IL31338A - Process for the pasteurization of egg whites - Google Patents

Description

Improved process for the pasteurisation of egg whites* STAUFFER OHEMICAL COMPANY Oi 29603 IMPROVED PROCESS FOR THE PASTEURIZATION OF EGG WHITES Abstract of the Invention A process for pasteurizing egg whites which comprises the steps of raising the pH of the egg whites about 0.5 to 1.5 units above the natural pH thereof. The egg whites are then heated to destroy the natural catalase. Then, a responsive amount of a peroxide material is added to the egg whites which are then reheated to a pasteurization temperature.

Background of the Invention There are a number of food poisoning microorganism that cause serious problems in the food industry. Among these different spoilage organisms which may contaminate foodstuff, the group Salmonellae have gained special importance.

Salmonellae are pathogenic gram~negative rod-like bacteria that have drawn much recent attention that is well documented in the literature. Of the several food areas involved, particular interest has" been generated in the reduction of Salmonellae in egg products The contents of an egg with unbroken shell may already contain bacteria caused by the infection of a laying hen. The exterior surface of the egg may be contaminated with bacteria from the intestinal tract of the hen, from the nest or from other material contacted after laying. Some of these can be introduced into egg products during breaking operations. Bacteria can also penetrate the shell from outside. The invading microorganisms million added Salmonellae per milliliter. However, it has been found in practice, that the bacterial count in this process is relatively high after treatment. Also, the aluminum sulfate in the egg whites will cause the appearance of small particles of precipitated egg proteins.

Another proposed solution to killing the bacteria within the egg whites is described and claimed in U. S. Patent No. 2,776,211*. This process involves taking the egg white at its normal pH, heating it to 100° to 130°F. for a period of 0.5 to 5 minutes. This is claimed to largely inactivate the indigenous catalase. Thereafter, sufficient hydrogen peroxide solution is metered in to give a concentration of 0.1$ peroxide in the egg whites. The egg whites are. the reheated and they are cooled and catalase is added to destroy the residual peroxide. This process is reported to produce sterile egg white. This process has a serious drawback because a relatively high amount of bacter may survive the pasteurization process when heat resistant bacteria strains are present in the egg whites.

Brief Description of the Invention It has been discovered that the number of Salmonellae bacteria killed during pasteurization thereof can be materially increased by incorporating within the egg whites an alkali agent to adjust the pH to at least from 0.5 to 1.5 units above the natural pH of the egg whites. Thereafter, the egg whites are heated to destroy the natural catalase and then a peroxide mater It has been found that with the use of the alkali agent with the hydrogen peroxide materially increases the kill of the . Salmonellae bacteria and also provides for residual killing thereof which is heretofore unknown, - . . j Detailed Description of the Invention In the practice of the present invention, egg whites are separated from yolk material in a conventional manner.

As is well known, the pH of the egg whites is approximately 9,0. Then, an alkaline, agent is added to adjust the pH of the egg whites to at least 0,5 to 1,5 units above the natural pH= The egg whites are then heated up to about 130°F, for about 0.5 to 5 minutes. After the egg whites have been heated to this temperature, the natural catalase is destroyed. Then they are treated with hydrogen peroxide. The amount of hydrogen peroxide added may range between 0,01 to 1,5$, preferably about 0,05 to 0,5$ by weight. Thereafter, the egg whites are heated to a temperature of about 115° to 130°F, for an additional 0,5 to 5 minutes.

The alkali agent employed with the present invention may be selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium hydroxide, calcium hydroxide, sodium phosphate, sodium bicarbonate, and the like.

By adjusting the pH. of the egg whites with the alkali agent as noted above, it has been found that the kill power of the presence of the alkali material within the eggs provides residual killing power of Salmonellae after the eggs have been cooled and the pH thereof readjusted to the natural level.

In order to illustrate the merits of the invention, the following examples are provided: EXAMPLE 1 Fresh egg whites were obtained in a hand operation by separating the same from the yolks and mixed to form a uniform batchy The natural pH of the egg whites was determined to be 8.6. A bacterial culture of Salmonellae senftenberg 775W was added to the egg whites to provide a concentration thereof of 170,000 per milliliter of egg whites. Then, a 10$ solution of sodium hydroxide was added thereto to raise the pH to 9.5. The egg whites were then heated for 1.5 minutes at 130°F. to destroy the natural catalase. Thereafter, hydrogen peroxide was added to the egg whites to provide a concentration of 0.1$ by weight of the egg whites. The egg whites were then reheated to 130°F. for 3.5 minutes holding time. The egg whites were cooled quickly to k0°Y. Catalase was then added to destroy the hydrogen peroxide. An assay of the egg whites in using standard microbiological procedures indicated that the sample was Salmonellae negative.

EXAMPLE 2 The procedure as set forth in Example 1 was repeated in its entirety, except the sodium hydroxide additive was omitted. n a of the asteurized e whites usin standard micro EXAMPLE 5 The procedure as outlined in Example 1 was repeated in its entirety except the hydrogen peroxide and sodium hydroxide were both omitted. An assay of the egg whites indicated a survival of 1220 Salmonellae per milliliter of egg white using standard microbiological testing methods.

EXAMPLE k Egg whites were obtained in a manner as set forth in Example. 1. A bacterial culture of Salmonellae senftenberg 775W was added to provide a concentration thereof of 9.2 millions per milliliter of egg white. Then, a 10$ solution of sodium hydroxide was added dropwise to raise the pH from 8.6 to 9,5. After preheating the egg whites for 1.5 minutes at 130°F., 0.2$ by weight hydrogen peroxide was added. The egg white was then heated to 130°F. for five minutes holding time, The pasteurized eggs were then assayed according to standard microbiological procedures, indicating Salmonellae negative.

