SACRIFICIAL ANTIOXIDANT

The present invention concerns the use of lignosulfonate as an antioxidant in combination with other antioxidants . Specifically, the invention concerns the use of lignosulfonates as a sacrificial agent in combination with other antioxidants. Since many antioxidants are not approved for consumption at large quantities the present invention affords an opportunity to reduce the added amount of antioxidant on account of the synergistic effect with lignosulfonates. One such example is the addition of ethoxyquin which may be added at reduced amounts to provide an equal antioxidant effect if added together with lignosulfonate .

According to one aspect of the present invention it has surprisingly been found that a mixture of lignosulfonate and ethoxyquin, rosmarinic acid or other antioxydants work better than the pure antioxidant alone. The selected antioxidant seems to be more stable in the solvent when lignosulfonates are present. Additionally lignosulfonates enhance the lifetime of antioxidants when added to organic materials or biological materials. The present invention thus also concerns the embodiments of a composition including an antioxidant in combination with lignosulfonates or sulfonated lignins to be used as an improved antioxidative substance for organic materials or biological materials and the use of lignosulfonates as an additive and enhancer for the antioxidative action of the antioxidants .

Background:

Organic matter has a strong tendency to react with oxygen and oxidize. This is true for most common organic materials, e.g., plastics, pesticides, cosmetics, elastomers, fibers, fuels, lubricants, silages, feeds and foods. Oxidation of organic materials takes place by a

number of processes: auto-oxidation, bio-oxidation, combustion, photo-oxidation. Antioxidants, inhibitors (of oxidation) or oxygen scavengers are organic or inorganic compounds that are added to oxidisable organic or biological materials to retard such oxidation, and in general to prolong the lifetime of the substrates.

Antioxidants are classified as either radical trapping (chain breaking) or peroxide-reducing, that describe the mechanisms by which they function. Radical trapping antioxidants function by reaction with the propagating oxygen free radicals in oxidation. The antioxidant thus competes with the organic substrate as a source of hydrogen for peroxy radicals in the oxidation sequence. The new compound formed must be stable and function as a chain terminator. Peroxide decomposing antioxidants reduce the hydroperoxidic and peroxidic products of oxidation to more innocuous compounds, usually alcohols or ethers.

Antioxidants in foods and feeds

Antioxidants retard the atmospheric oxidation and its degrading effects, thus extending the shelf life of foods and feeds. Examples of food oxidative degradation include products that contain fats and oils in which oxidation would produce rancid odours and flavours, some of which might even be harmful. Antioxidants are also used to scavenge oxygen and prevent the discoloration of cut or bruised fruits and vegetables. Food antioxidants are effective in very low concentrations and not only retard rancidity, but also protect the nutritional value of the food by minimizing the breakdown of vitamins and essential fatty acids. Both synthetic and natural antioxidants exist and examples are listed in Table 1.

Table 1. Food Antioxidants and Their Manufacturing Processes [1]

The antioxidants most commonly used to stabilize food include butylated hydroxyanisole (BHA) , butylated hydroxytoluene (BHT) , propyl gallate (PG) and tert- butylhydroquinone (TBHQ) . In Europe, other gallate esters, such as octyl gallate and dodecyl gallate are also used. Both BHA and BHT are fat-soluble, effective in protecting animal fat from oxidation, and often added during the rendering process. Use of BHT and BHA as direct food additives have been questioned as a result of increased incidence of cancer in animal studies. Propyl gallate is also effective, but it has limited fat solubility, and turns bluish black in the presence of iron. The TBHQ is most effective against oxidation in polyunsaturated vegetable oils, and is often used in soybean oil. [1] The most frequently used natural antioxidants are ascorbic acid (vitamin C) , its stereoisomer erythorbic acid and the

sodium salts thereof (sodium ascorbate, sodium erythorbate) , in addition to the mixed delta and gamma tocopherols. Tocopherols are not as effective in vegetable fats and oils as they are in animal fats. Citric acid and tartaric acid are also natural antioxidants (and antioxidant synergists) but are predominantly added to foods as acidulants [1] .

