Bio

Prof. M.W. Okoth

Professor  Michael W. Okoth  is a Chemical Engineer with vast training and experience in  Food Science and Technology with emphasis on Food Process Engineering.  He obtained B.Sc. (Eng) degree in Chemical Engineering from  Imperial College of Science and Technology, University  of London in 1978.

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Publications


Submitted

Kunyanga, CN, Imungi JK, Biesalski HK.  Submitted.   http://www.sciencedirect.com/science/article/pii/S0023643811002659 http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/17023 . AbstractWebsite

Certain indigenous foods commonly consumed by Kenyan vulnerable groups (the malnourished; children under 5 years of age; pregnant and lactating women; malnourished adults in cases of vitamin or mineral deficiencies, TB, diabetes, cancer, AIDS; refugees; orphans the elderly and the disabled) are not yet evaluated for phenolic content and health relevant functionality. The present study was therefore designed to analyze the phenolic content, antioxidant and antidiabetic properties of methanolic extract of raw and traditionally processed food ingredients. The total phenolic contents of the cereals, legumes, oil seeds and vegetables were ranged from 0.41 to 3.00 g/100 g DM. Amaranth grain (Amaranthus cruentus) and drumstick leaves (Moringa oleifera) exhibited significantly higher phenolic content than the other samples. The methanolic extract of the investigated samples showed promising levels of DPPH radical scavenging activity (81–89%); ferric reducing/antioxidant power (FRAP, 44–744 mmolL−1 Fe[II]/g extract DM); α-amylase (10–45%) and α-glucosidase (13–80%) inhibition activities. The food ingredients with high phenolic content exhibited relatively higher antioxidant and antidiabetic activities. The results indicate that soaking + cooking is the mild processing method to preserve the phenolic compounds and their health relevant functionality in the presently investigated cereal, legume and oil grains, while cooking is suitable treatment for vegetables.

2013

Onyango, C, Unbehend G, Mewa EA, Mutahi AW, Lindhauer MG, Okoth MW.  2013.  Strategies for the production of gluten-free bread from sorghum cassava flour blend. , Dresden: TUDpresstrend_and_opportunities.pdf
Wayua, FO, Okoth MW, Wangoh J.  2013.  Modelling of a locally fabricated flat-plate solar milk pasteuriser using artificial neural network. Abstract

The objective of this work was to develop an artificial neural network model to predict milk temperature of a locally fabricated solar milk pasteuriser, based on measures of error deviation from experimental data. A three-layer feed-forward neural network model based on back propagation algorithm was developed using the Neural Network Toolbox for MATLAB®. The inputs of the model were ambient air temperature, solar radiation, wind speed, temperature of hot water, and water flow rate through the collector, whereas the output was temperature of milk being pasteurised. The optimal neural network model had a 4-4-1 structure with sigmoid transfer function. The neural network predictions agreed well with experimental values with mean squared error, mean relative error and correlation coefficient of determination (R2) of 5.22°C, 3.71% and 0.89, respectively. These results indicate that artificial neural network can successfully be used for the prediction of the performance of a locally fabricated solar milk pasteuriser.

2012

Wayua, FO;, Wangoh J.  2012.  Survey of postharvest handling, preservation and processing practices along the camel milk chain in Isiolo district,Kenya. AbstractWebsite

