GEORGE, DANGO ZILPAH and Covenant University, Theses (2022) FUNCTIONAL DIVERSITY OF LACTIC ACID BACTERIA FROM FERMENTED RICE. Masters thesis, COVENANT UNIVERSITY.
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Abstract
Rice is a staple food consumed in the world. Current statistics of rice consumption in Nigeria at December 2021/2022 is 6.900 million tonnes, and 6.950 million metric tonnes. Rice is known for its rich energy source, because of its carbohydrate content. Rice can also serve as a functional food when fermented, releasing microorganisms with health benefits and also for its bio-preservative purpose. The aim of this study was to determine the functional diversity of Lactic acid bacteria (LAB) isolated from fermented rice (Oryza glaberrima, and NERICA). In this study different varieties of raw rice were fermented. LAB genera were isolated from the fermented rice. The cultural, morphological, biochemical, and genotypic characterization of the LAB isolates were performed using standard methods. Proximate, Phytochemical and Phytate (antinutritional agent) analyses were carried out using Association of Analytical Methods (AOAC) to evaluate the nutritional content of fermented rice. Probiotic parameters were assessed (phenol, bile-salt, and pH) and different concentrations of 0.5 %, 1 %, pH 2, pH 5 and pH 7 (control). Safety assessment assay using haemolysis test and antibiotic susceptibility test (using gram-positive antibiotic disk) was carried out on the LAB isolates. Overlay, Kirby-Bauer agar well diffusion, and microtitre plates methods were used in the analyses of antibacterial activities for the LAB isolates, this was done to screen isolates for genotypic characterization, and bio-preservative test using bioactive packaging. Genotypic characterization revealed the three isolates to be Lactiplantibacillus sp. Strain DGZ_2 ON954756, and two Pediococcus sp. DGZ-1 ON954755 and Pediococcus sp. DGZ 2 ON954757. The proximate, fermented rice showed Ash content (0.00 ± 0.001), moisture content 0.05 ± 0.02, carbohydrate (0.01 ± 0.02), protein (0.00 ± 0.001), crude fibre (0.00 ± 0.01) and fat contents (0.01 ± 0.02), phytochemicals present include Alkaloids, Quinone, Phenol, and Flavonoids. For the reduction in phytate content of two fermented rice sample, data obtained was reduction from 4.46 ± 0.02 – 3.47 ± 0.08 and 5.45± 0.02 – 4.46 ± 0.01. For the probiotic parameter pH of the LAB isolates showed better survival rate at pH 7 than pH 2, pH 5 were average survival rate was noted. In 0.5% Bile salt and phenol concentration the Lactobacillus species had better survival at 80, 85, and 91 % bile salt and 81, 81, and 84 % for phenol. The antibiotic susceptibility assay showed that LAB isolates were susceptible to erythromycin (10 μg), ciprofloxacin (10 μg) and streptomycin (30 μg). The hemolytic data obtained revealed that two Pediococcus sp exhibited α-haemolysis, only Lactiplantibacillus sp. exhibited ℽ haemolysis. LAB isolates showed inhibitory actions on foodborne pathogenic organism Listeria monocytogenes ATTC 78644 when overlay and micro-titre plate methods were used. For the shelf-life improvement of Carica papaya L when storage bags were treated with the three screened LAB isolates under 4 oC, the data obtained showed that Carica papaya L shelf life was extended when compared with the control stored at 4 oC. This study recommends fermented rice as a good functional food.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Fermented rice, Functional food, Lactic acid bacteria (LAB), Probiotics, and Shelf-life. |
| Subjects: | Q Science > Q Science (General) Q Science > QH Natural history > QH301 Biology |
| Divisions: | Faculty of Medicine, Health and Life Sciences > School of Biological Sciences |
| Depositing User: | AKINWUMI |
| Date Deposited: | 09 Aug 2022 11:02 |
| Last Modified: | 09 Aug 2022 11:02 |
| URI: | http://eprints.covenantuniversity.edu.ng/id/eprint/16133 |
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