February 1, 2015 Thesis Open Access

Shimelis Shumi

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  <dc:creator>Shimelis Shumi</dc:creator>
  <dc:date>2015-02-01</dc:date>
  <dc:description>The study was conducted with the aim of optimizing and characterizing antioxidant activity of
Camellia sinensis and evaluating its preservative effect on Niger seed and Soybean oils.
Camellia was prepared by investigating the effect of distilled water concentrations of 100, 150,
and 200ml, extraction temperature 80, 85 and 90 ℃ and contact time of 10, 35 and 60 min on its
antioxidant activity and extract yield. Based on ANOVA analysis, extraction parameters have
significant positive effect (P&lt;0.05) on Camellia antioxidant activity and its extract yield. The
best levels of extraction parameters for higher antioxidant activity and extract yield were
distilled water concentration of 200ml for 60min at 90 ℃. As DPPH free radical scavenging
activity results shown the highest antioxidant activity of Camellia was 96.1%. On the other hand
extraction parameters (solvent concentrations, extraction temperature &amp; contact time) were
optimized. The best extraction conditions were 200ml, 88 ℃ and 35 min and the results were
yield (79.850%) and Antioxidant activity (96.9810%). The preservative effect of Camellia was
also studied by performing Free Fatty Acids, Peroxide Value/Acid value on Niger seed and
Soybean oils. In the study, all samples were treated with 0, 1 and 2ml levels of Camellia extract
and analysis were conducted on weekly basis. Compared to Camellia extract containing Niger
seed and Soybean oils, control sample showed higher Free Fatty Acid and Peroxide Values in
each storage weeks.</dc:description>
  <dc:identifier>https://zenodo.org/record/2349</dc:identifier>
  <dc:identifier>10.20372/nadre:2349</dc:identifier>
  <dc:identifier>oai:zenodo.org:2349</dc:identifier>
  <dc:relation>doi:10.20372/nadre:2348</dc:relation>
  <dc:relation>url:https://nadre.ethernet.edu.et/communities/aau</dc:relation>
  <dc:relation>url:https://nadre.ethernet.edu.et/communities/zenodo</dc:relation>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>http://www.opendefinition.org/licenses/cc-by</dc:rights>
  <dc:title>Optimization and characterization of antioxidant activity from green tea (Camellia sinensis) and evaluation of its preservative effect</dc:title>
  <dc:type>info:eu-repo/semantics/doctoralThesis</dc:type>
  <dc:type>publication-thesis</dc:type>
</oai_dc:dc>