FR2693917A1 - Extn. of water sol. components from algae, esp. marine algae - by lyophilising algae, re-hydrating to original water content, and leaching, using demineralised water - Google Patents

Abstract

Water-sol. components are extracted from algae, esp. marine algae, by (a) rehydrating pre-lyophilised algae, with demineralised water, to the original moisture content, and (b) leaching the rehydrated algae in a semi-fluid bed, with demineralised water. The algae are cut into pieces and are stirred in a leach chamber of greater vol. than the vol. of the algae. Water passes upwards through the chamber and circulates in a closed cycle. After the treatment, the extract contg. the water-sol. components is purified by filtration through a frontal filter, and opt. then through a tangential micro-filter. ADVANTAGE - Treatment is at room temp. and avoids chemical additives.

Description

 The present invention relates to a process for extracting water-soluble elements from algae, in particular seaweed.

 Such processes are already known and reference may usefully be made to the patent documents FR-A-2 242 991 and FR-A-1 031 051 cited here by way of example.

 The first describes a process which consists in freeze-drying fresh seaweed previously cut and chopped and in macerating them in an aqueous solution of a specified acid. The extraction is favored by mechanical agitation under the action of a flow of ultrasound allowing better penetration of the acid.

 The disadvantage of this process is that it requires the use of an acid which can denature certain active ingredients contained in the cells of the algae and thus take away their value.

 Document FR-A-1 031 051 describes a process for extracting water-soluble elements which consists in subjecting previously dried algae to extraction with water by passing them through a stream of water while at the same time kneading.

 The object of the invention is to propose an extraction process which does not use any chemical compound and which is carried out at ambient temperature.

To do this, a method according to the invention consists in:
1) subjecting previously lyophilized algae to rehydration with demineralized water at the original humidity level, and
2) subject the rehydrated algae to leaching in a semi-fluid bed with demineralized water.

 During leaching, the algae cells undergo an osmotic process and the water-soluble elements they contain diffuse in demineralized water.

 In order to increase the extraction yield, demineralized water circulates in a closed circuit through the semi-fluid bed of algae.

 After several cycles, the extraction juice loaded with the water-soluble elements extracted from the algae cells is subjected to a purification operation.

This consists of filtration in filters of the frontal type and in a filtration circuit comprising a tangential micro-filtration apparatus.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among which:
Fig. 1 is a schematic view of an extraction installation for the implementation of an extraction method according to the invention, and
Fig. 2 is a schematic view of a filtration installation which can be used downstream of an extraction installation.

The process of the invention uses demineralized water. This water can for example be obtained from spring water to which the following operations are successively subjected:
a first filtration for the separation of large particles by means of a filter with absolute retention threshold at 5 microns,
organic matter filtration with an activated carbon filter,
demineralization treatment by ion exchange on resin, then
filtration of certain microorganisms in suspension by means of a filter with an absolute retention threshold of 1 micron.

 Typically, the demineralized water used has the following characteristics: its ph measured at 200 ° C. is 5 + 0.5, its concentrations of chloride and potassium ions are less than 0.1 mg / liter and those of phosphorus, iron, calcium, magnesium are less than 0.01 mg / liter.

 The algae which are used in the process of the invention are cut into pieces of a few centimeters and then lyophilized. These algae are for example of the type "Laminaria digitata", "Ascophyllum nodosum", etc.

 In a first step of the process of the invention, they are rehydrated at the original humidity level by soaking in demineralized water. The soaking time is approximately 15 minutes. 5.6 liters of demineralized water are used for this operation per 1 kilogram of lyophilized algae.

 The second step consists in subjecting the rehydrated algae to leaching in a semi-fluid bed.

 There is shown in FIG. 1, the diagram of an installation allowing the implementation of this leaching process in a semi-fluid bed.

 There is a first tank 1 in the lower part from which a first pipe 2 connects to the inlet of a circulation pump 3.

 The outlet of the pump 3 is connected to a first end of a pipe 4, the other end of which is connected to the base of a second tank 5.

 In the upper part of the tank 5, there is a return pipe 6 connected to the upper part of the first tank 1 and slightly inclined.

 The second tank 5 contains two grids 7 and 8 parallel to each other which form, with the side wall of the tank 5, a lix leach chamber containing the cut and rehydrated algae pieces from which the water-soluble elements are to be extracted. The volume of the Lix leaching chamber is greater than the volume of the algae pieces to be treated present in the Lix chamber.

 The pipes 2 and 4 and the pump 3, the tank 5, the pipe 6 and the tank 1 form a closed circuit which is traversed, in the direction shown by the arrows A, by demineralized batten.

Grids 7 and 8 are intended to prevent pieces of algae from leaving the leaching chamber
Lix while allowing the passage of demineralized water.

They consist for example of plates pierced with a multitude of holes.

 The volume of algae in the Lix chamber being less than the volume of the leaching chamber itself, turbulence is created in the Lix chamber which has the effect of circulating the pieces of algae (see arrows B showing these turbulence).

The algae pieces therefore form a semi-fluid bed.

