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WO1992017766A1 - 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
WO1992017766A1
WO1992017766A1 PCT/FI1992/000099 FI9200099W WO9217766A1 WO 1992017766 A1 WO1992017766 A1 WO 1992017766A1 FI 9200099 W FI9200099 W FI 9200099W WO 9217766 A1 WO9217766 A1 WO 9217766A1
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WIPO (PCT)
Prior art keywords
fat
approx
absorption
milk
carbon
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Ceased
Application number
PCT/FI1992/000099
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English (en)
Inventor
Lauri Jalkanen
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Individual
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Individual
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Publication date
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Publication of WO1992017766A1 publication Critical patent/WO1992017766A1/fr
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Classifications

    • 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 C-H absorption peak is located at a highly inconvenient place on the slope of a strong absorp ⁇ tion peak of water, where it is difficult to distinguish.
  • Fur ⁇ thermore as the composition of milk, i.e. the amounts of fat, proteins, lactose, minerals, and other constituents, varies, the proportion of water in the sample subject to determination is not always precisely known, and this may cause in the result an uncontrolled error which is further multiplied in the cor ⁇ rections calculated for proteins and lactose.
  • Another error source which hampers especially the use of the C-H bond is the scatter occurring in the sample alongside IR absorption.
  • the scatter caused by fat particles strongly affects the signals to be registered and thereby disturbs the determination of fat when the wavelength of the absorption peak corresponds to the diameter of the particles or is smaller than it.
  • the di ⁇ ameter of the fat particles in raw milk is in the order of 0.5- 5 urn, it follows from this that scatter strongly disturbs C-H bond absorption occurring at a wavelength of 3.5 ⁇ , unless the fat particles can be reduced to a diameter clearly below 3.5 ⁇ m in a homogenization before fat determination.
  • the mean diameter of the fat particles may be at maximum 2 ⁇ m, and usually the IR analyzers used for milk fat determina ⁇ tions are indeed equipped with homogenizers by means of which the fat particles can be chopped to the size level mentioned.
  • the opera ⁇ tion of the homogenizers gradually deteriorates so 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 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 disadvantages based on the use of the C-H bond are avoided.
  • the method according to the invention is characterized in that the determination is made from an absorption peak of fat-molecule carbon-carbon bonds at a wave number of approx. 1440 (1/cm).
  • the C-C bond absorption peak, at a wave number of approx. 1440, corresponding to a wavelength of approx. 7.0 ⁇ m, used according to the invention is located in the IR absorption spectrum at a place substantially more advantageous for analysis than the absorption peak of the C-H bond.
  • the absorption of water does not disturb the measurement, and therefore the reading of the absorbance of the peak is easier.
  • the peak yields a more reli ⁇ able determination result, which is not dependent on the amount of water in the sample.
  • the wavelength of the absorption peak, 7.0 ⁇ m is also clearly greater than the maximum diameter, approx.
  • the method according to the invention is relatively insensitive to errors due to the scatter of light.
  • the method thus yields a result in the correct direction even if the homogenization of the milk sample is deficient or is not done at all, albeit that in order to obtain precise results the homogenization of the sample to an average particle size pref ⁇ erably less than 3.0 ⁇ m continues to be recommended.
  • it is a significant advantage in the invention that, owing to lesser scatter, the proportion of the change in ab ⁇ sorption to the change in concentration is, especially at higher fat concentrations, greater than in the C-H absorption peak; this signifies a correspondingly improved determination precision.
  • the absorption peak of the C-C bond is being measured, regardless of the type of the emulsion, it is preferable to measure the absorption spectrum over a somewhat wider range, for example a wave number range of approx. 1380-1440, from which there is obtained the necessary reference wavelength, th absorption of which is subtracted from the absorption peak obtained.
  • the milk is first heated to 40 °C and mixed carefully in order to obtain as representative a sample as possible for the analysis. Homogenization is then carried out, whereafter the sample is analyzed by measuring its IR absorption at the desired wave ⁇ lengths.
  • the sample is analyzed by measuring its IR absorption at the desired wave ⁇ lengths.
  • it is pos ⁇ sible to measure the characteristic absorption peak, at a wave number of approx. 1550, of the protein present in the milk and the characteristic absorption peak, at a wave number of approx.
  • the method according to the invention can also be used for measuring emulsions containing other fats, such as vegetable fats.
  • the determination of the fat concentrations of such emulsions may be in practice sim ⁇ pler, since the compensations due to other constituents, neces sary in the case of milk, are not necessary.
  • Figure 1 depicts an infrared absorption spectrum of full milk (fat concentration 3.4 %) measured by means of a Mattsson FTIR spectrometer within a wavelength range of approx. 3.0-10 ⁇ m (wave number range of approx. 1000-3000),
  • Figure 2 depicts an infrared absorption spectrum measured from the same full milk by means of the same spectrometer within a wave number range of approx. 1000-3000, the effect of the water in the background having been eliminated.
  • Figure 3 depicts an IR absorption spectrum measured in accor ⁇ dance with Figure 2 from a milk sample having a fat concentra ⁇ tion of lower than 0.05 %
  • Figure 2 the absorption spectrum of which was measured from the same sample of full milk as was the spectrum according to Figure 1, shows the absorption peaks 1-4 produced by the dif ⁇ ferent bonds of the fat molecule without the disturbing back ⁇ ground effect of water.
  • the curve contains an absorption peak 5 due to the peptide bond of proteins at a wave number of approx. 1550 and an absorption peak 6 due to lactose at a wave number of approx. 1050.
  • Figure 3 the absorption spectrum of which was measured from a milk sample containing fat less than 0.05 %, the absorption peaks 1-4 due to fat bonds are clearly lowered as compared with the peaks in Figure 2, whereas the peaks 5 and 6 of lactose are substantially un ⁇ changed.
  • curve 7 depicts the dependence of absorbance on the fat concentration in the sample at the absorption peak of the C-C bond
  • curve 9 the dependence of absorbance on the fat concentra ⁇ tion at the absorption peak of the C-H bond.
  • the fat con ⁇ centration in the milk is determined from the C-C bond absorp ⁇ tion peak at a wave number of 1440, seen in Figures 2 and 3, by subtracting from this the absorption at a reference wavelength of approx. 1380, and by calculating the fat concentration using a formula having the form
  • the fat concentration is calculated using a formula having the form:

