Browsing by Author "Mongi, Richard J."
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Item Assessment of post-harvest handling practices: knowledge and losses of fruits in Bagamoyo district of Tanzania(IISTE, 2013) Kereth, Gudila A.; Lyimo, Monica; Mbwana, Hadijah A.; Mongi, Richard J.; Ruhembe, Carolyne C.The harvesting practices, knowledge and post-harvest losses of fruits along the supply chain in Bagamoyo District were investigated. 142 farmers, 50 retailers and 10 wholesalers dealing with fruits were involved in the study. Data were collected using structured questionnaires. The results indicate that, 90.14% of the respondents harvested fruits when they are just ripe and the great market losses were reported to occur due to rotting (microbial) at 63%, physiological at 20% and 17% by insects and rodents. Along the supply chain, mechanical damage was observed to be the major type of loss during harvesting (79%) and transportation (56%) while microbial damage was observed by majority (67%) during marketing. Poor infrastructure from farm to the market was observed to account for large percentage of losses in the market. The findings also shows that all farmers (100%) interviewed have no knowledge on post-harvest losses and management. In the view of the findings, it can be concluded that, post-harvest handling practices and knowledge of stakeholders involved in fruit sub sector in the country are not good enough to prevent the losses. It is therefore imperative to improve educational knowledge, skills and fruits quality from the field to reduce post-harvest losses.Item A comparative study of mango solar drying methods by visible and near-infrared spectroscopy coupled with ANOVA-simultaneous component analysis (ASCA)(Elsevier, 2019) Cheng, Weiwei; Sørensen, Klavs M.; Mongi, Richard J.; Ndabikunze, Bernadette K.; Chove, Bernard E.; Sun, Da-Wen; Engelsen, Søren B.The effect of mango solar drying methods (traditional and tunnel dryers) on the quality of dried mango slices was investigated by visible (VIS) and near-infrared (NIR) spectroscopy combined with the chemometric analysis methods of principal component analysis (PCA) and ANOVA-simultaneous component analysis (ASCA). Five batches of mango were investigated, each subjected to two/three different positions of three different types of dryers: electrical (reference), traditional, and tunnel dryers. The results of the visible and near-infrared spectra showed that the quality of the mango samples obtained from the electrical dryer (reference method) was the most uniform and conserved the highest content of carotenoids and chlorophyll pigments. The samples from the traditional dryer had the highest variation and content of residual water. ASCA analysis of visible and shortwave near-infrared (VIS-NIR) (including color information) showed that the batch effect was most dominant with a significance effect of 47.5%, whereas longwave near-infrared (NIR) spectra (chemistry) showed that the dryer effect was the most dominant with a significance effect of 38.3%. The factor of the fruit positions in the dryers proved not to be significant. The VIS-NIR spectrum is thus well adapted to measure the fruit maturity and the NIR spectrum has great potential to investigate and control the dryer performance. The latter clearly demonstrated that the tunnel dryer provides much more gentle and consistent drying process compared to the traditional dryer. In contrast, the samples from the traditional dryer showed chemical changes/decomposition.Item A comprehensive and comparative GC–MS metabolomics study of non-volatiles in Tanzanian grown mango, pineapple, jackfruit, baobab and tamarind fruits(Elsevier, 2016) Khakimov, Bekzod; Mongi, Richard J.; Sørensen, Klavs M.; Ndabikunze, Bernadette K.; Chove, Bernard E.; Engelsen, Søren BallingTropical fruits contribute significantly to the total fruit intake worldwide. However, their metabolomes have not yet been investigated comprehensively, as most previous studies revealed only volatile and bulk compositions. This study compares non-volatile metabolites of five fruits grown in Tanzania. A new methodology is developed for broad-spectrum GC–MS metabolomics in fruits using a new derivatization and a two dimensional peak deconvolution techniques. A total of 92 peaks were detected from fruits of which 45 were identified. Jackfruits contained the highest amount of carbohydrates, while baobab contained the highest amount of fatty acids. The highest content of organic acids was detected in tamarind. Principal component analysis revealed insights into metabolic differences