PHENOLIC CONTENTS AND ANTIOXIDANT ACTIVITY OF SUDANESE HONEY

Abstract

This investigation was carried out to determine the phenolic contents and antioxidant activity of Sudanese honey. Seven samples of Sudanese honey were tested for phenolic content, antioxidant activity and other parameters such as moisture, pH, refractive index, ash, total soluble solids, protein, electrical conductivity and colour intensity. Results of analysis demonstrated that there is a good amount of phenolic content and antioxidant activity in Sudanese honey. It ranged from 4.4 to 201.1 mg/TAE/100 g honey for phenolic content. The highest amount of total phenolic content was found in the Acacia nilotica honey (Sunut) 201.1 mg/TAE/100 g honey followed by the Balanites aegyptiaca honey (Heglig) 146.38 mg/TAE/100 g honey and then came Acacia seyal honey (Talih) 67.11 mg/TAE/100 g honey. Honey from Two types of Ziziphus spina-christi (Sidir of mountain and Sidir) showed similar values 21.98 and 20.15 mg/TAE/100 g honey respectively , while honey of Azadirachta indica (Neem) was found to contain 17.15 mg/TAE/100 g honey and honey from Cucurbita maxima Duch. (Pumpkin) was found to contain 4.44 mg/TAE/100 g honey. For antioxidant activity, it ranged from 3177 to 6247μg for dry weight sample cause 50% inhibition, which indicates antioxidant activity. The maximum antioxidant effect was found in Azadirachta indica honey (Neem) 3177 μg followed by Balanites aegyptiaca honey (Heglig) 4045 μg, then Ziziphus spina-christi honey (Sidir) 4068 μg, and Acacia seyal honey (Talih) 4679 μg, while Ziziphus spina-christi honey (Sidir of mountain) was 5125 μg. The minimum antioxidant effect was observed in 14 Acacia nilotica honey (Sunut) 6247 μg, followed by Cucuribia maxima Duch. honey (Pumpkin) 5323 μg. Results of this study showed highly significant differences (P<0.01) in phenolic contents of different honey samples. There was no correlation (r =0.441) between antioxidant activity and total phenolic content . Percent of inhibition increased with increasing the concentration. There was highly positive Correlation between concentrations (5, 25 and 50μl) of diluted honey samples and the percent of inhibition, which indicates the antioxidant activity. Results of parameters such as protein, oBrix and electrical conductivity are within the standard levels and they ranged from 0.200- 0.286, 75.2-79.0 and 0.20-0.80 for protein, oBrix and electrical conductivity, respectively. Highly significant differences (P<0.01) were observed for other parameters such as moisture, pH, refractive index and ash, with Values ranging from 16.20-21.27%, 3.70-4.80%, 1.4833- 1.4960% and 0.1207-1.205% , respectively.The Brix in honey showed significantly high negative correlation (P<0.05) (r=-0.869) with moisture content. Colour of honey samples was measured by using Aminolta chromameter and the values of L*, a* and b* were obtained and the values of chroma, hue angle, and browning index were calculated . The ranges of 24.47-59.44, -1.26-8.41 and 2.40-22.02 for L*, a* and b*, respectively, while the calculated ranges of 2.70-22.30, 62.68-89.51 and 11.76-82.35 were obtained for chroma, hue angle and browning index, respectively.