US3628916A

US3628916A - Determining the fat content of milk

Info

Publication number: US3628916A
Application number: US790931A
Authority: US
Inventors: Hanne Werner
Original assignee: N Foss Electric AS
Current assignee: N Foss Electric AS
Priority date: 1968-01-17
Filing date: 1969-01-14
Publication date: 1971-12-21
Anticipated expiration: 1988-12-21
Also published as: GB1259691A

Abstract

A batch of an oil-in-water emulsion such as milk or a milklike substance is stabilized by the addition of a viscosity increasing agent, a portion of the batch is analyzed to determine the fatty content thereof and the remainder of the stabilized batch is then utilized as a reference standard for checking and calibrating apparatus which is used to determine the fatty content of such emulsions by the light transmission characteristics thereof.

Description

0 Unite m States Patent:

[72] Inventor Hanne Werner Helsingor, Denmark [2!] Appl. No. 790,931 [22] Filed Jan. 14, 1969 [45] Patented Dec. 21,197] [73] Assignee N. Foss Electric AIS l-lillerod, Denmark [32] Priority Jan. 17, 1968 [33] Denmark [3| 154/68 [54] DETERMINING THE FAT CONTENT OF MILK 3 Claims, 2 Drawing Flgs.

I52] U.S.Cl 23/23], 99/54, 99/60, 99/15 I [SI] Int. Cl G0ln 33/04, A23c 3/08 [50] Field of Search 99/54, 60,

[56] References Cited UNITED STATES PATENTS 2,568,369 9/l95l Scholz 99/130 2,844,067 7/l958 Borg 23/23l 3,054,678 9/1962 Michencr et al... 99/l5l X 3,404.987 l0/l968 Kooistra et al 99/l5l X 3,434,846 3/l969 Scott 99/54 X FOREIGN PATENTS 609,282 I l/l960 Canada 99/54 Primary Examiner Lionel M. Shapiro Assistant ExaminerD. M. Nalf Attorney-Lackenbach & Lackenbach ABSTRACT: A batch of an oil-in-water emulsion such as milk or a milklike substance is stabilized by the addition of a viscosity increasing agent, a portion of the batch is analyzed to determine the fatty content thereof and the remainder of the stabilized batch is then utilized as a reference standard for checking and calibrating apparatus which is used to determine the fatty content of such emulsions by the light transmission characteristics thereof.

PATENTED M82119?! 3,628,916

A .5 r 3% N3 BY Ma ATTORNEYS DETERMINING THE FAT CONTENT OF MILK This invention relates to a preparation for controlling and adjusting an apparatus of the type used for determining the fatty content of an oil-in-water emulsion by measuring the physical properties of the emulsion such as sound or light transmission, a process for preparing said preparation, and a method for its application.

The known art comprises apparatus which determine the fatty content of an oil-in-water emulsion by measuring the physical properties of the emulsion such as sound or light transmission, but generally such apparatus are not stable over prolonged periods and require control and adjustment from time to time. Up to now this control has required complicated and time-consuming laboratory methods, and the adjustment could not therefore be made continuously, which has reduced the applicability of the apparatus.

The air of the present invention is to provide a preparation having stabilized physical properties, which preparation, after determination of its fatty content in an accurately adjusted apparatus or by conventional analytic methods, can be used for continuous control and adjustment or other similar apparatus.

This has been achieved by the preparation according to the invention which consists of an oil-in-water emulsion admixed with a stabilizing agent for maintaining the emulsified state.

As the said apparatus are usually intended for determining emulsions of a certain type and would render inaccurate results for emulsions of different types the preparation according to the invention may advantageously contain an emulsion of the same type as normally determined in the apparatus.

As stabilizing agent may be used any agent capable of main taining the emulsion in a stable state at room temperature and below, but which may be restored to the normal liquid state of the emulsion, for instance by changing the pH value of the preparation or by heating. According to the invention the preparation may conveniently contain a gelling agent of the type which causes the preparation to set at room temperature and below but restores the normal liquid state of the emulsion on being heated. Examples of such gelling agents are gelatine, carrageenanes, pectins, and agar-agar.

