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WO1992017767A1 - Procede de determination quantitative des graisses presentes dans une emulsion contenant des particules de graisse - Google Patents

Procede de determination quantitative des graisses presentes dans une emulsion contenant des particules de graisse Download PDF

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Publication number
WO1992017767A1
WO1992017767A1 PCT/FI1992/000100 FI9200100W WO9217767A1 WO 1992017767 A1 WO1992017767 A1 WO 1992017767A1 FI 9200100 W FI9200100 W FI 9200100W WO 9217767 A1 WO9217767 A1 WO 9217767A1
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WIPO (PCT)
Prior art keywords
fat
milk
approx
absorption peak
absorption
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Ceased
Application number
PCT/FI1992/000100
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English (en)
Inventor
Lauri Jalkanen
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Individual
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Individual
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Publication of WO1992017767A1 publication Critical patent/WO1992017767A1/fr
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/02—Food
    • G01N33/04—Dairy products
    • G01N33/06—Determining fat content, e.g. by butyrometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3577—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing liquids, e.g. polluted water

Definitions

  • the present invention relates to a method for quantitative determination of fat in an emulsion which contains fat par ⁇ ticles, in which method the infrared absorption of the emulsion sample is measured and the fat is determined on the basis of a specific absorption peak in the absorption spectrum by elimi ⁇ nating from it any error effect possibly caused by the other constituents of the emulsion.
  • the principal targets of quantitative fat determinations are milk and products made from milk.
  • the natural fat concentration in milk is usually within the range 3.0-5.5 %, but the fat concentrations in different milk products may vary from close to 0 to more than 40 %. Measurement of the fat concentration is required as a basis for the milk price to be paid to the pro ⁇ ducer and additionally in the quality control of products pre ⁇ pared from milk.
  • the determination of the fat concentration in milk on the basis of the absorption of the C-H bond does, however, involve prob ⁇ lems which are more difficult than the above-mentioned computa ⁇ tional correction of the error caused by proteins and lactoses.
  • the first problem to be mentioned is that the error-causing milk constituents which contain C-H bonds are by no means lim ⁇ ited to proteins and lactose; dozens of them are present in milk, at concentrations which vary with great random. Some of such constituents are vitamins, nucleic acids, esters of or ⁇ ganic acids, lactones, amino acids, amines, and cholesterol.
  • the concentrations of these substances are dependent, among other things, on the breed and state of health of the cow, on its feed, which varies from one season to another, and on the condition of the sample at the time of the analysis, which is dependent on the storage of the sample.
  • the concentration of each individual substance in milk remains usually so low that taking it into account in the determination of fat in the same manner as proteins and lactose is not possible in practice, but the combined total concentration of these substances in milk may rise up to 0.1 %, and in poorly stored samples even higher than this, in which case they will cause an error of a cor ⁇ responding order of magnitude in the fat concentration calcu ⁇ lated from the C-H absorption peak.
  • a further error source which hampers the use of the C-H bond is the scatter occurring in the sample alongside IR absorption.
  • the scatter caused by fat particles is inversely proportional to the fourth power of the wavelength used, and is additionally dependent on the ratio of the wavelength to the diameter of the fat particles in such a manner that, when the wavelength in ⁇ creases to a value higher than the particle diameter, the scat ⁇ ter rapidly decreases to an insignificant level. Scatter thus constitutes a problem in milk fat determination when the wave ⁇ length of the absorption peak used corresponds to or is smaller than the diameter of the particles.
  • the diameter of the fat particles in raw milk is in the order of 0.5-5 ⁇ m, it fol ⁇ lows from this that scatter strongly disturbs C-H bond absorp ⁇ tion occurring at a wavelength of 3.5 ⁇ m, unless the fat par ⁇ ticles can be reduced to a diameter clearly less than 3.5 ⁇ m, preferably to a diameter less than 2 ⁇ m, in a homogenization before the fat determination. Therefore it is stated in the above-mentioned EP patent publication 0012492 that the mean diameter of the fat particles may be at maximum 2 ⁇ m, and usually the IR analyzers used for milk fat determinations are indeed equipped with homogenizers by means of which the fat particles can be chopped to a size range of 0.5-1.5 ⁇ m.
  • the homogenizer is subject to gradual wear, whereby the dimensions of its mechanical parts are changed and its operating capacity deteriorated to the point that, with time, more and more poorly homogenized milk samples, containing also fat particles larger than 2 ⁇ m in diameter and giving erroneous results, arrive in the measuring cuvette.
  • the problem could be in part diminished by, for example, homogeniz ⁇ ing the sample several times, but this would lower the analyzer capacity to such an extent that the system is not practicable.
  • the object of the present invention is to provide a new method for quantitative determination of fat by an infrared absorption technique in which the above-mentioned problem of scatter and also the disadvantages associated with the use of the C-H bond are avoided.
  • the method according to the invention is charac ⁇ terized in that the determination is made from an absorption peak, at a wave number of approx. 1160-1190 (1/cm), of the single carbon-oxygen bonds (C-O) of the ester groups of the fat molecules.
  • the wave number, approx. 1160-1190, of the IR absorption peak used in accordance with the invention corresponds to a wave ⁇ length of approx. 8.4-8.6 ⁇ m, which is so much above the maxi ⁇ mum size, approx. 5 ⁇ m, of fat particles that scatter will no longer affect the result of the determination.
  • the measurement can be performed from raw milk, in which mere careful mixing suffices for providing a representa ⁇ tive sample.
  • the IR analyzer may be simpler in structure than previously.
  • a homogenizer typically made up of a hole and a ball spring-actuated against it, and the high-pressure pump required for it, can be omitted, and a conventional pump oper ⁇ ated at low pressures suffices for the feeding in of the sample.
  • the apparatus is simplified, also its maintenance requirement is reduced, and as the problems due to the wear of the homogenizer have been eliminated, the results obtained are more reliable than previously.
  • the absorption peak, at a wavelength of approx. 1160-1190, of the C-O bond, used according to the invention, is located in the IR absorption spectrum at a place considerably more ad ⁇ vantageous with respect to the absorption of water than is the absorption peak of the C-H bond.
  • the reading of the peak is there ⁇ fore easier and the determination result obtained is not de ⁇ pendent on the amount of water present in the sample.
  • the C-O absorption peak used is highly specific with respect to fat.
  • milk or milk products do not contain any constituents having a single C-O bond other than fat.
  • a reference wave number which may be, for example, a wave number of approx. 1200 or approx. 1300- 1350. For this reason it may be preferable to measure a con ⁇ tinuous infrared absorption spectrum within a somewhat wider wave number range, such as a range of approx. 1160-1350.
  • Figure 1 depicts an infrared absorption spectrum of full milk (fat concentration 3.4 %) measured by means of a Mattsson FTIR spectrometer within a wave number range of approx. 1000-3000, and
  • Figure 2 depicts an infrared absorption spectrum of the tri ⁇ glyceride ester of oleic acid, measured by means of the same spectrometer within a wave number range of approx. 1000-3000.
  • the absorption peak of the C-OH bond of lac ⁇ tose at a wave number of approx. 1050 is indicated in Figure 1 by reference numeral 5.
  • the concentration of fat in milk is determined from the absorption peak of the single C-O bond, seen in Figure 1 within a wave number range of 1060-1090, by subtracting from this the absorption at the ref ⁇ erence wave number, which may be, for example, the wave number 1200, and by calculating the fat concentration by using a formula having the form
  • the lactose correction coefficient by which the absorbance of the peak 5 is multiplied and then added to the fat concen ⁇ tration calculated from the C-O absorbance peak 4, is 0.203.
  • the following table shows the fat concentrations determined from 10 different milk samples on the basis of the absorption peaks of different bonds in the fat molecule, in each case as the mean of 100 successive individual absorbance measurements. For comparison, each sample was measured both after homogenizer treatment and unhomogenized.
  • results show that, when the determination is based on the absorption peak of the single C-O bond, the values obtained for the fat concentration within the framework of the reading pre ⁇ cision of the apparatus are the same regardless of whether or not the sample has been homogenized before the absorption meas ⁇ urement. In practice the results shows that the homogenization of a sample of raw milk is unnecessary in the method according to the invention.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Food Science & Technology (AREA)
  • Analytical Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Dairy Products (AREA)

