Dissertations & Theses

Influence of geographic location, emergence season and degutting method on quality of gonimbrasia belina

Sun, 01 Jan 2023 00:00:00 GMT

Influence of geographic location, emergence season and degutting method on quality of gonimbrasia belina Madimutsa, Obert Nobert Edible insects such as Gonimbrasia belina (mopane worm) consumption contributes to the sustainable supply of protein and other nutrients (iron and zinc) for low socio-economic communities. Moreover, mopane worms are a potential source of bioactive compounds such as phenolic compounds, which have antioxidant properties. However, the nutritional composition of foods of animal and plant origin is affected by different factors, including processing method, emergence season and sourcing geographical area though the above factors are cited as affecting the nutritional composition of edible insects, and there is limited information about their specific effects on mopane worm for full utilization of the resource. Mopane worms are bivoltine, producing two generations per rainy season which is also postulated to affect their nutritional value. Effects of emergence season, geographic location, and pre-processing techniques on their nutritional composition are relevant for dependable usage of mopane worm. The acceptance of mopane worm by consumers and its contribution to food security is well studied. However, there is still a knowledge gap in terms of food safety and anti-oxidant properties associated with this edible insect. Finding an answer to these areas has many implications; from enhancing the productivity of mopane worm and to developing better strategies of utilization of this important natural resource. In this study, the influence of geolocation and emergence season on mopane worms' nutritional composition was investigated. Proximate, mineral composition and fatty acid profile were analysed on degutted mopane worm samples collected over two mopane worm emergence seasons (November to December 2020 and 2021, April to May 2021, from three locations in Gwanda district, Zimbabwe. A further analysis on the effect of degutting method on the mopane worm's proximate composition, antioxidant capabilities, chemical, and microbial safety was conducted. Natural degutting process is when mature mopane worm remove their gut contents before they burrowing in the soil. Manual degutting process is when actively feeding mopane worm’s gut is pressed outside in order to remove the gut contents. Crude protein was determined by Kjeldahl method, crude fat by Soxhlet extraction, ash by incineration in a muffle furnace and crude fibre by chemical digestion followed by ashing. Mineral and heavy metal content was determined on an Atomic absorption spectrophotometer after wet ashing. Phosphorus was determined calorimetrically on a UV-visible spectrophotometer. Total phenolic content was determined by the folin-ciocalteau assay whilst the total flavonoid content was determined by the aluminium chloride assay. The crude protein content of mopane worms ranged between 52.5±0.21 v and 59.9±0.18 % DM and differed significantly (Bonferroni-correction α < 0.002) (p<0.05) between seasons, location and degutting method. Naturally degutted mopane worms had higher crude protein than manually degutted samples. Depending on the season, location, and degutting method, mopane worms' fat content varied considerably (Bonferroni-correction α < 0.002) (p<0.05) between 12.1±0.06 and 19.0±0.05 % DM. Season, location, and degutting technique all had a significant (Bonferroni-correction α < 0.002) (p<0.05) impact on the mineral content of mopane worms. Potassium (1195.3±0.4 – 1759.9±0.2), magnesium (104.6±0.3 – 225.5±0.3) and calcium (51.2±0.4 – 145.5±0.3) were the most abundant macro-elements (mg/100g DM), whilst iron (10.6±0.2 – 21.6±0.2) and zinc (12.7±0.1 – 17.9±0.4) were the most abundant micro-elements (mg/100g DM). Manually degutted samples had significantly higher (p<0.05) concentrations of zinc (16.1±0.3 mg/100g) and phosphorus (610.0±3.4 mg/100g). Mopane worm fat was found to contain high concentrations of oleic (ω-9) and linoleic (ω-6) and palmitoleic (ω-7) fatty acids using an Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR). The antioxidant activity against the DPPH radical (53.8±1.4 %), ABTS radical (97.8±0.18 %), Fe2+ metal chelating activity (56.6±0.01 %), PFRAP (0.25±0.01), total phenolic content (740±2.4 mg gallic acid eq/100 g) was high for naturally degutted samples, whilst total flavonoid content was high in manually degutted (16.8±0.02 mg QE/100g). However, samples that were naturally degutted exhibited a larger microbial load (TBC, coliforms, E. coli, as well as yeast and moulds) than samples that were manually degutted (p<0.05). S. aureus, Salmonella spp and heavy metals were not detected in naturally and manually degutted samples. The results showed that mopane worms can be used as an alternative protein source and a strong source of antioxidants. Harvesting mature mopane worm (naturally degutted) has an advantage of ensured high levels of macro and micro-nutrients and antioxidants but poses a great risk in terms of microbial safety. These results also suggest that mopane worm, could have a substantial role in reducing protein, zinc, and iron deficiencies in target communities.

