65 Records out of 22207 Records

Bacteriological contamination of farm and market Kale in Nairobi and its environs; pathogenicity and antibiotic sensitivity of isolated Salmonellae

Author: Kutto, Elisha Kimutai

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2012

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Bacteriology/Food contamination and poisoning/Nairobi, Kenya/Vegetables/Brassica oleracea/Escherichia coli/Salmonella/Drug resistance/Antibiotics ;

Abstract:

This study aimed at determining the microbiological safety of kale (Brassica oleracea Acephala), a green leafy vegetable produced and sold in Nairobi. The assessment was carried out on kale and water (used for irrigation on fanns and washing/refreshing of kale at the markets); the water being assessed as one of the sources of contamination for the kale. This was a cross-sectional study in which kale samples were collected from randomly selected fanners and traders. Data on fanning and trading practices was collected using questionnaires administered through personal interview. Samples were collected from selected peri-urban farms in Athi River, Ngong, and Wangige. They were also collected from traders from wet markets in Kawangware, Kangemi and Githurai, a supermarket and a high-end specialty store all within Nairobi city. Coliform counts, plus Escherichia coli and Salmonella species isolation and characterization were done. Isolated Salmonella were further analyzed for virulence, pathogenicity and antibiotic sensitivity. This study was necessary since there have been public health concerns over the poor practices in production and distribution of leafy vegetables in Nairobi and its environs. Mean coliform counts on kale leaves from farms ranged from1.6xl 05?9.lxl 04 to 4.0xl05?1.3xl05 colony forming units per gram (cfu/g) while those from the wet markets ranged from 1.1xl06?6.7xl05 to 1.1xl07?3.0 x l O'cfu/g, Kale samples from supermarkets had a mean coliform count of 2.7xl06 ?5.5xl05 cfu/g while those from high-end specialty store were 4.7xl05 ?2.3xl05 cfu/g. Coliform numbers obtained on kale samples from the wet markets and the supermarket were significantly higher (p<0.05) compared to those from farms. Kale samples purchased from high- end market had similar levels of coliform loads as those from the farms (p> 0.05). Escherichia coli prevalences in samples from farms ranged from 37.7% (6/16) to 81.1 % (18/22). Those from the wet markets ranged from 33.3% (6/18) to 62.5% (10/16) while those from supermarkets and high-end specialty store, were 20% (5/25 and 3115, respectively). Salmonella organisms were detected on 4.5% (1122) and 6.3% (1116) of samples collected from farms in Wangige and a market in Kawangware, respectively. It was also detected in 12.5% (1/8) of water samples used for washing/refreshing kale from a market in Kangemi. Fecal coliforms in water used on farms (for irrigation) and in the markets (for washing the vegetables) exceeded levels recommended by World Health Organization (WHO) counts of 103 per 100 milliliters. Salmonella strains isolated from kale and water were virulent and pathogenic to mice though they exhibited significantly lower (p<0.05) pathogenic characteristics when compared to those from human clinical sources. They also showed resistance to only Penicillin, out of the 9 antibiotics that they were screened for; unlike those from clinical sources which showed multi - drug resistance. This study has, therefore, demonstrated low bacteriological quality of kale and associated water in Nairobi and its environs. These may be carriers of pathogenic organisms which could cause disease to human consumers. The isolation of Salmonella organisms has further emphasized this, more so since the Salmonella isolates demonstrated resistance to some antibiotics. It is therefore recommended that good farming and handling practices be undertaken to increase the safety of leafy vegetables. Consumers are also advised to cook their vegetables well before consumption.

Bioavailability of antioxidant vitamins in selected indigenous vegetables and their potential use in management of HIV/AIDS in Butula, Busia Kenya

Author: Nambafu, Rachel Wanjiru

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2011

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Butula Division, Busia District ; AIDS (Disease) ; HIV infection ; Vitamins ; Vegetables ;

Abstract:

