anti-leukemia (Moore, et al., 1977) and herbicidal compounds (Entzeroth, et al., 1985). Some pigments have been produced from cyanobacteria (Jung and
Dailey, 1989; Paniagua-Michel and Sasson, 1995). Other products from microalgae are: amino acids (Kerby, et al.,
1988), and fertilizers (Boussiba, 1988).
Spirulina has been studied as
an animal cell-growth stimulant (Kerby and Rowell, 1992) and in the treatment
of residual waters using alginate (Cañizares, et al., 1993; Patnaik, et al., 2001). Phycocyanin shows activity on vegetable cell
cultures with production of secondary metabolites as anthocyanin (Ramachandra, et al., 1996). This pigment has the ability to inhibit oxidative damage in DNA
and hence it may be used as a therapeutic agent (Bhat, et al., 2001).
Spirulina is used in Japan and Taiwan as aquarium fish food, in United States to
enhance color, speed the growth and sexual maturation of canaries and exotic
birds (Saxena, et al., 1983). Cattle and horse breeders affirm that when
adding Spirulina to silage, the quantity of sperms in males and the
fertility in females are increased (Henrikson, 1994). Labeo rohita (rohu), an Indian carp,
showed greater growth after being fed with Spirulina (Nandeesha, et
al., 2001). In chickens, Spirulina
increases the mononuclear phagocyte system function thereby enhancing their
disease resistance (Al-Batshan, et al., 2001).
TOXICOLOGY
This
microorganism in general terms do not exceed the metal concentration limits
recommended by international agencies.
But due to the use of fertilizers, possible water and environmental
pollution optimal quality control and periodic revisions of this cyanobacteria
culture is necessary to detect high metal concentration values (Chamorro, et al., 1996). Studies in Mexico showed that the administration of S.
platensis to mice does not cause embryonic or fetal damages (Chamorro, et al., 1989; Chamorro and Salazar,
1990).
Absence
of phycotoxins in Spirulina is an advantage with respect to Microcystis,
Anabaena and Aphanizomenon, fresh water cyanobacteria that have
caused death in livestock and allergic or gastrointestinal reactions in human
beings (Chamorro, et al., 1996).
Chronic
and sub-chronic toxicity studies have not revealed toxic effects by Spirulina. The lethal dose (LD50) of Spirulina
has not been determined, since it would be necessary to dispense high
quantities in one single dose (Chamorro, et
al., 1996; Switzer, 1980).
The
main commercial large-scale culture of microalgae started in the early 1960s in
Japan with the culture of Chlorella, followed by Spirulina in the
early 1970s at Lake Texcoco, Mexico.
The third major microalgae industry was established in Australia in
1986. Commercial production of Dunaliella
salina was cultured as a source of β-carotene (Borowitzka, 1998).
The
first plant in USA (Earthrise Farms) for the exploitation of Spirulina,
built in 1981 in California, emerged as the result of a research work on its
culture by Dainippon Ink & Chemicals, Inc. of Japan and Proteus Corporation
of California (Vonshak, 1997), (Table 6).
Spirulina grows quickly and produces 20 times more protein by
surface unit that soy beams (Henrikson, 1994).
When comparing the growth of Spirulina and the agricultural crop
cycles, the difference in the time of production is noticeable. In agriculture, the harvest is obtained
after several months of cultivation, while Spirulina is produced
continually (Switzer, 1980).
Production
process of Spirulina requires clonal or unialgal cultures (isolation of
a single algal unit or trichome), (Vonshak, 1984; González, et al., 1995; Hoshaw and Rosowski, 1979).
The method begins with the determination of physical and chemical
parameters of the water sample, which constitutes the main ingredient of the
growth medium. The Spirulina
samples should remain under dim light or in darkness and at 20-25°C; freezing
temperature is not recommended because it favors lysis and death (Rippka,
1988). Isolation of the microorganism
is carried out under an intensely lighted
microscope and with a capillary pipette so that one and only one
filament is selected (Ayala, 2000) by
its morphological attributes (color, size of trichomes, length and apical
filament characteristics). If axenic
cultures, specific for physiologic and biochemical studies of algae, are
wanted, special treatments such as: centrifugation followed by ultrasonic
treatments with antibiotics and potassium tellurite are required (Hoshaw and
Rosowski, 1979).
Cyanobacteria
are grown in many liquid and solid culture media such as: BG11, ASM-1, Z8, SAG, BBM, AA, KMC, Kn
Cg-10, D (Rippka, 1988) and Spirulina grows in culture media such
as: Zarrouk, SSM (Sea Saltpeter
Medium) , Vonshak, Spirulina and AO (Ogawa and Aiba, 1977; Ayala and Bravo
R, 1982).
Zarrouk
medium (Zarrouk, 1966; Borowitzka, 1992) is frequently used during the
isolation process and the SSM medium is preferred in the industrial production
stage (Ayala, 2000). Eight mayor medium
factors influence the productivity of Spirulina: luminosity
(photo-period 12/12, 4 luxes), temperature (30°C), inoculation size, stirring
speed, dissolved solids (10-60 g/L), pH (8.5-10.5), water quality, macro and
micronutrient presence, (C, N, P, K, S, Mg, Na, Cl, Ca and Fe, Zn, Cu, Ni, Co,
W) (Ciferri, 1983; Ayala, 1998).
