PhD Graduands 2020

Nguetti Joseph Honore

Research Topic:
Pesticides Residues and Microbial Contamination of Tomatoes Produced and Consumed in Kenya
Nguetti Joseph Honore
Biography

Joseph Honore Nguetti is holder of a PhD in Food Safety and Quality graduated from the University of Nairobi (UoN) in 2020, the Royal Society for Public Health Level 2 in Food Safety and Hygiene, a MSc in the Arts of Peace and Development majoring in Public Health and of a BSc in Biochemistry. He is currently leading a private university in Cameroon and has respectively been, deputy coordinator of the coordination office for research and development, assistant coordinator of an Intra ACP research program AFIMEGQ funded by the European Commission at the University of Yaoundé 1 (UY1); Junior Professional Officer at the African Academy of Sciences (AAS) under the Organization for the Prohibition of Chemical Weapons (OPCW) and consultant of development in some local NGOs in Cameroon during which he served for some international organizations (UNIFEM) and bilateral cooperation organs (GIZ, CIDA and others). He contributed to develop three MSc programs established at the Biotechnology Center and at the Faculty of Medicine of the UY1. His works have been accepted for presentation in some international conferences. His research interest includes food safety and quality, health and development, peace and sustainable development. He has some publications and some international recognitions

Abstract

Abstract

Tomato is one of the most cultivated and consumed vegetables in the world.  The main production in Kenya is by small scale farmers who may not comply with the prescribed pesticides practices. A cross-sectional survey with tomato farmers using a semi-structured questionnaire was randomly administered to 52 participants in Mwea. A number of 240 tomatoes samples were collected twice a month from three open-air markets and two supermarkets from January to June 2017 in Nairobi for pesticide residues and bacteria analyses. For further studies, sampling of freshly prepared tomato for salad from three restaurants and three hotels of the four stars’ levels and above randomly selected in Nairobi was also conducted. Lastly, consumers’ awareness of pesticide residues and bacteria on fresh tomato was assessed using a semi-structured questionnaire administered to 101 households in Kangemi in Nairobi. Results show that, 93% spray pesticides once a week on-farms; 48.5% of tomatoes analyzed had pesticide residues of which 27.27% were single, 21.21% multiple and 6.06% and 1.51% had levels above EU and Codex MRLs respectively. Tomatoes had 96% of E. coli load and same samples had 20% of non-typed Salmonella spp. Single and multiple pesticide residues were detected in freshly cooked tomato of which, omethoate and dimethoate were above EU MRLs. Sociodemographic characteristics influenced consumers’ awareness (p< 0.05) on pesticides presence on tomato. The study concludes that, farmers in Mwea were conversant with pesticides, and most of them observe good practices. Consumers were slightly more aware of bacteria’s health effects than with pesticides.

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Research Supervisors

Research Supervisors

Prof. Jasper Kathenya Imungi,

Prof. Michael Wandayi Okoth,

Prof. Eric Simon Mitema,

Prof. Joseph Wang’ombe

ERICK OTIENO OGUMO

Research Topic:
Development of a Smart Prototype Solar Cooler to Replace Charcoal Cooler in Maintaining Quality and Shelf Stability of French Beans Along the Supply Chain in Kenya
ERICK OTIENO OGUMO
Biography

Dr Ogumo has been part of the University  of Nairobi for over the last two decades. He has just qualified for the award of PhD in Food Science and Technology. He joined the University of Nairobi in 1997 to pursue BSc in Agriculture, graduating in 2001. He then joined Homegrown Kenya Limited as a graduate trainee, climbing up the ladder to production manager. In 2005, he joined East African Growers Limited in the position of Group Agronomist. In 2008, he joined Flamingo/Finlays in the position of Group Agronomist responsible for East Africa. In 2012, he joined The Coca-Cola Company in the position of Supply Chain Agronomist to spearhead local sourcing for juice ingredients in Africa.

In 2010, Dr Ogumo came back to the University of to pursue Master of Science in Crop Protection, graduating in 2014.