HIV infection is characterized by a high preference of micronutrients deficiencies and wasting r that may vary considerably among different mv infected persons. High intake of micronutrients have been associated with reduced progression of HIV to AIDS and improved survival. Butula division in Busia district in Kenya is a region where indigenous vegetables do well during the rainy season but become scarce in the dry season. Vitamin A, C and E deficiency is a problem affecting people living with mv and AIDS (PL WHA). Deficiency of these antioxidant vitamins contribute to oxidative stress condition that accelerate death of immune cell and increase the rate of mv replication. The aim of this study was to identify vegetables rich in vitamin A, C and E with a view of assessing the bioavailability of these vitamins to PL WHA. The study investigated the feeding pattern of PL WHA in Butula Division, determined vitamin A, C and E content in selected indigenous vegetables and the bioavailability of these vitamins for use in the management of HIV and AIDS.The determination of Karotene and a-tocopherol content in selected fresh and dry vegetables (amaranthus, cowpea leaves, nightshade, slender leaf, pumpkin leaves and frying spider), and in sera were done using high performance liquid chromatography (HPLC) procedure. Starch, protein, animal and plants food sources accounted for 45.17 %, 21.9 %, 17.48 % and 73 % respectively of total foods consumed by PL WHA in Butula Division. Fresh blanched vegetables, contained high levels of f}-carotene; 4000-9700 J1g/100g and atocopherol levels; 3000-7350 J1g1I~ The solar dried vegetables contained J3-carotene levels ranging from 572 to 854 J1g1g dry weight (DW) and a-tocopherol levels ranging from 281 to 673 Ilg/g DW. Solar dried vegetables contained significantly lower (p<0.05) amounts of carotene and a-tocopherol as compared with fresh vegetables. L-ascoIbic acid content in selected fresh vegetables and fruit juices was determined by redox titration and contained levels ranging between 6 and 65 mg/lOOg. Pineapple juice was found to contain high level of vitamin C; with one glass of blended pineapple juice meeting the recommended dietary allowance (RDA) values. The mean serum retinol, a-tocopherol and f:k:arotene levels were 0.937, 0.144 and 17.7871lmolll respectively. The CD4+ cell counts of the PLWHA at baseline, determined using flow cytometer were within the normal range of 500-1500 cells/ul in blood while the CD8+ cell count was in the range of 300-3300 ceWJ11 of blood. Haemoglobin was less than 12 gldL and red blood cell width was less than 15.2 % indicating anaemia. 88.35% of the subjects had a CD4+/CD8+ ratio ofless than 1, 9.71% had a CD4+/CD8+ ratio range of2-3 and 1.94% had a ratio greater than 4. Normal CD4+/CD8+ ratio is in the range of 1-4. In the course ofJDV disease CD4 is often decreased and CDS increased so that the ratio is inverted77.95% of the subjects had a normal weight, 11.81% were underweight, 8.66% were overweight and 1.5']0/0 were obese. The bioavailability in the foods estimated using algorithm indicated a +2.17 change in serum carotene while there was +7.776 change in serum a-tocopherol levels indicating that the consumption of the food supplement would resuh to improving the bioavailability of these nutrients in PL WHA in Butula. Indigenous foods in Butula contain high levels of carotene and a-tocopherol which are moderately bioavailable if mixed in good proportion can meet RDA of the vitamins A, C and E which are 750J1g retinol equivalent/day, 6Omglday, 8mglday respectively (Combs, 1998) and boost the immunity of PL WHA. The results will provide nutritional information on the indigenous vegetables grown in Butula division and their potential use in the management of mv/AIDS.

Nutritional Phytochemical and in Vitro antimicrobial screening of some indigenous leafy vegetables

Author: Mibei, Elias Kibiwot

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2011

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Vegetables ; Corchorus olitorius ; Jute mallow ; Crotalaria ; Solanum scabrum ; Solanum nigrum ; Cleome gynandra ; Medicinal plants ; Escherichia coli ; Staphylococcus aureus ; Bacillus subtilis ; Pseudomonas aeruginosa ; Candida albicans ;

Abstract:

