School of Engineering and Technology

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Mechanisms of mechanical oil expression from rapeseed and cashew.
(University College Dublin, 1979-02) Mrema, Geoffrey C.
The conventional theory of oil expression from vegetable oilseeds suggests that before substantial oil expression can occur, the oilseed cellwalls have to be ruptured by a combination of physical (crushing) and thermal (cooking) pre-treatments. Results from oil expression tests using rapeseed and cashew on the Instron Universal Testing Machine have suggested an alternative mechanism in which up to 80% oil is expressed through a porous cellular microstructure under pressure without cellwall rupture and at ambient temperature. The porous mission electron microscopy. The cellwall pores (plasmodesmata) were of diameter 0.87 and 0.126 pm wall surface area for rapeseed and cashew respectively. The oil expression process has been successfully described by a mathematical model based on three modified form of Terr.aghi's equation for the consolidation of saturated soils., to describe the behaviour of the consolidating oilseed cakej the Hagen Poiseulle equation for flow of fluids to describe the flow of oil through the pores on the cellwall; and The model has Darcy 's law of flow of fluids through porous media to describe the flow of oil through the intra-kernel voids. in pipes, fundamental equations: a oil expression can occur, the oilseed cellwalls and average porosity of 0.093 and 0.171% of the cellnature of the cellwalls has been confirmed by trans been succeafully applied to experimental data which has revealed that the flow of oil across cellwalls in the seed kernel was the rate determining step. In addition the model was also used to analyse the performance of hydraulic and screw expellers. The study has suggested that the design of both hydraulic and screw expellers could be improved by incorporating an undrained compression pretreatment to rupture cellwalls 3 and by reducing the drainage area to 0.5% - 1.5%. Furthermore^ improved strategies for oil expression have been suggested in two cases, (a) For mechanical expression followed by solvent extraction it is proposed that the physical (pre-crushing) and thermal (cooking) pre-treatments be replaced by an undrained compression pre-treatment. are not r equired (b) where mechanical expression is the sole process^ the pre-crushing pre-treatment should replaced by an undrained compression pre-treatment.
Irrigation scheduling
(Sokoine University of Agriculture, 1984) Thadei, Simon y
This thesis deals with irrigation scheduling under rotational water supply. First, irrigation scheduling is defined and the general review of the principles, factors, methods, and scheduling techniques which must be considered before scheduling is given. This includes crop water requirements, factors affecting crop water requirements and methods for determining crop water requirements. Then soil waterholding capacity, irrigation requirements (efficiencies and leaching requirements), amount of water for irrigation, availability of water supply, and scheduling techniques are reviewed. Also, Tanzania's case study is given for two projects: Mbarali (a state farm) and Mombo (village owned farm). Finally, irrigation schedule is prepared for Mombo irrigation scheme.
Quality and quantity of maize and sorghum vegetative parts harvested at different stages of plant growth as fodder for livestock
(Sokoine University of Agriculture, 1994) Eligy J. M. Shirima
Two on-station research experiments were conducted at the Livestock Production and Research Institute, Mpwapwa and one at Pasture Research Center, Kongwa both in Central Tanzania from January to October, 1993. Four treatments in maize, grown in Mpwapwa station, were stripping (SR), topping (TP), stripping + topping (STP) at silking stage and whole plant stover (WPL or control) were assigned randomly within the four blocks of a complete randomized block design experiment. Only SR and WPL treatments were performed in sorghum trials in Kongwa under the same experimental design as in maize but each were replicated twice within each of the four blocks. Also three treatments replicated thrice for measuring the intake and digestibility of the SR, TP and WPL obtained from the maize trial were done at Mpwapwa center by using nine adult BHP male sheep. Complete block design was used by blocking the sheep on weight basis ranging from 29 to 37 kg live weights (mean 32.8 + 1.0). Both animals received equal amount of supplement diet (maize bran + sunflower cake). A village survey through questionnaire and physical body weight measurement of cattle every other fortnight was carried out in Berege village in Dodoma region from the start of the dry season (June) to mid- dry season (October). Sample collection of forage used by the animals was done on the same day after weighing the animals. Ten farmers with improved dairy cattle (Mpwapwa breed) were incorporated. An additional survey was also conducted in Kilimanjaro region among eight farmers to explore the farmer’s knowledge on the use of SR, TP and STP from maize. In maize the highest vegetative biomass production including the final residues after the grain harvest was gained with the STP treatment followed by TP with 5.44 t/ha and 5.35 t/ha respectively (p<0.05). Less fodder materials were collected from WPL (4.23 t/ha) due to field losses. No significant difference were found in sorghum fodder yields despite the leaf losses in WPL. Stripping in sorghum yield 2.2 t/ha and WPL as 1.8 t/ha. In maize total CP accrued from STP were (287 kg/ha) ), TP (234), SR (177) and WPL (138). The IVOMD of the fractions were in the order of 75%, 69%, 64% and 52% in SR, STP, TP and WPL fractions respectively. Seventy-three percent more CP was produced from SR of sorghum than WPL treatment with 123 kg/ha by 71 kg/ha respectively. Digestibility (IVOMD) of the SR leaves from sorghum was 79 % while 55 % from the WPL leaves. The feed intake of SR leaves in maize was more than twice (850 g/day) that of the WPL stover (361 g/day) when fed to sheep. The total digestible crude protein (DCP) from SR of maize was 51 % while the same from WPL was negative. With the supplement diets, the DCP of SR leaves improved slightly to 55 % but increased greatly in WPL to 51 %. From the village survey, the cattle in Berege suffered from lack of high quality feeds resulting in body weight losses during the later part of the dry season despite the bigger cultivated crop field farms than in Kilimanjaro region. With small areas of land in Kilimanjaro region, less than 1.5 ha, the maize fractions alone harvested before and after grain harvest accounted for over 39 % of the total annual cattle feed2 requirement while in Berege the combination of all dry residues after harvest (maize, sorghum and millet) formed 42 % of the total annual diet. This made the dependence of natural pasture in Kilimanjaro region to be only 28 % while in Berege village the cattle were still depending on 40 % natural pasture for the annual feed resources. Since the defoliation of maize and sorghum vegetative parts had no deleterious effects on the final grain yield, the technique should be introduced in Central Tanzania so as to make use of the enormous green materials lost in the wet season to be available in dry season. Their higher feeding value also will be an advantage to the farmers as they will buy less supplements to be added . to the forage to meet the animal requirements for maintenance and production.
