AU681096B2

AU681096B2 - Process for the recovery of valuable substances, in particular carotinoids from algae and installations suitable therefor

Info

Publication number: AU681096B2
Application number: AU53010/94A
Authority: AU
Inventors: Dragoljub Bilanovic; Friedrich-Helmut Mohn
Original assignee: Forschungszentrum Juelich GmbH
Current assignee: Forschungszentrum Juelich GmbH
Priority date: 1993-01-16
Filing date: 1994-01-04
Publication date: 1997-08-21
Anticipated expiration: 2014-01-04
Also published as: AU5301094A; IL108260A; PT101441A; PT101441B; ZA94269B; ES2069507A1; IL108260A0; DE4342798C2; DE4342798A1; ES2069507B1

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Forschungszentrum Jillch GmbH ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

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55 5 INVENTION TITLE: Process for the recovery of valuable substances, in particular carotinoids from algae and installations suitable therefor The following statement is a full description of this invention, including the best method of performing it known to me/us:-

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The invention relates to a process for the recovery of valuable substances, in particular carotinoids from algae growing in saline water or seawater by extraction with an appropriate solvent and to an installation suitable therefor.

Carotinoids and specifically carotin find extensive use in the foodstuff and pharmaceutical fields, specifically as antioxidants, as a precursor for Vitamin A as well as a yellow dyestuff.

For their recovery natural substances such as carrots (having a B-carotin content of about 0,02%) and other vegetables are primarily used. However, the recovery from algae biomass, in particular from the saltwater seaweed Dunaliella (having a content of 8% carotin), which grows respectively is cultivated in particular in relatively warm regions in salt or brackish water is particularly cost advantageous.

In the recovery of the carotin from the algae the general practice initially includes a preconcentration of the algae biomass from about 200 400 mg/i to 1 12 before carrying out an extraction of the carotin specifically with edible oil or supercritical

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2 Thus in US-PS 4 680 314 there is recommended an enrichment of the algae mass of Dunaliella salina by centrifugation, evaporative concentration etc, however, in particular by flocculative precipltation, e.g. by means of aluminium or iron chloride.

From the flocculated and precipitated algae sludge the algae are concentrated by flotation and are recovered in a yield of approximately 95% or more as a damp algae concentrate. By the addition of acid, in particular citric acid, preferably with heating to 80 0 C, the flocculent is separated from the cells which are then emulsified with oil in order to extract the carotin in which approximately 95% of the carotin accumulates.

P:\OPERMLA5301094.M00? .2416W -2- In US-PS 4 713 398 which refers to the above the use of edible oils, in particular vegetable oils is stressed which are to be used jointly with stabilisers, e.g. vitamin E, in the finely distributed algae-containing water/oil emulsion which is finally demulsified in order to yield an oily solution containing about 1 carotin.

According to US-PS 4 439 629 the culture broth of Dunaliella is initially treated for some time under warm conditions with calcium hydroxide followed by filtration in order to concentrate the algae, which are dried and extracted with methylene chloride. In the introduction, attention is drawn to the possibility in principle of extracting the saltwater/algae mixture with very large amounts of organic solvents and the substantial drawbacks of such a procedure, from which it is apparent that a person skilled in the art does not in practice avail himself of the available possibility of directly processing the algae-containing aqueous cultured broth with a solvent for carotin in order to recoer carotin.

15 Consequently, the previously practised recovery processes comprise a multitude of recovery steps some of which not only increase costs by in addition adversely affect the product.

Accordingly there still exists a need to simplify and render more economical the recovery process. Moreover it is desirable to recover as high as possible a quality of carotin. The 20 present invention therefore provides a process for the recovery o' 'uable substances from algae growing in saline water or seawater by extraction with an appropriate solvent, wherein the extraction of the valuable substance from a brine culture is carried out without preceding enrichment of the biomass, and wherein prior to or during the extraction the valuable substances are liberated from the algae by the superposition of adequate shear forces for 25 rupturing the cellular matter (maceration).

There is further provided an installation for the extractive recovery of carotin starting from algae cultures as described hereinabove, including a culture basin and extraction tanks, and including means for the transportation, cellular rupture and mixing with extraction agent in Ate connecting duct between the basin and tank(s).

IIIPls i I r~l IP~p~e P:\OPER\MLA\3010-94.002 2/197 The present invention provides a process as set out in the opening paragraph, wherein the extraction of the valuable substance from a brine culture proceeds without preceding enrichment of the biomass and wherein prior to or during the extraction a liberation of the valuable substance from the algae, in particular by the superposition of adequate shear forces for rupturing the cellular material (maceration) is taken care of.

*o o D In that process the algae-containing briny culture is directly brought together with solvents, ie part ediblealte oils with intensive intermixing, the simultaneous application of adequate shear forces for rupturing the cellular material being simultaneously taken care of.