Indigenous leafy vegetables (lL V s) are traditional vegetables whose leaves, young shoots and flowers are consumed. Four commonly-used ILVs were investigated in this study, viz.: Corchorus olitorius L. (Jute mallow), Crotalaria ochroleuca G. (Slender leaf), Solanum scabrum Mill. (Black nightshade) and Cleome gynandra L. (Spider plant). These ILVs were planted at Jomo Kenyatta University of Agriculture and Technology (JKUAT) Experimental Farm and harvested between 1 to 2 months after planting. Fresh, cooked and dried (shade and solar drying) leaf samples were analyzed for nutritional and phytochemical composition. The samples were also investigated for relative antioxidant and antimicrobial activities. Proximate composition results indicated that dry matter, protein, fiber, fat and vitamin C (16.8?0.17%, 3.7?0.62%, 2.l?0.SO%, 1.4?0.27% and lS3.68?7.7Smg/100g DWB, respectively) was significantly higher in C. olitorius as compared to the other three IL V s (P<O.OS). Crotalaria ochroleuca on the other hand exhibited higher contents of dry matter and ash (l8.2?0.20% and 11.2?0.49%, respectively). Vitamin C and ~-carotene contents of fresh leaf samples were significantly higher than those of dried and cooked samples (P< O.OS). Cleome gynandra exhibited significantly high carotene (8.73?0.16 mg/1 Oug), while S. scabrum had the lowest amounts of both carotene and vitamin C (4.SS?0.2S mg/l00g and 62.61?4.S7 mg/lOOg DWB, respectively). Besides, all cooked samples showed significantly lower carotene contents (P < O.OS) compared to fresh samples. The fatty acid profile indicated that the IL V s generally had a higher amount of unsaturated fatty acids than saturated fats. C. olitorius exhibited predominant amounts of fatty acids, whereas C. gynandra reported significantly lower amount compared to the other ILVs.The content of phenolic compounds and tannins in the leaf extracts was determined spectrophotometrically using Folin-Ciocalteu and Folin-Denis reagents and calculated as gallic acid and tannic acid equivalents, respectively. The total phenol contents varied from OAO?0.03 to 4AS?0.10 gllOOg and tannins from 0.70?0.03 to 7.2S?0.OS g/lOOg DWB; S. scabrum gave relatively high tannins and phenolic compounds. Flavonoid and alkaloid contents were between 1.39?0.08 to 6.32?0.20 gil ~Og and 3.23?0.18 to 1O.80?0.08 g/IOOg, respectively. The ability of the extracts to scavenge diphenyl picryl hydrazyl (DPPH) radicals was determined spectrophotometrically at S17nm. The four IL V extracts had significant radical scavenging effects and almost all reported a significantly higher percentage of DPPH inhibition than ascorbic acid (P < O.OS). The extracts of C. olitorius and C. gynandra were most effective since they had higher percentages of radical scavenging activity and lower ICso values (concentration which scavenged SO% of the DPPH radicals). The IL V extracts also displayed significant anti-microbial potency against microorganisms such as Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Candida albicans. The best activities against the micro- orgamsms were observed in C. gynandra extracts with mmimurn inhibitory concentration (MIC) below 200 mg/ml. The nutritional, phytochemical and antioxidant potential of the IL V s is of health or nutraceutical significance and should help encourage consumption of the IL V s. Though the processing and preparation methods such as solar drying and cooking reduced their final consumed amount, they should be dried in dry and dark place under low temperature and cooking should be done within a short time for maximum retention of nutrients. There is still much that begs for sustained research on IL V s, and this study forms the basis for future research, especially in regard to bio-prospecting and valorization (value addition) of the ILV biodiversity.

Environmental transmission pathways for Cryptosporidium parvum in urban small holder dairy production in Dagoretti division, Nairobi

Author: Monda, Joseph Gwaro

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2009

Holding Libraries: University of Nairobi Upper Kabete Library ;

Subject Terms: Cryptosporidium parvum ; Dagoretti, Nairobi, Kenya ; Water ; Milk ; Vegetables ; Fecal coliforms ; Infections ; Rain ;

Abstract:

A study was carried out to obtain an understanding of the role of environmental transmission pathways for Cryptosporidium parvum. Cryptosporidia 0(5/160) (4/60), (3/20) (71160) where manure we heaped for infectivity study. Twenty five percent (1/4) of treated well water, eighty eight percent (15/17) of untreated well water, and fourty two percent (5/12) of Nairobi City Council (NCC) water in storage facilities were positive for fecal colifonns while none was detected in the two samples of rain water and the three samples of NeC water sampled directly from the tap. Two samples of manure heaped for infectivity study from the first and second week respectively were positive on Immunochromatographic test indicating that they had viable C. oocysts. A quantitative risk assessment was carried out to assess the risk of infection with C. using the Codex Alimentarius framework, which comprises hazard identification, hazard characterization, exposure assessment, and risk characterization. Five major transmission pathways were identified and an event tree constructed to assess disease exposure in the two most vulnerable populations (malnourished children and people living with HIV AIDS PLWAs). From these observations, a probabilistic quantitative risk assessment model was developed and parameterised with data from the survey questionnaire, detailed mapping and secondary data which gave a daily risk of 2 cases per 10,000 people. Although cattle are the source of C. the risk from eating raw vegetables was three times higher than that associated with consuming milk. This was largely explained by good milk-handling and poor manure-handling practices. Information on risks associated with different pathways was used to develop community-based interventions for decreasing risks associated with urban cattle.

Development of an integrated production system for african indigenous leafy vegetables in Taita district

Author: Mnyambo, Juliah

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2009

Holding Libraries: University of Nairobi Upper Kabete Library ;

Subject Terms: Vegetables ; Amaranthus hybridus ; Solanum scabrum ; Taita District ; Wundanyi Division, Taita District ; Insecticides ;

Abstract:

In Kenya, the consumption of African indigenous leafy vegetables (AILV's) is increasing due to the public awareness on these vegetable's contribution to nutritional and economic values. However, several factors limit their production. The objective of this study was to improve the productivity of these vegetables by addressing their nutritional requirements and the insect pests problem The study which was carried out in Wundanyi location, Taita district, sought to establish major AILV's production constraints and to develop strategies to deal with the major constraints. This was done through Participatory Rural Appraisal (PRA) and a structured questionnaire. A total of 70 AlLV's producing farmers participated in the PRA and were also interviewed using the structured questionnaire. On farm studies were carried out in farmers' fields. Amaranthus hybridus and Solanum scabrum were selected based on preference by the community. Four plantings were done between May 2008 and February 2009. Farm yard manure levels at rates of 20t1ha 40tlha, 60tlha, poultry manure at rate of 40tlha, 20t1ha, 40tlha, 60tlha farm yard manure each top dressed with CAN- 1030kglha, DAP-200kglha top dressed with CAN-l 030kglha, farmer practice and a control; were evaluated for yield improvement. This was carried out in replicated field experiments. A study was also carried out to identify and quantify the pest complex in the selected study site. In addition, experiments to establish an action threshold for the major insect pest and assessment of different IPM components (Azadiractin, Dimethoate, Lambda-Cyhalothrin) were also carried out in farmer's fields. Results of the PRA and questionnaire showed that the area had several resources such as rivers and streams, which if well utilized could assure farmers of good AILV's yields. However, it was revealed that AILV's are allocated very small portion of the farmers' total land Though, most of the farmers used farmyard manures, they were not aware of the recommended rates. Several production constraints were highlighted These included low soil fertility, low yields due to lack of information on AIL V's agrononnc packages, insect pests and diseases, poor market organization and lack of capital. Others were, lack of quality seed, lack of irrigation facilities and lack of information on whether their cooking procedures preserve nutrients in the vegetables. The on farm study on production packages indicated that, incorporation of farmyard manure (20, 40, 60tlha), poultry manure (40t1ha) and inorganic nitrogen (N), significantly increased plant growth parameters (plant height, canopy width, number of branches, stem diameter) and yields. Yields obtained from plants which were grown with organic manures top dressed with inorganic N were higher than those from plants with manures alone. There were a variety of insect pests on both vegetables occurring at different stages of plant growth. Insects belonging to six insect orders (Coleoptera, Lepidoptera, Orthoptera, Homoptera, Heteroptera and Diptera) were identified as pests on the two vegetables. Aphids were identified as a major pest of both vegetables. However, red spider mites were a major pest of Solanum scabrum occurring during the dry hot weather. 10 aphids/ young leaf was established as an action threshold, a point after which the leaf begins to curl making the produce unmarketable. The management studies revealed that Azadiractin, Dimethoate and Lambda -Cyhalothrin significantly reduced aphids and red spider mites populations and maintained the quality of the produce for marketing. Cattle manure levels at the rates of 20tlha, 40tlha, 60tlha either alone or top dressed with C.A.N-l 030kg/ha and 40tlha poultry manure are recommended for use by small scale farmers to improve yields of AILV's, thus their incomes, health and livelihoods. The information on the pest complex and their damages can be used in designing management strategies for in

