Instruments to estimate natural juices in nectars

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Transcript Instruments to estimate natural juices in nectars

Instruments used for the
estimation of natural juices in
nectars –
Estimation of fruit content in fruit
nectars
Martin Kubík
Czech Agricultural and Food
Inspection Authority (CAFIA)
Workshop on Estimation of Natural Juices in Nectars,
Cairo, Egypt
10 - 11 November 2014
1
Why to measure fruit content?

To ensure compliance with current
(EU) legislation
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QUID requirements
General rules on labelling and
advertising
Specific requirements e.g. Fruit Juice
Directive
To help the consumer make better
food choices
2
In which products?
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
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fruit nectars- 25 – 50% fruit juice
fruit drinks – 5 -90% fruit juice
applicable (after consideration) to
other fruit and vegetable products
e.g. jams, preserves etc.
The calculation of the fruit juice content based on
analysis of the fruit nectars and drinks is an
important part of the authenticity control.
3
How to measure fruit content?

The basic approach :

Identify one or several “index-constituent(s)”
specific to a particular type of fruit

Determine the concentration of each indexconstituent in the product under investigation

Compare this concentration with that expected
for the pure fruit
J.F. Kelford, Analytical Problems with Fruit Products.
Food Preservation Quarterly 29, 65-71, 1969
4
How to measure fruit content
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Ideal properties for “index-constituent” :
Easy to measure with adequate accuracy
Present only in an fruit to be measured
Analyte in the ingredient is subject to very little
natural variation
Analyte level is unaffected by food processing
Is sufficiently rare or expensive that is unlikely to be
added
5
How to measure fruit content
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Ideal “index-constituent” is not always available
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Concentration in known constituents is influenced by
many factors:
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Variety
Maturity
Growing area
Climate
Fertilization

Irrigation
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Specific markers can be influenced by processing
techniques

Interference of other components in a complex food
matrix
6
How to measure fruit content
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Selection of the „best“ possible “indexconstituent (s)”
usually:
relevant and reliable authentic parameters as
established in the Code of Practice (AIJN) for juice
from one kind of fruit
Not all parameters can be used in general as a result
of interference caused by the use resp. addition of
- water used for dilution containing minerals as
sodium, calcium …
- sugars containing glucose, fructose, sucrose
- acids as citric acid, malic acid, …
- declared or undeclared fruit
7
How to measure fruit content
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Currently used “index-constituent” for fruit
juice content determination (do not interfere
with the water used or with the allowed
ingredients ):
Fruit acids (malic, isocitric, quinic, tartaric
shikimic…)
Minerals (K, Mg, P, Mn..)
Amino acids (formol number, proline..)
Flavonoides, sugars (alcoholic sugars),
anthocyanins, carotenoids….
8
How to measure fruit content

2 possible situations
1. composition of raw material is known (analytical
results available or raw material available)
Not common situation - calculation of fruit content
quite easy – just simple comparing results from raw
material (fruit juice) and product (e.g. nectar) and
calculation.
RISK
- raw material available is not really identical to raw
material used for manufacturing
- raw material is not authentic 100% juice
WRONG RESULTS
9
How to measure fruit content
2 possible situations
2. no exact knowledge about composition of
raw material just information from the label
e.g. „50% of fruit juice“
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10
How to measure fruit content
- calculation models
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several calculation models could be find in literature
for limited range of fruit
most of them based on calculation from analytical
results of chosen parameters in product of interest
and mean values from databases sometimes
including a so-called weighting coefficient
If the beverage contains more than one juice, or juice has been
added to acidifying or the problem for calculation is more
complex
11
How to measure fruit content
- calculation models
results from various models do not differs dramatically
up to 5%
but
undeclared fruits in case of adulteration or undeclared or
declared fruit for highlighting of colour (e.g. red beet
concentrate or elderberry concentrate) could have influence on
some parameters and be taken into account so e.g. suspicious
or outlined results is necessary to eliminate before calculation

