Optimization of Extract Yield and Total Phenolic Content of Pavetta crassipes leaves using Response Surface Methodology

The necessity to increase the utilization of some neglected but valuable plant leaves in the forest of African countries and use them to the advantage of man motivated the design of this work. The leaves of Pavetta crassipes plant were harvested and processed into fine powder of moisture content 8.15%. While the resulting dried Pavetta crassipes leaves extract obtained, had moisture content of 13.14%. The extract was obtained using central composite design. The design involved varying the extraction time (30 -50 min), extraction temperature (30 to 70oC) and ratio of material to extracting solvent (5 to 10 %). The design resulted into seventeen experimental runs. The responses such as the yield and the total phenolic content were measured. The results showed that the yield of the extract and the phenolic content ranged between 3.52 to 8.84 % and 30.53 to 55.57 mgGAE/100 g. Based on the degree of reliability, the system predicted the optimum extraction conditions as 60.94 oC, 57.70 min and 5 % for temperature, time and concentration respectively with the corresponding yield and total phenolic content as 8.84 % and 59.87 mgGAE/ 100g respectively. The optimum conditions were found to agree reasonably with the experimental conditions. The study concluded that response surface methology and the developed models could be used to produce the leaves extract of Pavetta crassipes plant on a large sclae with enhanced yeild and phenolic content.