In 2014, Dr Ogumo joined Tesco PLC in the position of Supplier Development Manager for Sub Saharan Africa, a role he held until 2018. Dr. Ogumo enrolled for PhD in Food Science & Technology in 2016 completing in 2020 September.Dr Ogumo is currently consulting for IFC/World Bank and UNIDO.He is also the co-founder of an agricultural consultancy firm, Cropmasters Limited.

 

Abstract

Abstract

French bean is one of the major horticultural crops exported from Kenya  into International markets. French bean production faces several challenges whose magnitude depend on whether the crop is produced in-house or with an out grower. Unlike with the large commercial growers who have well organized infrastructure to ensure quality food safety of the beans, small scale farmers have always struggled to keep up with the quality expectations of the markets.

This study was aimed at evaluating the performance of solar coolers in enhancing quality and shelf life stability of French beans with an overall of objective of developing a smart solar cooler to replace the use of charcoal coolers. A survey was done to understand the current knowledge and performance of charcoal coolers. Data were collected primarily from a household survey using a semi-structured questionnaire that was administered to 45 farmers that were selected at fixed interval purposively selected. To evaluate the effects of harvesting time and duration before cooling on the post-harvest quality and shelf-life stability of French beans, five harvesting times were evaluated; 7am, 9am, 11am, 1pm and 3pm. The harvested beans were then subjected to five different delay times before cooling; 0hr, 2 hours, 4 hours, 6 hours and 8 hours. The proximate compositions of the fresh French beans samples were determined using standard methods. The microbial quality of French harvested at different times of the day, 7am, 9am, 11am, 1pm and 3pm was also done using  standard plate technique. The samples were later graded and packed in modified atmosphere packaging (MAP) bags.

The study revealed that majority (80%) of the farmers adopted evaporative cooling technology using charcoal coolers and stored their produce for one to six hours (68%). 

The study revealed a significant loss of moisture and weight for every delay in start of cooling resulted in increase of protein by 18%, fat by 24%. Total viable counts (TVC) in these samples showed mean values ranging from 0.7 to 3.3×105 CFUs g-1 for total Enterobacteriaceae, Listeria monocytogenes, moulds and Staphylococcus aureus. Of the microorganisms isolated, Enterobacteriaceae (71.6%) was the highest, followed by Staphylococcus aureus (20.9%), Moulds (7.2%) and Listeria monocytogenes at 0.3%. The harvesting time and duration before cooling significantly (P≤0.05) affected the population of microorganisms with those harvested early in the morning recording the highest population.

The high presence of microbial load in samples harvested early morning can be attributed to poor hygiene of the harvesters  and too much leaf wetness in the morning. The weight of the stored produce reduced by 5% and 2.8% after seven hours under conventional field shed and fabricated solar cooler respectively. The volume of carbon dioxide and oxygen released from produce stored in conventional shed and those stored in fabricated solar cooler prototype significantly differed. Higher volume of CO2 accumulation was detected in produce stored in the conventional cooling method than those stored in the fabricated solar-powered cooler. Further research should be carried out to understand the influence of solar radiation on the development and existence of Listeria monocytogenes. It was evident that the Listeria monocytogenes  population decreased significantly with every delay in harvesting, which could also be attributed to dry leaf and pod surfaces.

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Research Supervisors

Research Supervisors

Dr. Catherin N. Kunyanga

Prof. John W. Kimenju

Prof. Michael W. Okoth

CAROLINE WAKUTHIE MUTHIKE

Research Topic:
Cancer screening and occurrence in Kangemi; potential prevention of cancer through consumption of African nightshade leafy vegetable, using a mice model
CAROLINE WAKUTHIE MUTHIKE
Biography

Caroline Wakuthie Muthike is a registered Nutritional Biochemist working as a working as a Tutorial fellow in the University of Nairobi. She is known for her passion to teach and research on relationship of disease, diet and nutrition lately African leafy vegetables.