EXAMPLE 5 The procedure as outlined in Example k was repeated in its entirety except no hydrogen peroxide, was added thereto. An assay of the pasteurized egg whites indicate a survival of 90 Salmonellae per milliliter of egg white'.

EXAMPLE 6 The procedure as outlined in Example was repeated in its entirety except the addition of sodium hydroxide was EXAMPLE 7 The procedure as outlined in Example k was repeated in its entirety except the sodium hydroxide and hydrogen peroxide were omitted. The pasteurized egg whites were assayed in accordance with standard microbiological procedures indicating a survival of 190,000 Salmonellae per milliliter of egg white, EXAMPLE 8 Egg whites were obtained in a manner as set forth in Example 1. A bacterial culture of Salmonellae typhimurium was added thereto to provide a concentration of lk millions per milliliter egg white Then, a solution of 10 potassium hydroxid was added dropwise to raise th¾ pH of the egg whites to 9.2. The egg whites were heated to 128°F, for 1.5 minutes. Then, 0,2$ by weight hydrogen peroxide, was added to the egg whites. The egg whites were heated to 128°F. for 3.5 minutes holding time.

After pasteurization, the .egg whites were quickly cooled to 38°F, An assay of the pasteurized egg whites using standard microbiological techniques indicated Salmonellae negative.

EXAMPLE 9 The procedure as outlined in Example 8 was repeated in its entirety except no additives were incorporated within the egg whites. An assay of the egg whites after pasteurization using standard microbiological procedures indicated a survival of 3^0,000 Salmonellae per milliliter.

EXAMPLE 10 The functional properties of the pasteurized egg whites of Example 8 were tested. The functional properties are expressed by the specific volume of the egg whites and by the specific volume of the cakes baked with the pasteurized egg whites. Under both .criterias, the specific volume, of the whipped egg whites and also of the cakes showed that the egg whites pasteurized with the additives of Example 8 are comparable to the functional properties of fresh egg whites indicating no damage in the functional properties.

EXAMPLE 11 The pasteurized eggs of Example 1 were tested for any indication of an alteration of the functional properties.

Accordingly., 176 grams of the egg whites were mixed with a kitchen style mixer for 90 seconds. The. amount of foam thus generated was then measured. The quantity of foam produced is a measure of the degree of protein denaturization that may occur during pasteurization. The. amount of foam produced by the egg whites in 90 seconds is inversely proportional to the amount of protein denaturized during pasteurization. The volume of foam produced under these conditions is reported as specific volume determined by dividing the total amount of foam generated in milliliters, by the weight of the egg whites in grams. Thus, the specific volume of less than 3 indicates an excessive denaturization of the egg whites 'that is undesirable. The measured, the baking performance thereof was measured by preparing angel food cake from the pasteurized egg whites.

Thus, the 176 grams of egg whites were beat for an additional two minutes with the kitchen style mixer. Thereafter, 2.^5 grams of cream of tartar, 0.70 grams of salt, and 8k.0 grams of sugar were added. The mixture was then blended for an additional two minutes. Then, a blend consisting of k2 grams of flour and 45 grams of sugar was folded into the whipped egg whites. The resulting batter was placed in six inch pans and baked for 30 minutes at 355°F. After baking, the volume of the egg whites were measured by standard seed displacement techniques. The specific volumes were determined by dividing the weight of the cakes in grams into the total volume. The specific volume greater than 3 is indicative of acceptable egg white functional properties In this instance, the specific volume was k.k. Any changes in opacity of the egg whites due to pasteurization was measured by visual observation. An increase in opacity of the formation of solid protein particles is indicative of protein denaturization. The egg whites pasteurized in accordance with this invention were clear.

EXAMPLE 12 The pasteurized egg whites of Examples 1 through 9 were assayed for bacterial flora count using standard microbiological procedures. The pasteurized egg whites were then stored at room temperature. At 2k hour intervals, the bacterial flora count was re-evaluated for three consecutive days. The egg whites as pasteurized in accordance with Examples 1, k and 8 indicated a decrease in bacterial flora count while all the other pasteurized egg whites indicated an increase in bacterial flora count.

Claims (1)

1. What is claimed is: 1. A process for pasteurizing egg .whites comprising the steps of: (a) raising the pH of the egg whites about 0.5 to 1.5 units above the natural pH; catalase^ (b) heating said egg whites to inactivate the indigen (c) adding a responsive amount of a peroxide material to said egg whites; Xd) reheating said egg whites to pasteurize them, 2. The process as set forth in Claim -1, wherein the pH of said egg whites is raised with a food grade alkaline material. 3. The process as set forth in Claim 2, wherein said alkaline material may be selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium hydroxide, calcium hydroxide, sodium phosphate, sodium bicarbonat and mixtures thereof. k. The process as set forth in Claim 1, wherein said between about 100°p egg whites are heated to a temperature θί-ϋ§ to 130°F. to inacti the indigenous catalase. 5, The process as set forth in Claim h, wherein said heat is maintained for a period of from 0.5 to 5 minutes. 6. The process as set forth in Claim 1, wherein said peroxide is present in an amount ranging between 0.01 and 1.5$ Τ· The process as set forth in Claim 1, wherein said, reheating temperature may range between.115 and 150°F. 8. The process as set forth in Claim 7, wherein said reheating temperature is maintained for a period of from 0, to 5 minutes. 9· The process as set forth in Claim 1, together with the additional steps of cooling said egg whites and readjusting the pH thereof to its natural level.