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Title: Biochemistry of antioxidants : antioxidant capacity measurment methods and their application to develop useful indicators of stability and functionality in food matrices
Author: Muhammad, Kwestan Rafat
Awarding Body: University of Plymouth
Current Institution: University of Plymouth
Date of Award: 2012
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Antioxidant properties of green tea (GT) have been widely reported. The antioxidant capacity (AOC) of green tea was investigated to include the effect of infusion time over 24 hours. The AOC was measured by the FRAP, DPPH, TEAC, and CBA assays. It was proven according that after 2 hours of brewing, tea has higher AOC and Total phenolic content (TPC), these significantly decreases after 4 hours. GT has a high amount of polyphenols with potent AOC. However, interactions between polyphenols and food matrix may decrease their potential benefit. The objective of this experiment was to test the hypothesis that the addition of milk (full fat, semi-skimmed, and skimmed) may affect the phenolic content and AOC was measured. The results indicated the plain GT had highest activity; then tea with FFM had a significantly higher amount of AO than others. Plant extracts possess health promoting properties. The objective of this study was to determine the TPC and AOA of different concentrations of spice extracts (fennel, clove, cardamom, cinnamon, ginger, anise, and black pepper) with DPPH, TEAC and Rancimat methods. At low concentration, black pepper had a highest activity but at high concentration, ginger showed the highest activity among the extracts. The TPC for spice extract was greater for anise. Results provided evidence that the studied spices may be used as a natural AO. In recent decades, saliva has emerged as a new way to diagnose and investigate basic health problems. In this study, salivary TPC and AOC were measured after consumption a single cup of green tea with and without of milk. In a healthy adult crossover design. The salivary AOC and TPC were measured before and after consumption up to 3 hours. Results indicated that milk decreased AOC of GT when compared with the control water. The activity reached peak 1 hour after ingestion and then decreased returning to the baseline. Results confirmed that saliva could be used as an easier and safer alternative to blood to assess AOA in humans.
Supervisor: Kuri, Victor Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Antioxidants, Free Radicals, Green Tea, Protein, Species, Saliva.