CA1313835C - Extraction of carotenoproteins from crustacean wastes - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A process is provided for the extraction of carotenoproteins from crustacean wastes. The process comprises the steps of (a) homogenizing the crustacean waste in water to form a homogenizate; (b) treating the homogenizate with at least 0.1%
w/w based on the crustacean waste of a proteolyte enzyme selected from the group consisting of animal-derived trypsin and a bacterial protease, at a temperature of 0°C to 50°C for from 1 to 24 hours; and (c) separating an aqueous solution of carotenoproteins therefrom, the carotenoproteins being substantially free of chitin and ash. Such carotenoproteins may be used as a tissue colorant feed supplement.

Description

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This invention relates to the extraction o~ carotenoproteins from crustacean waste products. Such carotenoproteins may be used as a source of tissue colorant feed supplement.
Carotenoid pigments are useful in rearing salmon and trout in hatcheries or fish farms. Such fish, when reared on conventional diets lack the skin and flesh coloration normally associated in the consumer mind with these fish species. The pigments found in the shells and tissues of crustaceans have been found to impart this colour to salmon and trout. Lyle K.
Anderson in Canadian Patent 1,044,505 issued on 19 December 1978 details an oil~based extraction method for the preparation of a carotenoid pigment from crustacean shell waste. However, problems associated with such products include a decreased stability to oxidation and reduced nutritive value.
It is an object of a broad aspect of this invention to mitigate problems of decreased stability and reduced nutritive value associated with prior art products, to provide a novel extraction process and to yield a product of an improved stability and nutritive value.
By a broad aspect of this invention, a process is provided for the extraction of carotenoproteins from crustacean waste comprising the steps of: (a) homogenizing the crustacean waste in water to form a homogenizate; (b) treating the homogenizate with at least 0.1% w/w based on the crustacean waste of a proteolyte enzyme selected from the groups consisting of animal-derived trypsin and a bacterial protease, at a temperature of ooc to 50C for from l to 24 hours; and (c) separating an aqueous .~31383~

- 2 -solution of carotenoproteins therefrom, the carotenoproteins being substantially free of chitin and ash.
In one variant thereof, the homogenization step is carried out in the presence of a chelating agent; ancl preferably wherein the chelating agent is ethylene diamine tetraacetic acid.
In other variants, the trypsin may he ~ovine pancreas trypsin or porcine pancreas trypsin; or the bacterial protease may be ENZECO AP_1TM or BIOCON.~M.
In still another variant, the treating step is carried out in the presence of a phosphate buffer.
In a still further variant, the process includes the step of adding an antioxidant and a protease inhibitor to the treated homogenizate bef~re the separation step; and preferably wherein the antioxidant is BHT and wherein the protease inhibitor is trasylol.
By another aspect of this invention, an extract composition is provided comprising a carotenoprotein substantially free of chitin and ash and containing major amounts of free astaxanthin, astaxanthin ester and purer amounts of astacene.
In one variant thereof, the extract composition is provided in combination with a protease inhibitor and an antioxidant; and preferably wherein the protease inhibitor is trasylol and wherein the antioxidant is BHT.
By still another aspect of this invention a feed supplement is provided containing such extract composition.

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- 2a -In the accompanying drawings, ~igure 1 shows a schematic outline of an embodiment of the invention; and Figure 2 compares the amino acid composition of carotenoprotein obtained by the process of the invention, the dietary requirements of rainbow trout and the amino acid proportions provided in a diet composed of 40% carotenoprotein with no other protein source.
Example 1 - Extraction of carotenoprotein with EDTA and proteolytic enzymes.
Extraction of carotenoprotein was carried out in the presence of 0.5M trisodium ethylenediamine tetra acetic acid (EDTA). Proteolytic enzymes were then used to facilitate extraction of carotenoprotein. The method involved homogenizing 25 g of either cooked or uncooked sample with 75 mL of col (-4C) 0.5M trisodium EDTA (pH 7.7~ using a POLYTRONTM at setting 6 for 2 min. To the homogenate was added 25 mg of one of BT = pure bovine pancreas trypsin, PT = technical grade porcine pancreas trypsin, and EP = ENZECO AP_1TM protease, or control = no enzyme added. The samples were shaken at 200 r.p.m. on a laboratory rotator at 4C for various time intervals from 1 to 2~ hrs. The homogenat~s were then filtered through several layers of cheesecloth and the filtrate pH was adjusted to 7.5 with 2M HCl and made to 45% saturation with solid ammonium sulfate. The carotenoprotein was recovered by centrifugation was suspended in 20 mL of 5mM phosphate buffer (pH 7O0~ 4C) and dialysed against 13~3~
- 2b -