Effects of dehydration of dark-green, leafy vegetables on bioavailability and bioconversion of serum beta-carotene among preschool children

Author: Oyugi-Nawiri Mildred Pauline

Awarding University: Kenyatta University, Kenya

Level : PhD

Year: 2008

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Vitamin A ; Vegetables ; Food preservation ; Children and youth ;

Abstract:

Vitamin A, an essential micronutrient has its deficiency remaining as a major public health problem in developing countries. The deficiency is caused by insufficient intake of foods rich in vitamin A or pro-vitamin A carotenoids and its prevalence contributes substantially to morbidity and mortality among children. Carotenoids, with (b-carotene as the primary pro-vitamin A carotenoid in dark green leafy vegetables (DGLVs), are important for their various biological functions. The DGLVs are season dependent but can be preserved by dehydration to ensure their availability during the dry seasons to reduce cases of the deficiency. The R-carotene content and retinol (vitamin A) in serum of preschool children after consumption of dehydrated cowpeas and amaranthus leaves were quantified. Preschool children (study subjects) were involved in a 13-week intervention period. Extracts from vegetable and serum samples were analysed by High Performance Liquid Chromatography. Elution was performed isocratically with systems of methanol:dichloromethane:water (79:18:3, v:v:v), methanol:dichloromethane:water (83:15:2, v:v:v) and acetonitrile:water (85:15, v:v) for vegetable samples, serum (3carotene (S-BC) and serum retinol (S-R) analysis respectively. Fresh blanched vegetable leaves, contained high levels of the all-trans b-carotene; 779-827mg/g DM for cowpeas and 553-639mg/g DM for amaranthus. Although they reduced with dehydration and cooking, retentions for b-carotene were over 50% after dehydration and cooking. Thus, recipes provided sufficient amounts of retinol equivalents (RE)/day from both fresh and sun-dried vegetables to meet the recommended daily allowances for the study subjects. Serum beta-carotene concentrations were found to be within the normal range at baseline and increased significantly post-interventional for both study groups (p<0.000, df = 110, for fresh vegetable group and p<0.000, df = 38 for dehydrated vegetable group. There was a negative correlation between the baseline S-BC and change in S-BC for study subjects. However, the increase in S-BC of subjects in the fresh vegetable group was higher as compared to those of the sundried group. Although the control group for the fresh vegetable study group had an increase in S-BC, that of the dehydrated group had a decrease, but these changes were not statistically significant. The subjects in the fresh and dehydrated vegetable groups had marginally lower S-R concentrations at baseline but there was significant changes after intervention (p<0.000, df = 110, for fresh vegetable and p<0.000, df = 38 for dehydrated group). McNemars chi-square tests showed that at baseline, 55% and 70% of study subjects in the fresh and dehydrated vegetable study groups respectively had low S-R concentrations with the percentages reducing to 36% and 30% respectively post-intervention. Correlation analysis was negative between the baseline S-R and change in S-R for subjects in both the study and control groups. While data from individual subjects support the homeostatic regulation of vitamin A status, this study concludes that, intervention with the dehydrated vegetables improved the bio-availability of beta-carotene and bioconversion of beta-carotene to retinol. The findings contribute to the link between increased consumption of carotenoids from DGLVs and bio-availability of the same.

Perceptions beliefs and practices on the health benefits associated with consunption of African leafy vegetables in Western Kenya

Author: Nyakoboke Oirere

Awarding University: Kenyatta University, Kenya

Level : MPH

Year: 2008

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Vegetables ; Nutrition ; Butere-Mumias District ; Traditions ; Diet ;

Abstract:

Many Sub-Sahara African countries are faced with food and nutritional insecurity. Declining production and utilization of African Leafy Vegetables (ALVs) would lead to reduced dietary diversity at household levels with associated adverse nutritional consequences. Furthermore, local indigenous vegetable species have not received as much promotional attention compared to the exotic crops counterparts. A crosssectional descriptive study was therefore designed to establish perceptions, beliefs and practices of community members on the health benefits associated with consumption of ALVs in Butere-Mumias District. A simple random sample size of 316 respondents was involved in this study. The study was designed to use both quantitative and qualitative data collection methods, including structured questionnaires, a week consumption recall, key informant interview guides and focus group discussions. Data was managed using SPSS software while analyses utilized Chi-Square test and Contingency Coefficient measures of association to test the hypotheses and establish relationship between variables. Consumption of ALVs among the Kwisero community members was found to be high with a majority of respondents (80.8%) consuming them 4 or more times a week. They mainly obtain them from their own farms. Overall, the most commonly consumed ALVs include Cowpea (Vigna unguiculata) (85%), followed by Jute plant (Corchorus) (73%), Spider plant (Cleome gynandra) (71%), African nightshade (Solunum spp.) (69%), Africa Sunhemp (Crotararia spp.) (59%), Leafy Amaranth (Amaranthus spp.) (43%), Pumpkin (Cucurbita maxima) (6%) and Vine spinach (Basella alba) (4%) in that order. There was a significant correlation between indigenous knowledge and consumption patterns of ALVs at 0.05 level of significance (p<0.005). There was no significant differences (p<0.005) found for gender, religion, education, type of house, head of household's occupation and family size and ALVs consumption levels. However, age, mother's occupation and type of roofing used were found to be positively correlated with ALVs consumption level. Various indigenous knowledge regarding health benefits of consumption of ALVs was established. From the study it can be concluded that culture plays a great role in ALVs consumption. Indigenous knowledge is embedded in their utilization and therefore critical for their promotion. There is therefore a need to explore traditional dietary patterns further which could potentially have health implications especially for non-communicable diseases.

Characterization of the inter and intra specific diversity and habitat association of native trichogrammatid species occuring on helicoverpa armigera hubner lepidoptera : noctuidae among vegetable crops in Eastern Africa

Author: Msanzu, Joseph Baya

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : PhD

Year: 2007

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Crops ; Vegetables ; African bollworm USE Helicoverpa armigera ; Helicoverpa armigera ; Pest control ;

Abstract:

The African bollworm, Helicoverpa armigera (Hubner) is an important pest world-wide, causing significant yield losses on many vegetable crops, including commercial, food and ornamental crops. The low economic damage thresholds in high value crops require a high level of control that leads to reliance on heavy and frequent use of synthetic pesticides. These pesticides have become inefficient and expensive for the resource-poor farmer, besides pest resistance and other environmental impacts. The stringent measures put by the European Union for pesticide-free fresh produce necessitate the search for safe and environmentally safe options in order to sustain the industry. Trichogrammatid egg parasitoids have been used elsewhere effectively for biocontrol of African bollworm. This study aimed at exploration of the diversity of indigenous parasitoids and associating them with the habitat in vegetable-based cropping systems in order to provide a basis for enhancing the impact of biological control of this pest in Eastern Africa. A survey for native species/strains of egg parasitoids focused on assembling native collections from contrasting vegetable-based ecologies in Kenya, Uganda, Tanzania and Ethiopia, through on-farm visits and on-station benchmark trials. An array of trichogrammatids, mainly of genera Trichogramma and Trichogrammatoidea were collected, besides scelionids (mainly Telenomus sp.). These were assembled from altitudes described as low (0-700 masl), medium (701-1200m asl) and high (above 1200m asl). The genus Trichogrammatoidea appeared more commonly than Trichogramma in all the four countries. Taxonomic characterization based on conventional methods (morphological features) resulted in five species, three Trichogramma species (Trichogramma sp. nr. mwanzai Schulten and Feijen, Trichogramma bruni Nagaraja, Trichogramma sp. Dr. r bruni Nagaraja), and two Trichogrammatoidea species (Trichogrammatoidea sp. nr. lutea Girault, and Trichogrammatoidea sp.nr. armigera Nagaraja). The two Trichogramma species (T. bruni and T. sp. nr. bruni), were new records in the region and on vegetable crops. Molecular characterization by ITS2-PCR adequately separated the native genera and species. This is quicker and could be a useful tool for inter-species differentiation, especially where males are absent or are broken in a collection. Generally, the two species, Trichogramma nr. mwanzai and Trichogrammatoidea nr. lutea were common in all major agro-ecologies (altitudes) and crops, although T. sp. nr. lutea was the more common. On-farm surveys focused on tomato (as target crop) but supplementary bench-marking sampling on four vegetable host crops (tomato, okra, capsicum, vegetable pigeon pea) and four other host crops (cotton, sorghum, sunflower and Kale) revealed that okra, tomato, sunflower and cotton were more preferred habitats that the other crops, especially by the genus Trichogrammatoidea. An attempt was made to evolve a prediction model for trichogrammatid species association with habitatlhost plants common in representative vegetable production ecologies. Reciprocal crosses of four strains from different geographical regions in Kenya resulted in general improvement of important biological parameters in most crosses. A quantum jump in fecundity was evident and its potential importance in Trichogramma mass production is outlined. This study has provided a firm basis for an ecological approach in understanding the distribution and diversity of species/strains of trichogrammatid egg parasitoids for better use in biological control programmes.

