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 consumer Law No 110/1997 Decree 332/1997 (Novelised version 92/2000) defines weigh part of fruit jam extra g fruit per 1kg product jam common 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 solidrefractometer K, malic and citric acid capillary isotachophoresis, electrophoresis phosphorspectrophotometry formol numberaccording to RSK sucrose, glucose, fructose and sorbitol HPLC anthocyanidinsspectrophotometry Markers and methods

Result and discussion Sample: 1 – sterilized strawberry jam 2 - strawberry jam 3 - low-energy jam 4 – strawberry 5 - home-made jam

Strawberry (data from literature)

Values calculate on 100% fruit content

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 300mm mobil phase : water : acetonitrile : formic acid (81 : 9 : 10 v/v) flow rate : 1ml/min injection : 20 μl detection : 525 nm calibration : 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 C 18 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, SO 2, phenols)

Conclusions continue with collecting of an other kinds of samples and their measuring trying to use some another markers trying to optimise a method for a measuring of content of anthocyanidins

Thank you for your attention