Comparative effect of crude pectinase and commercial enzymes in Shea fat extraction

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Date
SEPTEMBER, 2015
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Abstract
Pectinases are one of the most used enzymes in food industry. Enzymes are widely used to improve upon process parameters such as product yield and rate of product formation. Such biotechnological applications are not currently exploited by most industries in Ghana. The objective of the study was to determine the efficacy of locally produced pectinases from S. cerevisiae and other commercial enzymes in the extraction processes of shea butter. The crude pectinase was produced using corn cobs as a substrate and the microorganism Saccharomyces cerevisiae ATCC 52712 in a solid state fermentation process for four days. The crude pectinase had optimal protein concentration of 7 mg/ml with enzyme specific activity of 0.130 U/mg. The commercial enzymes were Viscozyme L (beta endo- 1, 3 (4)-glucanase activity with declared activity of 100 FBG/g as well as side activities of xylanase, cellulase and hemicellulases) and Pectinex 5XL (polygalacturonase activity with declared activity of 4500 PECTU/ml as well as arabinase side activity). The following operational parameters: water to seed (w/s) ratio, pH, hydrolysis time, enzyme dosage and temperature were optimized for better oil recover. The optimum w/s ratio in the present study was 4:1 for the enzymes and 2:1 for the control. The study revealed that the crude pectinase works under a wide range of pH. Crude Pectinase exhibited maximum activity at pH range of 3 to 6. Commercial Pectinex and Viscozyme showed maximum activity at pH range of 4 to 6. The maximum oil yield for crude pectinases and commercial Pectinex was obtained at 90 minutes and that of Viscozyme treated seed was observed at 60 minutes incubation time. When all parameters were optimized, the control gave an optimum oil recovery of 40 % while the application of the crude pectinase gave an optimum oil recovery of 44 % with an enzyme dosage of 1.2 %. The commercial Pectinex and commercial Viscozyme gave optimum oil recovery of 58.6 % and 72.0 % respectively at enzyme dosage of 0.8 %. Analyses of the proximate composition of the residues revealed that with the exception of protein, no significant variations were observed for the fiber and ash content. The physicochemical characteristics of the extracted oils such as Density, Moisture, Sample melting point (SMP), Unsaponifiable matter (UM) with the exception of the fatty acids (FFA) and peroxide value (PV), were not significantly affected (P ˃ 0.05) by the type of enzyme used. These results indicate the possible use of crude pectinase to improve shea fat extraction processes in Ghana if the enzymes are made available.
Description
A thesis submitted to the Department of Biochemistry and Biotechnology in partial fulfilment of the requirements for the award of the degree of Master of Science in Biotechnology.
Keywords
Aqueous extraction, crude pectinase, corn cobs, Saccharomyces cerevisiae, solid state fermentation
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