EP2179283A1 - Procédé de détermination de substances amères dans la bière ou le moût de brasserie - Google Patents

Procédé de détermination de substances amères dans la bière ou le moût de brasserie

Info

Publication number
EP2179283A1
EP2179283A1 EP08784377A EP08784377A EP2179283A1 EP 2179283 A1 EP2179283 A1 EP 2179283A1 EP 08784377 A EP08784377 A EP 08784377A EP 08784377 A EP08784377 A EP 08784377A EP 2179283 A1 EP2179283 A1 EP 2179283A1
Authority
EP
European Patent Office
Prior art keywords
beer
bitter substances
fluorescence
sample
lanthanide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08784377A
Other languages
German (de)
English (en)
Inventor
Ronald Eberl
Jürgen Wilke
Beatrix Parthey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hochschule Anhalt (FH)
Original Assignee
Hochschule Anhalt (FH)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hochschule Anhalt (FH) filed Critical Hochschule Anhalt (FH)
Publication of EP2179283A1 publication Critical patent/EP2179283A1/fr
Withdrawn legal-status Critical Current

Links

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
    • G01N33/14—Beverages
    • G01N33/146—Beverages containing alcohol

Definitions

  • the invention relates to a method for the determination of bitter substances in beer and beer wort.
  • This method includes both the qualitative determination, i. the detection, and the quantitative determination, i. the measurement of the concentration of bitter substances in beer and wort, a.
  • bitterness is one of the essential quality parameters of beer, which is also perceived and evaluated by consumers.
  • the characteristic bitter taste is caused primarily by the so-called iso-acids (IAS), which are formed during the boiling of the wort from the added Hopfendolden or hop products.
  • IAS isoacids
  • IAS have an influence on the shelf life or stability of beer and the characteristic of a long-lasting froth, which many consumers appreciate.
  • IAS isoacids
  • the concentration of isoacids (IAS) and thus the bitterness of the beer depends not only on the amount of starting materials (the alpha acids), but also, for example, on the temperature-time regime of wort preparation and fermentation, the pH value. Value, the concentration of other substances and the refining and filtering process.
  • the first method is based on the extraction of the bitter substances from the acidified sample with isooctane, a non-polar, water-immiscible liquid. After vigorous shaking of the two liquids and the separation of the aqueous and the isooctane phase, the extinction of the isooctane phase is measured with the aid of a quartz glass cuvette in the ultraviolet (UV) wavelength range.
  • UV ultraviolet
  • this method is mandatory under the analytical regulations of the German (MEBAK), European (EBC) and American (ASBC) brewery associations.
  • WO 2005/045421 A1 includes the qualitative determination of bitter substances in beer or intermediate products of beer production by means of UV / VIS spectroscopy. Bittern content can not be directly determined from the UV / VIS absorbance measurement, as the bitterness contributes less than 1% to the total absorption and its spectrum is greatly overshadowed by other UV / VIS absorbents.
  • the composition of the material matrix and thus also its influence on the measurement varies between the different beers in some cases very strong, but also in one and the same beer it comes through the influence of process variables and the natural variation of the vegetable source materials to different matrix signals.
  • the very small proportion of bitter substances in the total signal should be able to be separated according to the teaching of WO 2005/045421 A1 by means of chemometric methods.
  • DE 10233077 A1 discloses a rapid detection of beer and hop bitter substances in a liquid with the aid of carrier systems, the carrier systems being brought into contact either with or without pretreatment with an analyte.
  • the analyte is isolated thereon or in it.
  • the evaluation is carried out with a reagent integrated in the carrier material or a subsequent reaction step by means of optical methods.
  • the support systems consist of a porous matrix, such as a polymer, in which sorptive and reactive particles, for example of silicic acid-based material, are incorporated, or to which a coating which has been added with a silica material is applied.
  • silicic acid-based polymer materials are intended to impart the desired specific absorption properties to the carrier system.
  • the reagent required for detection can either be integrated directly into the carrier material or used in a subsequent step, the reagent consisting inter alia of a salt of the lanthanides dysprosium, samarium, europium or terbium.
  • the reagent consisting inter alia of a salt of the lanthanides dysprosium, samarium, europium or terbium.
  • this method too complicated and costly for an intended online application.
  • the object underlying the invention is to provide a cost-effective method that allows both the qualitative and a quantitative online determination of bitter substances in beer and wort.
  • the object of the invention is achieved by a method for the determination of bitter substances in beer or wort, which is based on the measurement of visible fluorescent light, which is emitted by the relevant bitter substances in the presence of certain lanthanide ions upon irradiation with ultraviolet light.
  • the sample is diluted to strong and added a specifically acting auxiliary reagent.
