GROWTH – DEDICATED CALL – 1/00
TOPIC III.18
Determination of the Milk Fat Content of Mixed Spreadable Fats
1. CONFORMITY WITH THE WORK PROGRAMME
This topic falls under the Competitive and Sustainable Growth Programme, generic
activity Measurement and Testing. Specifically, it is related to Objective GROW-20006.2.2 Measurement and Testing anti-fraud methodologies for which expressions of
interest have been called.
2. KEYWORDS
Spreadable fats, milk fat, vegetable fats, fat mixtures, quantification of mixture
components, chromatography, spectroscopy, multivariate data evaluation.
3. SUMMARY OF OBJECTIVES AND JUSTIFICATION
This research is required to enforce Council Regulation 2991/94, which stipulates that
the milk fat content of mixed spreadable fats, i.e. spreads containing vegetable and dairy
fat in varying proportions, has to be labelled. At present, no generally accepted test
method exists for this purpose. The project proposed is aimed at developing and
validating a method to monitor label conformity of fat blends with respect to their milk
fat content, thereby (a) satisfying the right of consumers for information, (b) protecting
consumers against fraud, (c) providing reliable evidence for successful prosecution of
unscrupulous manufacturers, and (d) supporting the development and implementation of
anti-fraud regulations.
In the EU the spreads market is a high volume business and could therefore be the target
of a minority of unscrupulous manufactures, ready to increase their profits by
“economic adulteration”. Since milk fat is more expensive than other commodities, a
considerable risk exists that mixed spreadable fats contain a smaller proportion of milk
fat than declared. The established method currently used by law enforcement authorities
relies on the determination of butyric acid, a unique constituent of milk fat. However,
the butyric acid concentration of genuine milk fat varies considerably, thus creating
large uncertainties when it is solely used as an indicator for the milk fat content in a fat
blend.
4. BACKGROUND
Whenever the price is high for a certain product and low for another group of different
but otherwise related items, a distinctive incentive exists for the unscrupulous
manufacturer to blend the cheaper product into the higher priced commodity to reduce
costs and improve profits. Moreover, if blends between the two commodities are
legalised, a strong need exists to verify the correct labelling of the blend by analytical
techniques to protect consumers from fraudulent malpractice.
DC 1/00/Topic III.18/ Pg 2
According to article 3 of Council Regulation 2991/94 the milk fat content of mixed
spreadable fats has to be labelled, as milk fat is the most expensive ingredient in the
blend. Traditionally, the butyric acid content is used for the quantification of milk fat in
mixtures. This approach is seriously hampered by the natural variation of this
component, and deviations of up to 10 % from the known milk fat content of fat blends
might occur when the milk fat used in preparing the blend is not available for analysis
(Molkentin and Precht, 1998). In addition, butyric acid is somewhat difficult to analyse
and quantify due to its volatility. The influence of varying butyric acid contents can be
countered by obliging manufacturers to archive a sample of the milk fat used for
formulating the blend, and making this sample available to control authorities upon
request. However, the EU Expert Group on Milk and Milk Products (DGVI/D.1)
identified two critical points when applying the butyric acid procedure: (i) definition of a
“suspected” sample, i.e. a sample with a lower than expected butyric acid content, and (ii)
possible manipulation of the composition of the archived milk fat component sample.
Several Member States oppose this approach, because the complicated logistics required
for handling the archived samples could seriously obstruct intra-Community trade.
The International Dairy Federation has also published a method for the determination of
milk fat in mixtures (Muuse and Martens, 1993). Provided that the fat mixture as well as
the mixture components are available, the milk fat content can be computed, but
repeatability values were rather poor (ranging from 5 % to 9 %).
Over the recent years, high-performance analytical techniques (gas-liquid
chromatography, high performance liquid chromatography, and various spectroscopic
techniques like infrared, nuclear magnetic resonance and mass spectrometry) advanced
the accumulation of considerable qualitative as well as quantitative knowledge about the
chemical constituents (fatty acids, triglycerides, partial glycerides, fat-soluble vitamins,
sterols) of natural fats and oils. The statistical evaluation of these data by sophisticated
computing procedures proved to be a versatile tool for tracing down fat mixtures. Most
of the statistical techniques employed (Principal Component Analysis, Linear
Discriminant Analysis, Artificial Neural Networks) are qualitative in nature, i.e. they
are aimed at grouping samples into several possible classes, thus allowing to judge
whether are a sample is authentic or not (Ulberth, 1994). A few quantitative approaches
based on Multivariate Linear Regression Analysis, Partial Least-Squares Regression
Analysis and Linear Programming of fat constituents have also been described in order
to develop calibration models for the estimation of the composition of fat mixtures (de
Jong and de Jonge, 1991; Precht, 1992; Ulberth, 1995; Lipp, 1996). In general,
promising results were obtained. The difference between experimentally found and true
values for the milk fat content in blends varied around 1 % (absolute). However, none
of the multivariate methods mentioned has been challenged, extensively tested, and
their performance validated with fat mixtures containing between 10 % and 80 % milk
fat, the lower and upper limits of the milk fat content in mixed spreadable fats (Council
Regulation 2991/94). The rigorous assessment of the efficiency of these novel
approaches, taking into account the natural compositional variation of the raw materials,
and their translation into a robust testing method suitable for routine laboratories is
therefore urgently needed.