In addition, several plant extracts are recommended as natural antioxidants, including rosemary extracts

{Rosmarinus officinalis) , and gum guaiac, a resinous secretion of a tropical evergreen, Guaiacum officinalis . This resin contains complex phenolic compounds chemically related to guaiacol, guaiaretic acid, and guaiaconic acid, Like other phenolic compounds, gum guaiac is more effective in animal fats than in vegetable oils [1] .

The activity of antioxidants in a food system is not only dependent on the chemical reactivity of the antioxidant (e.g., free radical scavenging, 3D structure and chelation) , but also factors such as physical location, interaction with other food components, and environmental conditions (e.g. pH) . One of the major factors affecting the activity of antioxidants that scavenge free radicals in foods is their partitioning behavior in lipids and water. For example, hydrophilic antioxidants are often less effective in oil-in-water emulsions than lipophilic antioxidants, whereas lipophilic antioxidants are less effective in bulk oils than hydrophilic antioxidants [2] . Modicied macromolecular lignins are proved to have both hydrophiolic and lipophilic parts .

Stabilisation of fuels, lubricants and polymers

Hydrocarbon fuels, gasoline, jet fuel and fuel oil are all subject to autooxidation. The main phenolic antioxidants for fuels are BHT, 2, 4-dimethyl-β-tert-butylphenol, and 2, 6-ditert-butylphenol. N, N' -di-sec-butyl~p-

phenylenediamine has been of great importance among the arαinic antioxidants. Added amount of antioxidant is in the ratio 0.5-1.0 kg per 1000 barrels of fuel (1 US barrel= 159 1). [3]

Antioxidants minimize the deterioration of lubricants by retarding viscosity increase, metal corrosion, and formation of acid, sludge, resins and lacquers. Commercial organic polymers, including thermoplastics, elastomers, synthetic fibers, and adhesives, are all susceptible to oxidative degradation during both processing and end use. For both lubricants, elastomers and thermoplasts, hindered phenolic antioxidants such as BHT are used.

Chemical composition of antioxidants

In the figures 1 to 6 below, molecular structures of some common antioxidants are listed. Trapping of intermediate radicals in molecules like BTA and BHT (Table 1) is a property that also is built in to lignins. The lignins structure contain both phenolic and non-phenolic moieties together with substituents that shield reactive positions, like in the above mentioned molecules. The tridimentional structure of lignosulfonates makes it suitable for stabilizing radicals. The introduced sulfonic acid groups in lignosulfonates turn the originally lipophilic lignin macromolecules into water soluble antioxidants. Autoxidation in mixtures containing hydrophilic and hydrophobic material the interface are most prone for the activity. The combined lipophilic and hydrophilic properties make the ligninsulfonates especially useful in the interfacing areas. Lignins also possess light- absorbing properties.

Ethoxyquin

There are several oxidation products of ethoxyquin formed. Only one of them is shown in Figure 7. Ethoxyquin is

particularly effective in protecting fish silage but may also be used to protect other types of silage as well. The molecule is both oil and water soluble. However, ethoxyquin is not very stable. It is unstable in acid, towards oxidizing agents and towards light. According to one aspect of the present invention it has surprisingly been found that lignosulfonate contributes to an increased stability of ethoxyquin.

Rosmarinic acid

Rosmarinic acid, CigHieOβ, is a natural polyphenol antioxidant carboxylic acid found in many Lamiaceae herbs used commonly as culinary herbs such as rosemary, oregano, sage, thyme and peppermint. Chemically, rosmarinic acid is a dimer of caffeic acid. It is a red-orange powder that is slightly soluble in .water, but well soluble is most organic solvents. [4]