 This turbulence increases the contact time of demineralized water with the algal cells and consequently increases the extraction yield. Thus, the diffusion of the water-soluble elements of the algal cells in demineralized water is favored by the circulation of the pieces of algae in the Lix leach chamber.

 In the installation shown, this circulation is further increased because the demineralized water circulates from bottom to top in the second tank 5. The current therefore opposes the natural movement of the algae due to their weight, which has the effect a counter-current extraction and this further increases the time of contact of the water with the algal cells.

 An extraction installation was carried out for the treatment of 1.2 kg of lyophilized algae. Rehydration is carried out by soaking in 6.8 liters of demineralized water. The Lix leach chamber has a volume of approximately 9 liters and the total volume of circulating water is 37 liters. The flow rate of pump 3 is between 300 and 400 liters / hour.

For some algae, we have provided in the room
Lix, an agitator 9 consisting of a plate which is rotated, by suitable means not shown, along the vertical axis of the tank 5. The agitator 9 further increases the turbulence currents in the Lix chamber and facilitates by therefore the osmotic process.

 However, the agitator 9 can disintegrate certain fragile algae, which would have the harmful effect of clogging the filters used downstream of the extraction treatment itself. Also, do not use, for this reason, with this type of algae, the agitator 9.

 The maximum yield of the process for extracting the water-soluble elements from the algal cells is reached after approximately one and a half hours of leaching in a semi-fluid bed.

 At this stage, the extraction juice present in the extraction installation, in addition to the desired active principles such as trace elements, certain proteins, amino acids, etc., also contains microorganisms, cellular debris from the mixing of algae in the leaching chamber, and of macromolecules, such as polysaccharides, large proteins, etc. This juice is therefore cloudy and physically and bacteriologically unstable. Also, once the actual extraction process has been carried out, this juice is purified. Fig. 2 shows the filtration installation then used.

 It is the valve 10 of the extraction installation, which is closed during the extraction process, which allows the extraction juice to be directed to the filtration installation.

 This includes, upstream, a first filter 11 whose function is to retain large particles, essentially algae debris from the extraction juice.

Its absolute retention threshold is around 128 microns.

 It also includes a pump 12 connected to the outlet of the filter 11 as well as to the inlet of a second filter 13 itself connected to a third filter 14.

 The filters 13 and 14 have the function of retaining the finer particles #whose dimensions are of the order of a micron. They are of the front filter type with a membrane made up of cellulosic polymer and their absolute retention thresholds are respectively 10 microns and 1 micron.

 The juice leaving filters 13 and 14 is clear but it still contains macromolecules, such as polysaccharides, as well as microorganisms. Their size is between 0.2 and 1 micron.

This juice is subjected to a tangential microfiltration process at the retention threshold of 0.22 microns to retain these macromolecules and these microorganisms without denaturing smaller molecules, such as certain proteins.
The filtration circuit then used is referenced 15. It consists of a tank 15a, of a pump 15b whose inlet is connected to the lower part of the tank 15a and whose outlet is connected to a tangential microfiltration device 15c. The latter has a first outlet 15C1 through which large molecules and microorganisms exit and a second outlet 15c2 from which small molecules such as trace elements, amino acids, peptides, proteins, etc. leave.

 The outlet 157 is connected to the upper part of the tank 15a.

 On outlet 15c2, the purified juice is clear and stable. However, it can still undergo a sterilizing filtration step with a cutoff threshold of 0.22 microns to eliminate any microorganisms that may still be present.

 Finally, a stabilizer can be added to the purified product for preservation.

RESULTS:
1.2 kg of algae of the Laminaria digitata type, cut into pieces of about 1 cm, were lyophilized and then rehydrated with demineralized water. The demineralized water used is obtained by the demineralization operation described above.

 Its ph measured at 200 C is 5 + 0.5. The concentrations of chloride ions and potassium are less than 0.1 mg / liter and those of phosphorus, iron, calcium, magnesium are less than 0.01 mg / liter.

 After rehydration for 15 minutes in 6.8 liters of water, these pieces of algae were subjected to leaching in a semi-fluid bed according to the method of the invention.

 The extract thus obtained was then subjected to a purification process such as that described above.

A clear pale yellow liquid was obtained with the following analytical characteristics:
ph (at 200 C) ~~~~~~~~~~~~~~ between 6 and 7
Density ~~~~~~~~~~~~~~~~~~~~~~ about 1
Refractive index ~~~~~~~ about 1.36
Dry residue (2g / 1050C / 1 h) ~~~ 1 to 1.5%
Its composition, expressed in% relative to the mass of dry residue it contains, is as follows:
Cl ~~~~~~~~~~~~~~~~~~~~ 16.90
K ~~~~~~~~~~~~~~~~~~~~~~~ 8.90
Mg ~~~~~~~~~~~~~~~~~~~~~~ 1.10
I- ~~~~~~~~~~~~~~~~~~~~~ 0.73
Total N ~~~~~~~~~~~~~~~~ 0.67
N NH4 + 0.19
Proteins ~~~~~~~~~~~~~~~ 3.00
Ca ~~~~~~~~~~~~~~~~~~~~~~ 0.37
P ~~~~~~~~~~~~~~~~~~~~~~~~~ 0.10
Total Fe ~~~~~~~~~~~ 7.8 10-3
Mn ~~~~~~~~~~~~~~~~~~~ 1.8 10-3
Cu ~~~~~~~~~~~~~~~~~ 0.61 10-3
The assays were carried out by colorimetry according to the Hach method for K, P, Fe, Mn, Ca, Mg, Cu, according to a sodium nitrite method for I-, and according to the Nessler method for total N and N NH4 +.