DC 1/00/Topic III.18/ Pg 3
De Jong, S., de Jonge, T.J.R. (1991) Computer assisted fat blend recognition using
regression analysis and mathematical programming. Fat Sci. Technol. 93: 532536
Lipp, M. (1996) Comparison of PLS, PCR and MLR for the quantitative determination
of foreign oils and fats in butter fats of several European countries by their
triglyceride composition. Z. Lebensm. Unters. Forsch. 202: 193-198
Molkentin, J., Precht, D. (1998) Precision of milk fat quantitation in mixed fats by
analysis of butyric acid. Chromatographia 48: 758-762
Muuse, B., Martens, R. (1993) Mixtures of milkfat with non-milkfat – determination of
the milkfat content. IDF Bulletin 285: 65-69
Precht, D. (1992) Detection of foreign fat in milk fat. II. Quantitative evaluation of
foreign fat mixtures. Z. Lebensm. Unters. Forsch. 194: 107-114
Ulberth, F. (1994) Detection of milk fat adulteration by linear discriminant analysis of
fatty acid data. J. AOAC Internat. 77: 1326-1334
Ulberth, F. (1995) Quantitation of foreign fat in foreign fat/milkfat mixtures by
multivariate regression analysis of fatty acid data. J. Agric. Food Chem. 43: 1556-1560
5. ECONOMIC AND SOCIAL BENEFITS
The development and enforcement of food standards has gained increasing importance
within the EU and is of direct concern to European citizens. One main positive impact
of this proposal on society will be to help increase consumer protection within the EU.
A scientifically well founded testing method which enables the enforcement of Council
Regulation 2991/94 will benefit consumers, who can be better protected against
potential malpractice of unscrupulous manufacturers of mixed spreadable fats.
Moreover, a standardised testing method will also be advantageous for the dairy as well
as for the fats and oils industry, since it will help fight unfair competition. Likewise,
effective testing of the milk fat content will foster the trustworthy of European suppliers
and vendors of mixed spreads in other markets, thus increasing competitiveness of the
European industry.
Unless there is a harmonised testing method available in the EU, significant differences in
the results obtained by food control authorities in the Member States could arise, and may
therefore necessitate costly re-testing. It is thus essential for this proposal to be conducted
at the Community level.
6. SCIENTIFIC AND TECHNOLOGICAL OBJECTIVES
The ultimate aim of the project is to develop, document and validate by an
interlaboratory study a methodology, which allows a reliable quantification of milk fat
in mixed spreadable fats. In particular, the technical objectives could be:
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to select constituents of milk fat and non-milk fats (fatty acids, triglycerides, partial
glycerides, components of the unsaponifiable matter) which could serve as potential
predictor variables for the calculation of the milk fat content in spreadable fats
to develop and/or improve existing analytical methods based on chromatographic
(GLC and HPLC) or spectroscopic (IR, NMR, MS) or other appropriate principles
for the determination of these predictor variables
to ascertain the fitness-for-purpose (accuracy, precision and ruggedness) of the
developed analytical tools to ensure that the data produced can stand up to scrutiny
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to study the natural compositional variation (seasonal, production system, climate,
and geographic origin) of the selected fat constituents on the Community level
to correlate the analytically determined amount of the predictor variable(s) to the
true milk fat content in model milk fat/non-milk fat mixtures using advanced
statistical techniques (multiple linear regression analysis, partial least-squares
analysis, or other suitable techniques) and develop calibration models for fat blends
containing between 10 % and 80 % milk fat, taking into account the natural
compositional variation of the ingredients
to compare the performance of different computational routines implemented in
commercial statistical software packages for modelling calibration functions
to ring-test the finally selected method
to write the standardised method in CEN-style format
The project should be organised along individual workstreams, i.e. partners with high
expertise in a particular analytical technique should develop and document suitable
analytical tools and the one best suited for the purpose should be collaboratively tested
and adopted as standard method.
New findings should be actively promoted through publications in scientific journals
and presentations at conferences and exhibitions. Moreover, compositional data of
spreadable fats and its constituent ingredients should be made available to interested
parties in form of an electronic database with access via the Internet.
7. TIME SCALE
Since Council Regulation 2991/94 is already in force and no efficient testing method for
law enforcement is available at present, the availability of a validated procedure at the
earliest moment possible would be highly welcomed by food control authorities, the oils
and fats industry and consumers.
The work load to be carried out under the project would justify a duration of three years.