According to the invention gelatine has proved particularly suitable as gelling agent, as the preparation made therewith possesses a good gel consistency without any tendency to separation of liquid and after heating to melting temperature has a consistency approximately like that of the original emulslon.

The present invention is particularly intended for use in connection with the apparatus for rapid determination of the fatty content of milk developed by applicants in the present application and sold under the name of Milko-Tester. The determination of the fatty content in a Milko-Tester is based on the ability of the milk-fat globules to diffuse and absorb part of the light transmitted through a milk sample. The principle of determining the fatty content is a measurement of the amount of light capable of penetrating a milk sample homogenized and diluted with a special liquid containing inter alia protein-dissolving tetrasodium salt of ethylene diamine tetraacetate (trade name: Versene). The more fat globules the milk contains the more the light will be diffused. By measuring the light transmitted through milk samples whose protein has been dissolved values are obtained which bear a certain relation to the fatty content of the milk sample. The principal reason why this relation is not complete is the phenomenon known from homogenized milk wherein the finely divided fat globules make the milk whiter in color because the many minute fat globules of the homogenized milk cause a greater diffusion of light than the smaller number of large fat globules of the nonhomogenized milk, and therefore milk samples having the same fatty content will produce different results when measured by light transmission where the size distribution of the fat globules varies. To equalize this source of error the milk is homogenized in four steps in the Milko-Testen The actual measuring of the light transmitted through the prehomogenized and diluted milk samples takes place while the samples pass a cuvette which is hit by light having a wavelength of about 600 nm. The penetrating light is registered by a photoelectric cell connected to a galvanometer wherein the scale is divided directly into fat percent.

A disadvantage in using the Milko-Tester is that previously it was not possible to control accurately and rapidly whether the reading of the apparatus was correct. The only possibility of control was to determine by traditional analytic methods the fatty content of a selection of the milk samples analyzed by the Milko-Tester.

For several reasons this method is inexpedient. The traditional analytic methods are laborious, and it requires time before the results are available. The Ross-Gottlieb method produces the most accurate results, but they are not available until the day after the analysis has been commenced. The results cannot therefore be used for a continuous control or adjustment, but only for correction of the previous day's Milko-Tester results. The Gerber method is less accurate, but the results are available substantially earlier and may therefore be used for a fairly reliable adjustment and current control of the Milko-Tester. Both methods require skilled staff and extensive laboratory equipment, which is unfortunate as the very idea of the Milko-Tester was to avoid this. Finally, as a disadvantage should be mentioned the necessity of using a comparatively large number of milk samples for controlling the Milko-Tester.

One embodiment of the preparation according to the invention has proved to be particularly suitable for rapid control and adjustment of the Milko-Tester. As the preparation in many respects was to act as a milk sample it was natural to base it on milk. As gelling agent gelatine was found to be particularly advantageous as its gelling ability is completely neutralized at temperatures above about 40 C., so that the preparation may without difficulty pass through the Milko- Tester, which itself heats the milk to 60 C. In accordance herewith a specific embodiment of the preparation according to the invention is characterized in that is consists of milk wherein at least 0.5 percent by weight of gelatine is dissolved.

To make the preparation resistant to microbiological decomposition it may expediently contain preservatives. Among the preservatives sodium benzoate alone was found to be in capable of giving the preparation adequate keeping qualities. It was then tried to use also a substance having a strong bacteriostatic activity. According to the invention it has been found to be particularly expedient together with the benzoate to use a quaternary ammonium compound, for instance alkyldimethylbenzylammonium chloride (trade name: Rodalon) in a concentration of about 0.1 percent active substance in the preparation.

The preparation according to the invention may generally be prepared by a process which according to the invention is characterized in that an oil-in-water emulsion is admixed with a stabilizing agent dissolved in the emulsion during heating, whereupon the mixture is cooled to form a gel.

For preparing the particular embodiment of the preparation especially suitable for controlling and adjusting the Milko- Tester milk is used as emulsion and gelatine as stabilizing agent. A preferred embodiment of the process according to the invention is characterized in that milk is heated to about 40 C. or above whereupon at least 0.5 percent by weight of gelatine is added while stirring and the solution formed is hottled if desired after filtration.

