AMETEFE, GEORGE DZORGBENYA and Covenant University, Theses (2021) PECTINASE PRODUCTION AND OPTIMISATION FOR FRUIT JUICE CLARIFICATION: EVALUATION OF FUNGAL ISOLATES FERMENTED ON SELECTED AGRO-WASTES. ["eprint_fieldopt_thesis_type_phd" not defined] thesis, Covenant University.
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Abstract
Pectinases are a group of enzymes that degrade pectin into simpler units. The enzymes have several industrial uses such as clarification of fruit juices. In this study, five pectinolytic fungi isolated from fruit wastes in dumpsites at Oshodi, Lagos State, were screened and identified using molecular techniques. They included two moulds (Aspergillus niger and Penicillium sp.) and three yeasts (Pichia kudriavzevii strain F2-T429-5, Pichia kudriavzevii strain CY902, and Saccharomyces cerevisiae). The five fungal isolates were screened for pectinase production using six agricultural wastes as substrates and three extraction solvents (distilled water, citrate buffer and 0.1 M NaCl). Pectinase production and optimisation studies were carried out using three fungi (Aspergillus niger, Penicillium sp., and Pichia kudriavzevii strain F2-T429-5) which showed larger zones of pectin hydrolysis relative to the other fungi; three agricultural wastes with high pectinase activity (Citrus sinensis ‘orange’ peel, Triticum aestivum ‘wheat’ bran, and the miracle berry ‘Thaumatococcus danielli’ fruit wastes), and best extraction solvent (0.1 M NaCl). Box-Behnken design, a response surface method (RSM), was used to predict the optimal conditions for enzyme production. The parameters investigated included fermentation duration, pH, temperature, particle size, the volume of inoculum, and agitation of the fermentation substrate (during enzyme extraction). The highest pectinase activity was achieved at approximately six days of solid-state fermentation using Aspergillus niger and orange peel. The optimal production conditions were: pH 4.0, temperature 21 oC, particle size 0.06 inches, inoculum volume 1.0 ml, and agitation duration 11.4 min. The best pectinase activity at the optimal conditions was 5.02 U/ml. The goodness of fit from the agreement of the predicted and adjusted R2 values in the analyses of variance (ANOVA) indicated the suitability of the quadratic models used for this study. The pectinase properties included: optimal pH 4.0, and temperature stability 20 oC. The pectinase was best activated by Na+ at 10 mM; beyond this level, there was reduction in the enzyme activity. The kinetic studies showed a Vmax of 4.40 U/ml and Km of 0.36 mg/ml. The optimised pectic enzyme preferentially (p<0.05) clarified orange juices compared to pineapple juices and the control (without the enzyme). There is a good prospect of producing pectinase from microbes isolated from local agricultural wastes. The pectinases can be used in the clarification of fruit juices.
| Item Type: | Thesis (["eprint_fieldopt_thesis_type_phd" not defined]) |
|---|---|
| Uncontrolled Keywords: | Agricultural wastes, Box-Behnken design, Clarification, Fungal isolates, Optimisation, Pectinase production |
| Subjects: | Q Science > Q Science (General) Q Science > QD Chemistry Q Science > QH Natural history > QH301 Biology |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Chemistry |
| Depositing User: | Mrs Hannah Akinwumi |
| Date Deposited: | 08 Nov 2021 13:36 |
| Last Modified: | 08 Nov 2021 13:36 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/15453 |
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