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A proficiency test scheme for the quality control of black tea and development of quality control material for internal quality control

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Abstract

A proficiency test (PT) was organized for quality control analysis of black tea. Test materials for the analyses of total content of powder tea, moisture, total ash, acid-insoluble ash, water-soluble ash, alkalinity of water-soluble ash, water extract, crude fiber and caffeine were sent to the participant laboratories (n:43) in 2009. The assigned value, standard deviation of the parameters and z-scores of the participant laboratories were calculated using the data reported by the participants. The percentage of the reported results for analytes was found to be ranged from 67.5 to 100%. Acceptable z-scores were achieved by 80.5–97.5% of the participant laboratories. More than 15% of unacceptable results were obtained for acid-insoluble ash and caffeine analyses. The quality control material for quality control analysis of black tea was developed from the remaining material.

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Acknowledgment

The authors would like to express thanks Trabzon Provincial Laboratory for the technical support.

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Authors and Affiliations

  1. Department of Food Engineering, Gumushane University, 29100, Gumushane, Turkey

    Cemalettin Baltacı, Huri İlyasoğlu & Sevim Beyza Öztürk Sarıkaya

  2. Trabzon Provincial Control Laboratory, 61100, Trabzon, Turkey

    Sevda Cavrar

  3. Department of Chemistry, Karadeniz Technical University, 61080, Trabzon, Turkey

    Nurettin Yaylı

Authors
  1. Cemalettin Baltacı
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  2. Huri İlyasoğlu
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  3. Sevim Beyza Öztürk Sarıkaya
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  4. Sevda Cavrar
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  5. Nurettin Yaylı
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Correspondence to Cemalettin Baltacı.

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Baltacı, C., İlyasoğlu, H., Sarıkaya, S.B.Ö. et al. A proficiency test scheme for the quality control of black tea and development of quality control material for internal quality control. Accred Qual Assur 16, 507–513 (2011). https://doi.org/10.1007/s00769-011-0799-5

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  • DOI: https://doi.org/10.1007/s00769-011-0799-5

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