Erosion hazard assessment in the upper Ewaso Ng’iro basin of Kenya: application of gis, usle and eurosem
(Sokoine University of Agriculture, 1999) Mati Bancy Mbura
A methodology was developed for assessing soil erosion hazard in the Upper Ewaso Ng’iro basin of Kenya, using Geographic Information Systems (GIS), the Universal Soil Loss Equation (USLE) and the European Soil Erosion Model (EUROSEM). The USLE was used in a GIS environment by creating thematic maps of R, K, L, S, C and P and then calculating soil loss by raster-grid modelling with Arc/Info GRID. The rainfall erosivity factor (R) was derived from relationships between rainfall amount and erosivity using erosion plot data from within the catchment. The nature of the relationship was found to be a function of agi o-climatic zones of the region. Mean annual erosivities ranged from 145 to 990 J m'2 hr'1. For a given amount of rainfall, erosivity was higher in zone IV than in the wetter zones 11-111. The soil erodibility factor (K) was estimated using the USLE nomograph and data from laboratory analysis of field samples collected from representative major soil mapping units. The K-values were low to medium, ranging from 0.10 to 0.25 over 84 percent of the basin. The topographic factor (LS) was obtained by creating Digital Elevation Models (DEMs) of the basin with TOPOGRIDTOOL of Arc/Info. These were then used to determine the slope steepness and length factor values, calculated with raster-grid modelling. Although DEMs proved a useful tool, maximum values of both steepness and length had to be set in this reconnaissance study to achieve reasonable results. A finer resolution of input data and a smaller grid cell size are needed for accurate determination. The cover and management factors (C) were obtained by determining the land cover types within the basin using remotely sensed data (SPOT 1 colour composite prints) and ground truthing studies. The factor values were estimated from USLE guide tables and measurements of cover from plots and test sites. Some 70 percent of the basin is covered by rangelands. The conservation practice (P) factor values were estimated from USLE guide tables and then applied to areas where soil conservation had been introduced /?. M. Mali PM > Thesis 1999 Silsoe College Cranfield .■Ihstract •'university II according to maps obtained from the Ministry of Agriculture. The USLE was validated using data from erosion plots. A value of R2 = 0.645 was obtained between predicted and measured values but the standard error was rather high (e = 5.745 t ha'1 yr'1). Using an annual soil loss of 9.0 t ha'1 yr'1 as tolerance level, some 36 percent of the basin was found to experience unacceptably high erosion rates. Most of this area was communal grazing land and cropland where soil conservation measures had not been applied. A critical land cover type within the grazing land is shrubland, where vegetation cover is less than 40 percent and high erosion risk was predicted and confirmed by field surveys. EUROSEM could not be integrated within a GIS in the time available for research. It was therefore simulated outside GIS environment, where it was applied to Embori and Mukogodo plot data using separate data sets for calibration and validation. Calibration was used to obtain input parameters for saturated hydraulic conductivity, cohesion and Manning’s roughness coefficients. Validation gave correlation coefficients of 0.907 and 0.840 for predictions of storm runoff and soil loss respectively at Embori; the corresponding values for bare soil plots at Mukogodo were 0.895 and 0.577. However, EUROSEM predicted runoff poorly (R2 = 0.570) and failed to predict soil loss at all the vegetated plots at Mukogodo. The model was applied to simulated vegetation covers of barley, maize, grass and forest for a 36.7 mm rainstorm at Embori. The simulated soil losses showed an exponential decrease with increasing cover. At a threshold cover of 70 percent, soil loss diminished to zero under grass and forest and decreased to a minimum value under barley and maize. These results support the USLE simulations, which showed that areas with more than 70 percent cover (such as forest) had a low erosion hazard, even with steep slopes and high rainfall erosivities. This research has demonstrated that GIS can be used with the USLE to assess and quantify erosion hazard, giving results that can be used for conservation planning. EUROSEM can be applied successfully to bare soil and cropland, but application to other land covers requires further investigation. Land cover and topography are the main factors controlling the spatial distribution of soil loss in the Upper Ewaso Ng’iro basin. Future conservation activities should be concentrated on the rangelands.