Despite the important contribution of camel milk to food security for pastoralists in Kenya, little is known about the postharvest handling, preservation and processing practices. In this study, existing postharvest handling, preservation and processing practices for camel milk by pastoralists in Isiolo, Kenya were assessed through crosssectional survey and focus group discussions. A total of 167 camel milk producer households, 50 primary and 50 secondary milk traders were interviewed. Survey findings showed that milking was predominantly handled by herds-boys (45.0%) or male household heads (23.8%) and occasionally by spouses (16.6%), sons (13.9%) and daughters (0.7%). The main types of containers used by both producers and traders to handle milk were plastic jerricans (recycled cooking oil containers), because they were cheap, light and better suited for transport in vehicles. Milk processing was the preserve of women, with fresh camel milk and spontaneously fermented camel milk (suusa) being the main products. Fresh milk was preserved by smoking of milk containers and boiling. Smoking was the predominant practice, and was for extending the shelf life and also imparting a distinct smoky flavour to milk. The milk containers were fumigated with smoke from burned wood of specific tree species such as Olea africana, Acacia nilotica, Balanities aegyptica and Combretum spp. Boiling was practised by primary milk traders at collection points to preserve milk during times when transport to the market was unavailable. Milk spoilage at the primary collection point in Kulamawe was aggravated by lack of cooling facilities. At the secondary collection point in Isiolo town, milk was refrigerated overnight before onward transmission to Nairobi. The mean quantity of traded milk was 83.2±3.8 litres. The main problems experienced by milk traders in Isiolo included milk spoilage (43.0% of respondents), delayed payments—after one or two days (19.9%), loss of money due to informal courier (12.2%), low prices of fermented milk (10.9%), milk rejection by customers in Nairobi (7.1%), inadequate supply during dry season (3.5%), loss of milk due to bursting of containers (2.1%) and milk not being supplied by producers due to insecurity (1.3%). In-depth understanding of the postharvest handling, preservation and processing practices would help to devise appropriate strategies that would increase the quantity and improve the quality of marketed camel milk. Such strategies should include the improvement of infrastructure such as milk transport, collection, cooling and processing facilities of suitable capacity.

Nungo, RA, Michael WO, Mbugua SK.  2012.  Scientific Research. Abstract

A study was carried out to assess the nutritional status of under-five child population within cassava consuming community in Nambale of western Kenya. A structured questionnaire was used to collect socio economic data, 24-hour food re-call and anthropometric measurements. Data were analyzed using Statistical Package for Social Sciences. Descriptive statistics were used while Pearson’s Chi Square and correlation coefficient (R) were used to test for statistical associations. A total of 320 households with 232 children participated. The findings showed nutrition status of children to be poor (<-2 SD), 26.6% were stunted, 13.9% underweight, and 10.1% were wasting. Malnutrition had reached its peak during the third year affecting boys more than girls despite a high mean score (9.2) for household dietary diversity. The findings established cassava utilization to be high (94.3%) and mainly as “porridge, boiled roots and ugali”. Eight staples including cassava were used for weaning and 66.4% of the children were fed three times daily. Cassava utilization was not a determinant of child nutrition status. Age of child and education level of head of household had strong but negative influence on child nutrition status, (Pearson’s R = -0.207: -0.174) indicating >50% changes in stunting could not be attributed to age of child or education level of the head of household. Farm ownership was a strong positive determinant of nutrition status, Pearson’s R = 0.233. This study has established that cassava cushions hunger and there is need to improve nutrient content.

Wayua, FO, Okoth MW, Wangoh J.  2012.  Thermal Performance of Four Types of Water Heating Flat Plate Solar Collectors for Providing Process Heat for Milk Pasteurisation. Abstract

Thermal performance tests were carried out on four water heating flat plate solar collectors with the aim to select a suitable one to be used to provide process heat for milk pasteurisation. The collectors included three commercial solar collectors purchased from local shops in Nairobi, Kenya and one prototype collector designed and fabricated by the author. The three commercial solar collectors had effective areas of 1.67, 1.87 and 1.83 m2 while the self-made collector had an effective area of 1.60 m2. Thermal performance of the collectors was determined in terms of the Hottel-Whillier-Bliss equation, with FR(α)e and FRUL indicating how energy is absorbed and lost from the collector, respectively. The FR(α)e values were 0.76, 0.75, 0.73, and 0.82, respectively, for the commercial collectors and the self-made collector. The FRUL values were 8.33, 12.01, 9.80 and 13.77 W.m–2.C–1, respectively. The instantaneous efficiencies for the four solar collectors ranged from 12 to 87%. The solar collector with the lowest FRUL value had a special (black chrome) selective absorber surface and was also the most cost effective collector for delivering temperatures of about 80°C. This collector is the most suitable for medium temperature applications such as provision of hot water for milk pasteurisation.