Discovery of Cucurbita maxima compounds as Schistosoma mansoni and Schistosoma haematobium inhibitors.

Mon, 01 May 2023 00:00:00 GMT

Discovery of Cucurbita maxima compounds as Schistosoma mansoni and Schistosoma haematobium inhibitors. Mtemeli, Floryn Lynorah Over 200 million people worldwide suffer from schistosomiasis, a disease usually associated with poverty and poor sanitation. A single drug, praziquantel (PZQ), has been used by the medical community since the 1970s. The emerging evidence of resistance of the Schistosoma parasite to praziquantel, and the drug's ineffectiveness against juvenile stages of the parasite, calls for alternative drug. The exploration of the inhibition potential of compounds from Cucurbita maxima using molecular docking studies on Schistosoma mansoni purine nucleoside phosphorylase (SmPNP) and Schistosoma haematobium 28-kDa glutathione S-transferase (Sh28kDaGST) was done. Following molecular docking studies and analysis of the active sites, the primary amino acids that were observed and shown to be involved in the SmPNP-ligand interaction are CYS 33, ARG 86, HIS 88, TYR 90, ALA 118, ALA 119, PRO 200, TYR 202, GLU 203, VAL 219, MET 221, THR 244, ASN 245, PRO 257 and HIS 259. For the Sh28dKa-ligand interaction, the primary amino acids were PHE 11, ARG 16, TRP 41, LEU 53, GLU 70 and SER 71. Momordicoside I aglycone binds to SmPNP HIS88 with the lowest binding energy of -7.9kcal/mol. Balsaminoside B binds to Sh28kDaGST with a binding energy of −7.6kcal/mol by hydrogen bond interaction with TRP 41, LEU 53 and SER 71. The anti-schistosomal activity of C. maxima seeds extract alone and in combination with PZQ on Schistosoma mansoni-infected mice and were also done. The parasites were sampled from the Mupfure River in the Mashonaland East province of Zimbabwe from three different village sites namely Chikanza, Matimure and Mwedziwandira. Infection of guinea pigs with Schistosoma haematobium was attempted. Unfortunately, the infection in the guinea pigs was unsuccessful. Results indicate a statistically significant reduction in granuloma size in the C. maxima extract +praziquantel treated group, with a 13,24% margin compared to the C. maxima seeds extracts treated group. Treatment by C. maxima seeds extract and C. maxima seeds extract + PZQ significantly reduced the egg count in intestines and live (p=0.00; p=0.00 & p=0.00), respectively. There was no significant difference in the effect of the village sites from where the parasites were sampled (p>0.05). The anti-schistosomal effect of C. maxima extracts and their synergistic effects when in combination with praziquantel were observed. In addition to providing a predictive model for interactions between C. maxima ligands, SmPNP and Sh28kDaGST, the in vivo work validated the in silco findings and confirmed that C. maxima does have antischistosomal properties. We propose that as future work, in vitro studies on the target proteins be carried out to elucidate the mechanism of action of the C. maxima plant. We also recommend performing selectivity tests of the best-performing compounds on the target proteins. Overall, our study lays a crucial foundation in the development of a new drug against schistosomiasis and we recommend that C. maxima seeds and their combination with praziquantel be considered as candidates for the development of a new drug against schistosomiasis.

Indigenous Culinary Claims and Molecular Gastronomy: developing a model for Culinary Tourism In Zimbabwe

