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Optimisation of the Amido Black assay for determination of the protein content of grape juices and wines
Author(s) -
Weiss Kathryn C,
Bisson Linda F
Publication year - 2001
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.847
Subject(s) - wine , chemistry , white wine , food science , grape wine , detection limit , wine color , chromatography , bovine serum albumin , vitis vinifera , botany , biology
While the heat/chill stability of white wines cannot be predicted from the total protein concentration, this information is useful in assessing the effectiveness of fining treatments. We have adapted the Amido Black assay for use in grape juice and wine. The response of bovine serum albumin (BSA) was similar in water, model wine and model juice. The linear range of the assay (<100 mg l −1 ) extends beyond protein concentrations typically found in grape juices and wines. The limit of quantification was 11.1 mg l −1 for BSA in model wine and 7.6 mg l −1 in model juice, while the limit of detection was found to be less than 3 mg l −1 in either solution. In contrast to other methods of protein determination, this assay is not affected by common wine phenolic and pectic compounds or by glutathione. The mean response of BSA was similar in model juice and red and white grape juices. The mean response of BSA in red wine was lower than in white wine and model wine ( p < 0.001), and there was considerable variation in response among wines. Protein concentrations determined using this method were reproducible (CV < 10%). This optimised assay can be used to monitor protein levels in grape juices and wines. © 2001 Society of Chemical Industry