3 changes of 6L of the same buffer at ~C overnight. The dialysed carotenoprotein was lyophilized prior to chemical analyses. Thin layer chromatography of carotenoid extracts.
The carotenoid extracts were chromatographed on silica gel G thin layer plates using the method of J. P. Meyers and D. Bligh in J. Agric. Food Chem 29, ~1981). The solvent system used for the chromatography was benzene: petroelum ether:acetone (10:3:2).
The relative mobilities of free astaxanthin, astaxanthin ester and asta~ene were compared to those of components in extracts from shrimp offal and -~.

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f`rom the caro,ter)oproteln Lsolate.
Proxlmate compo.siti.or) The proxllllate compositLorls oP uncooked shrimp processing wa3te, carotenoprotein and residue after freeze dryine are shown in Table 1.
'rhe chitin contained in these fractions was separately deterrnined and found to be 13.6~, 0% and 27.3% (dwb), respectivel.y. These data show that shrirnp carotenoprotein is enriched in protein by appro~xima.t.el,y,,.~O,%
and depleted of chitLn and..of.~h. About 80% of the protein and carotenoid wlth t~le shrimp processlng waste was recovered in the caroterloprotein fraction that was prepared with bovlne trypsln by the process outlined in Fi.gure 1. The influence of extraction time on the recovery of protein in the carotenoprotein fraction was studied.
Addition of' bovine trypsin, commercial grade porcine trypsLn or food grade Enzeco bacterial protease to the homogenate were all e~fective ln improving the recovery of protein Ln the carotenoprotein fract:Lon. The extraction of protein without added enzyme was somewhat faster with uncooked offal than with cooked offal. Part of the readily solubilized protein from uncooked offal may represent water soluble proteins normally lost durinx cookLng. It is also possible that endo~enous enzymes al.so contribute to the solubLlization of protein from uncooked sample.
Salmonids have a demanding requirement for dietary protein and excess chitin can be undesirable in aquaculture rations. On the basis of the above considerati.ons, the fractionation process outlined in Figure 1 would appear to improve the feed value of shrimp waste.

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,, TAl3L,E 1-: I'roxLnlate1 composlt~on of' f'reeze-dried shriMp waste, shrilnp carotel1oprotein and extracted residue1, ___ __ ___ _ _ ___ _ _____ ___. __ COMPONENTSHRIMP WASTE SHRIMP RESIDUE
Carotenoprotein _.____ __ ___ Crude protein2 43.13 ND ND
Protein 331.7 58.4 12.7 Crude Fat25.2 26.9 12.0 10 Ash 26.0 7.5 31.2 Moisture 4.4 3.5 6.3 Carbohydrate4 14.2 3.7 37.o ____ _ __ _ _ _ .
Total Astaxanthinl 11.9 116.0 ND
(mg%) Data are average values of duplicate determination; ND = not determined.
1 Data for uncooked shrimp waste processed as shown in Fig. 1.
20 2 N content x 7.25, not corrected for chitin 3 Protein determined by the Biuret method