With a view to the keeping qualities of the preparation it has furthermore been found to be expedient to subject the milk to low-temperature pasteurization and, to prevent the fat from rising during the pasteurization, to start with a mild homogenization of the milk.

The application of the preparation according to the invention for controlling and adjusting for instance the Milko- Tester may be carried out as follows:

A few bottles of each production are drawn for determining the value which it is desired to obtain for the contents of each bottle from the production in the Milko-Tester. The selected 3 4 bottles are placed in a water bath at 40 C. until the gel has readings on the Milko-Tester were taken 2, 3, 5, 7, l2, 14, 20, melted (about minutes), whereupon the contents of each and 26 days after preparing the two batches of the preparabottle is measured 2 or 3 times on a correctly operating Milkotion. 'lestcr. The average value is calculated, and the other bottles Of the four Milko-Tester results of each bottle the first one from the production are marked with this value. The accurate 5 was discarded with a view to possible errors due to carryovers. determination of the contents may, if desired, be made by The averages ofthe other three results are listed in table l.

using one of the conventional analytic methods.

The other bottles may now be used for controlling and ad- TABLE 1 uatmg other Mllko-Testers. The method is the following: Average of the Milko -rester results for W0 batches of A bottle is placed in a water bath as described above, and 2 preparation each kept in homes for difierem periods of time or 3 readings are taken on the Milko-Tester to be controlled. at

Number of days stored 2 3 5 7 ll H Batch 1: Average of individual bottles. 3. 6!! 3. 67 3. 65 3.66 3. 65 3.66 3.61 3. 64 3. 65 3.63 3.63 3.63 3.65 3.63 3.64 3. 6'. 3.63 3. 64 3.63 3.62 3.65 3.65 3. 64 3.62 3.66 3.64 3.67 3.64 3.64 3.66 3.63 3.67 3.64 3.63 3.66 3. 64 3.65 3.63 3. 64 3.64 3.64. 3.66 3.63 3.64 3.63 3.65 3.65 3.64. 3.63 3.63 3.63 3.65. .364. .3.65 3.66.. 3.63 3.67 3.64 3.65

Daily average 3.65 3. 65 3.64 3.65 3.64 3. 65 3. 64

Batch 2zAvsrage0i1ndividual b0ttles.... 4.01 4.02 4.00 4.00 4.01 4.02 4.02 3. 99 4.02 4.00 4.00 4.00 4.00 4. 02

Dally average... .000 4.01 4.00 4.00 4.00 4. 00 4.00 4.00 If the average result differs from the value stated on the bot- As appears from the table, the stress has been on determinatles, this variation may be used as correction for the results of tions shortly after and l, 2, and 3 weeks after the preparation the milk samples, and the Milko-Tester may be adjusted to of the batches. The additional samples were used for suppleshow the value stated. mentary measurings. The daily average is plotted in respectively FIG. 1 and FIG. 2 of the drawing, and it will be seen that EXAMPLE the variations are very small and occur within a very restricted Prepaflng the Preparation! interval, and the preparation must therefore be considered very stable after storage at 8 C. for more than 3 weeks.

To get an idea of the variation from bottle to bottle a calculation was made of the standard deviation from respectively the daily and the total average for the days where readings were taken of many bottles, and for all the bottles from each batch collectively. These results are listed in table 2.

l: 12 liters of cold milk are admixed with 3 grams of sodium benzoate per liter.

2: The milk is heated to 50 C. and homogenized at at least 50 atm.

3: Low-temperature pasteurization (30 minutes at 63 C.).

4: The 40-50 C. warm milk is admixed with 20 grams of gelatine per liter. Stirring.