  • the concept of the invention consists in attenuating the disturbing matrix effects on the fluorescence light measurements by dilution so that their influence on the measurement result can be neglected.
  • J.B. Tomlinson et al. Journal of the Institute of Brewing, Vol. 101, 1995, pp. 113-118.
  • the causes of the serious differences between the measurements in pure IAS solutions and beer were examined in more detail. It turned out that the material matrix of the beer actually plays a key role here.
  • the influence of the matrix is mainly due to the strong absorption of the excitation radiation and not due to the absorption of the emitted radiation, as erroneously in J.B. Tomlinson et al., Journal of the Institute of Brewing, Vol. 101, 1995, pp. 113-118.
  • the emitted fluorescence is measured at an angle of 90 ° to the excitation beam. This is generally based on highly diluted solutions whose absorption at the wavelength of the excitation radiation is negligible.
  • the method of "front face fluorescence" is used, as in the measurement methods according to JB Tomlinson et al., Journal of the Institute of Brewing, Vol. 101, 1995, pp 113-118 and Christensen et al , Journal of the Institute of Brewing, Vol. 111, 2005, pp.
  • the sample is diluted according to the invention.
  • the absorptive influence of the matrix weakens with increasing dilution, so that at a sufficiently high dilution the influence of the matrix is sufficient. che ⁇ d can suppress.
  • the concomitant reduction in the fluorescence intensity can be compensated by a corresponding sensitivity of the measuring arrangement. Measurements of low fluorescence intensities (and thus correspondingly low fluoride concentrations) can be realized with relatively little effort with today's device technology. Surprisingly, however, it has been shown in the present case that the measurement of the fluorescence of low fluorophore concentrations has no non-limiting limits.
  • Added lanthanide ions and a small amount of one or more certain auxiliary reagents which on the one hand induces the formation of bitter lanthanide complexes at low concentrations and on the other hand increase the fluorescence by increasing the quantum yield, 3. measures the resulting fluorescence, and 4. from the measured value via a simple, preferably linear relationship determined the desired bitter value.
  • organic compounds such as trioctylphosphine oxide (TOPO) and compounds of the compound classes organic phosphates and / or sulfoxides use.
  • TOPO trioctylphosphine oxide
  • compounds of the compound classes organic phosphates and / or sulfoxides use.
  • lanthanides are europium (Eu), dysprosium (Dy), terbium (Tb) and / or samarium (Sm).
  • the dilution of the sample is preferably carried out in a volume ratio of 1:20 to 1: 500.
  • the auxiliary reagent is added simultaneously with the dilution of the sample.
  • FIG. 1 the representation of the fluorescence of IAS solutions different
  • FIG. 2 shows the representation of the fluorescence signals of 20 different beer samples measured according to the invention as a function of the actual IAS contents
  • FIG. 3 shows the representation of the IAS concentrations of 20 beer samples determined according to the invention from the fluorescence signals as a function of the actual IAS concentrations.
  • sample solutions for fluorescence measurement will first be described with reference to the following exemplary embodiment. From 20 different types of beer (pils), 100 ml were taken and degassed by the action of ultrasound (2 min). 1 ml each of the samples was diluted 1: 250 with water. 1 ml of the diluted sample was pipetted into a fluorescence cuvette. Another pipette was used to add 100 ⁇ l of a 20 mM dysprosium (Dy) -
  • the substance to be measured is separated from the sample by chromatography and its concentration is determined using a suitable detector, in this case a UV detector.
  • a suitable detector in this case a UV detector.
  • a standard substance with a precisely known concentration of the substance sought is then analyzed. From the comparison of the two detector signals, the sought concentration can be determined.
  • IAS iso-alpha-acids
  • Fig. 1 includes a graph showing the fluorescence of IAS solutions of different concentrations prepared similarly as in the previous procedure.
  • europium (Eu) ions were added as lanthanide ions.
  • the values obtained without the addition of auxiliary reagents and those of the samples in which trioctylphosphine oxide (TOPO) was used as an additional auxiliary reagent can be compared with one another at specific concentration values using the diagram. It shows at the lower concentration values below the threshold concentration of about 5 mg / l IAS, that there without Addition of the auxiliary reagent which returns fluorescence scores close to zero. This strong and nonlinear decrease in fluorescence is due to inhibition of complex formation.
  • the addition of trioctylphosphine oxide (TOPO) abolishes this inhibition and, as is clear from FIG. 1, leads to the occurrence of evaluable linear concentration-dependent fluorescence signals even in these areas of low concentration of IAS.
  • FIG. 2 shows the results of the fluorescence measurement as a function of the values of the reference method (HPLC).
  • the line is the result of a linear regression of the measured values.
  • the statistical evaluation gives a linear correlation coefficient of 0.945 and a standard deviation of the regression line of 1.7 mg / l.
  • FIG. 3 shows the relationship between the IAS concentrations determined on the basis of fluorescence and those analyzed by means of HPLC in the examined samples.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

