A NEW SILAGE AID, PROCESS FOR PREPARING THIS SILAGE AID AND USE OF THIS SILAGE AID

Abstract: This invention relates to a new silage aid, process for preparation of this silage aid and use of the silage aid. The silage aid comprises at least one antioxidant selected from the group 2,6-di-tert-butyl-4-methylphenol (BHT), 3-tert-butyl-4-hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ), tocopherol and gallates; at least one short chain carboxylic acid; and optionally at least one salt of said acid. These antioxidants are food approved. The present silage aid is useful for preservation of organic by-products, and particularly for protection of fish oil during a fish silage process.

Description: A new s i l age a i d , process for prepari ng thi s s i l age aid and use of th i s s i l age a i d This invention relates to a new silage aid. process for preparation of this silage aid and use ot the silase aid. When preparing silage from for instance fish waste, the raw mateπal is treated with acid to obtain the optimum pH (3 5-4 5) with regard to enzymatic hydrolysis, and to prevent the growth of bacteπa dunng storage. Dunng the silage process hydrolysis results in the formation of emulsions made up of an acidic water phase, an oil phase and solids The degree of phase separation in these s\ stems depends upon the type of raw matenal used. Oxygen is easily transferred through water which unfortunately gives nse to oxidative degradation of the oil phase This lipid oxidation results, of course, m a reduced nutntional value of the oil as an ingredient both for feed and for food Likewise, it implies a reduced quality of the oleochemicals made from fish silage oil. To overcome these problems it would be a great advantage if an antioxidant well suited for the protection of fish oil could be present dunng the silage process The most favourable way to include an anuoxidant would be as a constituent of the silage aid Generally, it would be necessary to have at least 1% antioxidant in the silage aid Vvater soluble antioxidants are easily included in an acidic silage aid. Unfortunately though, these compounds will not be able to protect the oil after separation since they will not be associated with the oil phase. Furthermore, the antioxidants that are food approved in Europe and/or the US at present, are mainly fat soluble compounds, e.g 2.6-dι-r -butyl-4-methylphenol(BHT). 3-rert-butyl-4-hydroxyanιsole.BHA). terr-butylhydroquιnone(TBHQ). tocopherol and the gallates All of these food approved antioxidants are also commercially available in formulations with emulsifying agents, but unfortunately the emulsifying agents are in general hydrophobic. and thus these formulations are not well suited to an acidic water medium The antioxidant ethoxyqum is an exception with regard to the properties descnbed abo\ e Ethoxyqum is a secondary, cyclic amine Hence, it is well known that ethoxyqum is soluble in acids at low pH ( <3 ). as this implies protonation of the ammo group and thereby formation of a hydrophihc salt. As pH nses to 4-5 however, ethoxyqum ill be deprotonated and consequently, will again become fat soluble Thus, by choosing the proper concentration ot acid it is possible to have ethoxyqum in the lorm ot a hydrophi e salt in the silage aid. w hile during the silage process the salt is deprotonated. becomes fat soluble and consequently will be able to protect the oil against lipid oxidation. Likewise, other antioxidants with an amino group may be suitable for this use. The preparation of ethoxyqum formiate salt, and this salt dissolved in formic acid is disclosed in Norwegian patent application no. 851007. Unfortunately though, ethoxyqum or other known antioxidants ith an amino group, are not iood approved Therefore, when food approv al has been required, no silage aid soluble antioxidants ha\ e been a \ ailable to date Thus it is a main object of the present invention to provide a new silage aid comprising a tood approved antioxidant This and other objects ot the invention is achieved by the attached claims. The invention w ill be further explained below The antioxidants BHT. BHΛ. tocopherol. TBHQ and propyl gallatei PG ) are practical!