Abstract

Abstract

Cancer is a disease that is steadily on the rise in Kenya despite the fact that two-thirds of the prevalence is due to preventable causes. The study was carried out in two phases. In the first phase, a baseline survey was carried out in Kangemi a slum in Nairobi County. . In the second phase, laboratory analysis used a factorial design. The two treatments assessed were, cooked vegetables, raw vegetables, against a control on mice model. The association between gender and cancer screening was significant (χ28.034, DF=1, P=0.005). There was a significant association between occupation and cancer screening (χ228.158, DF=6, P=0.000). There was a significant relationship between knowing the benefits of leafy vegetable consumption and cooking time (U=33, p=0.008). In the second phase, the antioxidant activity of African nightshade leafy vegetable significantly increased when cooked (t=43.57, P= 0.000). In addition, expression of the urokinase plasminogen activator protein was reduced in mice fed with cooked vegetables by about 97% while the mice fed on raw vegetable expression was down-regulated by about 39% as compared to the control.

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Research Supervisors

Research Supervisors

Prof JK Imungi 

Prof. Wambui Kogi-Makau 

Dr. Edward Muge

Sussy Munialo

Research Topic:
FACTORS INFLUENCING MAIZE YIELD GAPS ON SMALLHOLDER FARMS IN VIHIGA AND KAKAMEGA COUNTIES OF WESTERN KENYA
Sussy Munialo
Biography

 society that is food secure is productive and independent. Children are able to go to school and adults engage in constructive activities that sustainably contribute to national economic development thus alleviating human suffering. This has always been my passion that propelled me to undertake a career in agricultural sciences. 

I have been working with small holder farmers to improve nutritional intelligence and transform livelihoods by integrating my professional skills in Soil Health, Agronomy, Socio-economics and Remote Sensing. My current research focus is on understanding causes of large yield gaps on smallholder farms by integrating biophysical, agronomic and socio-economic factors. My previous research work focus was on improving nutritional and economic wellbeing of smallholder women farmers through utilization of African Leafy Vegetables. The research work has also helped publish 4 articles in peer review journals.

Achieving food security and economic wellbeing requires a multi-disciplinary approach where different factors and actors are involved. My professional background in Agricultural Resource Management has helped me gain multi-disciplinary skills in agronomy, socio-economics and soil health which will be useful in contributing towards food security and in my career progression.

My educational background includes a Msc. of Science degree in Agricultural Resource Management and Bsc. In Agricultural Education and Extension from the University of Nairobi

I also love gardening, reading inspirational books, cooking, walking and meeting new people.

 

Abstract

Abstract

Yields of staple crops such as maize (Zea mays), rice (Oryza sativa) and wheat (Triticum aestivum) have stagnated in many parts of Sub Saharan Africa resulting in large yield gaps which have exacerbated food insecurity. 

A multi-disciplinary approach comprising of different data collection; soil sampling, field measurements, household surveys, on farm experiments, satellite imagery) and analysis methods; Generalized Linear Mixed Model (GLMM), Classification and Regression Tree analysis (CART), Factor Analysis (FA), Linear Mixed Effects Model analysis (LMER) and Spatial Analysis Techniques was used to investigate causes of yield gaps in Mukuyu-Kakamega and Shikomoli-Vihiga of Western Kenya. 

The average maize yield and yield gaps for Mukuyu were 3.8 t ha-1 and 1.8 t ha-1 while for Shikomoli they were 2.7 t ha-1 and 2.6 ha-1. Factors influencing yield gaps included; education, age, membership to groups, access to markets, family labour, gender, credit facility, maize variety, crop residue, quantity of organic and inorganic fertilizer use, maize density, chlorophyll values, maize height, and depth to compact layer which were consistent across the study sites. Weed cover at early stages and maize density at late stages were the most limiting factors in maize production in Mukuyu and Shikomoli, respectively.

Large yield gaps > 30% exist on smallholder, and policy measures aimed at improving soil fertility, market accessibility, relaying agricultural information and encouraging family involvement in agronomic activities are needed to improve yields. Agro-ecology and field specific measures focused on improving particular soil nutrient types and levels, weed management and plant density are also required.

 

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Research Supervisors

Research Supervisors

Prof. Cecilia M. Onyango,

Department of Plant Science and Crop Protection,

University of Nairobi.

 

Prof. Willis Oluoch Kosura,

Department of Agricultural Economics,

University of Nairobi.

 

Prof. Ingrid Öborn,

Department of Crop Production and Ecology,

Swedish University of Agricultural Sciences.