BHT

Butylated hydroxytoluene (BHT) , is a lipophilic (fat- soluble) organic compound that is primarily used as an antioxidant food additive (E number E321) as well as in cosmetics, pharmaceuticals, jet fuels, rubber, petroleum products, and embalming fluid. The species behaves as a synthetic analogue of vitamin E, primarily acting as a terminating agent that suppresses autoxidation, a process whereby unsaturated (usually) organic compounds are attacked by atmospheric oxygen. BHT stops this autocatalytic reaction by converting peroxy radicals to hydroperoxides. [5]

Silage

In industrial fish farming and catching of fish as well as preparing fish products, there are produced substantive quantities of waste material. Fish waste is subjected to

auto-degradation from enzymes liberated during the preparation process. Addition of a preservation additive helps conservation of the waste making it into a valuable stable raw material, silage. As preservation additive, acids of different types are often used, normally formic acid. Under the right conditions, i.e. temperature above 5 ⁰ C, and a pH between 3.5 and 4.5, the fish mass will start to decompose. The low pH value will prevent bacteria to grow, at the same time as the fish mass will undergo autolysis (decompose) , and a floating, easy to handle mass is obtained. The autolysis process is faster at temperatures around 40 ⁰ C. The same is true for other biological materials, e.g. from slaughterhouses, food and feed industries.

By-products from fisheries and slaughterhouses go both to consumption and to more high-grade applications. With the help of biotechnology one can expect a lot of new valuable by-products from the fish breeding and animal farming industry. For example:

- High quality omega 3-oils and cod liver oil

Gelatine from fish skin, heads and bones, technological use, pharmaceutical and in food industry.

Phosphor-containing lipids (phospholipids ) from milt , used for infant nutrition as well as intravenous nutrition .

DNA from milt, used in cosmetic and pharmaceutical industry

Organic substances from fish and animal entrails (enzymes) for industrial processes.

Fermented fish sauce as taste enhancer.

Also silage from animal waste materials (e.g. from slaughterhouses) or waste materials from the food industry (excess production materials) may be treated similarly with

the fish silage indicated supra. Although the composition of the different types of materials may differ (different ratios of fat, oil, proteins, saccharides, connective tissue, etc.) the process for producing silage from these types of materials will be equal (see infra) . As raw material for fish silage as well as animal silage one can use nearly all types of waste from the fish and/or animal industry.

Silage additive One of the preferred acids to treat raw fish material as well as animal raw material for producing silage is formic acid. Formic acid give minor residual taste to the silage, as well as it is an effective acidulant. In Table 2 some physical and chemical properties for organic acids are listed.

Table 2. Physical and chemical properties for organic acids. [6]

Antioxidants are also preferred to be used when producing fish and/or animal silage. Marine lipids from fish contain high levels of long chain polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) . The PUFAs are readily oxidized by molecular oxygen. This oxidation means a corrosion of the unsaturated compounds, which results in rancidity of the fats and a reduced product quality after processing. Fish meal and fish oil contain relatively high concentrations of PUFAs and are therefore especially prone to oxidation [7] . The most common methods for analyzing primary lipid oxidation are the peroxide value or

conjugated dienes, and the aniside value as a number for secondary oxidation products.

To prevent the oxidation of especially fishmeal and - oil, as well as meat and waste products from the meat and/or food industry, the industry currently uses synthetic antioxidants like: ethoxyquin (E324), BHA (butylated hydroxyl anisol, E 320) and BHT (butylated hydroxyl toluene, E321) . Antioxidants prevent the oxidation of the fatty acids by preferential reaction with oxygen. Synthetic antioxidants are the most commonly used antioxidants in food systems because of their chemical stability, low cost and availability.

Prior art:

In the literature the antioxidant effect of lignin in food, polypropylene, plastics and rubber, styrene and archais oils have been reported [7-12] .

There is but one patent upon a fish silage formulation of carboxylic acid in combination with antioxidants, i.e. NO Patent: 309796 Bl owned by Kemira and by the inventors K. Aasbø, H. Breivik. This patent concerns at least one antioxidant amongst: 2, 6-di-tert-butyl-4-metylfenol (BHT), 3-tert-butyl-4-hydroxyanisol (BHA) , tert-butylhydroqinon (TBHQ) , tokoferol and gallates, combined with at least one short chained carboxylic acid, or at least one salt thereof.