and similarities, while hierarchical cluster analysis correctly grouped the fruits according to their relationships in plants’ phylogenetic tree. The developed methodology could potentially be applied in large-scale studies on fruit quality, authenticity/variety, optimization of post-harvest processing and storage.Item Descriptive sensory analysis, consumer liking and preference mapping for solar dried mango cv Dodo(IISTE, 2013) Mongi, Richard J.; Ndabikunze, Bernadette; Chove, Bernard; Wicklund, TrudeDescriptive sensory characteristics, consumer liking and preference mapping of solar dried mango cv Dodo were investigated in this study. Three solar drying methods solar cabinet direct dryer (CDD), cabinet mixed-mode dryer (CMD) and Tunnel dryer (TD) were used to dry mango samples while fresh sample was used as control. Descriptive sensory analysis was performed by 15 trained panelists who used 6 descriptors to quantitatively describe the sensory characteristics of mango samples while 78 consumers were used to assess the degree of liking of products’ sensory attributes using nine-point hedonic scale. External preference mapping was performed by relating sensory data with hedonic responses. Randomized complete block research design with panelists and samples as main principal factors was used. The results showed significant differences (p<0.05) in mean intensity scores of whiteness, hardness and sweetness attributes with dried samples having higher values than their fresh counterparts. Fresh sample had significantly (p<0.05) higher colour intensity score than dried samples. The consumer study showed that, with exception of taste attribute, consumers showed significant (p<0.05) differences in colour, texture, mouth feel and overall acceptability with fresh samples having higher values than dried counterparts. Moreover, the preference mapping results showed colour and acidity (flavour) attributes to be the main driver for positive consumer preference for fresh samples. Among the drying methods, tunnel dryer showed a relatively close relationship with these attributes than cabinet dryers. In conclusion, solar drying has significant effect on sensory attributes of dried mango especially colour and flavour which is also dependent on the drying method employed. Therefore, selection of appropriate drying method which will retain these attributes is of greater importance for consumer acceptability and marketability.Item Effect of solar drying methods on proximate composition, sugar profile and organic acids of mango varieties in Tanzania(Elsevier, 2022) Mongi, Richard J.; Ngoma, Selestin J.Solar drying is a simple and affordable alternative technology for reducing the enormous post-harvest losses of agricultural produce in developing countries. However, it may result in nutritional loss if not well applied. The objective of this study was to investigate the effect of solar drying methods on proximate composition, sugars and organic acids of different mango varieties ( Dodo, Viringe and Kent ) in Tanzania. The varieties were dried using cabinet mixed-mode and tunnel dryers and analyzed for the named parameters. Potassium, sucrose and citric acids were the most abundant mineral, sugar and organic acids in mango varieties respectively. Proximate composition, sugars and organic acids differed significantly (p < 0.05) between fresh and dried samples and between drying methods with all fresh samples having higher values. Despite the loss, a significant quantity of proximate composition ( > 65%), sugars (87-99%), and organic acids (71-80.1%) were retained in dried samples, with tunnel samples having higher retention than cabinet samples except for sugars. This suggests that solar drying technology is suitable for the preservation of mangoes due to its minimal effects on proximate composition, sugar and organic acids, hence, its application in the country is highly recommended.Item Effect of solar drying methods on total phenolic contents and antioxidant activity of commonly consumed fruits and vegetable (mango, banana, pineapple and tomato) in Tanzania(Academic Journals, 2015) Mongi, Richard J.; Ndabikunze, Bernadette K.; Wicklund, Trude; Chove, Lucy M.; Chove, Bernard E.The effects of solar drying methods [Cabinet direct (CDD), cabinet mixed mode (CMD) and tunnel (TD) drying] on total phenolic content (TPC) and antioxidant capacities of commonly consumed fruits and vegetable in Tanzania were investigated. The TPC and FRAP in mangoes (Mangifera indica cv. Dodo, Viringe and Kent), bananas (Musa acuminata, cv. Kisukari, Kimalindi and Mtwike), pineapples (Ananas comosuss cv Smooth cayenne) and tomatoes (Lycopersicum esculentum cv. Tanya, Cal J and Onyx) were evaluated using Folin-Ciocalteu reagent and ferric reducing antioxidant power (FRAP) methods, respectively. There were significant (p<0.05) variations in TPC (mg GAE/100 g DM) and FRAP (μmol/100 g DM) among the fresh fruit and vegetable samples. The highest TPC was in tomato (476.6±8.6 - 538.9± 1.4) and lowest in banana (139.3±2.3 - 189.2±2.7). Drying methods had significant (p<0.05) effect on TPC and antioxidant values of the samples. All fresh samples had higher TPC levels but declined significantly in dried samples with the exception of tunnel dried tomatoes. Among the dried samples, the tunnel dried samples had less TPC loss (6-16%) than the cabinet dried samples (17-42%). The cabinet direct and mixed mode samples were not statistically different (p>0.05) from each other. However, tunnel dried samples had less FRAP loss (6-13%) which were statistically different (p<0.05) from the cabinet dried samples (14-56%). Percentage TPC and FRAP recoveries (%) differed significantly (P<0.05) between the varieties within the fruits/vegetable for both drying methods. A strong correlations between TPC and FRAP in both fresh (R2= 0.970) and dried samples (R2=0.8636) suggests that solar drying methods have significant effects on total phenolic contents and antioxidant activities of fruits and vegetables with tunnel drying method giving significantly less effects.Item Protein content and anti-nutritional factors in pigeon pea and effect of its protein isolate on physical properties and consumer preference of beef sausages(Elsevier, 2022) Gomezulu, Alice D.; Mongi, Richard J.Prolonged consumption of chemical binders in sausage can cause health effects. Pigeon pea is rich in protein which can be isolated and used as an alternative to chemicals and soybean protein in the manufacture of sausages. The objective of this study was to assess protein content and anti-nutritional factors of pigeon pea varieties and the effects of its protein isolate on physical properties and consumer preference as a replacement of chemical binders. Pea protein was isolated from rich protein variety and used for sausage preparation at 2, 4, and 6% with plain (CB) and chemical phosphate binder (PhosB) sausages served as control samples. The sausages were assessed for texture profile, water solubility index (WSI) and consumer preferences. The improved variety had significantly (p < 0.05) higher protein content than its local counterpart and both varieties had lower anti-nutritional factors than maximum limits. The 6% pea protein isolate (PPI) resulted in softer and more preferred sausages than control and phosphate binder sausages. Furthermore, the PPI resulted in increased cohesiveness, springiness and adhesiveness more than control samples but similar to phosphate binder sausages. Therefore, pea protein isolate up to 6% enhances physical and consumer preference of beef sausages and can serve as an alternative replacement of chemical binders in beef sausages.Item Quality assessment of Ugali blended with orange-fleshed sweet potato to alleviate vitamin A deficiency in Tanzania(Academic Journals, 2021) Fortunatus, Roman M.; Simonne, Amarat H.; Mongi, Richard J.Approximately 38% of Tanzanian children have vitamin A deficiency (VAD), and the majority of them do not have access to vitamin A-fortified foods. Orange-fleshed sweet potato (OFSP), a new crop in Tanzania, is rich in β-carotene, and could be a cheaper solution for VAD. The objectives of this study were to develop a type of Ugali (stiff maize porridge) fortified with OFSP, to correlate its β-carotene content (using colour measurement), and to assess its proximate composition and consumer acceptability. Ugali was prepared using maize flour with various amounts of added OFSP (0, 30, 50, 70 and 100%). Samples of Ugali with more OFSP had higher colour values (a* and b*) that imply the increase in β-carotene as the OFSP amount increased. The proximate compositions of Ugali with different amounts of OFSP were different (P<0.05). All samples that were made with the mixture of OFSP and maize flour have shown to have higher sensory scores than those with 100% maize or 100% OFSP; Ugali with 50% OFSP was most favourably rated by Tanzanian consumers. This sample was selected as a potential possibility for everyday consumption since it was shown to potentially supply more than 50% of the RDA of provitamin A for a specific age group. This supplementation method may be simple, affordable, and effective in reducing VAD in Tanzania.