Performance evaluation of an indigenous irrigation system at towero village, western Uluguru mountains, Tanzania
(Sokoine University of Agriculture, 2000) Kongola, Malongo John Mussa
Indigenous irrigation methods in mountainous areas are a result of people’s efforts to survive on limited land resource bases. The adoption of an irrigation method depends on whether it does not affect the soil. While surface methods are common in the Uluguru Mountains, drag hose sprinkling is receiving wide use at Towero. Drag hose sprinkler irrigation refers to the local use of sprinklers where water pressure is obtained by gravity flow. Effects of indigenous irrigation systems’ practices on soil erosion were evaluated using field data and aerial photographs. Field data were obtained from six slopes, ranging from 6 to 84%. Two versions of aerial photographs were used to produce land-use maps for 1964 and 1992, respectively. Traversing produced the land-use map of 1999. Land-use analysis revealed that between 1964 and 1999, the area under indigenous irrigation increased by 0.81 ha/ycar. Between 1964 and 1999 the settlement area increased by 0.83 ha/year. Deforestation rate was 6.48 ha/year. Mean crop yields for leeks ranged between 9.65 — 13.53 tonne/ha. Mean specific yields ranged between 0.65 - 1.09 kg/m3. Mean water conveyance, application and storage efficiencies were 83.72%, 86.20% and 99.64%, respectively. All fields wereii over-irrigated based on soil moisture data which were taken daily. Over-irrigation caused inequitable water distribution. Daily sediment load transport in canals A, B and C were 22.2 kg, 187.6 kg and 54.7 kg, respectively. Total sediment loss was 264.6 kg per day. Net downslope splash loss at 84, 70, 65, 24 and 15% slope was 28.9, 19.1, 12.0, 6.0, and 1.0 kg/ha, respectively. The effects of indigenous irrigation systems’ practices at Towero were: soil loss in the form of splash erosion and sediment load transport, and acceleration of deforestation in pursuit for more agricultural land. Hence, efforts to promote soil conservation practices at Towero are essential.
Modelling the water balance of a small catchment: a case study of Muhu catchment in Southern highlands of Tanzania
(Sokoine University of Agriculture, 2000) T. Shiba, Sipho Simeon S.
I'he water balance ol'Muhu catchment located in the Southern Highlands of Tanzania in Iringa region was modelled by establishing the empirical relations that exist between storage parameters, rainfall parameters and runoff components. Storage parameters included soil moisture storage and interception. Rainfall parameters included rainfall amount, intensity, duration. throughfalL stemflow and evaporation. Runoff components included total runoff, direct runoff and base How. The catchment's physical and hydrological characteristics that affect these parameters were determined. 1 he assessment of hydrological and physical properties showed that the soils were predominantly sandy clay, having high organic matter content, with a moderately rapid hydraulic conductivity (Ks) of 4.2 cm/h and infiltration rale of 3.8 cm/ h. The bulk density was generally low with an average of 0.9 g/cnT for 0-15 cm depth: 1.1 Ig/cm5 for 15-30 cm depth and 1.30 g/cm’ for 30 - 45 cm depth. The catchment had a slope steepness of 35 % and a varying vegetal percentage cover of about 56 %. The 1997/98 waler year was exceptional with high rainfall (1934 mm) mainly due to the El-nino phenomenon. Sixty-seven percent of the rainfall received in the catchment penetrated the canopy to reach the forest floor as throughfalL On average 3.3 % of the rainfall reached the forest floor as stem flow' while 25.5% of the rainfall was intercepted by the canopy. ThroughfalL stemflow and interception were linearlyIll related to rainfall. Die regression coefficients of all the relationships were significantly different from zero al 1% level (fteO). With increasing percentage surface cover, interception increased while throughfall decreased. The storage capacity of the forest cover was estimated to be 0.7 mm. Il has been found in this study that stream flow and runoff have gradually been increasing since the 1994/95 season. However the rainfall trend docs not support this development. A consideration of runoff curve numbers showed that the observed trend was partly due to catchment degradation, farming activities in the area have gradually been substituting the forest with arable land, thus reducing surface cover. Records indicated that the lowest recorded daily mean How was 0.27 m'/s. while the highest was 1.6 m'/s. I he water balance was positive during the first five months of the wet season. The highest water balance was in April. During this period there was more recharge to the soil moisture and ground water storage. Water balance was negative in the remaining seven months of the water year, with the lowest in September. The developed direct runoff model and water balance model were found to be valid and useful in estimating the respective parameters in forested catchments of the southern highlands of Tanzania.
Repair costs of tractors and comparison of mechanization strategies under Tanzanian conditions
(University of Munich, 2000-08) Mpanduji, Sylvester Michael
Influence of quality attributes on the market value of fresh sweet potato tubers and processed cassava.
(Sokoine University of Agriculture, 2001) Ndunguru,Gabriel t.
Cassava (Manihot esculenta Crantz} roots and sweet potato (Ipomoea batatas (L) Lam) tubers are important staple food crops in several areas of Tanzania. Studies were conducted in Mwanza and Dar es Salaam markets in order to assess the factors that influence the quality and market value relationship of fresh sweet potato tubers and processed cassava roots. Consumers and traders in Mwanza preferred sweet potato tubers which are wholesome and free from infestation. White processed cassava root products were preferred by traders and consumers in Mwanza. Valuation assessment made on sweet potatoes showed that, broken, cut and weevil infested tubers sold were at 12.1, 14.2 and 36.6 percent discount respectively. Average valuation discount of processed cassava roots were 10 to 15 for yellow, 20 to 25 for greenish and 35 to 40 percent for dark product. Causes of losses in quality of sweet potato tubers were due to operations related to handling and transportation. Occurrence of broken tubers, skinning injury and cuts increased significantly with handling and transportation (P < 0.001). The largest loss in quality occurred between the lakeshore and the port at Mwanza when sacks were loaded and unloaded from the ship and handled at the port.iii Broken sweet potato tubers and skinning injury increased significantly ( P < 0.001) during handling and transportation from Gairo to Da es Salaam Impact shock loggers provided a low cost method for comparing the handling of sacks during transportation. Shock impact record increased with increase in the height form which sweet potato sacks were dropped (R2 adjusted = 0.875). Multiple linear regression analysis indicated that the number of impact in the category between 0.2 and 2 g significantly correlated with skinning injury (P=0.001), (R2 adjusted =0.651) and broken tubers (P=0.001), (R2 adjusted = 0.407) respectively. Weight loss during storage increased significantly (P=0.01) with shock impact and skinning injury. Dropping sacks of sweet potato tubers significantly (P < 0.01) increased the occurrence of broken tubers The use of cardboard boxes filled with fewer tubers instead of overfilled polypropylene sacks and adoption of improved management procedures in the handling and transport are recommended.
