Browsing by Author "Chove, Lucy Mlipano"

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Detection of proteolysis in milk by four selected methods
(The University of Reading, 2009) Chove, Lucy Mlipano
Sensitive methods that are currently used to monitor proteolysis are limited due to their high cost and lack of standardisation for quality assurance in the various dairy laboratories. In this study, four methods, trinitrobenzene sulphonic acid (TNBS), reverse phase high pressure liquid chromatography (RP-HPLC), gel electrophoresis and fluorescamine, were selected to determine their suitability for the detection of proteolysis in milk by added trypsin, plasmin, Pseudomonas fluorescens NCIMB 701274 (414) and Pseudomonas fluorescens NCIMB 702085 (416) and Bacillus licheniformis enzymes. Raw, pasteurised and UHT milk used to study proteolysis were analysed by the four methods. Pseudomonas fluorescens enzyme was extracted in this study since commercial enzymes are not available. All four methods confirmed that Pseudomonas fluorescens 416 was more proteolytic than Pseudomonas fluorescens 414. Dialysis was effective in the purification of Pseudomonas fluorescens (Ps. fl.) enzymes increasing the detection limit for the fluorescamine method, which had a low upper detection limit. Prominent peaks by RP-HPLC were shown to occur between 20-30 min for Pseudomonas fluorescens but 20-25 min for Bacillus licheniformis. RP-HPLC confirmed a peptide peak at 35 min in pH 4.6 soluble extract, which was absent in 6% TCA soluble extract, was from plasmin. Casein breakdown profiles by gel electrophoresis confirmed preference for 0-casein degradation over a and K-caseins by both Ps. fl. and B. licheniformis. Comparison of raw and pasteurised milk (72, 85 and 90°C for 15 s) revealed that pasteurisation was insufficient to inactivate plasmin inhibitors. The pH 4.6 and 6% TCA soluble extracts of UHT skim milk with added trypsin or plasmin showed high correlations (R2 > 0.93) by the TNBS, fluorescamine and RP-HPLC methods, confirming increased proteolysis during storage. Gel electrophoresis showed that breakdown products from trypsin were similar to plasmin although the former caused more extensive proteolysis than the latter due to higher enzyme activity, y-caseins, formed as a result of P-casein degradation disappeared (1484 and 742 BAEE units of added trypsin on days 3 and 7) due to extensive proteolysis. This finding had not previously been reported. Milk processed at high temperatures (110, 120, 130 and 142°C for 2 s) had lower proteolytic activities than raw milk and milk heated at 85°C implying inactivation of plasmin at temperatures of 110°C and above. This was observed in all the methods assessed. The TNBS method was recommended on the basis of its accuracy, reliability, simplicity and cost.
Detection of proteolysis in milk by pseudomonas fluorescens using urea PAGE method
(Macrothink Institute, 2017-12-28) Chove, Lucy Mlipano; Alistair, Grandison; Michael, Lewis
Proteolysis of milk during storage by two strains of Pseudomonas NCIMB 702085 (414) and NCIMB 701274 (416) was investigated using the Urea PAGE method. Pseudomonas fluorescens enzymes were also extracted and purified by dialysis before inoculation into UHT skim milk in an attempt to partially purify the enzyme. Results showed that dialysis removed some peptides and amino acids which would interfere with the assay procedure. The method also confirmed that Pseudomonas fluorescens NCIMB 701274 (416) was more proteolytic than Pseudomonas NCIMB 702085 (414). Thus, Urea PAGE is a useful method for monitoring proteolysis in milk by Pseudomonas fluorescens.
Effect of depth and distance of the borehole from the septic tank on the physico-chemical quality of water
(Macrothink Institute, 2017-12-28) Chove, Lucy Mlipano; Mongi, Richard; Chenge, Lawrence
A study to examine the effect of depth and distance of the boreholes from the septic tank on physico-chemical parameters of the borehole water consumed in Dar Es Salaam, Tanzania was conducted. Samples were collected from 48 boreholes in Ilala, Kinondoni and Temeke districts and subjected to pH, B.O.D (Biological Oxygen Demand), total hardness, copper and lead analyses in relation to safety and quality levels set by WHO and TBS. Analysis by R-statistics indicated that pH and B.O.D significantly (p<0.05) decreased as the depth of borehole increased, whereas total hardness was significantly (p<0.05) higher in very deep boreholes than the other heights. Total hardness and pH were not significantly (p>0.05) affected by distance between septic tank and borehole and the B.O.D levels were significantly higher in the borehole water situated near the septic tank than those which were far. Based on the physico-chemical characteristics of water, 25% of the samples did not comply with WHO and TBS specification limits while 75% complied, most of which had shallow depths and were situated near the septic tank. It may thus be concluded that both the distance and the depth between septic tank and borehole influenced physico-chemical characteristics of water.
Effect of final moisture content, cooling time and paddy variety on milling quality of rice (Oryza sativa, L.)