Sun, 01 Jan 2023 00:00:00 GMT

Indigenous Culinary Claims and Molecular Gastronomy: developing a model for Culinary Tourism In Zimbabwe Margaret, Nyarota Destinations around the globe have used their indigenous cuisines as a new tourism product whose uniqueness, authenticity and the general quality has given them a niche market for a competitive advantage. However, for other destinations, especially in developing countries, not much has been done. This was as a result of a lack of preservation of indigenous cuisines for that uniqueness and authenticity, and Zimbabwe is no exception. Furthermore, there is generally a lack of rational understanding of the phenomenon involved in the food preparation process which is key for the development of quality cuisines. The uniqueness of a country’s cuisines is embedded in indigenous people’s methods and procedures of food preparation and cooking (indigenous culinary claims). The aim of this study was to: assess the validity of Zimbabwe’s indigenous culinary claims through molecular gastronomy for the development of a model for culinary tourism. The specific objectives of the study were as follows: 1) to establish the nature of culinary tourism in Zimbabwe 2) to assess the extent to which indigenous cuisines are being consumed by tourists in Zimbabwe. 3) to explore the available indigenous culinary claims in Zimbabwe 4) to conduct an assay of Zimbabwe’s indigenous culinary claims through molecular gastronomy and 5) to develop a model for culinary tourism in Zimbabwe from the indigenous culinary claims and molecular gastronomy. The pragmatic philosophy was applicable and mixed methodology were used to cater for the multidisciplinary nature of the study. Similarly, a number of research designs were employed: survey, exploratory, descriptive, and experimental and observation. Data was collected from tourists, hospitality industry practitioners, indigenous elderly women, food science students, hospitality lecturers and canteen staff using structured and open-ended questionnaires, observation guides and in-depth interviews. These respondents were sampled through, purposive, convenient and snow balling methods. Thematic analysis was used for qualitative data, while the quantitative data used descriptive and non-parametric statistical methods from SPSS version 23. Tables, charts, graphs were used for quantitative data presentation, while qualitative data was presented in themes. The study findings indicated that culinary tourism in Zimbabwe was made up of a product which is compromising on the quality of indigenous cuisines in that: they were lacking in variety, the indigenous taste, authenticity and uniqueness and the prices were rather on the high side. Furthermore, the indigenous cuisines were still not a motivation for the choice of the destination. Findings on the indigenous culinary claims were based on the importance attached to the local foods, which was the reason for the indigenous people to attach that iv value to food preparation and everything else that was related to their cuisines. Indigenous culinary claims focused on coming up with a specific quality of the product, therefore, all methods and procedures had explanations to why and how. Claims validation indicated that specific aspects of the cuisine were affected by the processes and procedures in its preparation and cooking as well as its service. The conclusion drawn from the study was that the indigenous culinary claims were valid, because the dishes prepared using the indigenous claims had better quality than those which did not follow the specification. The study findings can assist in informing policy on product development in the hospitality industry. On the practical side, the culinary claims and molecular gastronomy model can be used in developing indigenous cuisines and other culinary products for culinary tourism. This study, fulfils Education 5.0, when the model is used in the hospitality industry. This study recommends the exploration and validation of indigenous culinary claims to continue in other provinces of Zimbabwe,and the industry should start using the mode proposed by this study. The validation of indigenous culinary claims can be done using the qualitative method in other studies to complement the quantitative findings study of claims validation can use the qualitative method.

Geospatial Assessment of Habitat Disturbance and Land cover change in a Human-Mediated Ecosystem, Midlands Black Rhino Conservancy, and Zimbabwe.

Sun, 01 Jan 2023 00:00:00 GMT

Geospatial Assessment of Habitat Disturbance and Land cover change in a Human-Mediated Ecosystem, Midlands Black Rhino Conservancy, and Zimbabwe. Kunedzimwe, Francisca The main purpose of the research was to assess the extent of disturbance and land cover changes using geospatial technology in the Midlands Black Rhino Conservancy, Kwekwe, Zimbabwe which is a human mediated environment. Recent research has established that conservancies are undergoing structural changes mainly characterized by changes in land cover commonly referred to as patch dynamics. There is little knowledge as to how this global phenomenon is being understood (extent and consequences of patch dynamics). This research aims to fill the currently outlined gap in innovative geo-technological ways to determine and assess the occur rence of this disturbance and quantify its extent. An analysis of trends was done and land use land cover maps from 1980, 1990, 2000,2010 and 2020 were created from remotely sensed images. The generated images were classified to detect changes that occurred over time in the human mediated environment where mining activities, agriculture and some other activities are taking place. Patch analyst was used for the landscape assessment and characteristic determi nation; land use land cover statistics were generated for each land cover map for a specific year. Net primary production was estimated using remote sensed imagery to determine the changes in vegetation productivity. The overall transformations in the area of study showed a decrease in forest cover, lake, grassland and increased bare land as well as an increase in the areas occupied by human activities such as agriculture and mining among others. The changes that were detected were predominantly derived by the indiscriminate logging for mining and agricultural purposes. The decrease in habitat sizes resulted in the decrease in habitat richness, heterogeneity, fragmentation and the complexity of form and increased land use intensity. A decrease in net primary productivity was also detected through the computing of NDVI. There is a beneficial trade off that is provided by the approach of this research work especially be tween very expensive ground surveys and the low-priced image processing analysis. Results of this research further the understanding of spatial dynamics in a protected area and its key drivers.