Assaying the Relationship Between Resistivity and Concentration in Ocimumgratissium Flavor Extracted by Traditional and Conventional Methods

Abstract

The extract of basil leave were prepared by two different methods; modification of an African cultural practice where specified weights in grams (between 100 and 300) of (non blemished, dust free) fresh basil leaves were harvested stalk free and heated (incinerated) stuffed in a clay earthenpot on a charcoal stove for nine (9) hours. The partially charred leaves were discarded and the pot thoroughly washed with 300ml distilled water. Finally, 200ml of distilled water was poured into the pot, covered and allowed to stand for 12 hours, before storing the water at 4°C in tightly sealed plastic containers, labeled as subunits of sample A. In the second procedure, basil leaves collected as in the first procedure were in separate batches stuffed into the distillation bottle with 200ml of distilled water. Distillation was carried out for 2 hours and distillates collected and stored in tightly sealed plastic bottle labeled as subunits of sample B. The samples (A and B) including their subunits were (within 30 minutes of extraction) subjected to spectrophotometry, pH, and Total soluble solids (TSS) analysis. A 20 man trained panelist were employed in sensory evaluation of the (300g leaf) extracts (after storing at 4°C for 96hours) in terms of colour, flavour, flavour interference and general acceptability. Furthermore, 20ml of each (300g leaf) extract of Aand B were poured into a curvet of 2mm pathway. These were one after the other placed into an electric circuit with the poles submerged into opposite ends of the curvet. The following parameters were read from the meters when the circuit was completed: current, voltage and resistance to flow of electricity across the sample. Sample A (the extract made by the modified traditional practice) had the highest general acceptability compared to sample B and the natural leaf (control sample). It had significantly lower color and flavor interferences, with average of 8/10 flavor intensity recording. Resistance to flow of electricity for both samples (A and B), were inversely proportional to leaf orflavour extract concentration with a gradient of 0.001. It is therefore possible to compute concentrations of flavor components from resistance to flow of electricity with gradient and intercepts derived from graph (Figure 1). TSS, pH and temperature of samples followed the same pattern as electrical resistivity.