 

Prof Sigrun Dahlin,

Department of Soil and Environment,

Swedish University of Agricultural Sciences.

 

 

Nancy Karimi Njeru

Research Topic:
Contribution of push-pull cropping system to management of ear rots and mycotoxin contamination in maize in western Kenya
Nancy Karimi Njeru
Biography

Nancy Njeru was a PhD Crop Protection student at the University of Nairobi (2017-2020). She is currently a Research Scientist at the Regional Laboratory for Mycotoxin Research and Capacity Building located at Kenya Agricultural and Livestock Research Organization (KALRO), Katumani, Machakos County, Kenya, where she leads daily activities in the Lab, oversees technical aspects of Aflasafe manufacture, in the Aflasafe factory, coordinate activities with other departments and supervisors, observe work and ensure employees are working according to standards, create schedule and assignments, and ensure safety and maintenance of staff. Her research and professional interests include microbiology, mycology, food safety and crop protection. Nancy received her BSc in Microbiology and Biotechnology and MSc in Microbiology from the University of Nairobi. Her MSc research was on: Influence of cropping systems and crop residues on the occurrence of Fusarium Head Blight of wheat (Triticum Aestivum L.) and associated mycotoxins in Narok County, Kenya. She has published in peer reviewed journals and presented in international conferences.

Abstract

Abstract

 

Push-pull is a cereal cropping system that has recently been reported to reduce incidences of ear rots and mycotoxins in maize. However, the effectiveness and mechanism involved is not yet understood. This study determined, the (i) socio-economic and agronomic factors associated with the occurrence of ear rots and contamination of maize with mycotoxins in different cropping systems in western Kenya, (ii) impact of insect management under push-pull cropping system in managing aflatoxin and fumonisins, (iii) role of soil health improvement under push-pull on the population of mycotoxin-producing fungi and (iv) effect of desmodium roots exudates on mycotoxin producing fungi of maize. 

Knowledge on aflatoxin was higher among elderly aged 45 to 60 years while knowledge of ear rots increased with level of education and non-push-pull respondents were more knowledgeable. Aflatoxin levels significantly increased with stemborer infestation of maize. Stemborer and fall armyworm damage, Fusarium ear rot infection, A. flavus and F. verticillioides populations were significantly (P < 0.05) reduced under push-pull cropping system. Aflatoxin levels were not significantly different between cropping systems, but fumonisin were significantly lower under push-pull cropping system. There was positive and significant correlation among insect damage, ear rot, ear rot fungi and mycotoxin levels in maize. Populations of fungi and nutrients in soils were not significantly different between the cropping systems. Desmodium extracts roots significantly reduced radial growth of toxigenic A. flavus and F. verticillioides through reduced spore germination and germ tube elongation. In conclusion, planting maize under push-pull cropping system indirectly reduced mycotoxin contamination.

Important Links

Research Supervisors

Research Supervisors

Prof James W Muthomi _ University of Nairobi

Dr John M Wagacha _ University of Nairobi

Prof Zeyaur R Khan _ Internation Center of Insect Physiology and Ecology (icipe)

Dr Charles AO Midega _ icipe

Ahmed Mohamed Musa

Research Topic:
ANALYSIS OF INSTITUTIONAL DYNAMICS AND THEIR INFLUENCE ON LIVESTOCK EXPORT TRADE IN THE BERBERA CORRIDOR OF SOMALILAND
Ahmed Mohamed Musa
Biography

Ahmed M. Musa is a postdoctoral researcher at the Diaspora Humanitarian (D-Hum) in complex crises project funded by the Danish government. His PhD research, funded by the Danish Government, focused on the institutional dynamics of livestock export trade in the Berbera corridor. His publications include peer-reviewed journal articles, policy briefs, blog posts, book chapters, reviews, and technical reports. I have middle-level management experience with different organizations. He has worked with/for organizations including ActionAid Somaliland, Somaliland National Electoral Commission (NEC), Somali Observatory of Conflict and Violence Prevention (OCVP), Rift Valley Institute (RVI) and Peace Research Institute Oslo, Norway (PRIO) and conducted dozen M & E exercises and Consultancy Work for international organizations including Progression Somaliland, Caritas Switzerland/Luxembourg and the Swiss Agency for Development and Cooperation (SDC). He has been awarded with two capacity-building scholarships (2016-2019 and 2020-2022) from the consultative research committee for development research (FFU), Denmark.