An examination of alternative fertilizer transportation, warehousing and application systems for agricultural cooperatives
(Sokoine University of Agriculture, 2004) Kilima Fredy Timothy Mlyavidoga
The difficulty of controlling cost in a dynamic industry where competitiveness and costs are changing over time has long been recognized. Conventional wisdom suggests that players who succeed in such an industrial setting are those who capture the opportunities presented by a new business environment while maintaining economic efficiency (Bello, Lohtia and Sangtani; Flint). In recent years, one of the business challenges for fertilizer suppliers in the United States has been to keep pace with the changing business environment. The changes arise from changing demand, growing global competition, increased regulations in the industry for environmental and safety reasons, and improvements in the transportation and application methods. The improvement in fertilizer distribution and application methods is by and large a reflection of changes in the physical condition and operating characteristics of highways, and changes in farm transportation and application equipment (USDA, Agricultural Cooperative Service). Changes in fertilizer demand and increased market competition are attributable to changes in farm application systems, and consolidation of farming business that has decreased the number of farms and increased the average farm size (Norton).
The impacts of frozen storage and fatty acid oxidation on silver carp myofibrillar protein functionality
(Jiangnan University, Wuxi, JiangsuProvince, P.R., 2006) Mlyuka, Erasto
Silver carp (Hypophthalmichthys molitrix) is a freshwater species living in temperate conditions (6-28 °C) and its natural distribution is in Asia. It is generally cultured and marketed locally alive or fresh in most of the producing countries. China is the largest producer of silver carp in the world; however, its market price is relatively low compared to most other species, normally costs 8-10Yuan/kg. In order to keep the product longer and further extend the markets instead ofjust consuming it fresh, processing technologies for adding value and frozen storage are of significantly important for this fish species. In this thesis, the report is mainly focused on the study done on isolation of myofibrillar protein from silver carp; exposing the isolated myofibrillar protein to oxidative environment simulated using an iron oxidation model system to mimic the oxidative stress during processing and frozen storage. Also the impacts of the iron oxidation model system, fatty acid oxidation and frozen storage on protein functionality of silver carp myofibrillar protein isolate were evaluated. Oxidative damage to silver carp myofibrillar proteins isolate (MPI) was investigated by measuring changes in physico-chemical, and functional properties after exposure to iron-catalyzed oxidation system (IOS). Iron oxidized MPI exhibited an increase in carbonyl content and dityrosine, which were significant and negatively correlated with protein solubility (PS) (r=0.85), (r=0.80) and gel strength (GS) (r=0.95), (0.93), respectively, however the decrease in total thiol group content was significantly and positively correlated with PS (r=0.77) and GS (r=0.89). These led to significant changes (P<0.05) observed in the protein and functional properties of oxidized MPI. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis demonstrated that IOS resulted in a major loss of myosin and actin associated with formation of protein polymers as supported by gel-permeation chromatography (GPC) results. The total fat content of silver carp MPI was 0.6%, it is mainly composed of unsaturated fatty acids of which about 34% constituted by eicosapentaenoic acid, ( 2O:5co-3), docosahexaenoic acid, ( 22:6co-3), and linolenic, ( 18: 3m-3) as the main co-3 poly-unsaturated fatty acids (PUFAs) as well as linoleic acid, (18:2co-6) and arachidonic acid, (20:4co-6), the main co- 6 PUFAs in fish , unfortunately PUFAs are prone to oxidation producing reactive oxygen species capable of modifying protein structure. This study suggests that the decreased functionality of proteins in muscle foods exposed to an oxidative environment could be due to chemical and physical changes resulting from oxidation reactions. It was found that silver carp myofibrillar protein is susceptible to an iron-catalyzed oxidation causing a significant loss of its functionality, thus a study was carried out to iii Jianenan University, M.Sc Thesis, 2010 Abstract determine the susceptibility of silver carp protein to natural oxidants (fatty acids or fatty acids oxidation products) in frozen storage with respect to its functionality. Frozen stored myofibrillar protein isolate with 0.6M NaCl or myofibrillar protein isolated from previous frozen stored whole fish and fish mince of silver carp at -18°C for 90 days were assessed for protein and lipid oxidation with regard to protein functionality. The addition of sodium chloride to 0.6M at pH6.5 improved protein functionality especially water holding capacity of frozen stored myofibrillar protein isolate from 5.3 to 6.4mL/g MP1 after 90 days of frozen storage. However, the differential scanning calorimeter results showed that, sodium chloride significantly increased thermal susceptibility of myosin from 48.12 to 46.40°C with 0.1M NaCl and 0.6M NaCl frozen stored for 90 days, respectively. Whole fish frozen storage was more susceptible to oxidation compared to fish mince and myofibrillar protein isolate due to their different lipid content. On contrary, myofibrillar isolated from frozen whole fish showed significant changes in protein functionality may be due to great loss of amino acid such as cysteine, lysine, histidine and methionine during frozen storage. On the other hand investigation was done on stabilization and oxidation protection of silver carp MP1 stored at -18 °C, 90 days and composed of MPI, 8% cryoprotectants (4% sucrose and 4% sorbitol) with or without antioxidants (0.2% ascorbate, 0.2% a- tocopherol, or their combination) and packed in a polyethylene bag, sealed under air. MPI without cryoprotectants and antioxidants was the control. Compared with the control, cryoprotectants increased PS (protein solubility), WHC (water holding capacity), OHC (oil holding capacity), EC (emulsification capacity) and GS (gel strength), also, the cryoprotectants and/or antioxidants decreased MPI oxidation susceptibility as well as susceptibility of myosin to thermal denaturation. After 30 days of frozen storage, there were no significant differences ((P>0.05) of storage time on alteration of protein functionality and actin susceptibility to thermal denaturation between cryoprotectants and the control. Antioxidants minimized oxidation effects on MPI frozen storage. Therefore, the present study reveals that, improvement in the functional properties of silver carp MPI were greatly influenced by cryoprotectants and antioxidants, this reflect a great role played by sucrose/ sorbitol and antioxidants in protecting native protein structure to a greater extent owing to impact of frozen storage and oxidation respectively.
