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