Determination of fruit content in strawberry jam on the basis of analyses
of selected chemical markers
Objectives
• to resume the chemometric methods for the fruit content determination in strawberry jams
• to optimise the method of HPLC determination of strawberry anthocyanidins
Czech legislation
Law No 634/1992 on protection of consumerLaw No 110/1997
Decree 332/1997 (Novelised version 92/2000)
defines weigh part of fruit
jam extra - 450 g fruit per 1kg product
jam common - 350 g fruit per 1kg product
strawberry jam (single sort) – 400 g fruit per 1kg product
minimal refractive solid content
strawberry jam – 60%
sterilized strawberry jam – 50%
low-energy jam – max. 40%
refractive solid refractometer
K, malic and citric acid capillary isotachophoresis, electrophoresis
phosphor spectrophotometry
formol number according to RSK
sucrose, glucose, fructose and sorbitol
HPLC
anthocyanidins spectrophotometry
Markers and methods
1 57.1 16.3 20.1 20.7 1.0 - 622.2 119.4 49.8 11.2 11.2 61.1 1.0 45.02 44.8 21.7 12.5 10.7 1.2 - 656.8 117.4 48.0 12.0 5.5 60.5 7.6 50.03 38.4 7.7 15.2 15.3 1.0 0.2 601.4 252.5 52.7 10.1 15.0 40.9 3.9 50.04 3.7 1.3 0.9 1.5 0.6 - 490.8 307.7 149.5 27.9 7.8 8.5 20.4 100.05 55.8 5.6 24.9 25.2 1.0 - 790.8 94.9 57.6 13.6 5.9 60.6 2.0 50.0
sam
ple
suga
r g/
100g
suc.
g/1
00g
glu.
g/1
00g
fru. g
/100
g
glu:
fru
sorb
. g/1
00g
citr.
ac.
m
g/10
0g
anth
. spe
ctr
mg/
100g
Fn m
l0.1
mol
Na
OH/1
00 m
l
fruit
cont
ent
per 1
00g
prod
uct b
y gi
ven
prod
ucer
g
mal
. ac.
m
g/10
0g
K m
g/10
0g
P m
g/10
0g
Rf °B
rix
Result and discussion
Sample: 1 – sterilized strawberry jam2 - strawberry jam3 - low-energy jam4 – strawberry5 - home-made jam
marker range averagesugar 2.81 – 9.81 g/100g 6.45 g/100gsucrose 0.2 – 1.3 g/100g 1.01 g/100gglucose 1.8 – 3.2 g/100g 2.49 g/100gfructose 1.7 – 2.3 g/100g 2.19 g/100gsorbitol - -citric acid 600 – 1100 mg/100g 816 mg/100gmalic acid 90 – 300 mg/100g 185.4mg/100g
K 147 – 166.4 mg/100g 155.5 mg/100gP 23 – 35 mg/100g 28.3 mg/100gformol number 8 – 13 ml0.1 molNaOH/100ml 10.5 ml0.1 molNaOH/100ml
anthocyanidins 23.4 – 24.2 mg/100g 23.8 mg/100g
Strawberry (data from literature)
Values calculate on 100% fruit content
Rf °Brix
citr. ac. mg/100
g
mal. ac. mg/100
g
K mg/100
g
P mg/100
g
Fn ml0.1mol NaOH/100
ml
Sorb g/100g
anth. spectr mg/100
g
1 61.1 1382.7 265.3 110.7 25 24.9 2.32 60.5 1313.6 234.8 96 24 11 15.23 40.9 1202.8 505 105.4 20.2 30 0.4 7.74 8.5 490.8 307.7 149.5 27.9 7.8 20.45 60.6 1581.6 189.8 115.2 27.1 11.8 4
Many factors affecting the accuracy of fruit content estimation
variability of raw material change during processing and storage analytical methods
product prescription (e.g. addition of acid)
Method for determination anthocyanidins by HPLC conditions of HPLC method column : NOVA – PAK R C18, 4 μm 3.9 mm x 300mmmobil phase : water : acetonitrile : formic acid (81 : 9 : 10 v/v)flow rate : 1ml/mininjection : 20 μldetection : 525 nmcalibration : external standard (pelargonidine chloride)
Sample preparation
sample mixture with solution (methanol : acetic acid : water 25 : 1 : 24)
filtration vacuum evaporation hydrolysis (HCl)
purifying of sample on the cartridge SEP-PAC C18
vacuum evaporation dissolve sample and determination on HPLC
Result and discussion
- variability of raw material- strawberry cultivar- physiological state of plant and fruit- agriculture conditions - anthocyanidins are quite unstable
affecting factors
Affect many factors for determination of anthocyanidins
- structure of molecule - presence of some enzymes - pH- temperature- oxygen presence- irradiation- some substances influence anthocyanidins´ colour (e.g. ascorbic
acid, SO2, phenols)
Conclusions
continue with collecting of an other kinds of samples and their measuring trying to use some another markerstrying to optimise a method for a measuring of content of anthocyanidins
Thank you for your attention
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