Browsing by Author "Ndabikunze, Bernadette K."

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    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.
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    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 Balling
    Tropical 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.
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    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.