AND FATS FROM AN ANIMAL MATERIAL

Field of the invention

[0001] Animal tissues, especially those considered rejects from an animal processing plant; contain fats and proteins valuable for further use as feed or energy. Animal tissues are normally disposed with the help of water as a means to provide flow. This invention separates water, proteins and fats, each with very little contamination from the others, therefore allowing them to have high purity and value. The present invention achieves this through a very economical process, reducing the energy costs and eliminating the need for oxidation ponds to dispose of the water, given the high purity obtained.

Description of the invention

[0002] The method of the present invention for separating water, proteins and fats from disposed animal materials of a meat processing plant comprises the use of a mixture of two solvents. Preferably, the term "material" refers to an animal tissue mixed with water and flocculants such as polymers, ferric chloride and aluminum sulfate which are often added by meat processing plants to agglutinate solids in the water.

[0003] The material to be treated by the method of the invention is a liquid or paste like material. The material-can be any animal product, consisting mainly of proteins, fats and water, and might include other naturally occurring components of food such as salts, vitamins, antioxidants and sugars.

[0004] This material is an emulsion formed in the disposing process of the meat processing plants. This emulsion is the material to be treated. Normally it is formed in the aeration process of the water treatment section of the plant, and appears as a floating foam.

[0005] In a first step, the emulsion is dissolved in a mixture of two solvents. Particularly, the method of the invention comprises the use of a mixture of two solvents wherein one of the solvents is a polar solvent and the other solvent is a non-polar solvent. Mixing is performed between 15°C and 35°C, or in some embodiments between 20°C and 25°C. Different methods may be employed to mix the emulsion and solvents provided turbulence is created. In one embodiment, energy is added at about 250 watt hr per metric ton of total mix. The polar solvent is a compound containing at least one hydroxyl group (-OH). In one embodiment, the polar solvent is selected from the group consisting of C1-C5 linear alcohols and C1-C5 branched alcohols. In one embodiment, the polar solvent is 1-propanol. The non- polar solvent is a C5-C8 saturated hydrocarbon. In one embodiment, the non-polar solvent is a linear C5-C8 saturated hydrocarbon. In one embodiment, the non-polar solvent is linear or normal heptane. All solvents are initially at 100% concentration. The polar solvent/non-polar solvent mixture breaks up the emulsion. The polar solvent reduces the ionic capacity of the water, allowing the proteins in suspension to precipitate. The non-polar solvent dissolves the fats. When the material is mixed with the polar/non-polar solvent mixture three components are produced: two liquid phases and a precipitate, the precipitate mainly consisting of proteins, salts and sugars. Due to its lower density, the non-polar solvent containing the fats is the upper phase and the water/polar solvent containing the precipitate is the lower phase. In one embodiment, the proportion for carrying out the method of the invention is 1 : 1 : 1 by volume (material: polar solvent : non -polar solvent), to assure differentiation of phases due to their different densities. Other proportions may be employed, including but not limited to 1 : 1 : 1.5, 1 : 1 :2, 1 : 1 :3, 1 :0.9: 1 and 1 :0.8: 1. In one embodiment, other proportions, especially more heptane, that enhances the difference of density between the heptane : fats mixture (usually, 0.75 grams/ml) and the water : 1-propanol mix (usually 0.80 grams/ml) may be used.

[0006] In the second step, the liquid phases obtained in the first step are separated from the precipitate (mainly proteins). This separation is performed between 15°C and 35°C, or in some embodiments between 20°C and 25°C. This separation is performed by standard procedures, such as decantation or centrifugation. In one embodiment, centrifugation may be about 100,000 G-seconds. In one embodiment, decanting may occur for one day but other periods may be used. The separation of the solids and the liquids has been performed in two stages. The first stage employs a horizontal centrifuge designed to handle solids, normally known as a decanter. In the second stage, the large molecular weight proteins from the precipitate obtained in this centrifugation can be further treated, e.g. dried with an evaporator to be recovered and used as animal feed.

[0007] In the third step, the two liquid phases are separated by decantation or centrifugation to obtain a lower phase and an upper phase. Both methods, decantation and centrifugation, have been tested with success, but decantation has proven to be more economical. This decantation is performed between 15°C and 35°C, or between 20°C and 25°C. Centrifugal forces no greater than 1000 G-seconds were tested.