 The assays of total nitrogen, calcium, magnesium, iron, copper and manganese require prior mineralization of the algae extract.

 This was carried out by dehydration and carbonization of the extract in the presence of concentrated sulfuric acid and by decomposition after addition of hydrogen peroxide.

 The presence of mucilages has been demonstrated by precipitation under the action of barium salts.

 According to the same process and under the same conditions as those described above, the water-soluble elements were extracted from 1.2 kg of algae of the Ascophyllum nodosum type.

 A clear, orange-colored liquid was obtained.

Its analytical characteristics are as follows:
ph (at 200 C) ~~~~~~~~~~~~~~ between 6 and 7
Density ~~~~~~~~~~~~~~~~~~~~~~ about 1
Refractive index ~~~~~~~ about 1.33
Dry residue (2g / 1050C / 1h) ~~~ 0.7 to 1%
Its composition expressed in% relative to the mass of dry residues it contains is as follows::
Cl- ~~~~~~~~~~~~~~~~~~~~ 14.80
K ~~~~~~~~~~~~~~~~~~~~~~~ 7.40
MG ~~~~~~~~~~~~~~~~~~~~~~ 1.50
I- ~~~~~~~~~~~~~~~~~~~~~~ 0.14
Total N 1.40
N NH4 + 0.13
Proteins ~~~~~~~~~~~~~~~ 6.80
Ca ~~~~~~~~~~~~~~~~~~~~~~~ 0.59
P ~~~~~~~~~~~~~~~~~~~~~~~~~ 0.11
Total Fe ~~~~~~~~~~~~ 12 10-3
Mn ~~~~~~~~~~~~~~~~~ 3.3 10-3
Cu ~~~~~~~~~~~~~~~~~ 0.61 10-3
The extraction yields measured from different samples were between 40 and 50%.

Claims (15)

 1) Process for extracting water-soluble elements from algae, in particular seaweed, characterized in that it consists of:  a) subjecting said previously lyophilized algae to rehydration with demineralized water at the original humidity level, and  b) subjecting the algae thus rehydrated to leaching in a semi-fluid bed with demineralized water.  2) Method according to claim 1, characterized in that the algae are cut into pieces.  3) Method according to claim 1, characterized in that said leaching consists of the passage of demineralized water through a leaching chamber which contains the pieces of rehydrated algae to be treated and whose volume is greater than the volume of said algae.  4) Method according to claim 1, 2 or 3, characterized in that the demineralized water which passes into the leaching chamber circulates in a closed circuit.  5) Method according to one of the preceding claims, characterized in that the demineralized water circulates in the leaching chamber from bottom to top.  6) Method according to one of the preceding claims, characterized in that the pieces of algae are stirred in the leaching chamber.  7) Method according to one of the preceding claims, characterized in that after a predetermined treatment time, the extraction juice loaded with water-soluble elements extracted from the cells of the algae is subjected to a purification operation consisting of filtration in front type filters.  8) Method according to claim 7, characterized in that said purification operation further consists of filtration in a filtration circuit comprising a tangential micro-filtration apparatus.  9) Installation for extracting water-soluble elements from algae, in particular marine algae, for implementing the extraction method according to one of claims 1 to 8, characterized in that it comprises a leaching chamber ( Lix) and a closed circuit (1, 2, 3, 4, 6) of demineralized water which passes through said chamber (Lix).  10) Installation according to claim 9, characterized in that said leaching chamber is formed in a tank (5) between two transverse grids (7, 8) fixed to the walls of said tank (5).  11) Installation according to claim 9 or 10, characterized in that the two grids (7, 8) of the leaching chamber are substantially horizontal and in that demineralized water passes through said leaching chamber from bottom to top.  12) Installation according to one of claims 9 to 11, characterized in that it comprises a purification installation consisting of a filter (13) of the front filter type at the absolute retention threshold of about 10 microns.  13) Installation according to claim 12, characterized in that said purification installation comprises, downstream of the first front filter (13), a second front filter (14) whose absolute retention threshold is of the order of 1 micron.  14) Installation according to one of claims 12 or 13, characterized in that said installation further comprises a filtration circuit (15) which comprises at least one tangential micro-filtration device (15c).  15) Installation according to claim 14, characterized in that said filtration circuit (15) consists of a tank (15a), a pump (15b) whose inlet is connected to the lower part of the tank ( 15a) and the outlet of which is connected to said tangential microfiltration device (15c), the latter comprising a first outlet (15c1) connected to the upper part of the tank (15a), and a second outlet (15c2) from which comes out purified juice.