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Phenolic content of strawberry spreads during processing and storage Mirta Kadivec, Špela Može Bornšek, Tomaz Polak, Lea Demšar, Janez Hribar, and Tomaz Pozrl J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf4035767 • Publication Date (Web): 30 Aug 2013 Downloaded from http://pubs.acs.org on September 4, 2013
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Journal of Agricultural and Food Chemistry
Phenolic Content of Strawberry Spreads during Processing and Storage
MIRTA KADIVEC, ŠPELA MOŽE BORNŠEK, TOMAŽ POLAK*, LEA DEMŠAR, JANEZ HRIBAR, TOMAŽ POŽRL
Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
*Corresponding
author
(Tel:
+386-1-320-37-43;
Fax:
+386-1-256-62-96;
E-mail:
[email protected])
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Abstract
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This study provides a comprehensive and systematic evaluation of phenolics in strawberry
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spreads processed according to different industrial procedures and stored under several
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storage
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spectrophotometrically, and individual phenolics by combined liquid chromatography and
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mass spectrometry: six anthocyanins, four phenolic acids, two flavonols, one flavanol and one
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flavone. During storage, the phenolics were modified. The total anthocyanins, vanillic acid,
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kaempferol and luteolin decreased, while salicylic and gallic acids increased. Total phenolics,
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cyanidin 3-(6''-succinyl-glucoside) (here observed for the first time), protocatechuic acid,
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quercetin and catechin remained stable. The best phenolic retention was observed in spreads
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stored at 4 °C. Therefore, the proposed storage process (use of a cold chain) indicates good
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retention of phenolics in strawberry spreads, which maintain high nutritional and sensorial
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quality.
conditions
for
up
to
19
weeks.
Total
phenolics
were
determined
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KEYWORDS: strawberry spread, storage, phenolics, anthocyanins, phenolic acids,
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flavanols, flavonols, flavones, liquid chromatography–mass spectrometry
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Journal of Agricultural and Food Chemistry
INTRODUCTION
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Strawberry (Fragaria x ananassa Duch.) is widely consumed, both as fresh fruit and as an
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ingredient in processed foods, such as spreads, jams, syrups, alcoholic and nonalcoholic
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beverages, teas, sweets and dairy products. Strawberry fruit are a very rich source of bioactive
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compounds, which include vitamins C and E, and phenolic compounds.1,
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effects of strawberry fruit on human health have been attributed to their high levels of a wide
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variety of phytochemicals, of which the phenolics constitute the greatest proportion, and they
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contribute to both the sensorial attributes and the nutritional value of strawberry fruit.3
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Furthermore, several studies have shown that strawberry fruit generally have high levels of
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antioxidant capacity, which is again linked to the levels of phenolic compounds in the fruit.1, 2,
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4, 5
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The beneficial
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Phenolic compounds are a large, heterogeneous group of secondary plant metabolites that are
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widespread in the plant kingdom. The major phenolics in strawberry fruit have been described
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as the 3-glucosides of pelargonidin and cyanidin (anthocyanins), followed by quercetin and
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kaempferol (flavonols), catechin (flavanols), hydrolyzable tannins (ellagitannins and
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gallotannins), phenolic acids (hydroxybenzoic and hydroxycinnamic acids), and condensed
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tannins (proanthocyanidins). The nutritional contributions and phytochemical compositions of
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the strawberry have been extensively reviewed very recently.3
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The first characteristic of any food that is noted is its color, and this predetermines the
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expectation of both flavor and quality. The color of strawberry fruit is a consequence of the
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presence of anthocyanins that belong to the flavonoid category. They are widespread, water
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soluble, plant pigments that produce red, blue and purple colors in fruit and flowers.6 In
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strawberries, the anthocyanins are the best known and quantitatively the most important
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phenolics.3 Despite their low bioavailability, anthocyanins have intracellular antioxidant
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activity if applied at very low concentrations (nM range), thereby providing a long-sought
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rationale for their health-protecting effects, in spite of their unfavorable pharmacokinetic
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properties.7 Their color is pH dependent, as red at pH
