http://hdl.handle.net/10386/72 2026-04-05T17:46:41Z http://hdl.handle.net/10386/5107 Antioxodative, anti-inflammatory and antimycobacterial activities of artemisia afra subfraction against mycobacterium smegmatis Matlala, Mabasa Precious Tuberculosis (TB) is a well-known communicable disease discovered decades back and continues to be a persistent socio-economic burden worldwide with the increasing number of multidrug-resistant and extensive-drug resistant forms. Medicinal plants have been accredited as potential sources of natural pharmaceuticals against TB. The aim of the study was to investigate the efficacy of antioxidative, anti-inflammatory and antimycobacterial activities of Artemisia afra extracts and sub-fractions. Mycobacterium smegmatis was used as a surrogate for Mycobacterium tuberculosis (Mtb). The aerial parts of A. afra plant were dried and ground into fine powder. The powdered plant material was extracted using hexane, chloroform, dichloromethane, ethyl acetate, acetone, ethanol, butanol, methanol, and water. All the solvents demonstrated good extraction capacity. The qualitative phytochemical analysis was done using standard chemical tests and thin layer chromatography. Standard chemical tests showed the presence of saponins, steroids, tannins, cardiac glycosides, terpenes, and flavonoids in the extracts. Phytochemical analysis revealed more fluorescing compounds at 365 nm. The methanol extract had the highest amount of total phenolic (190.31±5.81 mg GAE/g), tannin (339.92±11.28 mg GAE/g) and flavonoid contents (1333.07±12.97 mg QE/g). All the tested A. afra extracts had low ferric ion reducing antioxidant power. However, the acetone extract showed notable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging potential. Anti-inflammatory activity was investigated using the egg-albumin denaturation assay, where the acetone extract demonstrated the higher activity than diclofenac sodium. Furthermore, the acetone extract exhibited noteworthy antimycobacterial activity against M. smegmatis observed on the three chromatograms developed in BEA, CEF and EMW mobile systems with minimum inhibitory concentration of 0.521 mg/mL. Cytotoxicity was tested against the THP-1 cell-line monocytes. The differentiation of THP-1 monocytes into macrophage-like cells was induced by phorbol 12-myristate 13-acetate (PMA). The acetone and methanol extracts had less toxicity at the lowest concentration of 125 µg/mL. Column chromatography was used to fractionate the active acetone extract; and its subfraction of intermediate polarity had the highest inhibitory activity against M. smegmatis at MIC value of 0.078mg/mL. Moreover, the subfraction was able to prevent initial cell attachment to form biofilms in a concentration dependent manner and the matured formed biofilm after 24hrs was also reduced. Growth inhibitory activity monitored in different time intervals and anti-inflammatory activity were also observed. Results obtained from LC-MS analysis revealed several compounds at different retention times from both the acetone crude extract and the sub-fraction. The crude extract contained lesser number of compounds as compared to the sub-fraction. These results suggest that the acetone sub-fraction from the aerial parts of A. afra may be a good candidate for further anti-TB drug development Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2025 2025-01-01T00:00:00Z http://hdl.handle.net/10386/4940 An investigation of fermentation and maturation temperatures on the chemical and sensory characteristics of the starter-culture based marula fruit wines Ramoba, Louis Temperature is an important factor that affects the growth and activities of wine microorganisms, which then influences the chemical profile and consequently the organoleptic characteristics of the wine. The aim of the study was to evaluate the influence of varying temperatures for fermentation, maturation and storage conditions on the chemical, nutritional and sensory characteristics of starter-culture-based marula fruit wines. Clarified sweetened marula fruit juices were fermented at 15 °C and 25 °C, and one portion from each was matured and aged at the same temperatures. Another portion from each fermented wine was matured and aged at 4 °C, whereas the reference wine was fermented at 25 °C using the clarified unsweetened marula fruit juice, and matured and stored at 15 °C and 4 °C. The microorganisms isolated from bottled aging wines were identified with the 16S rRNA region. Organic chemicals such as sugars, alcohols, glycerol, pH, acids, esters, tannins, and antioxidants were determined using conventional chemical analysis method, spectroscopy and chromatographic methods. Selected nutrients such as minerals, proteins, cholesterol, crude fats and vitamin C were determined as well. All the wines were subjected to panel testing. The microbial species that were identified in the aging marula wines at different temperatures include Saccharomyces cerevisiae, Lactobacillus brevis, Acetobacter lovaniensis, Acetobacter ghanensis, Raoultella terrigena, Raoutella ornithinolytica and Bacillus species. The naturally occurring citric acid which influences titratable and total acidity in wines was detected at higher concentration, while lactic and acetic acids were the least produced. An increase in higher alcohols and spicy esters was observed in the wines that were produced at 25 °C, whereas the level of fruity esters increased in wines that were stored at 4 °C. The wines preserved and improved some of the essential nutrients such as proteins and minerals, whereas vitamin C levels dropped in the wines that were produced at elevated temperatures. The wine that was fermented at 15 °C, matured and stored at 4 °C was the most appreciated as compared to wines that were produced at elevated temperatures. These findings asserted the development of good flavours in wines produced at lower temperatures, as is the case with marula fruit wine wherein the complex intensive flavour profile and good balance can be attained at lower production temperatures. Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2024 2024-01-01T00:00:00Z http://hdl.handle.net/10386/4929 Improvement of the alcohol content and an investigation of fermentation and maturation temperatures on the chemical and sensory characteristics of unpasteurised starter culture-based marula fruit wine Mapheto, Ramatsobane Phangisile Robyn Marula fruit wine is an alcoholic beverage that is produced through fermentation of marula fruit juice. The traditional marula fruit wine has a low alcohol content and spoils quickly. This study investigated the production of a high alcohol wine through starter culture-based fermentation of unpasteurised marula fruit juice. The influence of varying fermentation and maturation temperatures (15 °C and 25 °C) on chemical and sensory properties were explored. Selected chemicals, nutritional content and sensory characteristics were evaluated. The fermentation rate at 25 °C surpassed that at 15 °C, with wines reaching 1.0 °Brix in 10 days and 30 days, respectively. Alcohol content increased gradually and reached 12% as sugar got utilised. A pH of 3.44 – 3.88 deterred spoilage microorganisms yet Bacillus species, commonly found in soil and associated with winemaking, were observed in the wines at 15 °C and 25 °C post fermentation. Evaluation of organic acids revealed citric acid dominance (3.28 – 5.70 g/L), along with malic acid (2 – 6 g/L) and low levels of acetic acid (< 2.1 g/L), contributing to desirable sensory characteristics. While temperature variations did not significantly influence higher alcohols, levels at 25 °C were higher than at 15 °C. Mineral concentrations fell below dietary recommendations, with notable potassium and sodium quantities. Protein content ranged from 7.5 to 11 μg/mL. The antioxidant, vitamin C, ranged from 96.6 – 128.7 μg/mL in the 25 – 4 °C wine during the storage phase. The interactions of the chemicals and yeasts contributed to the sensorial characters of the wine. The wine fermented and stored at 15 °C, i.e., 15 – 15 °C and 15 – 4 °C demonstrated to be the most appreciated for taste. This could be attributed to the residual sugar content and higher alcohols for its sweetness and fruity taste. The findings demonstrated that varying temperature did not influence most of the selected nutritional content. Additionally, 25 °C should be used to initiate fermentation, 15 °C for maturation and finally 4 °C for aging to balance the rate of fermentation progression and the production of good wine character. Despite a general understanding of the impact of temperature on flavour development and chemical contribution, the full extent of its influence remains a subject of ongoing exploration. Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2024 2024-01-01T00:00:00Z http://hdl.handle.net/10386/4805 Evaluation of the microbiological, nutritive and health properties of a millet-based fermented beverage Mogashoa, Dipoelo This study explored the potential of millet as a mainstream food source, emphasising its exceptional nutritional composition that promotes good health. The research focused on millet-based mageu, analysing two formulations: one with 90% millet flour and the other with 50%, over an 8-week storage period. The assessment included lactic acid bacteria (LAB), total aerobic bacteria, Escherichia coli, and moulds/yeasts. LAB were examined for probiotic traits like acid and bile tolerance, antibiotic susceptibility, and antioxidant activity. Chemical profile, nutritional, and sensory characteristics of mageu products were also evaluated. Viable LAB cells in both mageu formulations ranged from 193 × 104 to 24 × 106 CFU/mL, surpassing total aerobic bacteria (2.0 × 102 – 7 × 105 CFU/mL) and fungal counts (1.1 × 102 – 7.05 × 103 CFU/mL); E. coli was not detected. Identified as Pediococcus pentosaceus MD02 and Pediococcus acidilacti MD01, these LAB strains exhibited sensitivity at pH 1.5 for a short exposure time of 3 hours and tolerant to moderate acidity of pH 3 for a longer exposure time of 36 hours. The LAB strains further showed 40% – 90% survival rate in a low (0.3%) and high (0.9%) bile salt concentrations after exposure for short (24 hours) and longer (48 hours) periods. P. pentosaceus MD02 exhibited a higher antioxidant capacity of 38.85%. The strains showed resistance to streptomycin and penicillin. Mageu pH decreased from 4.2 to 3.2, and total titratable acidity increased from 0.16% to 0.27%. Antioxidant activity was lower than L-ascorbic acid. Proximate analysis revealed increased protein (42 – 58 μg/mL), crude fat (0.54 – 0.96 g/mL), moisture (85% – 99%), and ash (9.8% – 13%). Minerals (calcium, potassium, magnesium, sodium, phosphorus) ranged from 1.2 – 9.6 mg/mL, and sugars (glucose 2 – 47 mg/mL, sucrose 4 – 96 mg/mL) were detected. Sensory evaluation varied, with mageu 5:5 preferred. Millet-based mageu, fermented with LAB, demonstrated probiotic properties, nutritional value, and favourable sensory attributes and the natural bitter taste of millet was neutralised. Millet emerges as a highly nutritional alternative to staple cereals. This study highlights the potential of millet as a mainstream, health-promoting food source, addressing the demand for diverse and nutritious alternatives to traditional cereals like maize, sorghum, and wheat. Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2024 2024-01-01T00:00:00Z