Physico-chemical properties and antioxidant potential of syrup derived from ‘Madhura’ sweet sorghum grown in different locations in Kenya

Sweet sorghum (Sorghum bicolor (L) Moench) represents an analogous crop to sugarcane with similar accumulation of sugars in its juicy stems but with a higher agronomic stability to temperature fluctuations, less water requirement and better tolerance to salinity, alkalinity and drought. Sweet sorghum production has recently been introduced in Kenya. The production of SS syrup which has wide application in the food industry would add value to sweet sorghum production and enhance the sweet sorghum value chain, thereby providing additional livelihood opportunities to farmers involved in its cultivation. The present study was undertaken with the objective of producing sweet sorghum syrup; analyze its physical, chemical and antioxidant properties; and the influence of cultivation location on the properties of the syrup. The colour coordinate values of Chroma and Hue angle were indicative of the dark brown coloration of the syrups and were most influenced by location compared to Lightness (L*) values at pd”0.05. The density and the moisture content showed no significant difference while apparent viscosity and total acidity were significantly different between the syrups from the two locations. The sweet sorghum syrups from the two locations had fructose levels of 12 and 2%, sucrose at 66 and 88% while and glucose levels were 17 and 6%, respectively. Calcium was the macro-element with the highest concentration ranging between 108 to 272.33 mg/100g of syrup and was significantly different (p<0.05) between the locations. For micro-elements, magnesium had highest concentration (124 and 118 mg/ 100 g). The sweet sorghum syrups exhibited high level of total phenolic content and total flavonoid content at 261.31 mg Gallic acid equivalent and 197.50 mg quercitin acid equivalent per 100g syrup, respectively. The radical scavenging activity being greater than 50% even at low syrup concentrations indicates that the sweet sorghum syrups are potent free radicalscavengers. This study shows that the sweet sorghum syrup is comparable to sugarcane syrup and can be of applicable use in Kenya’s food industry since its physical and chemical attributes as well as antioxidant properties have therapeutic potential.