4 Carbohydrate calculated by difference and represents chitin and other minor solids.

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Amino acid cornpo~,itlon of carotenoproteln The amino aci(l data presented in Table 2 indleate that carotenoprotein isolate(l by t~le procedure outllned in Fi8ure l, is particularly rlcn in elutamic acid and aspartlc acid, similar to earlier findings on carotenoprotein derived from a copepod. The amino aeid composition of the produet extracted with bovine trypsin is only marginally different from that of the untreated product. On a rnole percent basis, the carotenoprotein obtained by extraction with bovine trypsin is a somewhat better source of essential amino acids isoleucine, leucine, phenylalanine, threonine, tryptophan and tyrosine than the earotenoprotein obtained ln the absenee of added enzymes; whieh in turn is a somewhat better source of arglnine, methionine and lysine. The valine and histidine levels of the carotenoprotein extraeted wlth bovine trypsin were slmilar to those in the product obtained in the absence of added en~yme. Figure 2 compares the levels of essential amino acids from rainbow trout nutrition with the carotenoprotein isolate prepared with bovLne trypsin. The carotenoprotein isolate contains an exeess of essential amino aeids required for rainbow trout. As ean be seen from Figure 2 a ration eontaining 40~ earotenoprotein, and no other protein source, would be more than adequate in all essential arnino aeids with exception of cystine. The second limiting amino acids are methionine, arginine and lysine. A ration of l~o~ carotenoprotein would also eontain more that 50 me% of earotenoids, an amount suffieient to pigment rainbow trout.

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. I'ABL.E 2: Amino Acid Levels in Carotenoprotein Amino AcidControlcontrolBT-treatedBT-treated ,~ proteinmole ,~6% proteinmole ',~

Alanine 5.17 7.97 5.20 7.75 Arginine 6.12 4.83 4.46 3.39 Aspartate11.14 11,,49 10.80 10.77 Cysteic acid 0.22 0.17 0.77 0.60 Cystine O.IJ0 0,46 0.58 0.65 Clutamate12.06 11,,26 11.78 l0.63 Glycine 4.46 8,18 ll.77 8.43 Histidine3.02 2.67 2.95 2.52 Hydroxylysine o.o9 o.o7 0.22 0,17 Hydroxyproline 0.09 0.07 0.18 0.20 Isoleucine4.68 4.89 5-14 5.18 Leucine 7.05 7.37 7.97 8.06 Lysine 6.71 6.28 5.66 5.14 Methionine2.62 2.40 1.88 1.68 Phenylalanine 1l.83 4.01 5.66 4,54 Proline 4.25 5.07 4.3ll 5.00 Serine 4.68 6.09 5.54 6.97 Taurine 0.09 0.12 0.12 0.14 Threonine5.38 6.21 6.25 6.95 Tryptophan1.17 0.78 2.40 1.56 Tyrosine 4.3ll 3.29 4.86 3.56 Valine 5.42 6.33 5.42 6.11 . . . ~
Data are averaee values of duplicate determinations.

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Recovery of c~IrotenoLcI plgments Approxl~nately ~0% of the carotenoids with shrimp processing wastes (Il - 12 mg% fwb) were recovered in the carotenoproteLn fractlon when bovine trypsin was included in the extraction medium. The use of trypsin increased the recovery of pigment at all extractlon tlmes employed. The bacterial protease was le~s effective than trypsin(s) in recovering carotenoprotein despite its effectiveness in solubilizing protein. The specificity of this enzyme is broader than that of trypsin and its action may result in excessive hydrolysis of protein associated with the carotenoprotein complex and thereby lead to insolubllity ln the aqueous extraction solution or to instability due to dlsruptlon of the protective environment provided by association with protein. Further study with different enzymes, as well as varying concentrations of en~ymes will be necessary to elucidate the reason for the dLfferences in yield obtained wlth trypsin and bacterial protease.
The maximum absorbance of the carotenoid fraction from shrimp waste and from carotenoprotein isolate was ~I75 nm in petroleum ether.
These results are consistent with other reports for total astaxanthin.
Thin layer chromatography of the carotenoLd fraction from raw or cooked shrimp offal separated three distinct orange-red components. The separated components of raw and cooked shrimp waste had Rf's 0.29 -0.32, 0.53 - 0.57 and 0.71 (Table 3). The absolute identities of these components have not been established as standards were not available ior comparison. Based on spectral characteristics and relative mobilities in thin layer chromatography the components of shrimp extract would appear to be astacene, astaxanthin and astaxanthin ester. The carotenoid fraction from the digested homogenate (Figure 1), prepared with or without trypsin, separated into three zones as did the acetone extract from raw or cooked shrimp extract; however, the zone corresponding to spot 3 had a faster Rf value than did spot 3 from the starting material. Further study will be necessary to determine whether the change in Rf is the result of change(s) in the chemical structure of astaxanthin ester or to a change in association of the pigment with other components in the extract. However, the relative amounts of the minor component, tentatively identified as a degradation product of astaxanthin called astacene, did not appear to change as a result of the procedures employed for carotenoprotein isolation.