Root-zone soil moisture redistribution in cropping systems under freeze-thaw conditions
(University of Manitoba, 2008) Kahimba, Frederick Cassian
The availability and distribution of soil moisture within the root zone is a key factor in ensuring better crop growth performance and attaining improved yield. The soil moisture is influenced by farm management practices such as cover cropping that affect the freeze-thaw processes during the fall. This in turn may influence accumulation and redistribution of soil moisture during the winter, and thereafter, the soil’s response to thawing during spring, and availability of soil moisture for the subsequent season. The impact of cover cropping systems on soil temperature, infiltration, and soil moisture redistribution due to soil freezing and thawing was investigated. In addition, the effect of cover crop on the within-season and subsequent-season crop performance and yield was also investigated. Time Domain Reflectometry (TDR) and Neutron Scattering (NS) methods were used to measure the unfrozen and total water contents, respectively. Soil temperature was measured using thermocouples embedded in the soil profile. Soil moisture and soil temperature data were collected from August 2005 to September 2007. Laboratory calibration of the TDR miniprobes indicated the maximum cable length for the RG-58 50 Q coaxial cable to be 40.0 m when 35 mm TDR miniprobes were used. Since the TDR was found to overestimate the liquid water content at soil temperatures below 25°C, a method to correct the field measured TDR soil moisture for temperature effects was developed. During soil freeze-up, water from unfrozen soil layers below the freeze front migrated towards frozen layers above. Compared to non-cover crop treatment, the cover crop treatment did not freeze earlier during the fall, froze to a shallower depth during the i
Socio-economic assessment of agricultural commercialisation of indigeneous african vegetables: a case study of african eggplant in Arumeru district
(Sokoine University of Agriculture, 2008) Kalugira E. G
A study aimed at assessing the socio-economic impact of household’s participation in commercialization African eggplant (solarium aethiopicum) was carried out in four villages in Arumeru district in Tanzania. The study determined the existing extent of commercialization of African eggplant by households, determined and compared at different levels of commercialization the household members’ time allocation, income levels and ownership by gender, as well as land resource allocation for different crops. Data were collected by structured questionnaire for individual farmers supplemented by interview checklists for focus group. SPSS computer programme was used for data analysis. The results showed that: African eggplant growers had significantly higher extents commercialization than non growers. Time spent by household’s members, income levels and women’s control of income was also higher in African eggplant growers. The average land allocation for food crops was 0.76 hectares and 0.70 hectares for African eggplant growers and non-growers respectively which is insignificantly different between the two farmers’ categories. Time in hours per day spent by family members for African eggplant growers was 7.64 while for non-growers was 5.2. Moreover, total annual income in Tanzanian shillings (TShs) of African eggplant growers was 2 449 617 compared to 2 030 767 for non-growers. In case of women’s control of income, there was a slight difference between the two categories in which for African eggplant growers decision making by both husband and wife was higher. The following policy implications have been raised: Commercialization of African eggplant should be enhanced notably through improving technologies. Participation of women should be safeguarded by increased access of women to credit for the short term financing of cash crop productive inputs. Acquiring land for production of African eggplant through renting instead of using land which has been used for production of food crops should be maintained.
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 high temperatures treated milk by reverse phase high performance liquid chromatography (RP-HPLC)
(Academic Journals, 2014-02) Chove Lucy M.; Grandison S. Alistair; Lewis Michael J.; Issa- Zacharia Abdulsudi
Proteolysis of UHT milk during storage is one of the problems affecting the dairy industry worldwide. Native enzymes have been implicated as being the main cause of spoilage of such milk. In the current study, reverse phase high pressure chromatography (RP-HPLC) method was used to detect proteolysis by native enzymes in high temperature heated milk. The aim of this research was to assess susceptibility of milk to proteolysis by native enzymes, after being subjected to various temperature- time processing conditions. Samples of raw and heated milk were clarified prior to analysis. Clarification was carried out to obtain pH 4.6 and 6% TCA soluble extracts, which were injected into RP- HPLC after filtration. This method confirmed that raw milk and milk processed at 85°C /15 s were the most proteolysed, indicating that the high temperatures employed during this study (110, 120, 130 and 142°C for 2s) inactivated the native enzymes. The RP-HPLC method is a useful method for the detection of proteolysis in milk.
