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7. Opublikowane badania własne

l.iUnu 118 <2015' W-70

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Prediction of the hydrophilic antioxidant capacity of tomato pastes from the IR and fluorescence excitation-emission spectra of extracts and intact samples

Joanna Orzeł^J. Ivana Stanimirova\ Bogusława Czamik-Matusewicz^b,

Michał Daszykowski^J *

* fnsn»rr of Chemiitry. Uniwmify of SiJruo. 9 Szkolno Street 40-006 Katowice. Roland ^k Farulty of Chemutry. Uniwmty of Wrocław. 14 Joliot Cune Srrret. 50-383 Wrocław. Poland

ABSTRACT

ARTICLE INFO

Anicie hlttory:

Remvrd 78 Novrmber 2014 Rerelvcd In revlsed form 12 pnuary 2015 Accrpird 19 January 2015 Ąyąllablf online 12 February 2015

Keyward%:

TAC

ORAĆ

Flber npiics prohe IR-ATR PLS N PIS

The performance of the recently prnposed excitation-emission fluorescence method was compared to the method using infrared measurements for the evaluation of the antioiidant properties of intact samples and eitracts that had been obtained from tomato pastes. The oxygrn radical absorbance capacity assay (ORAĆ] was applied m order to estimate the antioxidant capacity of the exrracts. while the Folin-Ciocalteu reagent was adopted for the evałuation of the total phenotic content. The oprimal extraction conditions for tomato pastes (three minutes of somcation under 80 C) were determined using the ccnnal composite design. Chemomenic models such as the parciał least squares regnession and ils N-way wariant were further constructed in order to predici the antioxidant capacity or toial phenolic content of the samples using either the IR or fluorescence spectra. The prediction enrors that were obtained for the total antioxidant content were ewaluated as the Trolox equivalents from the ORAĆ assay and were found to be cqual to 2.011 (14.21*) for the fluorescence and 2.426 (17.15*) for the IR spectra. respectively. The prediction errors of the total phenolic content expressed as gallic acid equivalents were 0 067 (10 781) for the fluorescence and 0.033 (5.16*) for the IR spectra, which were used as independent wariables in the regression models.

c 2015 Elsevier B.V. Ali rights reserved

1. Introduction

Anhoxidants an? vital compounds and their content. which is exprwsed as the total antioxidant capacity (TAC) in various food commodities. is a subject of a great interest for researchers and consumer*. The number of sdenhfic papers that deal with the evaluation of the TAC in different food matrices has been growing steadily for the past seweral years. Simultaneously. consumer awans ness of the TAC and its importance as a quality parameter for food commodities has also increased. Therefore, it is not surprising that the main goal of organizations like ORAĆ watch (established in USA] is to introduce information about the TAC leuels on producr La bel*. A major difficulty in making this information avaiLable to the consumer is the inconsistency of the procedure(s) that are used for evaluating the TAC Ali of the procedures are based on the Chemical reaction between free radicals that are deliberately ge nera red and the antioxidants that are

* Corrwponding juthor. Tel: -* 48 12 3S9 1568: U* ♦ 48 12 2S9 9978. t-mail addrea imlawyktfus.t-du |>l (M. Datrykowski).

lUtp. 'j(Jx doi orgjlU.    ulani a.2015.Ul.026

0019-9140/t 2015 Ehcvicr B-V. Ali rlghM reten/ed.

contained in the sample being analyzed. This reaction is usually monirored using a spectraphocometer or fluorometer and the result is expressed with respect to a selected standard antioxidant (eg.. Trolojc. vitamin C or gallic acid). Several generatora of free radicals. such as eg, AAPH (2J2’-Azobis(2-amidinopropane) dihydrochloride), ABTS (2.2'-azino-bis(3-ethylbenzochiazoline-6-sulfonic aod)) oc DPPH (2.2-diphenyl-l -picrylhydrazyi), are available (1J. Furthermore. meth-ods based on the reduction of cupric |2| or ferric (31 ions are also used. DiflFerences in the reaction mechanisms between various free radicals and the antioxidants that are contained in a food sample result in the determination of different TAC values. Moreover, the large variety of availab!e TAC assays and their inconsistencies are not the only concem. Some authors argue in the literaturę that the TAC parameter of a given food commodity is afTected by several exteraal factors induding its geographical origia the cultivation approach that was used. the time of harvesting and the type of food Processing 14-111. Therefore. the TAC of each produaion batch should be carrhjfly monitored. Unfonunately, in practice, standard assays require a substantial amount of solvents and reagents and rhey are also expensive. time-consuming and laborious. Therefore, new

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