Changes in Anthocyanins and Polyphenolics During Juice Processing of Highbush Blueberries (Vaccinium corymbosum L.)

Authors

  • G. Skrede,

    Corresponding author
    1. Author Skrede is with Matforsk, Norwegian Food Research Institute, Osloveien 1, N-1430 Aas, Norway.
      Direct inquiries to author Skrede (E-mail: grete.skrede@matforsk.no).
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  • R.E. Wrolstad,

    1. Authors Wrolstad and Durst are with the Dept. of Food Science and Technology, Oregon State University, Cor-vallis, Or eg., U.S.A.
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  • R.W. Durst

    1. Authors Wrolstad and Durst are with the Dept. of Food Science and Technology, Oregon State University, Cor-vallis, Or eg., U.S.A.
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  • The senior author was supported by a grant from the Norwegian Research Council for her stay at Oregon State University. We thank the Oregon Blueberry Commission, Brian Yorgey, Department of Food Science and Technology, OSU, and Finn Maage, Norwegian Agricultural University, Aas, Norway, for providing fruit. The laboratory and pilot-plant assistance of Eric Ferreira and Kenneth Stewart is appreciated. Donald A. Griffin of the OSU Department of Environmental and Molecular Toxicology performed the ESMS analyses.

Direct inquiries to author Skrede (E-mail: grete.skrede@matforsk.no).

ABSTRACT:

Frozen blueberries (Vaccinium corymbosum L.) were processed into juice and concentrate, and the changes in anthocyanin pigments and polyphenolics (cinnamates, procyanidins, flavonol glycosides) were monitored. While juice yield was 83%, only 32% of the anthocyanins were recovered in single-strength juice. Flavonol, procyanidin and chlorogenic acid recoveries in juice were 35%, 43%, and 53%, respectively. The proportion of polyphenolics remaining in the press-cake residue ranged from 1% (chlorogenic acid) to 18% (anthocyanins). Pronounced losses of anthocyanins and polyphenolics during milling and depectinization are believed to be due to native polyphenol oxidase. Losses during concentration ranged from 1.5% (anthocyanins) to 20% (procyanidins). Striking changes occurred in the anthocyanin profile with malvidin glycosides being most stable and delphinidin glycosides the least.

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