} insoluble in water, and experiments e show n that then solubilm in mineral acids (hydrogen chloride, sulphuric acid) is also quite low (see Table 1 ) U nexpectedly how e . ei . we have now tound that these highly hydrophobic antioxidants are soluble in the short chain carboxylic acids tormic. acetic and propiomc acid (see Table 1 ) Further experiments ha\ e shown that when using a silage aid compnsmg BHA. TBHQ or PG dissoh ed in 857. formic acid, a superior quality ol the fish oil product as compared to the product ot the same process using only 85 c r formic acid (Table 2 ) is obtained When the silage aid containing antioxidant is blended w ith the fish waste raw material, the hydrophobic antioxidant is associated with and protects the oil phase. Thus, we have tound a method w hich is convenient on a technical scale and which leads to superior quality ot the products ot the silage process. Generally , the amount of silage aid needed w ill depend upon the ty pe ot fish w aste used and the choice of acid Also, the amount ot antioxidant needed, may depend upon the raw material used or the requirements regarding the stability of the isolated oil. This implies that the required amount of antioxidant dissolved in the acid may vary. Furthermore, we have shown by experiments that the solubility of BHT in formic acid increases when BHA is present in the acid. This was a surprising result. The silage aid might further comprise additives like, anti-microbiell compounds (e.g. ethyl benzoate or benzoic acid), anti-fungal compounds, anti-corrosive compounds, chelating compounds (e.g. citric acid), compounds improving the handling properties (e.g. glycerol), and oxygen scavengers. The present invention also comprises to firstly dissolve the said antioxidants in a short chain carboxylic acid, and subsequently adding a mineral acid in the purpose of decreasing pH. The short chain carboxylic acids according to this invention might be used either alone or in combination with their corresponding salts. Further, the aforementioned acids might be used as a mixture or as a mixture together with any of their salts. The present invention is documented by experiments performed for a fish silage process. This invention will of course also prevail for other processes where acidic preservation is used. Fish silage shall only be considered as an example. The invention is applicable in acidic preservation of other organic by-products like slaughter waste, poultry waste and food waste, as well. Table 1. Solubility (weight %) of antioxidants in different acids. BHA TBHQ PG BHT Toco- ! pherol 5 M hydrogen chloride J < 0.1% < 0.1 % < 0.1 % < 0.1 % 1 < 0.1 % 4 N sulphuric acid a < 0.1 % < 0.1 % < 0.1 % < 0.1 % : < 0.1 % 85% formic acid b >5% >5% > 10% < 0.25% ! < 0.5% 98-100% formic acid" >10% >10% >10% < 0.25%^ < 0.5% 100% acetic acid b >10% >10% >10% >10% 1 >10% 100% propionic acid b >10% > 10% <10% > 10% >10% a)A mixture of antioxidant(40mg) and mineral acid(40g) was thoroughly shaken at 23°C. b)A mixture of the chosen amount of antioxidant( 10-400mg) and acid(4g) was thoroughly shaken at 23°C. c )0.25% BHT is not soluble in formic acid. When 0.5% BHA is added to the formic acid. BHT is soluble. Example I: Experimental procedure for a lab-scale fish silage process. The raw material. Atlantic salmon viscera, was ground in a kitchen grinder, and the resulting minced fish waste was thoroughly blended before it was portioned into separate batches each containing 500 gram. Silage aid (2% vol./wt.; lOmL) 85% formic acid with or without 0.75% wt./vol. of dissolved antioxidant was added, and the content of each batch was mixed to ensure a homogenous distribution. The batches was stored for eight days in an oven at 35±2°C. before a standard procedure for silage work up was conducted. This included warming the silage at 90±1 °C for 1 minute, tempering, and finally separating the oil after centrifugation. The isolated oils were analysed to determine the POV and / AV. Furthermore, weight gain (at 35±1°C) as