knowledge about composition of possible ingredients is
esential
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12
How to measure fruit content
- influence of ingredients
1% of Tri potassium citrate increases level of K for
3600 mg/kg
 chokeberry increases level of sorbitol
 elderberry increases level of isocitric acid
detection via anthocyanins profile
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addition of synthetic malic acid – detection via
fumaric acid
13
How to measure fruit content
- calculation models examples
Early attempts
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1940 : Hinton and Macara. The Composition of some
Jam Fruits and the Determination of the Fruit Content
of Jams
1949 : Steiner …. 1965 : Nehring and Klinger
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Combination of two or three index constituents in a linear
equation to give fruit content
Ingredient content = a1X11 + a2X12 + a3X13
where X1j is the analytical determination and aj is an
appropriate factor
Most common index-constituents
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Ash, potassium, phosphate
14
How to measure fruit content
- calculation models examples
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•
orange nectar/drink (1):
Gesellschaft Deutscher Chemiker/GDCh, Flüssiges
Obst 6, 1979)
orange juice content (%)
potassium (analyzed) mg/l
phosphate (analyzed) mg/l
proline (analyzed) mg/l
formol number (analyzed)
L-malic acid (analyzed) mg/l
D-isocitric acid (analyzed) mg/l
=
x 20/1750
x 20/460
x 20/750
x 15/18
x 15/1500
x 10/90
+
+
+
+
+
15
How to measure fruit content
- calculation models examples

•
orange nectar/drink (2):
Bielig/Hofsommer (Technical University Berlin, privat,
1983)
orange juice content (%)
potassium mg/l
phosphate mg/l
proline mg/l
formol
L-malic acid mg/l
D-isocitric acid mg/l
=
x 15/1900
x 20/460
x 20/800
x 20/20
x 10/1700
x 15/90
+
+
+
+
+
16
How to measure fruit content
- calculation models examples

•
orange nectar/drink (3):
Ooghe (Zeitschrift für Lebensmittel-Untersung und –
Forschung 1990:191)
orange juice content (%)
potassium mg/l
D-isocitric acid mg/l
L-lysine mmol/l
L-arginine mmol/l
=
x 25/1900
x 25/90
x 25/0,19
x 25/3,11
+
+
+
17
How to measure fruit content
- calculation models examples
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•
orange nectar/drink (4):
Czech Agriculture and Food Inspection Authority
(CAFIA)
orange juice content (%)= average of following results:
potassium mg/l
x 100/1900
magnesium mg/l
x 100/115
phoshorus mg/l
x 100/163
formol number
x 100/20,5
L-malic acid mg/l
x 100/1900
D-isocitric acid mg/l
x 100/100
ash g/l
x 100/3,5
18
How to measure fruit content
- calculation models examples
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Comparison of the results obtained using
different formulas:
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sample - orange nectar (50% of orange juice
declared)
•
•
GDCh
Bielig/Hofsommer
CAFIA
– 56,7 %
– 53,9 %
– 52,7 %
•
Max diference
4%
•
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How to measure fruit content
- calculation models examples
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apple nectar/drink (1):
• Koch (Flüssiges Obst 2, 1980)
apple juice content (%)
potassium mg/l
phosphate mg/l
ash g/l
=
x 33,3/1175
x 33,3/200
x 33,3/2,5
+
+
20
How to measure fruit content
- calculation models examples

•
apple nectar/drink (2):
Gesellschaft Deutscher Chemiker/GDCh,
Lebensmittelchemie und gerichtliche Chemie 36, 1982)
apple juice content (%)
potassium mg/l
phosphate mg/l
sorbitol mg/l
L-aspartic acid mg/l
=
x 35/1150
x 35/210
x 10/4000
x 20/100
+
+
+
21
How to measure fruit content
- calculation models examples
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•
apple nectar/drink (3):
Bielig/Hofsommer (Technical University Berlin, privat,
1983)
apple juice content (%)
potassium mg/l
phosphate mg/l
sorbitol mg/l
L-asp+ser+asn+glu+ala mmol/l
=
x 35/1150
x 35/200
x 10/3000
x 20/3,32
+
+
+
22
How to measure fruit content
- calculation models examples

•
apple nectar/drink (4):
Czech Agriculture and Food Inspection authority
(CAFIA)
orange juice content (%)= average of following results:
potassium mg/l
x 100/1200
magnesium mg/l
x 100/58
phosphorus mg/l
x 100/58
formol number
x 100/6,5
L-malic acid mg/l
x 100/3000
ash g/l
x 100/2,7
sorbitol g/l
x 100/4,75
(phloridzin mg/l
x 100/32)
23
How to measure fruit content
- calculation models examples
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•
grapefruit nectar/drink:
Gesellschaft Deutscher Chemiker/GDCh, Flüssiges
Obst 12/1981)
grapefruit juice content (%)
=
potassium mg/l
phosphate mg/l
proline mg/l
formol number
D-isocitric acid mg/l
x 20/1400
x 20/370
x 10/450
x 30/19
x 20/200
+
+
+
+
24
How to measure fruit content
- calculation models examples

