DK143656B - PROCEDURE FOR THE RECOVERY AND STABILIZATION OF FAT AND FAT MATERIALS AND PROTEIN AND PROTEIN MATERIALS FROM PROCESS WATER - Google Patents

Description

ns) DENMARK \ S [)

| J | (2) PROCEDURE WRITING (11) 1436-56 B

DIRECTORATE OF PATENT AND TRADEMARKET

(21) Application No. 678/7 ^ · (51) lnt.CI.3 C 11 ® 13/00 (22) Filing date Feb 8 197 ^ (24) Running Day Feb 8 197 ^ · (41) Aim. available Aug. 10 1974 (44) Posted Sep 21 1981 (86) International application no.

(86) International filing day (85) Continuation day - (62) Master application no. -

(30) Priority 9th Feb. 1973, 539/73, NO

(71) Applicant A / S APOTHEKERNES LABORATORY FOR SPECIAL PREPARATIONS, N-Oslo 2, NO.

(72) Inventor Gunnar Hall, NO.

(74) Clerk of the Office of Industrial Excellence v. Svend Schønning.

(54) Process for the recovery and stabilization of fat and fat 'like substances and protein and protein-like substances from process water.

Process water and wastewater from food industries often contain large amounts of fat, fat-like substances, proteins and protein-like substances that represent a not insignificant potential value. The said substances, moreover, contribute significantly to a considerable amount of pollution by easily decomposing aerobically Q and thus disturbing the oxygen balance in recipients.

G The present invention relates to a process for recovering substances from the grease veneer industries, margarine industries and other food industries, whereby, in addition to obtaining a water purification effect, the recovered substances also obtain increased stability.

2 143656

It is known that one can use, for example, acid hydrolyzing 3+ 3+ metal salts as a flocculant, for example Fe salts and Al salts. In addition, it is known that these salts also have a demulsifying effect as well as an effect that causes colloidal protein systems to break. The disadvantage of using this type of salts in connection with said process water is that they act as catalysts for the autoxidation of fatty substances and thus reduce their value as recovered material by the formation of ketones, peroxides and aldehydes.

For the process of the present invention 3+, the acidic hydrolyzing metal salt, e.g., a Fe salt, is included in a complex compound with the fats. After good mixing and sufficient reaction time, an alkaline earth metal hydroxide, eg CaCOH 2, is added, after which the complex precipitates as a co-precipitate which can be separated by sedimentation, centrifugation or flotation as a sludge. This complex, eg Fe-fat-Ca, is insoluble by the addition of strong mineral acid at room temperature, which is a clear indication that this is not a precipitated metal hydroxide but an acid-insoluble complex.

It has been found that the sludge has a significantly greater stability than, for example, Fe (OH) 2 - fat sludge where fat is adsorbed, suggesting that the catalytic effect of the metal ion is inhibited, possibly by chelation. See curves for Examples 1, 2 and 3, viz. 1-4.

In process water from the food industry, fat and proteins occur in varying ratios. If the amount of protein is significant in relation to the amount of fat, ie. constituting more than 10 µ / o of the total solids in the process water, it may be necessary to lower the pH with a mineral acid to liner 4 before, simultaneously or after the addition of the acidic hydrolyzing metal salt. This proves to be absolutely necessary for efficient complexation of water-soluble proteins, but less necessary for colloidal protein / fatty process water.

After addition of the alkaline earth metal hydroxide, the complex also precipitates here as a coprecipitate which can be separated by sedimentation, centrifugation or flotation and the sludge is insoluble by the addition of strong mineral acid. This sludge can be of great value in, for example, premixes where it is important to avoid oxidized fatty products which have been found to be toxic.

A complex precipitation of the proteins carried out in accordance with the present invention also provides improved digestibility with subsequent heat treatment and drying compared to acid-precipitated proteins because the precipitation of the complex occurs at 11 neutral pH range. This is shown in the curve in FIG. 5 regarding digestibility set against pH.

Instead of using an alkaline earth metal hydroxide, it is also possible in the process of the present invention to use alkali metal hydroxide if an alkaline earth metal salt is already present.

In many cases, it is a condition of separation by flotation that an anionic polyelectrolyte is added after the alkaline earth metal hydroxide. Flotation will in most cases be the most current principle, as this treatment can achieve a sludge concentration of 15% or more.

Example 1

The test used process water from a margarine plant. Three comparative experiments were performed; 1) The fat content of the process water was separated by micro flotation, ie. by adding water which is air-saturated at a pressure of 4 ato. The recovery result is shown in Table 1 below. The fat which floated was used in autooxidation experiments.

2) Jem (III) chloride and lime were added to the process water in known manner. In this treatment, flocs were formed which floated in the manner described above. The sludge was then scraped off and used for the autoxidation test. The recovery results are shown in Table 1.

3) Iron (H1) chloride was added to process water as well as, acid in sufficient quantity to lower the pH to less than 4, after which lime was added to pH 7.5. The recovery results are shown in Table 1.

$ 14,355

Table 1

Sample Trial Fat mg / 1 Recycled, .¾ raw water - 1780

Effl. 1) 872 51

Effl. 2) 157 91.7

Effl. 3) 52 97.8

To determine the stability of the recovered fat against auto-oxidation, the anisidine value, as determined by U.P.A.C. standard method used as parameter.