By the presence of the oil, which can moreover be el.ployed in relatively small amounts as compared with the liquid quantities of the culture there surprisingly results a facilitation of the processing of the highly concentrated brines which normally causes problems, and the relatively high density thereof in turn facilitates the separation of the two liquid phases (oil/brine) from one another which is necessary after the mixing step. The thus admitted finely particulate dispersion of the oil in the "algae- St o containing culture broth" separates relatively rapidly from the carotin depleted brine 6 and can be returned from a further carotin enrichment by extraction, the disposal of the aqueous phase (for example by discharge into the sea) causing no problem.

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Advantageously a brine culture having a salt concentration of 18 to 30%, in particular of 22 to 28% is processed in the process according to the invention.

It stands to reason that in the process according to the invention as well it is possible to add stabilisers such as e.g. vitamin E to the oil in spite of the fact that the risk of product impairment is clearly reduced by the reduction of the process steps and thus the duration of the process and the fact that immediately after the maceration or simultaneously therewith the carotin is taken up by the oil phase.

0* As in the known processes it is possible to use various salt: respectively seawater algae as a starting material. However, the process was investigated in particular in the context of algae of the species Dunaliella.

The oils to be used are in particular vegetable oils such as sunflower oil, soya oil or almond oil as well as avocado oil for cosmetic purposes if the final product is intended for such use. 1 10% based on the brine culture quantity is particularly advantageous.

The amount of oil to be added is appropriately adapted substantially to the carotin content of the cellular mass in the brine volume to be treated.

Preferably, the solution of valuable products thus obtained after the extraction in particular the carotin solution in an oil acceptable for use in a food context is again used for the extraction of further carotin from further culture charges with stepwise accumulation of the carotin in the solution respectively in the solvent.

Prior to or during the extraction care is taken of a cell rupturing whereby the carotin is liberated which can be attained specificlly by the supeposition of suitable shear forces by means of separate dispersing means or during pumping or mixing.

Suitable apparatus for the intensive mixing with simultaneous maceration are in particular high speed gear rim colloid mills, as are commercially available e.g. from the firm Kinematica AG, Littau/Luzem (Switzerland), under the name Megatron, in particular Megatron MT-types.

By heating, for which temperatures up to about 70°C can be used, the effectivity of the process can be increased. A subsequent degassing of the carotin solution after the extraction promotes its storage properties. After subsequent re-extraction the carotin can be obtained in a pure form.

According to the invention in particular Dunaliella cultures in brine are employed as a starting material for the recovery of carotin therefrom. In this context the following steps are e.g. employed: 1. Pumps convey the algae-containing suspension into storage vessels. Between the pump and vessel(s) a comminution installation, e.g a macerator or a tooth dispersion mill is installed inline for the rupturing of the algae cells.

Conceivably, instead, a mixing pump or a comminution means which applies high shear forces onto the suspension and simultaneously acts as a pump could be employed.

2. Prior to or during or after the comminution process the oil enters into the pump flow, e.g. 10% by volume of the conveyed algae suspension.

3. The mixture of the oil which now contains carotin, algae debris and culture liquor is kept in the collecting vessel 1. After from a few seconds up to minutes the carotin-containing oil separates and floats on the surface.

4. The oil is drawn off and once again fed into the next algae suspension flow which is then kept in the vessel 2.

5. In the meantime, the salt water and the algae cells freed of carotin are removed from the vessel which is now available for a new process.

The accompanying sketches in accordance with Figs. 1 to 12 serve for illustrating the process.

According to Fig. 1 the algae culture is transported from the algae basin I by means of a pump 1, preferably in the form of a centrifugal pump, for cell rupturing through a wet comminution plant 2 e.g. a macerator. As an alternative to 1 and 2 one might also employ a pump which applies high shear forces onto the product and which by way of a by-pass circulates the product or a self-conveying macerator. Downstream of or in the wet comminution plant 2 fresh extraction medium, in particular oil, is added to the culture so treated at 7 in a predetermined ratio to of the volume flow of the aqueous mixture. The oil/brine mixture containing the algae ruptured at 2 flows through a mixer 3, represented e.g. by a static mixer, which takes care of an adequate distribution of the oil in the aqueous mixture, but without an emulsion being formed.

From there the mixture enters into the tank 4 Fig.2 shows charging the next following tank B in the same manner, whilst during that same period phase separation takes place in tank A and the aqueous phase collecting at the bottom is drained from the tank (Figs. 2 and and can be discharged without any problems, since no additional chemicals have been used. Settling and discharge proceed simultaneously so that after charging the tank B there is present in tank A virtually only carotin-containing oil, which after switching the charging means to tank C is fed instead of the fresh oil fed via 7 ,r in addition thereto, by means of the displacement pump 5 by way of the pipeline 8 to the transition between the macerator and mixer. An outlet pipe leading to a product solution collector 6 branches off the duct 8 (Fig. 4).