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rABLI~ 3: Thlrl layer chrornatoeraphy of carotenoid extracts Sarnp]e Spot' Wavelength of Relative Rf Tentative max.absorbance Amount(~)2 values identiflcation - - _~ _ _ _ ___ _ _____ _ _ Raw of cool<ed 1 475 nm 5--10 0.31-0.32 astacene shrinnp waste 2 475 nm 45-50 0.53-0.57 astaxanthin 3 475 nm 45-50 0.71 -0.72 astaxanthln ester Shrimp 1 475 nm 5-lo 0.29-0.32 astacene carotenoprotein 2 4'75 nm45-50 0.54-0.58 astaxanthin 3 475 nm 45-50 0.86-0.88 astaxanthin ester Data represent ranges obtained for 6 deterrninations; 1 = In all cases, 3 distinct components were separated from the extract; 2 Relative 20 amount estimated visually.

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~xampLe 2 - L~xl;raction of caroteno~rotein wlth proteolytic enzyme3 A modified t`orm of` t~le procedure clescribed in FiKure 1, wa~s used to extract carotenoprotein ~rom stearned shritnp offal. The Modiflcation involved treating 25 e of the sl1rimp offal in 75 ml of 5mM phosphate b~lffer (p~l 7.7) with 25 mg of proteolytic en~yme at 50C In the absence of a chelating agent.
Using t~le modified process, the trypsins were again more effective in extracting both carotenold pigments and protein f`rom the shrimp offal than the bacterial proteases applied. The PT was most effective in extracting protein (13.71 mg/0.1 g sampla, equivalent at 90.35% of total protein in the offal) up to 30 min incubation at 50C.
After 30 min. the amount of protein extracted declined and this was probably due to excessive proteolysis giving rise to smal]er peptides and/or amino acLds that were not recovered by the ammonium sulfate treatment.
The trypsins were equally effective in extractlng total astaxanthin from shrimp offal by the modified process. The maximum amount of astaxanthin was extracted after 30 min incubation at 50C.
Beyond the 30 min lncubation period, the level of astaxanthin declined similar to the results for the protein extraction.
~ 3Owever, while the amount of protein extracted by this procedure was higher than that obtained with chelating agent at relatively lower temperatures, the maximum amount of astaxanthin extracted tabout 72.89 ug/g sample, equivalent to about 73% recovery) was lower than what was obtained when extraction was done in the presence of a chelating agent at relatively lower temperatures.
The modified process reduces substantially the extraction time and recovers more protein from the offal. However, the material so obtained may be relatively more susceptible to microbial spoilage because of the absence of E~TA. It was also observed during the extraction that the fat (carotenoid pigments) tended to separate from the protein during centrifugation. However, the two components were readily re-associated in a suspension with 5mM phosphate buffer that could be dried completely to fine powder by lyophilization.

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~o l~BIE 4: Tlme course for extraction of plgments and proteln Enzyme Time Astaxanthin Protein n applied (mln) ~g/g sample % recovery

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BT 10 48.96 50.75 7 PT 49.95 57.15 2 EP 42.99 42.90 2 BP 42.12 49.26 2 BT 20 65.00 76.73 7 PT 60.77 82.96 2 EP 53.88 66.65 2 BP 52.55 70.15 2 BT 30 72.89 85.90 7 PT 70.37 90.35 2 EP 61.45 70.15 2 BP 60.71 74.15 2 BT 40 59.07 78.07 7 PT 56.38 78.70 2 EP 1~6.03 57.25 2 BP 48.99 66.10 2 - _ Total protein in shrimp offal was determined as 15.17 mg/100mg sample by the 8iuret method; total astaxanthin was determined as 105.2~g/g sample by the method oi` Saito and Regier 1971; n = number of times determinations were carried out.
BP = Biocon [TM] bacterial protease.
It should be emphasized that the process with a chelating agent is best carried out at low temperatures to minimize undesirable reactions during the slower action of the chelating agent. When the chelating agent is not used the process is best done at high temperature (e.g.
50C) using more enzyme.