(Pearl Research Journals, 2016) Furahisha, Kulwa; Chove, Lucy Mlipano; Chaula, Davis
The study was carried out to establish the effects of three factors -final moisture content (FMC), shade-cooling time (CT) and paddy variety on rice milling quality. Paddy was sun dried to final moisture contents ranging from 9.0 to 15.5% (on wet basis) and shade-cooled for 0, 6, 12, 18, and 24 h at ambient temperature (27.20 to 35.10 o C). Five paddy varieties, TXD 88, TXD 306, SUPA, IRRITA 1, and IRRITA 2 were studied. The milling tests were carried out using a laboratory rice mill. Latin square design with 5 replications (5x5 orders) was used. Physical properties and milling quality in terms of total rice yield (TRY), head rice yield (HRY) and whiteness index (WI) were analyzed. The physical properties differed significantly (P<0.05) among varieties. SUPA had good size, shape and chalkiness whereas TXD 88 had poor quality for all these parameters. IRRITA 1 and IRRITA 2 produced higher TRY compared to other tested varieties. TXD 88 had higher whiteness index but lower HRY compared to other tested varieties. Higher yields, which were significantly different for TRY and HRY (P<0.05) were obtained at moisture content between 9.0 to 12.5% for TRY, but between 10.5 to 14.0% for HRY
Effects of smoke, hexanal, and calcium chloride on post-harvest quality of oranges [Citrus x sinensis (L.) Osbeck] cvs Msasa and Jaffa under different storage durations and conditions in Tanzania
(The UWI, 2018) Baltazari, Anna; Mtui, Hosea Dunstan; Mwatawala, Maulid Walad; Chove, Lucy Mlipano; Sullivan, J. Alan; Paliyath, Gopinadhan; Subramanian, Jayasankar
Experiments were conducted to assess the effects of hexanal, calcium chloride, and smoke on the post-harvest quality of oranges under ambient (room) temperature (28±20C) and reduced temperature storage (18±20C) conditions on two varieties of sweet orange (Citrus x sinensis (L.) Osbeck) cvs ‘Msasa’ and ‘Jaffa’. Fruit were dipped in enhanced freshness formulation (EFF) containing hexanal as the key ingredient at 0.01%, 0.02%, and 0.04% (volume/volume), or calcium chloride solution at 1%, 2%, and 4% (weight /volume) for five minutes each, or subjected to a smoking regime, simulating a popular traditional practice, by burning 0.5 kg, 1.0 kg, and 1.5 kg of dried banana leaves, or left untreated (control). Various parameters including physiological weight loss, fruit firmness, total soluble solids (TSS), titratable acidity (TA), and the TSS/TA ratio were assessed to determine effects on post-harvest quality of fruit. Results indicate that hexanal and calcium chloride treatments significantly (p < 0.001) reduced physiological weight loss, maintained fruit firmness and significantly higher TSS in both varieties compared to smoke treatment and untreated controls. Reduced temperature storage also significantly (p < 0.001) lowered physiological weight loss of hexanal- and calcium chloride-treated oranges. Based on the results of this study, post-harvest dip treatments with hexanal solution at 0.02% or calcium chloride solution at 2% coupled with reduced temperature storage at 18°C are recommended to maintain the quality of fresh oranges in Tanzania. On the contrary, the application of smoke is highly discouraged as it reduces the quality of oranges.
Fruit consumption and storage practices among rural households in Chamwino district, Dodoma, Tanzania
(Academicjournals.org/AJFS, 2023-05) Chove, Lucy Mlipano; Mwanri, Akwilina Wendelin; Ngawembela, Mwanaisha Assim
Fruit consumption is still a challenge in many parts of Africa, and hence micronutrient deficiency continues to be a serious problem in the continent. This study was conducted between December 2017 and May 2018 in Chinoje and Mzula villages in Chamwino district, Dodoma to assess availability of fruit, consumption, storage practices and nutrient content. People responsible for food preparation were interviewed from 345 randomly selected households by using semi-structured and food frequency questionnaires. Multiple logistic regression model was used to determine the relationship between frequency of fruit consumption and household socio-economic features by using SPSS. Laboratory analysis was conducted to determine nutrient content of baobab, which was the most consumed fruit. Analysis of Variance (ANOVA) was used to determine if significant variations existed in the nutritional quality of baobab fruit by using SAS. Only 35% of the households consumed fruit daily, while the majority consumed fruit from one to three days in a week. Monthly income, household size and headship significantly affected fruit consumption at p<0.05. Most of the baobab fruits were stored in polypropylene sacks (77.4%), followed by plastic buckets (3.3%) and others as shelled fruit (18.4%). Significant losses in Vitamin C and total carotenoids were observed in baobab fruits that were stored in sacks. Storage of baobab fruit in plastic bucket is recommended for quality maintenance of nutrients.
