Evaluation of Antioxidant Properties of Dry Soup Mix Extracts Containing Dill (Anethum sowa L.) Leaf

Soups are consumed for nutritive benefits and also by patients whose intake of solids is considerably reduced due to several pathological reasons. Dehydrated soup mix is a convenient product due to its less volume and long storage life at ambient temperatures. Soup mix formulated with functional ingredients, modified potato flour (thickening agent), and dill leaf powder (DLP) was evaluated for its antioxidant properties. Aqueous and methanolic extracts of soup mix were prepared, and their total phenolic content, reducing power ability, and free radical-scavenging activity were determined. Significant improvement in total phenolics was observed as a result of addition of DLP that led to enhancement of its antioxidant properties. The phenolic acid profile of the soup mix base contained mainly tannic acid, while protocatechuic, gentisic, vanillic acid, and syringic acids were contributed by DLP. The reducing power ability of soup mix was increased by about 2.5 times in aqueous and about seven times in methanolic extracts, as a result of DLP addition. Concentration-dependent scavenging activity was observed, and IC50 (scavenging of 50% 1,1-diphenyl-2-picrylhydrazyl radical) values were reduced from 16.5 to 3.8 mu g/mL in aqueous and from 9.1 to 3.9 mu g/mL in methanolic extracts as a result of addition of DLP. The moisture-humidity relationship studies of soup mix conducted to determine its sorption behavior showed that the product exhibited caking tendency above 8.9% moisture corresponding to a critical relative humidity of 56%.