A combination of formic acid and antioxidant is the marked leader in Norway as conservation medium in silage of fish. Formic acid is added to adjust pH to 3.7-4 and reduce the growth of bacteria in the silage. Antioxidant is added to reduce the rancidity process of the fish oil. The often used antioxidant is ethoxyquin seen in Figure 4(1, 2- dihydro-β-etoxy-2,2, 4-trimetylquinoline (CAS-Nr 91-53-2). Ethoxyquin, a cyclic amine, is soluble in acids at low pH

(<3) since the amino group is protonated and a hydrophilic salt is formed. An increase in pH, 4-5, gives deprotonation and the ethoxyquin is oil soluble. Ethoxyquin is particularly effective in protecting fish ensilage, although it can be used in other application arias as e.g. silage from slaughter houses. As mentioned the molecule is both oil and water soluble. However, ethoxyquin is not very stable. It is unstable in acid, towards oxidising agents and towards light. Thus, in one aspect the present invention concerns stabilizing ethoxyquin while simultaneously provide an improved and synergistic effect for its scavenging properties by using lignosulfonates .

General disclosure of the invention:

Lignosulfonate may according to the present invention be used as antioxidant in combination with other antioxidants. Specifically, the invention concerns the use of lignosulfonates as a sacrificial agent in combination with other antioxidants. In the literature the antioxidant effect of lignin in food, polypropylene, plastics and rubber, styrene and archais oils have been reported [6-11]. According to the present invention it was surprisingly found that lignosulfonates also exert a synergistic effect in combination with antioxidants ex. ethoxyquin, rosmarinic acid etc.

To assess and verify the effect of lignosulfonate as antioxidant several lignosulfonic samples have been tested in different antioxidant screenings [13, 14] . The samples tested gave good antioxidant score, and the results are shown in table 3 below. Table 3. Samples tested for antioxidant effect [14].

*Fractionated samples with a certain molecular weight average. Note: The numbers in the columns are corrected for dry matter content .

Five types of lignosulfonates were investigated; sodium lignosulfonate, a desulfonated oxidized lignosulfonate, and three fractions of a sodium lignosulfonate; low, medium and high molecular weight. As can be seen from the table 3 above, it is evident that all of them show good antioxidant effect. The desulfonated oxidized lignosulfonate had the best antioxidant effect compared to the sodium lignosulfonate samples. Further the high molecular weight fraction of lignosulfonate had superior antioxidant capacity than the low molecular weight fraction. As a comparison the synthetic antioxidant Ethoxyquin, gave the highest score in the test. The antioxidant BHT scored lowest in the test showing that lignosulfonates possess good antioxidative properties. All over the table above shows that lignosulfonates as general possess antioxidative capacity.

The present invention provides an option to reduce the amount of added antioxidants in the fish and/or animal

and/or food silage. Since many antioxidants are not approved for consumption at large quantities ex. ethoxyquin the present invention affords an opportunity to reduce the added amount of antioxidant on account of the synergistic effect with lignosulfonates . One such example is the addition of ethoxyquin which may be added at reduced amounts to provide an equal antioxidant effect if added together with lignosulfonate. In comparison the toxicity of lignosulfonate is almost non existing (LD ₅₀ > 10g/kg) . [16]