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Analytical Chemistry (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analysing Materials By Optical Means (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 technique 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 d'émulsion. L'essence de l'invention réside dans le fait qu'à un nombre d'ondes d'environ 1440 (1/cm) la pointe de la courbe d'absorption des liaisons carbone-carbone des molécules de graisse est utilisée pour réaliser lesdites déterminations. Lorsque les déterminations sont pratiquées sur du lait ou sur un produit laitier, l'effet, sur ladite pointe de la courbe, des protéines et du lactose présents dans le lait est défini en mesurant les pointes d'absorption caractéristiques desdites substances et en effectuant, sur la base des valeurs mesurées, une compensation de la valeur de la concentration de graisses indiquée par la pointe d'absorption de la liaison carbone-carbone. Dans ce cas, la détermination peut être basée sur un spectre d'absorption infrarouge continue, mesuré dans une fourchette de nombre d'ondes comprise entre environ 1050 et 1550.
PCT/FI1992/000099 1991-04-05 1992-04-03 Procede de determination quantitative des graisses presentes dans une emulsion contenant des particules de graisse Ceased WO1992017766A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI911654 1991-04-05
FI911654A FI87837C (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
WO1992017766A1 true WO1992017766A1 (fr) 1992-10-15

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PCT/FI1992/000099 Ceased WO1992017766A1 (fr) 1991-04-05 1992-04-03 Procede de determination quantitative des graisses presentes dans une emulsion contenant des particules de graisse

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FI (1) FI87837C (fr)
WO (1) WO1992017766A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102866126A (zh) * 2011-07-05 2013-01-09 重庆华邦制药股份有限公司 一种定量测定化合物中晶型比例的方法

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 (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102866126A (zh) * 2011-07-05 2013-01-09 重庆华邦制药股份有限公司 一种定量测定化合物中晶型比例的方法
CN102866126B (zh) * 2011-07-05 2016-03-23 重庆华邦制药有限公司 一种定量测定化合物中晶型比例的方法

Also Published As

Publication number Publication date
FI87837B (fi) 1992-11-13
FI87837C (fi) 1993-02-25
FI911654A0 (fi) 1991-04-05

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