Abstract

L'invention concerne un procédé de détermination quantitative des graisses présentes dans une émulsion contenant des particules de graisse, par exemple du lait ou un produit laitier. Le procédé fait appel à une tehnique d'absorption infrarouge dans laquelle la détermination est basée sur une valeur d'absorption de pointe spécifique constatée dans le spectre d'absorption de l'échantillon de l'émulsion. L'essence de l'invention réside dans le fait qu'à un nombre d'onde d'environ 1160-1190 (1/cm) la pointe de la courbe d'absorption des liaisons uniques carbone-oxygène des groupes ester des molécules de graisse est utilisée pour réaliser ladite détermination. Lorsque les déterminations sont pratiquées sur du lait ou sur un produit laitier, l'effet du lactose peut, si on le souhaite, être pris en compte en mesurant la pointe d'absorption caractéristique du lactose et en effectuant, sur la base de celle-ci, une correction de la valeur de la concentration de graisses indiquée par la pointe d'absorption de la liaison carbone-oxygène. Comme la diffusion des valeurs n'affecte pas la pointe d'absorption de la liaison C-O, les déterminations selon l'invention peuvent être réalisées directement en utilisant du lait entier, sans traitement d'homogénéisation préalable.
PCT/FI1992/000100 1991-04-05 1992-04-03 Procede de determination quantitative des graisses presentes dans une emulsion contenant des particules de graisse Ceased WO1992017767A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI911655 1991-04-05
FI911655A FI87838C (fi) 1991-04-05 1991-04-05 Foerfarande foer kvantitativ bestaemning av fett fraon en emulsion som innehaoller fettpartiklar