Spirulina production may be carried out in closed and open systems. The first one involves laboratory photo
bioreactors (Materassi, et al., 1980;
Torzillo and Carlozzi, 1996; Watanabe
and Hall, 1996). This is not used in
industrial production. The open system,
denominated raceway (Figure, 5), due to its low production cost, easy
handling and high production of biomass, is frequently chosen for industrial
production. This method uses a pond with a central islet, a motor operating a
paddle wheel which allows continuous displacement of the liquid culture in the
peripheral channel. Paddle wheels speed
in the order of 20 cm s-1 has been recommended. If necessary, plates may be introduced to
avoid dead point formation. When this
type of reactor is located outdoors the following factors should be considered
as modifiers on the cyanobacteria growth:
the medium composition (Ciferri, 1983), evaporation speed, culture
contamination, and temperature (35°C–38ºC)(Walmsley, et al., 1981).
Productive
process has five stages: Filtration and Cleaning, a nylon filter at the
entrance of the water pond is needed; Pre-concentration, to obtain algal
biomass which is washed to reduce salts content; Concentration, to
remove the highest possible amount of interstitial water (located among the
filaments); Neutralization, to neutralize the biomass with the addition
of acid solution; Disintegration, to break down trichomes by a grinder; Dehydration
by spray-drying; this operation has great economic importance since it involves
about 20-30% of the production cost (Ayala and Laing, 1990); Packing is
done in sealed plastic bags to avoid hygroscopic action on the dry Spirulina;
and Storage, in corrugate cardboard boxes, and in fresh, dry, dim,
pest-free, and clean storeroom, preventing Spirulina pigments from
deteriorating (Ayala, 1998). Quality
control for Spirulina as a food includes microbiological standard tests,
chemical composition test, and test for heavy metals, pesticides and extraneous
materials (insect fragments, rodent hair and feather fragments) (Belay, 1997).
The
above-mentioned facts stress Spirulina is a non-noxious microorganism
with a very high nutritional and economic potential for animal consumption
including man. It may be cultured in
laboratory, pilot plant and at industrial scale in a simple way. However, like in all food processing, it is
necessary to maintain good production conditions and quality.
A
bibliographical review on Spirulina identifies this microorganism as microalgae
or bacteria, by botanists and bacteriologist respectively. This study has revealed a rather
significant number of research studies done on its properties, some of these
are related to human and animal food uses.
Spirulina is claimed as a non-toxic, nutritious food, with some
corrective properties against viral attacks, anemia, tumoral growth and low
prostaglandins production in mammals; and as a source of the yellow coloration
of egg yolk when consumed by hens, and a growth, sexual maturation and
fertility factor, in bovines. This
material contains proteins, carbohydrates, essential fatty acids, vitamins,
minerals, carotenes, chlorophyll a and phycocyanin. Spirulina may be produced in rather
simple pilot plants or industrial installations if good conditions and quality
controls are assured.
TABLES
Food Type
|
Crude Protein %
|
|
Spirulina powder |
65 |
|
Whole
Dried egg |
47 |
|
Beer
Yeast |
45 |
|
Skimmed
powdered milk |
37 |
|
Whole
soybean flour |
36 |
|
Parmesan
Cheese |
36 |
|
Wheat
germ |
27 |
|
Peanuts |
26 |
|
Chicken |
24 |
|
Fish |
22 |
|
Beef meat |
22 |
Table
1. Quantity of Spirulina proteins
and
other foods (Henrikson, 1994).
Vitamins
|
mg 100 g-1 |
|
Provitamin
A |
2.330.000
IU kg –1 |
|
(β-carotene) |
140 |
|
Vitamin
E |
100
a-tocopherol equiv. |
|
Thiamin
B1 |
3.5 |
|
Riboflavin
B2 |
4.0 |
|
Niacin
B3 |
14.0 |
|
Vitamin
B6 |
0.8 |
|
Vitamin
B12 |
0.32 |
Folic acid
|
0.01 |
Biotin
|
0.005 |
Phantothenic acid
|
0.1 |
Vitamin K
|
2.2 |
Table 2. Vitamins in Spirulina powder (Belay,
1997).
|
Fatty acid |
Fatty acids (%) |
|
(C14)
Myristic acid |
0.23 |
|
(C16)
Palmitic acid |
46.07 |
|
(C16:1)D9 Palmitoleic acid |
1.26 |
|
(C18:1)D9 Oleic acid |
5.26 |
|
(C18:2)D9,12 Linoleic acid |
17.43 |
|
(C18:3)D9,12,15 g-Linolenic acid |
8.87 |
|
Others |
20.88 |
Table
3. Fatty acid composition of Spirulina
platensis powder (Othes and Pire, 2001).
Mineral
|
mg 100g-1 |
|
Calcium |
700 |
Chromium
|
0.28 |
|
Copper |
1.2 |
|
Iron |
100 |