According to one aspect of the present invention it has also surprisingly been found that a mixture of lignosulfonate and ethoxyquin work better as an antioxidant than ethoxyquin alone, or than an additive effect of lignosulfonate and ethoxyquin (synergism) . The ethoxyquin is more stable in a solution when lignosulfonates are present as well. Lignosulfonate has limited solubility in an oil phase. Without wanting to be limited by theory, the lignosulfonate could thus act as a sacrificial agent in the water phase. If lignosulfonate is oxidised first, then ethoxyquin will be protected. It should be noted that the lignosulfonate concentration is much higher than the ethoxyquin concentration. So even if lignosulfonates are much less effective on weight for weight basis, the total effect could be larger. The lignosulfonate (and sodium sulphate added as a part of the lignosulfonate solution) could also salt out the ethoxyquin and force more of it into the oil phase. Lignosulfonates have a strong dark colour and absorb strongly in the ultraviolet part of the spectrum. The dark colour could thus protect the ethoxyquin towards degradation due to the effect of light. Ethoxyquin seems to have a maximum in the UV adsorption at 280 nm (or the same as lignosulfonates) .

Different aspects of the present invention (among others) may be summarized by the following items:

- The use of lignosulfonate as an antioxidant in combination with other antioxidants to obtain a synergistic effect

- The use of lignosulfonate together with at least one further antioxidant in the stabilisation of organic and/or biological material, wherein the further antioxidant is selected from the group consisting of organic and/or inorganic antioxidants.

- The use of modified lignins together with at least one further antioxidant in the conversion of animalic material such as fish and/or meat and/or food material into silage, wherein the further antioxidant is selected from the group consisting of organic and/or inorganic antioxidants.

- A composition for converting animalic material such as fish and/or meat and/or food material into silage, said composition comprising lignosulfonate and an organic acid together with a further antioxidant or a composition for converting fish and/or meat and/or food material into silage, said composition comprising lignosulfonate and an organic acid.

- A composition for converting animalic material such as fish and/or meat and/or food material into silage, said composition comprising lignosulfonate and an organic acid together with a further antioxidant or a composition for converting fish and/or meat and/or food material into silage, said composition, where the lignosulfonate is of the type calcium, sodium, magnesium and ammonia lignosulfonates .

- A composition for converting animalic material such as fish and/or meat and/or food material into silage, said composition comprising lignosulfonate and an organic acid together with a further antioxidant or a composition for converting fish and/or meat and/or food material into silage, said composition, where the lignosulfonate is of

the type sodium lignosulfonates, in the molecular weight average range Mw = 25-40 kDa.

The composition of the silage product would as an example comprise 10-90% orgagnic acid, 0.2-3.0 % Ethoxyquin and 5- 50% lignosulfonate (depending upon the dry matter content of the lignosuolfonate solution used) . Other examples of solutions comprising Ethoxyquin, lignosulfonate and acid according to the present invention include: Acid in the range of 40-90%, more preferred 50-80%; Ethoxyquin in the range of 0.2-1.5%, more preferred 0.2-1.5%; and lignosulfonate in the range of 5-30% (all of the percentages referring to w/w based on the dry matter content of the lignosulfonate solution used) .

To illustrate the present invention the following figures have been provided:

Figure 1 - Structure of BHT (2, 6~di-tert-butyl-4- methylphenol) .

Figure 2 - Structure of BHA (3-tert-butyl-4- hydroxyanisole) .

Figure 3 - Structure of tocopherols (7-

Oxabicyclo [4.1.0]heptane-3-carboxylic ac±d _r 1 , 4-butanediyl ester, homopolymer (9CI)).

Figure 4 - Structure of rosmarinic acid.

Figure 5 - Structure of Ethoxyquin.

Figure 6 - Structure of Gallic acid.

Figure 7 - Oxidation product of Ethoxyquin.

Figure 8 - Autoxidation of rosmarinic acid with oxygen at elevated temperature without and in the presence of two different lignosulfonates.

Figure 9 - Peroxide values as a function of time. Composition of products: EQ: % ethoxyquin, NAac: % LS, FA: % Formic acid (85 %) .

Examples :

EXAMPLE 1

A stability study of ethoxyquin in formic acid compared to ethoxyquin in formic acid/lignosulfonate solution has been performed.