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StabiLity o~ Caroterlolds wlth Carotenoprotein Incubatlon of` the fiLtrate fraction obtained by bovine trypsln treatment (flgure 1), for 21 days at llC or at 30C resulted in about 60%
109s of total carotenolds. The filtrate fraction did not develop off odor or show usual signs of bacterial spoilage for the duration of the experiment. This would appear to be due to the preservatlve value of trisodium ED'I'A.
Inclusion of antioxidant (BHT) and protease inhibitor (trasylol) with the flltrate fraction was very effective in stabilizlng the carotenoids at 30C aud less effective at 40C. The 8reater stability of shrimp carotenoids at higher temperature indicates carotenoicls may be lost by a coupled oxidatlon mechanlsm. It is known that the oxidation of carotenoid pigments may be coupled to the oxidation of poLyunsaturated fatty acids and the enzymic oxidation of certain fLsh lipids may occur more rapidly at temperatures near 0C than at temperatures near 30C. It would seem from the foregoing that the initial heat treatment was not adequate to effectively inactivate enzymes that participate in the oxidation process, and further treatment of shrimp waste to completely inactivate suoh enzymes may improve the stability of the produot at 40C.
The finding that trasylol in combination with or without BHT aids in stabilizing the carotenoid fraction may be explained on the basis that continued protein hydrolysis decreases the protective value related to protein-pigment association Extraction of carotenoprotein from crustacean offal improves the nutritive value of the raw material by reducing the content of ash and chitin and ef`fectively concentrating protein. The process recovers the carotenoid fraction in an aqueous dispersion. The recovery of carotenoids is desirable since its addition to the rations of pen reared salmonids serves to color the flesh and give a product having a desirable orange-red color. The presence of residual EDTA with the product appears to prevent microbial deterioration. The loss of carotenoids in the carotenoprotein extract can be prevented by addition of protease inhibitor and antioxidant and holding at 30C.

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the extraction of carotenoproteins from crustacean waste comprising the steps of:
(a) homogenizing said crustacean waste in water to form a homogenizate;
(b) treating said homogenizate with at least 0.1% w/w based on said crustacean waste of a proteolyte enzyme selected from the groups consisting of animal derived trypsin and a bacterial protease, at a temperature of 0°C to 50°C for from 1 to 24 hours; and (c) separating an aqueous solution of carotenoproteins therefrom, said carotenoproteins being substantially free of chitin and ash.

2. The process of claim 1 wherein said homogenization steps is carried out in the presence of a chelating agent.

3. The process of claim 2 wherein said chelating agent is ethylene diamine tetraacetic acid.

4. The process of claim 1 wherein said trypsin is bovine pancreas trypsin or porcine pancreas trypsin.

5. The process of claim 1 wherein said bacterial protease is ENZECO AP-1TM or BIOCONTM.

6. The process of claim 1 wherein said treating step is carried out in the presence of a phosphate buffer.

7. The process of claim 1 including the step of adding an antioxidant and a protease inhibitor to said treated homogenizate before said separation step.

8. The process of claim 7 wherein said antioxidant is BHT
and wherein said protease inhibitor is trasylol.

9. An extract composition comprising a carotenoprotein substantially free of chitin and ash and containing major amounts of free astaxanthin, astaxanthin ester and purer amounts of astacene.

10. The extract composition of claim 9 in combination with a protease inhibitor and an antioxidant.

11. The extract composition of claim 10 wherein said protease inhibitor is trasylol and wherein said antioxidant is BHT.

12. A feed supplement containing the extract composition of claims 9, 10 or 11.