Fruit consumption and storage practices among rural households in Chamwino district, Dodoma, Tanzania
(African Journal of Food Science, 2023-07) Ngawembela, Mwanaisha Assim; Mwanri, Akwilina Wendelin; Chove, Lucy Mlipano
Fruit consumption is still a challenge in many parts of Africa, and hence micronutrient deficiency continues to be a serious problem in the continent. This study was conducted between December 2017 and May 2018 in Chinoje and Mzula villages in Chamwino district, Dodoma to assess availability of fruit, consumption, storage practices and nutrient content. People responsible for food preparation were interviewed from 345 randomly selected households by using semi-structured and food frequency questionnaires. Multiple logistic regression model was used to determine the relationship between frequency of fruit consumption and household socio-economic features by using SPSS. Laboratory analysis was conducted to determine nutrient content of baobab, which was the most consumed fruit. Analysis of Variance (ANOVA) was used to determine if significant variations existed in the nutritional quality of baobab fruit by using SAS. Only 35% of the households consumed fruit daily, while the majority consumed fruit from one to three days in a week. Monthly income, household size and headship significantly affected fruit consumption at p<0.05. Most of the baobab fruits were stored in polypropylene sacks (77.4%), followed by plastic buckets (3.3%) and others as shelled fruit (18.4%). Significant losses in Vitamin C and total carotenoids were observed in baobab fruits that were stored in sacks. Storage of baobab fruit in plastic bucket is recommended for quality maintenance of nutrients.
Nutritional quality and functional properties of baobab (Adansonia digitata) pulp from Tanzania
(Canadian Center of Science and Education, 2016) Aluko, Angela; Kinyuru, John; Chove, Lucy Mlipano; Kahenya, Peter; Owino, Willis
Baobab (Adansonia digitata L.) is a majestic tree associated with human habitation in some of the semi-arid regions of Africa and establishes an enormous economic and nutritional importance to the rural residential districts. The fruit pulp is considered to be of high nutritional significance; particularly vitamin C and calcium, also possess antioxidant functions as well as high dietary fiber content. Although it is a potential fruit for improving local diets and livelihoods,this fruit is underutilized and its potential not yet fully acknowledged. This work was contracted with the aim of defining the nutritional quality and functional properties of baobab pulp harvested from some selected parts of Tanzania. Results indicated that the pulp from the three locations had moisture content which ranged between 9.16% to 10.30%, fat 0.46%-1.98%, ash 4.75%-5.21%, fiber 5.91%-9.65%, protein 3.23%-3.53%, carbohydrate 80.49%-85.19, vitamin C 169.74mg/100g-231.57mg/100g, beta-carotene 2.16 mg/100g-3.19mg/100g.Fructose 0.56±0.15-0.81±0.17g/100g, glucose 0.77±0.26-0.87±0.31g/100g and sucrose 0.75±0.25-0.84±0.29g/100g. The substantial differences (p≤ 0.05) between locations were observed in fat, crude fiber, carbohydrates, and fructose. Vitamin C, beta-carotene, protein, ash, moisture, sucrose and glucose showed no significance difference (p≤ 0.05) among locations. The functional properties included emulsification, foaming and gelling properties which ranged between 37.9-45.15%, 1.85-6.57% and 11-12% respectively and were significantly different (p≤ 0.05) among locations. The results show that baobab pulp has a good content of nutrients and functional properties which can be useful in food industries.
Preliminary study on the role of ionic calcium in gelation and proteolysis of UHT milk
(Macrothink Institute, 2017-12-28) Chove, Lucy Mlipano; Lewis, Michael
A study was conducted to determine the influence of ionic calcium on gelation and proteolysis in milk. Raw milk was heated to 142 °C for 2s followed by cooling to 5 °C to make UHT milk. Two sequestering agents, Trisodium citrate (TSC) and Sodium hexametaphosphate (SHMP) were added at 0.04 - 0.08% (w/v) to the processed UHT milk to reduce the ionic calcium levels. Proteolysis and gelation were induced by addition of trypsin (248 BAEE units), 0.03% (v/v) chymosin and 10 6 cfu/mL Pseudomonas fluorescens NCIMB 702085 (Ps. fl. 416) to UHT milk. Samples were stored at 25 °C for 21⁄2 weeks to monitor gelation and Ca 2+ and some were incubated at 37 °C for 2h to monitor proteolysis. SHMP reduced more Ca 2+ than TSC. Ca 2+ reduction was accompanied by an increase in pH, most evident with TSC at 25 °C. Gelation was not observed in samples inoculated with Ps. fl. 416 (with sequestering agents) even after 9 days of storage, suggesting the importance of calcium in gelation. Chymosin treated samples gelled on day 0, whereas other samples gelled after 4 days. Trypsin increased Ca 2+ to levels higher than originally present in control UHT skim milk. Although in the current study, proteolysis was higher in samples inoculated with Pseudomonas fluorescens 416, no clear relationship was established between proteolysis and gelation in UHT milk. This observation implies that proteolytic activity is not influenced by Ca 2+ . However, longer time study using sodium azide to prevent bacterial contamination would be required to confirm these findings.