Experimental

An analysis method for determination of ethoxyquin reported by He and Ackman [15] have been introduced. The analyses were performed on an Agilent 1100 liquid chromatography system equipped with a Macherey-Nagel HPLC Column, CC 125/3 Nucleodur C18 Pyramid 3μm column and a UV detector. The absorbance was measured at 280 nm. The column temperature was 27 ⁰ C and the flow of the mobile phase was 1 ml/min. The solutions to be investigated contained 50:49:1 of formic acid: sodium lignosulfonate: EQ (w/w%) and was compared to a control 50:49:1 of formic acid: water : EQ (w/w%), it was not taken into account that the formic acid was 85 %, the EQ sample was 75 %, and the solution lignosulfonate solution was 35 % dry matter.

100 g of each sample was prepared and split into two samples that were stored in respectively a glass and a metal container. This was done to see the effect of light upon the samples.

Analyses of the amount of ethoxyquin in the samples were performed for 10 weeks.

Results

Results from the stability study of ethoxyquin are shown in table 4.

After 2 weeks storage 94 % of the added ethoxyquin is remaning in the sample containing lignosulfonate, whilst in the sample containing no lignosulfonate only 70 % is remaining. After 10 weeks storage 70 % of the added ethoxyquin is remaning in the sample containing lignosulfonate, whilst only 1 % remains in the sample without lignosulfonate.

Table 4. Ethoxyquin (%) in samples upon storage

EXAMPLE 2

The trial in example 1 was repeated with a set of new samples, Sample 1: 0.35 g ethoxyquin, 80.00g Formic acid (85%), and 19.65 g lignosulfonate solution, sample 2: 0.35 g ethoxyquin, 80.0Og Formic acid (85%), and 19.65 g MQ- water. The samples were stored in glass and metal containers for 5 weeks. Analyses of the amount of

ethoxyquin in the samples were performed each week according to procedure described above.

Results

Results from the stability study of ethoxyquin are shown in table 5.

Table 5. Ethoxyquin (%) in samples upon storage

After 5 weeks storage no ethoxyquin is found in the sample stored in a metal container, whilst only 9 % is left in the sample stored in the glass container when no lignosulfonate is added. In the samples added lignosulfonate 66 and 50 % respectively, of ethoxyquin is still available after 5 weeks storage. Addition of lignosulfonate significantly increases the stability of ethoxyquin.

EXAMPLE 3

The combined effect of lignosulfonate was in addition shown in autoxidation experiments using two different lignosulfonates and rosmarinic acid as a representative for a different antioxidant. The antioxidant rosmarinic acid was completely degraded in an atmosphere of oxygen at 65 ⁰ C during a period of four days with intermittent saturation

with oxygen twice a day. In parallel the same concentration of antioxidant, rosmarinic acid 1%, was supplemented with lignosulfonate . The tested lignins were a sodium lignosulfonate (LS 1) and a calcium lignosulfonate (LS 2) , both added in the same amounts based on dry content (17%) . Samples were withdrawn daily and the amount of remaining antioxidant was chromatographically quantified. Reversed- phase HPLC with UV-detection at 280 nm was the method of choice for monitoring the positive effect of LS.

Results

A saving of almost half of the most expensive and reactive antioxidant was obtained when the most efficient lignosulfonate tested was used (Table 6, Figure 8) .

Table 6. Autoxidation of rosmarinic acid.

EXAMPLE 4

Laboratory trials preparing fish silage from minced salmon added formic acid and ethoxyquin, with and without lignosulfonate, have been performed. A mixture of 0.65 (w/w%) ethoxyquin, 19.4 (w/w%) lignosulfonate, and 80 (w/w%) formic acid was compared to a competitor product containing 0.5-1.0 (w/w%) ethoxyquin in an 85 % formic acid solution. Isolated fish oil have been analysed with respect to peroxide values.

Experimental

1 day fresh salmon were chopped into pieces and minced in a food processor. 1500 g of minced fish were placed in plastic bottles and added 45g w/w % sample the first day. The bottles were shaken to get a good mix with the fish. Day two more acid was added to achieve a pH between 3.3 and 3.4. The silage samples were placed in a water bath during the entire experiment in order to retain a stable temperature of 23 degrees.