Status assessment and roadmap for improvement of food safety management systems in Africa: the case of Tanzania
(Ghent University, 2015) Kussaga, Jamal Bakari
Chapter 1 reviews various literature sources to provide an overview of the characteristics of food production sectors and the legal framework for food safety in Tanzania and tools used to measure performance of food safety management systems in the food industry'. It was found that Tanzania’s economy depends on agriculture: the manufacturing sector being largely agro-based and composed of micro- and small-scale enterprises. Majority of the food companies target the domestic market, especially, the dairy sector, while a few sectors like fish and horticulture produce for the export market, The current food laws and regulations are not yet adequate and well enforced to provide maximum protection to consumers. Besides, there is no national food safely policy as yet. Several institutions are involved in the food control without proper coordination and harmonisation of responsibilities. Furthermore, application of best practices and hazard analysis critical control point principles is not mandatory to food sectors serving the domestic market, limiting their use. This situation could contribute to food safety problems (including microbiological and chemical contamination and foodbome diseases) along the local and export food-value chains. Lastly, the chapter highlights also on the scientific tools, the food safety management system-diagnostic instrument and microbiological assessment scheme, developed by various researchers which were further used in this study. Chapter 2 provides a broad overview of the deficiencies and opportunities for improvement of food safety management systems of the African food industry-. Several literature sources were consulted to provide insights in food safety status of African food products, deficiencies of current food safety management systems, hurdles due to context characteristics and possible improvement strategies. Literature on microbiological and chemical safety of various products including fruits and vegetables, fish, meat, dairy and cereals were analysed to get insights in the current safety status of African food products. It was found that microbiological and chemical contamination exceeded the legal limits in most of the products targeted for export and local markets in the reviewed reports. Analysis of the deficiencies of food safety management systems in the reviewed reports revealed that the majority of core control and assurance activities were not yet developed, whereas for the ones developed (i.e. export oriented and large-scale companies), many were at basic level. The hurdles due to context characteristics in the reviewed reports were observed at government (due to poor legal framework for food safety), sector/branch organisations (lack of sector organisations and guidelines), market/rctail (inadequate food safety demands), and company levels (poor workforce quality, high dependency on chain actors, stakeholders’ conflicting demands) which affect performance of food safely management system in Africa. Lastly, measures for improvement were proposed at government (strengthen the national legal framework for food safety, formation of accreditation bodies and food safety education at all levels):sector/branch organisations (formation of sector guidelines and recommended use of traceability systems and auditable standards), inarkct/retail (private certification and price premiums, and expertise support) and company levels (technological innovations in hygienic design of equipment and facilities, set-up assurance activities, and creating supportive administrative structures). These measures were used as inputs for the development of generic roadmap for improvement of ESMS in Tanzanian food industry. Chapter 3 applied the food safety management system-diagnostic instrument to analyse the set-up and operation of food safety management system (control and assurance) activities in view of system output and context riskiness in 22 dairy processing companies in Tanzania. I lierarchical cluster analysis with the furthest neighbour and squared Euclidean method was used to analyse data; then, Kruskal Wallis Non Parametric test was applied to determine the significant differences among the clusters. Three clusters of companies di Hering in levels of set-up and operation of the ESMS and system output, but all operated in a similar moderate-risk context were identified. Cluster IA and IB had moderate system output, whereas cluster II had poor-moderate level. The microbiological assessment scheme was applied in one company to get deeper insight on the actual microbiological safety output of the current systems of dairy' processing companies. Six indicator micro-organisms for faecal hygiene {Escherichia coli), personal hygiene {Staphylococcus aureus), pathogens {Listeria monocytogenes. Salmonella spp.) and general process hygiene {Enterobacteriaceae and total viable counts) were analysed in nine critical sampling locations along the cultured milk production line. The actual microbiological assessment indicated contamination of products, food contact surfaces, and hands of the personnel with indicator microorganisms of faecal hygiene {Escherichia coli), personal hygiene {Staphylococcus aureus), and pathogens {Listeria monocytogenes) beyond the set limits. A two-stage intervention approach was proposed to enable commitment and sustainable improvement on the longer term. In the first stage, less demanding interventions (in terms of expertise/technology, financial and human resources) were recommended, whereas, high demanding measures (expensive and time consuming) were suggested in the second stage. Similarly, these interventions were used to develop the generic roadmap for improvement of food safety management systems in Tanzanian food industry. Chapter 4 assesses the food safety management system output in view of the current design and operation of food safety management system activities and context riskiness of these systems in order to identify the opportunities for improvement of the risk-based food safety management systems in the fishery sector. The diagnostic instrument was applied to assess the design and operation of core control and assurance activities in view of context riskiness and system output in 14 fish processing companies in Tanzania. Hierarchical cluster analysis with the furthest neighbour and squared Euclidean method revealed 2 clusters (cluster I and II) differing in system output but with similar level of food safety management systems (average level) and context riskiness (moderate-risk). In overall, cluster I companies had good system output while cluster II had moderate to good output. However, majority of the fish companies needed improvement of their FSMS to higher levels and reduce the context riskiness to assure good system output. A two-phase intervention approach was also proposed to implement the suggested measures in the fish companies. The less expensive interventions (like sanitation procedures, recruitment of skilled personnel on permanent basis) that can be implemented in the short- term are recommended for phase I. More expensive interventions (such as setting-up assurance activities, hygienic design of equipment and facilities, automation of the production process and sanitation) to be adopted in the longterm are proposed for phase II. These measures were also used as inputs to develop the generic roadmap for improvement of food safety management systems in Tanzanian food industry. Chapter 5 describes a combined assessment by the diagnostic instalment and microbiological assessment scheme to assess microbiological safety output of a risk-based food safely management system of a fish exporting company. The food safety management system diagnosis indicated average food safety management system activities which operated in moderate-risk context level but with good