5: Filtration through a fine-mesh strainer. TABLE 2 6: Gradual admixture during stirring of ml. 2 percent 50 Average values and corresponding standard deviations cal Roclalon (or other quaternary ammonium compound). l fid n th basis of table TABLE 2. AVERAGE \ALUEB ANI) CORRESPONDING STANDARD DE- vlATmNs CALCULATED ()N THE BASIS OF TABLE 1 Number of days stored 7 All 2 7 14 20 results First IJHLI'II 0054:0021 0054:0015 3. 0540. 012 3. 64*0. 015 3. 64:0. 017 Slt'Olld butt-h a. 004:0. 020 4.0040. 011 4.00:0.018 4.00;i;0.016 4 00:0.010 7: Tapping into bottles of 200 ml. Table 2 shows that the standard deviation is between one and 8: Cooling in a water bath to 8-l0C. Cool storage. Notes: 60 two hundredths percent of fat, which is within the standard Raw milk of good bacteriological quality is used. It is impordeviation for repeated measurings of the same milk sample tant that the admixture of Rodalon takes place gradually and with the Milko-Tester. Therefore there has been no significant during stirring as otherwise precipitation may occur in the difference between the results of the individual bottles from milk. 65 the same batch of preparation.

Testing the preparation The testing did not include examinations of the keeping To test the suitability of the preparation for controlling and qualities of the Preparation when at tampemmles adjusting the Milko-Tester it was examined whether a series of above but the stability of the gel "P to melting poi"t different samples from the same production were so uniform at and the effect of the Preservation made it P d k so ll h aft r storage f diff r t i d f time ble that the samples would withstand storage for a shorter or they would give the same reading on the Milka-Tester. For the longer Period of time also tempermllles above testing two separate batches of the preparation were prepared No attempts were made to determine the fatty content of according to the above directions and each tapped into 60 200 the preparation by the traditional analytic methods, and it is ml. bottles. probably inadvisable to employ these methods for determining At few days intervals a number of bottles from each batch the values desired for the samples of the preparation on the were taken out from the cool store. After melting the gel four Milko-Testel' as h m g niz milk amples are known to readings of each bottle were taken on the Milko-Tester. The Produce MilkWTeSlel' results which iff r f m he Corresponding results of the Gerber and Rose-Gottlieb determinations. The safest method of determining the values desired for the preparation on the Milka-Tester will therefore be the method according to the directions stated.

The testing proved that by following the directions it was possible to prepare series of samples which were so uniform and kept so well when stored at 8 C. that the samples showed the same result on the Milko-Tester more than three weeks after their preparation.

Later two batches of preparation were prepared by a procedure differing slightly from the aforesaid, namely in that the admixture of Rodalon was made first simultaneously with the admixture of benzoate, and the low-temperature pasteurization was performed last on the filled and sealed bottles. This amended procedure should have no effect on the results rendered by the preparation on the Milka-Tester, but should improve its resistance to microbial decomposition. Bottles from the said batches were stored for four months at room temperature with no visible signs of any change.

We claim:

1. Method of calibrating an apparatus for determining the fatty content of milk by measuring light transmission therethrough comprising preparing a mixture of milk and approximately one-half to two percent gelatin, dividing said mixture into a plurality of samples, subjecting a number of said samples to an accurate determination of the fatty content thereof, marking the remaining number of said samples with the fatty content determined from said accurate detennination, and calibrating such apparatus by measuring the light transmission through at least one of said marked samples.

2. Method defined in claim 1 further comprising heating said marked samples to recover the normal liquid state of the mixture before measuring the light transmission therethrough to calibrate the apparatus.

3. Method of preparing a sample for calibrating an apparatus for determining the fatty content of milk by measuring light transmission therethrough comprising, preparing a mixture of milk and approximately one-half to two percent gelatin, dividing said mixture into a plurality of samples, subjecting a number of said samples to an accurate determination of the fatty content thereof and marking the remaining number of said samples with the fatty content determined from said accurate determination.

i i t i

Claims

2. Method defined in claim 1 further comprising heating said marked samples to recover the normal liquid state of the mixture before measuring the light transmission therethrough to calibrate the apparatus.
3. Method of preparing a sample for calibrating an apparatus for determining the fatty content of milk by measuring light transmission therethrough comprising, preparing a mixture of milk and approximately one-half to two percent gelatin, dividing said mixture into a plurality of samples, subjecting a number of said samples to an accurate determination of the fatty content thereof and marking the remaining number of said samples with the fatty content determined from said accurate determination.