a function of time was registered to determine the IP of the oils. The results are presented in Table 2. Example II: Experimental procedure as in Example I. but the raw material in this series was whole herring. The results are presented in Table 2. Table 2. Comparison of the results from analysis of various oil quality parameters ', determined for fish silage oil produced 15 using silage aid with or without dissolved antioxidant. a)POV(Peroxide value. Ph. Eur. V.3.4.5): determines the amount of primary oxidation products, hydroperoxides. in the oil. p-AV/p-Anisidine value. IUPAC 2.504); determines the amount of some secondary oxidation products, alkenals. in the oil IPdnduction period), a measure of the shelf life of the oil. given as the number of day s it takes before the oil shows detectable weight gain due to oxygen absorption b)The experimental procedure tor lab-scale silage experiments is given abo\ e in example I c)The concentration of antioxidant giv en in parenthesis, is based on the amount of fish waste used in these experiments

Claims: Claims 1 Silage aid comprising at least one antioxidant selected from the group 2.6-dι-tert-butyl-4-methylphenol (BHT). 3-terr-butyl-4-hydroxyanιsole (BHA). tβrt-butylhydroquinone (TBHQ), tocopherol and gallates. at least one short chain carboxylic acid, and optionally at least one salt of said acid 2 Silage aid according to claim 1. wherein the short chain carboxylic acid is formic acid, acetic acid and/or propionic acid 3 Silage aid according to claim 1 or 2, wherein the short chain carboxylic acid is formic acid of concentration 60-100%, preferred 83-98% 4 Silage aid according to claim 1 or 2 claims, wherein the short chain carboxylic acid is acetic acid or propionic acid of concentration 60-100%. preferred 80- 100% 5. Silage aid according to any of the proceeding claims, wherein 0.1-10% of the antioxidant. preferced 0.3-2%, is dissolved in the short chain carboxylic acid 6 Silage aid according to any of the proceeding claims, comprising an antioxidant selected from the group BHA. TBHQ and propyl galate (PG). and formic acid 7 Silage aid according to any of the proceeding claims, compnsmg BHA and BHT, and formic acid 8 Process for preparation of a silage aid comprising at least one antioxidant selected from the group 2,6-dι-tert-butyl-4-methylphenol (BHT). 3-ter?-butyl-4-hydroxyanιsole (BHA), r_.?τ-butylhydroquιnone (TBHQ), tocopherol and gallates. a short chain carboxylic acid, and optionally at least one salt of said acid, by dissolving the antioxidants in the acid 9 Process according to claim 8. by dissolving 0 1- 10% of the antioxidant. preferred 0 3-2%. in a short chain carboxylic acid of concentration 60- 100% 10. Process according to claim 8 or 9. by dissolving 0.1-10% of the antioxidant. prefened 0.3-2%, in formic acid, acetic acid and/or propionic acid of concentration 60-100%. 11. Process according to claim 8. 9 or 10. for preparation of a silage aid comprising 5 2.6-di-tert-butyl-4-methylphenol (BHT) and 3-tert-butyl-4-hydroxyanisole (BHA), and formic acid, by a) dissolving BHA in the acid, and b) subsequently, dissolving BHT in the solution obtained in step a). 10 12. Use of a silage aid comprising at least one antioxidant selected from the group 2.6-di-tert-butyl-4-methylphenol (BHT). 3-tert-butyl-4-hydroxyanιsole (BHA). tert-butylhydroquinone (TBHQ), tocopherol and gallates; a short chain carboxylic acid; and optionally at least one salt of said acid, for protection of fish oil during a fish silage process. 5 13. Use of a silage aid comprising at least one antioxidant selected from the group 2.6-di-tert-butyl-4-methylphenol (BHT). 3-tert-butyl-4-hydroxyanisole (BHA). tert-butylhydroquinone (TBHQ), tocopherol and gallates; a short chain carboxylic acid; and optionally at least one salt of said acid, during preservation of organic by-products. 0

Inventors: AASBOE KARI, BREIVIK HARALD, AASBOE, KARI, BREIVIK, HARALD
Applicants: AASBOE KARI, BREIVIK HARALD, NORSK HYDRO AS, AASBOE, KARI, BREIVIK, HARALD, NORSK HYDRO ASA
Application year: 2000
Main classification: A23K3
IPC codes: A23K3