Fig. 5 corresponds substantially to Fig. 3, except that in this case the charging of the tank C with simultaneous emptying of the tank A is shown whilst simultaneously the aqueous phase is drained from the tank B. Fig. 6 illustrates the increased oil concentration, due to the use of carotin-containing oil as an extracting agent, of the oil phase which in tank C during settling floats to the top.

The further Figs. 7 12 serve to illustrate the increasing enrichment of carotin-in the oil phase by step-wise recycling thereof from the respective tanks.

After adequate accumulation of carotin in the oil phase a more thorough separation of the demixing phases is taken care of so that henceforth only the carotin-enriched oil phase is fed to the collector or vessel 6 (Fig. 12).

The number of the recycling steps depends of course on the solvent capacity of the oil for carotin and the carotin concentration contained in the aqueous medium. This L 9, I sl solvent capacity of the oil may optionally be increased by heating. In this context the rate of temperature equalisation between the phases and the respective temperature dependabilities of the solubilities in both phases obviously plays an important role.

The process described in the aforegoing essentially for the recovery of carotin is also applicable to other valuable substances which may be recovered from algae, such as e.g. fatty acids which may for example be extracted with ether.

According to the invention B-carotin is recovered in particular.

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*oe II

Claims

1. A process for the recovery of valuable substances from algae growing in saline water or seawater by extraction with an appropriate solvent, wherein the extraction of the valuable substance from a brine culture is carried out without preceding enrichment of the biomass, and wherein prior to or during the extraction the valuable substances are liberated from the algae by the superposition of adequate shear forces for rupturing the cellular matter (maceration).

2. A process according to claim 1, wherein the valuable substances to be recovered are or include carotinoids.

3. A process according to either claim 1 or claim 3, wherein a brine culture having a salt concentration of 18-30% is processed.

4. A process according to claim 4, wherein the brine culture has a salt concentration of 22 to 28%. A process according to any one of claims 1 to 4 for the extraction of carotin, wherein an oil approved in the food industry is employed in such amount as is adequate for dissolving the carotin contained in the brine culture.

6. A process according to claim 5, wherein the amount of oil is selected between 1 and 10% based on the culture amount. o•

7. A process according to any one of claims 1 to 6, wherein the solution of valuable substances derived from the extraction is again used for the extraction of further carotin from further charges of brine culture with a step-wise accumulation of the S carotin within the solution. P:\OPER\MLA\53010.9N002- 2416/97 -9-

8. A process according to any one of claims 1 to 7, wherein the maceration and mixing of the liquid phases proceeds simultaneously in a high speed gear ring colloid mill.

9. A process according to any one of claims 1 to 8, which comprises heating to temperatures up to 70°C during the extraction. A process according to any one of claims 1 to 9, which comprises a final degassing of the solution of valuable substances after the extraction.

11. An installation for the extractive recovery of carotin starting from algae cultures according to anyone of claims 1 to 11, including a culture basin and extraction tanks, and including means for the transportation, cellular rupture and mixing with extraction agent in the connecting duct between the basin and tank(s).

12. An installation according to clanim 11, wherein the means for transport, cellular rupture and mixing with extractants are combined at least in part in one aggregate.

13. An intallation according to either claim 11 or claim 2, including three individual tanks, of which the capacity, the feed cross-section and feed capacity as well as the outlet cross-section are adapted to the settling rate of the oil/water mixture in the tank such that the charging period corresponds to the settling and discharge period. SSS* I' s- d~ B B B 0@ S S An installation for the extractive recovery of carotin from algae cultures growing in saline water or seawater, substantially as hereinbefore described with reference to or as illustrated in the accompanying drawings. /$1-6r A process as claimed in claim 1, substantially as hereinbefore described. A process for the extractive recovery of carotin from algae cultures growing in saline water or seawater, substantially as hereinbefore described with reference to or as illustrated in the accompanying drawings. l i e The aLtep, -f atur,, i.cauijtifLtLl dud C== disclosed herein or referred to or id ed in the specification and/or cla- this application, individuall o lectively, and any and all combinations DATED this FOURTH day of JANUARY 1994 Forschungszentrum JUlich GmbH by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s) C RC P A2( -n c *Zv-Q I. Abstract The recovery of valuables, in particular carotinoids from seawater algae such as specifically Dunaliella, is attained by extraction of the valuable substance from the brine culture without preceding enrichment of the biomass, care being taken before or during the extraction that an adequate liberation of the valuables from the algae is brought about by the application of adequate shear forces. In particular B-carotin, starting from brine cultures of Dunaliella may be extracted using an oil allowed for food purposes in an amount of preferably between 1 and 10% based on the brine culture. Preferably brine cultures having a salt concentration of 18 to 30% in particular 22 to 28% of salt are processed. Preferably the oil which is dispersed using a high speed colloid mill with simultaneous maceration of the algae (after phase separation has Staken place) is recycled to the extraction stage with progressive enrichment of the valuable substance in the solution. valuable substance in the solution. 0* ooo