 

Abstract

Abstract

In the last four decades, Somalia’s economy has evolved from a centralised economy under socialist institutions to a largely stateless and deregulated economy that has attracted interest from scholars. Over the years, inconsistent insights and accounts on the performance of the economy have been put forward by scholars and practitioners. The foremost purpose of the thesis was to analyse institutions, formal and informal, and their influence on the export livestock trade in the Berbera corridor. To empirically investigate livestock trade in the Berbera corridor, the study combined different qualitative and quantitative methods. This study reveals findings that are contrary to the prevailing understandings in Somalia’s post-war stateless economy in several respects. In contrast to the literature that stresses the positive performance of Somalia’s stateless economy, the findings show that livestock export trade in the Berbera corridor suffers from absence of state, hence lack of formal institutions and regulations. Examples of market failures that resulted from the absence of these institutions include perpetual livestock import bans and rejections, breach and lack of contract enforcement, increased fraudulence in the import markets and cashless and dollarized livestock trade in both local and international markets. In addition, the findings show the limitations of the informal institutions that have been credited to the performance of Somalia’s stateless economy. The informal institutions consequently fall short of reducing risks, harassment and, fraud in the international livestock trade.   

 

Important Links

Research Supervisors

Research Supervisors

Dr. Oliver Vivian  Wasonga

Prof. Dr. Tobias Hagmann

Dr. Nadhem Mtimet

Dr. Oscar K. Koech

Raphael Lotira Arasio

Research Topic:
Analysis of the Evolution and Functionality of Income-generating Pastoral Community Groups in northern Kenya.
Raphael Lotira Arasio
Biography

Raphael holds three degrees from the University of Nairobi, Kenya: a bachelor’s degree in veterinary medicine, an MSc. in veterinary epidemiology and economics, and a Ph.D. in Range Management.
Raphael is currently (Year 2020) working for the Karamoja Resilience Support Unit of Tufts University as a Senior Resilience Advisor. Raphael has supported development and humanitarian livestock
programs funded by donors and government in East Africa and the Horn of Africa for more than 20 years. He has previously worked for GIZ-IS, Land O’Lakes, Farm Africa, VSF-Belgium, and the
Catholic Diocese of Torit. In these roles, Raphael used participatory methodologies to design, implement, and publish a variety of studies and evaluations of animal health, livestock
marketing, pastoral livelihoods, and resilience.

Abstract

Abstract

Whereas there is abundance of information on community groups that engage in income generation in the rural agricultural and peri-urban areas, information on community groups in pastoral areas still remains scarce. This study sought to analyze how income-generating pastoral community groups, particularly those involved in the marketing of sheep and goats evolved over time and function. The study was done in Marsabit County as an example of the vast dryland in Kenya facing the same problems of market
access and sustainability of community groups. Mixed methods approach was used in data collection and the data was analyzed both quantitatively and qualitatively. The results revealed that, different entities played different roles over time in the formation and development of income-generating pastoral community groups. There was a remarkable increase over time in the self-initiated groups and this latter trend resulted from the weaknesses of the pre-dominantly externally supported older generation of groups that affected their sustainability. Both factors external and internal to the community influenced the increasing
emergence and evolution of groups. The social and governance factors contributing to successful functioning of groups were linked with the way the Rendille community is socio-culturally organized
and governed. The results also revealed the emergence of an approach where groups give loans to members to engage in sheep and goats trade individually, and well-functioning groups had
endogenous (initiated by groups themselves) mechanisms that they use to deal with organizational, governance, business management, and livestock marketing constraints. These insights from history and functionality are important for promotion of sustainable income-generating pastoral community groups in general and group marketing of sheep and goats in particular, and have practical implications for practice and policy.

Important Links

Research Supervisors

Research Supervisors

Dr. Oliver Vivian Wasonga
Dr. David Jakinda Otieno
Prof. Brigitte Kaufmann