system output. The actual microbiological assessment involved 7 microbiological indicators for pathogens {Vibrio cholerae. Listeria monocytogenes and Salmonella spp.), faecal hygiene {Escherichia coli), personal hygiene {Staphylococcus aureus), and general process hygiene {Enterobacteriaceae and total viable counts) analysed in 12 critical sampling locations along the frozen Nile perch fillets processing line. Enterobacteriaceae and total viable counts exceeded regulatory limits in raw materials and working tables, whereas Staphylococcus aureus on operator's hands were beyond the general microbiological guidelines in the fish industry. Among the intervention measures for improvement included hygienic design, specific produclion/sanitation procedures and independent validation, process automation and change in personnel recruitment criteria. Likewise, the proposed measures were used to develop roadmap for improvement in the Tanzanian food industry. Chapter 6 involves a comparative assessment of the design and operation of food safety management system activities between the domestic oriented companies (dairy sector) and export oriented companies (fishery sector). The food safety management system-diagnosis data from Chapter 3 (dairy' sector) and Chapter 4 (fishery' sector) were evaluated to identify possible causes in the differences in the systems performance between the two sectors. Fish companies had average food safety management system and medium-good system output, while dairy' companies indicated basic-average food safety management systems and moderate system output. However, the food safety management systems of both sectors operated in moderate-risk context. This illustrates that both sectors need specific measures to improve their food safety management systems and reduce the risk-level of the context to guarantee food safely. The measures to reduce the level of context riskiness included putting high and specific requirements on operators’ competence level, describing all activities in standard operating procedures, and setting requirements on product use by major customers. The measures on the design and operation of food safely management systems involve use of industrial cooling facilities, hygienic design, strict raw material control, specific sanitation programmes, and analysis of critical control point. Dairy' companies need to set-up assurance activities including validation, verification, documentation, and record-keeping system. Enabling regulatory' environment (like national food safety policy, proper enforcement of laws and regulations) has to be established for the entire food industry (including the domestic market oriented sectors), to improve the design and operation of current core control and assurance activities and guarantee food safely. improvement technological infrastructure The measures to reduce the level of context riskiness included putting high and specific requirements on operators’ competence level, describing all activities in standard operating procedures, and setting requirements on product use by major customers. The measures on the design and operation of food safely management systems involve use of industrial cooling facilities, hygienic design, strict raw material control, specific sanitation programmes, and analysis of critical control point. Dairy' companies need to set-up assurance activities including validation, verification, documentation, and record-keeping system. Enabling regulatory' environment (like national food safety policy, proper enforcement of laws and regulations) has to be established for the entire food industry (including the domestic market oriented sectors), to improve the design and operation of current core control and assurance activities and guarantee food safely. Chapter 7 brings about the general discussion, roadmap for improvement of food safety management systems in the Tanzanian food industry', conclusions and recommendations for further research. Two concepts, the food quality relationship model and the improvement cycle were used to design the roadmap. The food quality relationship describes food quality as a function of food behaviour and human behaviour, food behaviour is dependent on dynamic product properties (food dynamics) and the applied technological conditions to stabilise the properties. Human behaviour is dependent of the dynamic individual decision-making of employees (human dynamics) and the applied administrative conditions to direct this behaviour (setting procedures and working practices in place). The improvement cycle involves three steps: (1) mapping the problem area (collecting information about the problem and documentation), (2) analysing the problem area (identification of causes and effects), and (3) redesigning (development and implementation of solutions). Based on the food quality relationship model, three levels of increasing efforts were defined; 1) changes in product and people behaviour, 2) changes in process conditions and administrative conditions, and 3) changes in the technological and organisational arrangements. Fish and dairy’ processing companies could use the generic roadmap to derive their company specific roadmaps towards more effective food safety management systems. Although this study was exclusively conducted in fish and dairy' sectors, the proposed generic measures for improvement could be also used by other food production sectors. However analysis of other sectors like fruits and vegetables, meat and poultry', and hospitality industry would identify specific deficiencies in their food safety management systems and tailor-made measures for each sector could be proposed to ensure supply of safe products for the entire nation. Moreover, this study focused on the techno-managerial approach of food safely management systems, however, the human factor, the so called ‘food safety climate or culture* could have an important role in the final performance of a food company. Therefore, future studies could take into consideration the food safety climate factor.
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, 2015-05) 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 2 2 correlations between TPC and FRAP in both fresh (R = 0.970) and dried samples (R =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.
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.
Influence of botanic and geographic origin on quality of honey from Tanzania.
(Sokoine University of Agriculture., 2016) Shekilango, Salama Ghuio
In aview of the expanding global market, characterization of floral and geographic origins of honey has become a more important issue than ever. In general, prices of honey at the international market are set according to floral and geographic origin of the nectar, which relate to the chemical composition. This study was conducted to assess and characterize Tanzania honey from different floral origins and geographic zones based on physicochemical properties and minerals content, sugar profile, total phenol and antioxidant activities as well as sensory properties and consumer acceptability. Samples from two floral origins, Miombo and Acacia were collected from five different zones in Tanzania namely Central. Coastal. Lake. Northern and Southern zones and subjected to chemical and sensory analyses. Complete randomized block design with floral origin and geographic zones as main principal factors were used to assess the effect of these factors on stated parameters. Moisture content, ash, pH, acidity, viscosity and colour were determined as per methods described in AOAC (2005). Phenolic content was determined using modified Folin Ciocalteau method and antioxidant activity using Ferric Reducing Antioxidant Power (FRAP) assay. Sugar profile and quantification was performed using Shimadzu high- performance liquid chromatograph equipped with refractive index detector (RID-10A) as per method 977.20 in AOAC (2005). Minerals: copper, zinc, lead, iron, calcium and