Publications (1)

Publication Number Publication Date
WO1992017767A1 true WO1992017767A1 (fr) 1992-10-15

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001004612A3 (fr) * 1999-07-09 2001-07-19 Foss Electric As Procede determinant le contenu d'un composant dans un echantillon de fluide et appareil a cet effet
AT408376B (de) * 1999-04-07 2001-11-26 Lendl Bernhard Dr Verfahren zur infrarot-optischen bestimmung der konzentration zumindest eines analyten in einer flüssigen probe
RU2205382C2 (ru) * 1995-04-06 2003-05-27 Альфа Лаваль Агри Аб Способ и устройство для количественного определения частиц в жидких средах
WO2005036181A1 (fr) * 2003-10-17 2005-04-21 Alberta Research Council Inc. Procede de caracterisation d'une dispersion a l'aide de techniques de transformation
EP1710556A2 (fr) 1995-04-06 2006-10-11 DeLaval Holding AB Procédé et appareil de détermination quantitative de particules dans des fluides
WO2012072143A1 (fr) 2010-12-03 2012-06-07 Foss Analytical A/S Analyse spectrale de l'infrarouge central d'un matériau hétérogène en écoulement
WO2021186421A1 (fr) * 2020-03-20 2021-09-23 Perkinelmer Health Sciences B.V. Détection de composition de fluides non homogénéisés

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4076983A (en) * 1975-08-04 1978-02-28 Sir Howard Grubb Parsons & Company Ltd. Analysis of emulsions and suspensions
US4247773A (en) * 1978-12-06 1981-01-27 A/S N. Foss Electric Method for quantitatively determining fat in a fat-containing sample
US4310763A (en) * 1979-10-15 1982-01-12 John Shields Electro-optical analyzer for measuring percentage by weight of fat, protein and lactose in milk
US4447725A (en) * 1981-06-15 1984-05-08 Biggs Delmar A Quantitative measurement of fat, protein and lactose in dairy products
EP0122749A1 (fr) * 1983-04-05 1984-10-24 Shields Instruments Limited Mesure de graisse

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4076983A (en) * 1975-08-04 1978-02-28 Sir Howard Grubb Parsons & Company Ltd. Analysis of emulsions and suspensions
US4247773A (en) * 1978-12-06 1981-01-27 A/S N. Foss Electric Method for quantitatively determining fat in a fat-containing sample
US4247773B1 (fr) * 1978-12-06 1983-08-09
US4310763A (en) * 1979-10-15 1982-01-12 John Shields Electro-optical analyzer for measuring percentage by weight of fat, protein and lactose in milk
US4447725A (en) * 1981-06-15 1984-05-08 Biggs Delmar A Quantitative measurement of fat, protein and lactose in dairy products
EP0122749A1 (fr) * 1983-04-05 1984-10-24 Shields Instruments Limited Mesure de graisse

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2205382C2 (ru) * 1995-04-06 2003-05-27 Альфа Лаваль Агри Аб Способ и устройство для количественного определения частиц в жидких средах
EP1710556A2 (fr) 1995-04-06 2006-10-11 DeLaval Holding AB Procédé et appareil de détermination quantitative de particules dans des fluides
AT408376B (de) * 1999-04-07 2001-11-26 Lendl Bernhard Dr Verfahren zur infrarot-optischen bestimmung der konzentration zumindest eines analyten in einer flüssigen probe
WO2001004612A3 (fr) * 1999-07-09 2001-07-19 Foss Electric As Procede determinant le contenu d'un composant dans un echantillon de fluide et appareil a cet effet
WO2005036181A1 (fr) * 2003-10-17 2005-04-21 Alberta Research Council Inc. Procede de caracterisation d'une dispersion a l'aide de techniques de transformation
WO2012072143A1 (fr) 2010-12-03 2012-06-07 Foss Analytical A/S Analyse spectrale de l'infrarouge central d'un matériau hétérogène en écoulement
WO2021186421A1 (fr) * 2020-03-20 2021-09-23 Perkinelmer Health Sciences B.V. Détection de composition de fluides non homogénéisés

Also Published As

Publication number Publication date
FI87838B (fi) 1992-11-13
FI911655A0 (fi) 1991-04-05
FI87838C (fi) 1993-02-25

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