Distribution of bound and free phenolic acids in oranges (Citrus sinensis) and Grapefruits (Citrus paradisi)

Authors

  • Hanna Peleg,

    1. Department of Biochemistry and Human Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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  • Michael Naim,

    Corresponding author
    1. Department of Biochemistry and Human Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
    • Department of Biochemistry and Human Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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  • Russell L Rouseff,

    1. Department of Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850, USA
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  • Uri Zehavi

    1. Department of Biochemistry and Human Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Abstract

Free phenolic acids may be the precursors for vinyl phenols and off-flavours formed in citrus products during storage. Quantitative determination of free and bound phenolic acids in fruit parts of grapefruit (Citrus paradisi Macfadyen) and oranges (Citrus sinensis (L) Osbeck) was performed by extraction with ethyl acetate, silica gel column chromatography and HPLC analyses of samples before and after alkaline hydrolysis. The content of free and bound phenolic acids was further determined in juice derived from fruit harvested early, mid and late in season. As found previously for ferulic acid, phenolic acids occur mainly in bound forms in grapefruits and oranges. In both fruits the peels contained the major portion of cinnamic acids compared with the endocarp, and the flavedo was richer in hydroxycinnamic acids than the albedo. In most cases, hydroxycinnamic acid content was in the following order: ferulic acid>sinapic acid>coumaric acid>caffeic acid. Results showed that the content of bound cinnamic acids was unchanged or slightly elevated from early to late season. However, the content of free acids was reduced during that period.

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