magnesium were determined using Atomic Absorption Spectophotometer (AAS). sodium and potassium using flame photometer as described by AOAC standard methods (2005). Quantitative Descriptive sensory analysis was done using a panel of 8 trained judges using 9 point an unstructured line scale for rating the intensity of an attribute while consumers acceptability study was done using a 9 point hedonic scale as described by Lawless and iii Heyman (2010) to evaluate acceptability for the attributes of colour, aroma, viscosity and general acceptability. Data were analysed by R software for univariate Analysis of Variances (ANOVA) to determine significant variations between the main factors. Means were separated by Tukey's Honest significant differences at p < 0.05. Multivariate Principal Component Analysis (PCA) was done by Latentix software and Cluster analysis was done by Latentix and R software to determine the systematic variations in the study variables. Most properties of honey varied significantly (p < 0.05) between geographical zones and floral origins with values of honey from Mioinbo floral origin being higher compared to honey samples from Acacia origin. Northern zone honey samples within Mioinbo origin had significantly (p < 0.05) higher moisture content, ash and acidity while Lake zone honey samples had significantly (p < 0.05) higher viscosity. Southern highland Mionibo honey samples had higher colour value on pfund scale. PCA results showed that colour and viscosity had more effect on the variability of physico chemical properties. Phenolic content (mg gallic acid equivalent/100g) and antioxidant activities as pM Fe2‘/100g were significantly (p < 0.05) higher in the Northern zone than in other zones. Honey samples from Mioinbo had significantly higher values of 127.9 - 395.2 pM Fe2+/100g than Kcacia honey samples with values of 119.5 - 168.8 pM Fe27100g between floral origins. Bi plot from principal component analysis, PCI explained 99.2% of variations and showed that both parameters (total phenol and antioxidant activity) had higher effect on the variability. A strong correlation (R2 = 0.929 and R2 = 0.869) between phenolic contents and antioxidant activities were observed in both Mioinbo and Acacia honey samples. respectively. iv There were significant differences (p < 0.05) in fructose, sucrose and total sugars between zones and floral origins. Fructose was found to be the most dominant sugar in the honey samples in each zone and floral origin with the highest contents observed in Acacia honey samples (44.7 - 47.0 g/lOOg) than their Miombo counterpart (39.5 - 42.0 g/lOOg). Glucose, the second dominant sugar was not significantly (p > 0.05) different between floral origins and among zones. Sucrose occurred in small amounts in honey samples from all zones and floral origins. The variation of each sugar between zones within each origin were also significant (p < 0.05) with Northern zone had the highest content of total sugar. PCI bi plot explained 90.7% of total variations with high contribution from fructose and total sugars. Potassium was observed to be the most abundant macro minerals in the honey samples (380.2 - 3488.1 ppm) followed by magnesium (128.1 - 2409.5 ppm), calcium (86.3 - 336.6 ppm) and sodium (78.1 - 165.3 ppm) while iron was the most abundant micro minerals (24.5 - 36.0 ppm) followed by zinc (2.5 - 8.7 ppm) and copper (0.2 - 0.5 ppm). The northern zone honey samples from both floral origins had lead contents above maximum allowed limits as per Tanzania honey standard. The variations in macro minerals between zones were significant with Northern zone having higher contents of Ca. Mg, K and Na in samples originating from Miombo floral origin. Furthermore, the variations in mineral contents between floral origins were also significant with honey samples from Miombo floral origin having significantly much higher content of minerals than Acacia honey samples. Multivariate cluster analysis revealed grouping/similarities of zones according to the mineral they contain. In quantitative descriptive analysis, variations in mean intensity scores of attributes between zones were significant (p < 0.05) in aroma, clarity, hue, viscosity and whiteness, respectively for honey samples from Miombo origin. Southern zone showed high values in aroma and hue, Central zone had high viscosity values while Coastal zone had highest V values in clarity and whiteness compared to other zones. In sample from Acacia origin. Northern zone had significantly (p < 0.05) highest scores in aroma, viscosity and whiteness where Lake zone had high values in clarity and Central zone had high values in hue. Therefore, the study has revealed that fructose was the most abundant sugar in the honey samples while potassium and iron arc the most abundant macro and micro minerals in honey samples under the study. Furthermore, geographical zones and floral origins have significant influences on physical chemicals properties, total phenols and antioxidant activities sugar, minerals and sensory properties of honey samples from five geographical zones and two floral origins in Tanzania. It is therefore recommended that, honey be included in human diet due to its high nutritional and antioxidant properties. In addition, further research be undertaken to create a data base which will successfully enable characterization of Tanzania honey, thus increasing its competitiveness in the local and international market.view
Development and sensory evaluation of yoghurt flavoured with solar dried fruits
(Pearl Research Journals, 2017) Ndabikunze, B. K.; Mumba, F. G.; Ngowi, H.; Chove, L; Mongi, R; Abdulsud, I.
A study of developing solar dried fruit (5%) flavoured yoghurts using three types of fruits was conducted to determine acceptability and shelf life of developed products. A total of six samples namely banana, mango, pineapple, banana/mango, banana/pineapple and mango/pineapple were used as flavours in yoghurts. They were added either as fruit pieces or as powders. Shelf life projection study suggested that developed yoghurt products could be stored for up to 21 days at 4 °C without undergoing spoilage. Plain yoghourt (control) was the most liked sample and scored highest mean values for all attributes, which was significantly different from all other samples (p<0.05). Among the fruit flavoured yoghourts, mango was the most preferred sample in terms of flavor, aroma and general acceptability whereas the pineapple was the least acceptable. Although yoghurts flavoured with fruits pieces scored higher mean values in all sensory attributes than yoghurts flavoured with powdered fruits, no significant differences (p>0.05) between the two forms of fruit flavours was found. This needs to be further investigated. Thus, although the control was the most liked sample, solar dried fruit can be successfully used as yoghurt flavour, which may improve the texture and nutritional quality of the formulated yoghurts, making them available throughout the year, hence increasing farmer’s income.
Monitoring proteolysis in milk caused by pseudomonas fluorescens by the TNBS method
(Pearl Research Journals, 2017-11) Chove, L. M; Grandison, A.; Lewis, M.
The objective of this study was to monitor proteolysis of milk during storage at 20 and 4° C by two strains of Pseudomonas fluorescens namely: NCIMB 702085 (416) and NCIMB 701274 (414) by the TNBS method. Since commercial Pseudomonas fluorescens enzymes are not available, live Pseudomonas fluorescens microorganisms were inoculated into milk followed by extraction and purification by dialysis. Bacterial enzymes obtained were then inoculated into UHT skim milk. Non-inoculated milk was used as a control. Results obtained showed that Pseudomonas fluorescens NCIMB 702085 was more proteolytic than Pseudomonas fluorescens NCIMB 701274. It was concluded that the TNBS method proved useful in monitoring proteolysis in milk by Pseudomonas fluorescens.

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