The effect of potassium fertilization of kale production.

Author: Obanyi, Stella Nyanduko

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2006

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Crops ; Vegetables ; Kale ; Fertilizers ; Potassium ;

Abstract:

ABSTRACT NOT AVAILABLE

The influence of storage conditions on the stability of b-carotene in solar-dehydrated dark green leafy vegetables

Author: Ndiritu, James Wanjohi

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2006

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Vegetables ; Food preservation ; Drying agents ; Vitamin A ;

Abstract:

Adequate consumption of fruits and vegetables is effective in prevention and combating micronutrient deficiencies such as vitamin A deficiency (VAD). Pre-formed vitamin A sources of food such as meat, milk and eggs are not always available to the poor in developing countries and dark-green leafy vegetables (DGLV) are the main source of these vitamins in the diet of many people. In many rural communities in Kenya, these vegetables constitute the main diet in many households. They supply most of the vitamin A and minerals requirements such as calcium, zinc and iron. These vegetables grow in plenty during the rainy season but become scarce or not available during the dry season and in times of drought. Their consumption and availability is limited to the wet season due to the lack of proper preservation and storage procedures. In some areas, traditional methods of sun drying are used but these results in a significant loss of vitamin value in these vegetables. Subsequent losses are experienced when the dried vegetables are stored under ambient (normal) conditions. A major concern in the nutritional value of these vegetables is the loss of carotenoids during dehydration and in storage, b-Carotene, the major carotenoid in these vegetables is known to undergo an oxidative degradation during dehydration and storage of these vegetables. An ideal storage procedure for these vegetables should eliminate oxygen in the packaging containers. In this study, the stability of b-carotene in dehydrated DGLV samples of amaranthus (amarathus hybridus (I1)), nightshade (solanun nigrum), and cowpea leaves (vigna unguiculata) stored with oxygen absorber for a period of up to six months was investigated. Oxygen absorption within the packaging material was based on the reaction of iron (steel wool) with oxygen. The dehydration process was achieved by drying the vegetables usin solar dryers for six hours. The content of (b-carotene in the fresh samples ranged between 781.94 and 1047.45 mg/g dry matter (DM). Dehydration resulted in a loss of betweO'n 16.41 and 32.28% bcarotene. A loss of 61.4 to 81.3% was noted for samples stored under normal conditions. The content of (b-carotene was considerably higher in samples stogy under oxygen absorber at the end of storage time as compared to those stored under normal conditions ' for the three vegetables. The amount of (b-carotene was enhanced by 30% in oxygen absorber as compared to storage under ambient (normal) conditions. Under these normal conditions, the level of 0-carotene decreased gradually from dehydration stage towards the end of storage period. Samples stored under inert atmosphere showed a nearly perfect stability throughout the entire storage time while those stored under iron steel wool oxygen absorber showed a relatively high stability from the initial stages. The removal of oxygen in the storage packaging improves the retention of (b-carotene and hence its stability during storage. All the vegetable samples showed the presence of the transition metals, iron and copper ranging from 0.20 wg/g to 0.25 mg/g for iron and 1.23 NLmg/g to 1.76 mg/g for copper. Normally presence of these metal ions in vegetable samples aids in the degradation of (b-carotene by acting as catalysts in the oxidation process.