L'invention concerne un procédé de détermination de substances amères dans la bière et le moût de brasserie. Ce procédé repose sur la mesure de lumière fluorescente visible émise par les substances amères d'intérêt en présence de certains ions de lanthanoïdes lorsqu'elles sont éclairées par de la lumière ultraviolette. Le procédé se caractérise par une forte dilution de l'échantillon et par l'ajout d'un ou plusieurs réactifs auxiliaires déterminés qui induisent la formation, normalement inhibée, de composés complexes d'ions de lanthanoïdes et de substances amères et renforcent ainsi de manière sélective la fluorescence mesurable de ces complexes.
EP08784377A 2007-07-28 2008-07-23 Procédé de détermination de substances amères dans la bière ou le moût de brasserie Withdrawn EP2179283A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200710035561 DE102007035561B3 (de) 2007-07-28 2007-07-28 Verfahren zur Bestimmung von Bitterstoffen in Bier oder Bierwürze
PCT/DE2008/001197 WO2009015640A1 (fr) 2007-07-28 2008-07-23 Procédé de détermination de substances amères dans la bière ou le moût de brasserie

Publications (1)

Publication Number Publication Date
EP2179283A1 true EP2179283A1 (fr) 2010-04-28

Family

ID=40040078

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08784377A Withdrawn EP2179283A1 (fr) 2007-07-28 2008-07-23 Procédé de détermination de substances amères dans la bière ou le moût de brasserie

Country Status (3)

Country Link
EP (1) EP2179283A1 (fr)
DE (1) DE102007035561B3 (fr)
WO (1) WO2009015640A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111257487B (zh) * 2020-01-17 2022-09-09 广州南沙珠江啤酒有限公司 一种果啤快速分类鉴别方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10233077A1 (de) * 2002-07-19 2004-01-29 Nitzsche, Frank, Dr. Verfahren zum Nachweis bestimmter Stoffe oder Stoffgruppen mittels sorptiver und reaktiver Teilchen in poröser Matrix, direkter oder anschließender selektiver Komplexierung und optischer Auswertung
DE10360302A1 (de) * 2003-12-20 2005-07-21 Ronald Dr. Eberl Verfahren zum Nachweis von Bitterstoffen in Bier oder Bierwürze

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2009015640A1 *

Also Published As

Publication number Publication date
DE102007035561B3 (de) 2009-03-19
WO2009015640A1 (fr) 2009-02-05

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