The anisidine value tells about the fat / oil content of aldehyde compounds and the structure of the carbon compounds, and is used for 1 day as an indicator analysis for the fat / oil quality. In the auto-oxidation test, the three sludge samples were weighed to have an equal amount of fat. The samples were then placed on a thermostatically controlled water bath at 80 ° C - 1 ° and air was bubbled through. At time intervals, subsamples were sampled, fat extracted and anisidine values measured. FIG. 1 shows the results of said autoxidation experiments.

The curves show that the fat content of sludge from experiments 1 and 2 was oxidized significantly faster than the fat content of sludge from experiment 3, which sludge was recovered by the method of the present invention. Thus, the experiments show that the fat content of sludge from Experiment 3 is substantially more stable than the fat content of sludge from Experiments J and 2.

Example 2 In this experiment, process water from sebum smelting was used. The water is slightly alkaline, has a brownish color and is bleached with emulsified grease. The process water was treated in the same manner as described in Example 1. The results from the recovery of fat are shown in Table 2.

, 143β $ 6 5

Table 2

Sample Experiment Fat mg / l Recovery 1% raw water - 1140

Effl. 1 1 106 90.7

Effl. 22 93 91.8

Effl. 33 36 96.4

To examine the stability of the fat mud, "The Oxygen Bomb Test" was used. This is a method where the current sample is introduced into a chamber which is put under pressure of air. The chamber with the sample is heated to a certain temperature and the pressure reduction due to the oxygen uptake of the fat is read continuously. This analysis gives eb measure of the autoxidation as a function of time. FIG. 2 shows the results of these experiments.

The curves show that the fat content of sludge from Experiment 1 and Experiment 2 was oxidized significantly faster than the fat content of sludge from Experiment 3, which sludge was recovered by the process of the present invention.

Example 3

In this experiment process water from a slaughterhouse for pigs and cattle was used. The process water had pH = 6.8, it was red-colored by blood proteins and contained some suspended particles. The water content of fat was relatively low in relation to the protein content.

Experiments: 1) Flocculation with iron (III) chloride. Various amounts of FeCl 2 were added to the process water and flocculated.

The flocs formed were relatively stable and flotated by the addition of dispersion water (air saturated water at 4 ato).

A bulky sludge formed. The liquid phase under the sludge was still red-colored by blood proteins, and this shows that the method is not suitable for precipitation of said proteins. Suspended material, on the other hand, was effectively reduced. Results are shown in Table 3.

6 1433S6 2) Flocculation with iron (III) chloride + lime.

Various amounts of FeCl 2 were added to the process water, and the pH was adjusted to pH = 7.5 with Ca (OH) 2. The flakes easily floated by the addition of dispersion water but formed a relatively voluminous slurry. The liquid phase under the sludge was still red in color, and this proves that this method was also not suitable for the recovery of blood proteins. The results are shown in Table 3.

3) Different amounts of FeCl 2 were added to process water with subsequent acidification with HgSO 4 to a pH below 4. After a certain mixing and reaction time, Ca (OH) 2 was added to pH 7.5. In this treatment, stable flocs were formed which, after the addition of dispersion water, rapidly rose to the surface and formed a relatively concentrated sludge. The liquid phase under the sludge became clear and colorless in this treatment. The results are shown in Table 3, where S.t. stands for suspended solids.

T a b e 1 3

Sample Test mg / 1% mg / l% mg / l

Proteins Reclaimed Fat Did Not Win * Raw Water - 940 - 306 - 468

Effl. 1 1 560 40.5 44 85.6 56

Effl. 2 2 410 56.3 37 87.9 44

Effl. 3 3 37 90.75 29 90.5 31

The three types of sludge obtained contained most of the process water's fat, and studies on stability by • autoxidation were conducted.

The three sludge types were treated as in Example 1, ie. with warm and ample supply of air by blow-through. Samples were taken at different time intervals, and peroxide value and fat self-extinction were measured, see fig. 3, respectively. 4th

The peroxide value was determined according to A.O.A.C. standard method, and is an expression of the degree of fat oxidation. The curves of FIG. 3 shows that the fat content of sludge from experiments 1 and 2 oxidizes considerably faster than the fat content of sludge from experiment 3, which sludge is recovered by the method of the present invention.

7 U3 $ S6

For the determination of fat self-extinction, the same method as for determining the anisidine value is used. The self-extinction of fat is an expression of the degree of oxidation and stability of the fat, since an unstable fat will quickly stain due to, among other things, oxidation. The curves of Fig. 4 show that the fat content of sludge from experiments 1 and 2 is considerably more unstable than fat in sludge from experiment 3, which sludge is recovered by the method of the present invention.

When it comes to digestibility of proteinaceous material, we know from previous experiments that the pH during drying must be in the neutral range. FIG. 5 shows% digestibility at various pH values during drying. The experiment gives reason to believe that the Fe-protein complex will have a relatively high digestibility.

The patent does not cover the use of the present process in the manufacture of foodstuffs.