Evaluation of antimicrobial and antioxidant properties of Tanzanian honey from two Agro-ecological Zones

A DISSERTATION SUBMITTED IN PARTIAL FULLFILMENT OF THE REQUIREMENT OF THE DEGREE OF MASTER OF SCIENCE IN FOOD QUALITY AND SAFETY ASSURANCE OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.

A study was conducted to assess the quality of Tanzanian honey based on antioxidant properties and antimicrobial activities on bacteria and fungi in relation to its physico-chemical properties. Two types of honey samples (stinging and stingless bees’ honey) were collected from central zone (Singida and Dodoma) and western zone (Tabora and Shinyanga). Honey samples were analysed for anti-microbial activities, anti-oxidant properties (total phenols, vitamin C) and physico-chemical properties pH, colour, pH, reducing sugar and minerals. Fifty four percent of tested honey samples inhibited microbial growth while 46% did not. The microbial inhibition zone ranged from 8.5 - 14.16 mm (stinging bee honey) and 10.56-15.13 mm (stingless bee honey). The stingless honey from Shinyanga town, Bukombe and Nzega and that from Singida town and Issuna were more effective in microbial growth inhibition. Candida albicans was more sensitive (23.1%) to stingless bee honey, followed by Staphylococcus saprophyticus (33%), Salmonella typhi (32%), Escherichia coli (19.2%) and Aspergillus flavus (16.0%). Antioxidant, total phenols and vitamin C content were significantly (P<0.05) higher in stingless bee honey than that of stinging bee honey. Antioxidant (FRAP) ranged from 322.16 - 973.57 μMFe(II)/100g, total phenol 13.87 – 33.55 mg/100g and vitamin C 2.54 - 10.99 mg/100. There was no significant (P>0.05) difference in pH between honey types. Potassium was highest while Zn was lowest in stinging and stingless honey samples. Colour grading of stingless bee honey ranged from extra light amber - light amber while that of stinging bee honey ranged from water white - light amber. There was a positive and significant (P<0.001) correlation between honey colour, antioxidant, total phenol and mineral content. Stingless honey from western zone is superior to stinging bee honey in antioxidant and antimicrobial properties and therefore is recommended to be used as a valuable food product, preventive and curative medicine.