•
lemon nectar/drink (1):
Gesellschaft Deutscher Chemiker/GDCh, Flüssiges
Obst 12/1981)
lemon juice content (%)
potassium mg/l
phosphate mg/l
proline mg/l
formol number
L-malic acid mg/l
D-isocitric acid mg/l
=
x 20/1400
x 20/350
x 10/400
x 15/17
x 10/2700
x 25/250
+
+
+
+
+
25
How to measure fruit content
- calculation models examples

•
lemon nectar/drink (2):
Ooghe (Zeitschrift für Lebensmittel-Untersung und –
Forschung 1990:191)
lemon juice content (%)
potassium mg/l
D-isocitric acid mg/l
L-asparagine mmol/l
total amino acids mmol/l
=
x 25/1420
x 25/355
x 25/4,05
x 25/19,1
+
+
+
26
How to measure fruit content
- calculation models examples
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•
passionfruit nectar/drink:
Rother/Gesellschaft Deutscher Chemiker/GDCh, 1989,
not published)
passionfruit juice content (%)
potassium mg/l
phosphate mg/l
formol number
L-malic acid mg/l
D-isocitric acid mg/l
L-aspartic acid mg/l
=
x 20/2900
x 10/580
x 20/32
x 10/2900
x 20/270
x 20/930
+
+
+
+
+
27
How to measure fruit content
- calculation models examples

•
apricot nectar/drink :
Wallrauch/Gesellschaft Deutscher Chemiker/GDCh,
1987, not published)
apricot juice content (%)
potassium mg/kg
magnesium mg/kg
formol number
L-malic acid g/kg
citric acid g/kg
D-isocitric acid mg/kg
sorbitol g/kg
=
x 15/2800
x 20/95
x 20/26
x 5/8
x 5/8
x 20/110
x 15/4
+
+
+
+
+
+
28
How to measure fruit content
- calculation models examples
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•
strawberry nectar/drink :
Wallrauch/Gesellschaft Deutscher Chemiker/GDCh,
1987, not published)
strawberry juice content (%)
potassium mg/kg
magnesium mg/kg
formol numbrer
L-malic acid g/kg
phosphate g/kg
D-isocitric acid mg/kg
=
x 20/1650
x 25/110
x 5/12
x 10/2,1
x 15/620
x 25/47
+
+
+
+
+
29
How to measure fruit content
- calculation models examples
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•
cranberry nectar/drink :
E. Coppola, 4th European Symposium on Food
Authenticity, Nantes, 1997
cranberry juice content (%) = (%)= average of following
results:
quinic acid %
malic acid %
citric acid %
x 100/1,06
x 100/0,78
x 100/1,06
Additional requirements:
No sorbitol or fumaric acid, Glu/Fru ratio always > 1,8, four major
anthocyanins
30
How to measure fruit content
- calculation models examples
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multifruit nectars/drinks
2 kinds of fruits - some rough calculation possible
necessary to find parameters which are present in one
fruits and not in the other
e.g.
combination strawberry x apple
sorbitol and phloridzin present in apple but not present
in strawberry
isocitric acid present in strawberry but not present in
apple
only some combination of fruits are possible
generally – lack of specific parameters
more fruits - impossible
31
How to measure fruit content
- other techniques
o FT IR
• Quantitative method using simple linear regression and
PLS analysis
• Showed determination of fruit content feasible in
strawberry jam
• Wilson et al., Food Chemistry, 47 (3), 303-306, 1993.
o DNA
• Quantitation of the fruit species in a product requires
availability of selective oligonucleotides (PCR primers and
hybridisation probes).
• the accuracy of the method is affected by :
• Quality of DNA (DNA degradation!)
• PCR inhibitors present in the matrix
• DNA extraction efficiency
32
How to measure fruit content
- other techniques
o on the basis of hemicellulose (apricot
strawberry) –specificity?
Uncertainty of fruit content
estimation
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every laboratory method has some
uncertainty
in case of fruit content 2 sources of
uncertainty
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methods of measurement
variability of fruit
In case of more parameters used for calculation
some elimination of uncertainties
 result ± 10% abs. 50% (40% – 60%) Knechtel,
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EQCS-Workshop 2005
result ± 20-25% rel. CAFIA
Recommendations
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Calculation models have to be used with
expertise
The whole analytical picture has to be
considered
Consider elimination of obvious
outliers
On basis of selected reliable
authentic parameters calculationmodels for other fruits can be
developed
35
Thank you for your attention
36