[0008] In the fourth step, the lower phase from the third step, mainly comprising the water/polar solvent and the lower density proteins is passed through a filtering medium or through an evaporation process to remove any materials of lower density, for example the polymers. In one embodiment, the range of temperatures for the filtration step is 35°C to 40°C. The lower density proteins can be further treated, e.g. dried with an evaporator, to be recovered and used as animal feed. Several methods can be used to recover the alcohol from the water and obtain a large amount of pure water to be disposed economically, for example, salting out, use of entrainers such as cyclohexane, N-heptane, isooctane, benzene, or diisopropyl ether, pervaporation, filtration, or simple evaporation. Filtration and simple evaporation are two preferred methods. In one embodiment, and after passing through the filtering medium, a salt is added to the liquid phase, preferably sodium chloride (NaCl), in order to remove the alcohol in the water. Salt is added until saturation, which is about 30% by weight salt to total mixture. Other salts known to one of ordinary skill in the art may be used, such as potassium acetate and calcium chloride.

[0009] In the fifth step, the upper phase from the third step, mainly consisting of non- polar solvent and fats, is subjected to a separation process, preferably, the non-polar solvent and the fats are separated by evaporation. In one embodiment, this evaporation is performed at 100 torr of absolute pressure and between 80°C to 100°C.

[0010] Before this evaporation of the non-polar solvent, the fats can be further filtered at a temperature of from about 30°C to about 40°C to separate light fats from heavy fats. The fats can be used as feed or energy. Heavy fats are those that do not pass through a filtration medium of 30,000 daltons, and light fats are those which do pass through the filtration medium of 30,000 daltons. The filtration is performed at a very low porosity, about 30,000 daltons. Membranes used are of polyvinylidene fluoride (PVDF) and are commercially available from several suppliers such as GE Osmotics and Sepro. This porosity can be considered the molecular weight cutoff. This separation has been shown to substantially improve the quality of the recovered light fats. The peroxide content in the filtered fat is zero, and the filtered fat has low odor and color. Low color numbers are defined according to ASTM test D1500. Most of these fats are derived from intestinal tissues from the processed animal, and therefore absorb odors of substances normally processed by these organs, also known as feces Since the filtration is performed at a very low porosity, most of the microorganisms, including viruses, are removed, suspending the further oxidation of the fats.

[0011] The process may be summarized as follows. A method for extracting proteins and fats from an animal material comprises the following steps:

mixing the animal material and water to form an emulsion; mixing the emulsion with a mixture of two solvents thereby producing an upper liquid phase, a lower liquid phase and a precipitate containing protein;

separating the liquid phases from the precipitate;

separating the upper liquid phase and the lower liquid phase;

separating the lower liquid phase from lower density precipitates;

thermally treating the upper liquid phase to remove the fats from the solvents; and, removing water from the solvents.

[0012] All recovered solvents are reused after their recovery.

[0013] The following examples will serve to further illustrate the present invention without, at the same time, however, constituting any limitation thereof. On the contrary, it is to be clearly understood that resort may be had to various embodiments, modifications and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the invention.

Example 1

[0014] A small pilot plant was constructed. Fifteen separate samples of animal tissue from different food processing plants employing different technologies were tested to determine the flexibility and capacity of the methods of the present invention to provide equal quality of products in each condition. Each sample was a metric ton. The following tests were used to measure fats, proteins and water.

[0015] Fat in the solids AOAC International (AO AC) 920.39A

[0016] Protein in the solids AOAC 990.03

[0017] Water in the solids AOAC 930.15

[0018] Peroxide value in the fat American Oil Chemists Society (AOCS) Cd8-53

[0019] Water in the fat AOAC Ca2b-38

[0020] The results from each sample processed with the methods of the present invention were similar. Recovered solids (proteins) had less than 1% of fats (wt. %) The fats were actually not detectable using AOAC 920.39A

[0021] The recovered fats contained less than 1% of peroxides. The peroxides were actually not detectable using American Oil Chemists Society (AOCS) Cd8-53. [0022] The recovered water was evaporated and tested for BOD (Biological Oxygen Demand) and contaminants were not detected. After passing through an activated carbon filter the water was drinkable.

[0023] All patents, patent applications, publications, and abstracts cited above are incorporated herein by reference in their entirety. Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations thereof will be readily apparent to those of skill in the art without departing from the spirit and scope of the invention as defined in the following claims.