Akweya, BA, Gitao CG.  2012.  The acceptability of camel milk and milk products from north eastern province in some urban areas of Kenya. AbstractWebsite

A total of 138 households were interviewed on various aspects of camel milk and camel milk products using a single-visit multiple-subject diagnostic survey in Garisa, Wajir and Eastleigh the main urban centres with high camel milk consumption. 75% of the respondents generally take camel milk or milk products every day. Raw and sour milk are the most popular products. The most important purchasing criterion for raw camel milk was taste (19 and18%) while packaging was more important for pasteurized milk (18, 18 and 16%) for Wajir, Garisa and Eastleigh respectively. For Yoghurt, the most important purchasing criteria were taste (18%) and aroma (19%). The taste of sour milk is the most important attribute in both Garisa (30%) and Eastleigh (24%). To enhance marketing of camel milk, the appropriate attributes demanded by customers needs to be seriously addressed. Promotion of camel milk and products to non conventional consumers should be done in order to increase their consumption.

2011

Abong', GO, Okoth MW, Imungi JK, Kabira JN.  2011.  Effect of packaging and storage temperature on the shelf life of crisps from four Kenyan potato cultivars. American Journal of Food Technology. 6(10):882-892.2011_-_crisps_and_shelf_life.pdf

2010

Abong, GO, Okoth MW, Imungi JK, Kabira JN.  2010.  Evaluation of selected Kenyan potato cultivars for processing into potato crisps. AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA. 1(5):886-893.
Abong', GO, Okoth MW, Kabira JN.  2010.  Characteristics of fresh (ware) potato traders in Nairobi and Nakuru towns, Kenya. Contribution of Agricultural Sciences towards achieving the Millenium Development Goals. , Nairobi: FaCT Publishing, Kenya.2010_-_potato_traders_e-book_publication.pdf
Abong', GO, Okoth MW, Imungi JK, Kabira JN.  2010.  Characteristics of the industry, constraints in processing, and marketing of potato crisps in Kenya. Journal of Animal & Plant Sciences. 8(1):936-943.
Abong', GO, Okoth MW, Imungi JK, Kabira JN.  2010.  Consumption patterns, diversity and characteristics of potato crisps in Nairobi, Kenya. Journal of Applied Biosciences. 32:1942-1955.2010_-_crisps_and_consuption_kenya.pdf
Abong, GO;, Okoth MW;, Imungi JK;, Kabira JN.  2010.  Consumption pattern and characteristics of potato crisps in Nairobi city, Kenya. Abstract