Day 1 (0), 4, 7 and 14 100 g fish silage from each bottle was transferred to centrifuge tubes and centrifuged at 3000 rpm for 15 minutes. Fish oil was separated from the silage and frozen (-20 ⁰ C) . The oil phase was analysed for peroxide values .

Results

Figure 9 shows peroxide values for fish oil extracted from fish-silage prepared with an ethoxyquin/formic acid additive compared to an ethoxyquin/lignosulfonate/formic acid additive. The silage conserved with the additive containing lignosulfonate contains less primary oxidation products , i.e. has lower peroxide numbers.

EXAMPLE 5

A silage trial with Norwegian Salmon was performed in collaboration with a large Norwegian producer of marine byproducts. The performance of a product containing 0.35 (w/w%) Ethoqyquin (EQ), 19.6 (w/w%) lignosulfonate (LS) and 80 (w/w%) Formic acid was compared to a formic acid based competitor containing 1.0 (w/w%) ethoxyquin. The quality of products produced from fish silage conserved was analysed with standard methods .

A 2.5 % dosage of was used during the production of 280 tons of silage. This dosage gave a pH of 3.6 in the silage. Typically, the pH in silage is adjusted to below 4.

Results

The results from analysis of fish silage stabilised with a ethoxyquin, lignosulfonate, formic acid product (0.35 % Ethoqyquin, 19.6 % lignosulfonate and 80 % Formic acid ) compared to silage stabilised with a formic acid based competitor containing 1.0 % ethoxyquin are shown in table 7.

Values of pH, total volatile nitrogen (TVN), protein-, fat- and dry matter content were all in the same range as the competitor. For peroxide values, aniside values, biogenic amines and analysis on microbial flora the ethoxyquin, lignosulfonate, formic acid product gave superior results.

Table 7. Large scale silage trial

* < 100 means below detection limit.

In addition to the synergistic properties of lignosulfonates on antioxidants according to the present invention, the addition of lignosulfonates to acidified fish silage does not have any detrimental effects with respect to microbial growth in the silage, as evidenced by the results shown in in table 7 supra where all the values for microbial flora, mould or yeast are below the detection limit (less than 100/g (ml)).

The present invention also concerns a kit for preservation of organic or biological materials including a composition comprising lignosulfonates and/or modified lignins and an

acid as disclosed supra in a separate container, and wherein the kit further comprises the additional antioxidant in a separate container. Such a kit will also include instructions for use and optionally instructions for storage of the kit. For improving the shelf life of the second antioxidant (besides the lignosulfonates and/or modified lignin) it may be stored in a sealed container (optionally under an inert atmosphere such as N ₂ or CO ₂ ) or in an evacuated container. The container for storing the antioxidant may also include a light-impenetrable material for protecting the antioxidant from photo-degradation. The acid in the container including the lignosulfonate (s) and/or modified lignin may be an inorganic acid such as hydrochloric, phosphorous, sulfuric acid and/or an organic acid such as formic acid, acetic acid, lactic acid, propionic acid, butyric acid. The antioxidants in the second container of the kit according to the present invention may be ethoxyquin, rosmarinic acid, BHT, tocopherols, vitamin C, catechins, gallates, and especially preferred ethoxyquin, or the further antioxidant may be an inorganic substance, e.g. sulfites or iodide. The lignosulfonate and/or modified lignin included in the first container in the kit according to the invention may as an example be selected from the group calcium, sodium, magnesium or ammonia lignosulfonates, most preferred sodium or calcium lignosulfonate . In a special embodiment the lignosulfonate included in the kit according to the present invention is of the type sodium lignosulfonate, in the molecular weight average range Mw = 25-40 kDa .

In addition to the above discovered synergistig effect of lignosulfonates and/or modified lignins, such compounds also posses the properties of being anticorrosive hereby protecting metallic components of equipment used for mixing and/or processing the silage or biological material [17] .

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