Objective: To determine the consumption pattern and characteristics of potato crisps in Nairobi City, Kenya. Methodology and results: Potato crisps consumption pattern was studied using studied structured questionnaires to collect data from 215 crisps consumers. A total of 80 shops were surveyed to establish the brands and characteristics of potato crisps sold within Nairobi City. The available brands were then sampled and evaluated at the University of Nairobi. Of the sampled 215 consumers were males while 67.4 % were females. A majority, 73.9 % consumed potato crisps on average once a week. A part from gender, the frequency of purchasing crisps was also influenced by factors such as occasions, seasons and availability of money. Most consumers (22.3 %) preferred Tropical heat brand, 10.82 % preferred Krackles while the least (0.57 %) preferred Pringles, Delice and Highlands crisps. The most preferred flavor was onion and slightly salted crisps. The most purchased packaging units (51.7 %) ranged from 30-50 g due to affordability, retailing at Kshs. 30-40 (about 0.5 USD) compared to units of 150 g and above that were least purchased (1.7 %) due to their high costs, retailing at Kshs. 100 (about 1.5 USD) and above. A total of 28 % of the consumers bought crisps for self-consumption while 72 % purchased both for self and family members. All the outlets surveyed (100 %) sold potato crisps. Only 15 % of the outlets stocked potato crisps and other potato products such as chevda and potato sticks. A total of 24 brands of crisps were sold in Nairobi city. The most stocked brands in the outlets were Tropical heat and Krackles that were available in 46 and 45 % of the outlets surveyed, respectively. All the shops surveyed stocked brands of crisps made in Kenya while only 15.3 % of the outlets also had imported brands. The units of packaging ranged from less than 10 g to 1 kg. The most popular unit packages (40 %) varied from 10 to 100 g as they were cheap and affordable to most customers selling between Kshs. 10 to Kshs. 60. The study indicates that potato crisps are highly consumed by young children and youths in their teen ages while parents were moderate buyers of the products. Laboratory characteristics of the brands evaluated included colour, size, thickness, moisture, salt and oil contents that significantly (PB0.05) differed among the brands. The oil content ranged from 24.37 to 40.22 % while the moisture and salt contents varied from 1.09 to 5.45 %, and 1.10 to 2.96 %, respectively. Conclusions and application of results: Consumption of crisps in Nairobi city depends on gender, occasions, and seasons of the year and availability of disposable income. Except in the sizes, most brands had characteristics that conformed to the standards set for crisps. This study provides a view of the current scenario in the crisp market and is useful information to consumers, processors and policy makers in the potato sub sector.

2009

Abong', GO, Okoth MW, Karuri EG, Kabira JN, Mathooko FM.  2009.  Evaluation of selected Kenyan potato cultivars for processing into French fries. Journal of Animal & Plant Sciences. 2(3):141-147.
Abong, GO, Okoth MW, Karuri EG, Kabira JN, Mathooko FM.  2009.  Nutrient contents of raw and processed products from Kenyan potato cultivars. Journal of Applied Biosciences. 16:877-886.
Abong, GO, Okoth MW, Karuri EG, Kabira JN, Mathooko FM.  2009.  Levels of reducing sugars in eight Kenyan potato cultivars as influenced by stage of maturity and storage conditions. Journal of Animal & Plant Sciences. 2(2):76-84.2009_-_redsugar_and_potato.pdf
Gichohi, KE;, Wandayi OM;, Imungi JK;, Okoth M;, Njenga JN.  2009.  Seminar on Food Science and Technology special project proposals and research findings.
Abong, GO;, Okoth MW.  2009.  Edward G. Karuri1, Jackson N. Kabira2 and Francis M. Mathooko3. Abstract

Potato is an important crop in Kenya, with a major role in food and income security, being second only to maize in terms of utilization.• Production occurs mainly in the highlands (1500-3000 m above sea level).• Many potato varieties including Roslin Eburu, Roslin ...

GICHOHI, PROFKARURIEDWARD, WANDAYI PROFOKOTHMICHAEL.  2009.  Abong. Journal of Animal and Plant Sciences, Vol.2, issue 2: 76-84. Abstract
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G.O, A, M.W O.  2009.  Abong. African Journal of food, Agriculture, Nutrition and Development 9(8), 1667-1682. (www.adfand.net). Abstract

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2008

Okoth, MW.  2008.  Ustainable Food Security Systems..

2006

2005

Ndugire, N;, K’omudho B;, Kuhumba F;, Onyango JC;, Okoth MW;, Magambo J;, Ikiara M;, Mutunga C.  2005.  Selection, design and implementation of economic instruments in the solid waste management sector in Kenya: The case of plastic bags. AbstractWebsite

The generation of solid waste has become an increasing environmental and public health problem everywhere in the world, but particularly in developing countries. The fast expansion of urban, agricultural and industrial activities spurred by rapid population growth has produced vast amounts of solid and liquid wastes that pollute the environment and destroy resources.

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