Sensory Attributes of Coffee under Different Shade Regimes and Levels of Management

Despite coffee bean physical and beverage quality attributes being inherent factors, the environment, which includes crop management factors, can play a major role in determining their expression. This study was conducted to evaluate the effect of management and shade levels on beverage quality of coffee. The study was carried out at the Kenya Agricultural and Livestock Research Organization, Coffee Research Institute (KALRO-CRI) farm in Bungoma County, Kenya. The coffee management levels were categorized depending on field operations and application of inputs. The different shade levels were based on the distances from the trunk of shade tree and shading levels were estimated by measuring the Photosynthetic Photon Flux Density (PPFD) in µmol m-2 s-1 using a Line Quantum Sensor. The sensory characteristics fragrance/aroma, flavor, aftertaste, acidity, body, balance and overall were assessed by a panel of seven trained judges. The beverage quality, except for acidity and balance, were largely unaffected by management or shade levels, however trends showed that most of the variables, on average, had higher scores in shade than in full sun. Shade was positively correlated with all sensory variables while management was negatively correlated with all. This suggested that use of shade, under low management, could offset the limited application of external inputs to some extent. Keywords: Coffea arabica, shade, management levels and quality

The population structure of wild sorghum species in agro-ecological zones of Western Kenya

There is need to understand the genetic structure of wild sorghums that grow alongside cultivated traditional sorghum varieties in order to assess the potential effect of crop genes in wild populations. In this study, 175 wild sorghum samples were collected from 13 agroecological zones (AEZs) from three counties in Western Kenya and genotyped using microsattelite markers. Crop alleles were observed in wild sorghum populations. The range of allelic frequencies varied from low (˂0.4), to moderate (0.4-0.7) and to high (0.7) in the AEZs. Wild sorghum populations had moderate to high expected heterozygosity (HE) values of between 0.453 in LM1 to 0.715 in LM2. Differences in the magnitude of diversity was significant in the counties (Busia HE = 0.59 – 0.71; Homabay HE = 0.58-0.68 and Siaya HE = 0.45-0.59) but not distinct among the AEZs. Whole population FIS, FST and FIT values were low at 0.15, 0.16 and 0.29, respectively indicating low level of inbreeding, low genetic differentiation of the population and low to moderate deviation from Hardy–Weinberg (HW) equilibrium respectively. The deviation from HW equilibrium was significant in some wild populations from Siaya and Busia. Intra-population diversity (HS) was larger than inter-population diversity (DST) in 13 populations from the sampled AEZs, indicating the importance of gene flow between populations of wild sorghums. Heterozygosity values under mutation drift equilibrium (HEQ) varied under infinite allele model (IAM), two–phase model (TPM) and the step wise mutation model (SMM). However, significant population bottlenecks were absent in the wild sorghums. Presence of significant geographic county clusters and lack of significance on AEZ clusters indicate that human activities have had more influence on the distribution and diversity of wild sorghums than the prevailing climatic conditions. Efforts towards physical and genetic containment of crops genes need to be enhanced for successful ecologically sensitive confined field trials and future adoption of transgenics in cropping systems.Keywords: Diversity, Sorghum bicolor, Sorghum halepense, Sorghum sudanense, microsatellite loci.Abbreviation: AEZ, Agro-ecological zone; DST, inter-population gene diversity; FIS, fixation index; FIT, index of deviation from HW equilibrium; FST, degree of population differentiation; GST, proportion of inter-population gene diversity; HE, expected heterozygosity; HEQ, heterozygosity values under mutation drift equilibrium; HO, observed heterozygosity; HT, total gene diversity; IAM, infinite allele model; SMM, stepwise mutation model; TPM, two-phase model; LM, lower Midlands; UM, upper midlands; HB, Homabay; SY, Siaya; BU, Busia counties; SSR, simple sequence repeats

Influence of Crop Age on Nutritional Quality and Hydrogen Cyanide Levels of Roots from Popular Coastal Kenyan Cassava Varieties

The research activities were funded by National Commission for Science, Technology and Innovation (NACOSTI) 2015/2016 FY, laboratory reagents were funded by East African Agricultural Productivity Project (EAAPP) Abstract Cassava is an important crop in coastal Kenya commonly harvested at 12 months after planting but earlier during food shortages. There is limited information that addresses the effect of early harvesting on root quality especially for newly released varieties. Varieties Tajirika, Karembo and Kibanda Meno (roots) were harvested at different ages from Research Centres, studied for nutritional quality and hydrogen cyanide levels for safe utilization. Results showed significant (p < 0.05) interaction effect of varieties and crop age on studied nutrients. Karembo and Tajirika had peak dry matter of 43.42% and 41.42% respectively at 12 months while the peak for Kibanda Meno was 44.99% at 9 months. Mean starch content varied with variety; Karembo (91.3%), Kibanda Meno (93.4%), and Tajirika (85.5%). Karembo and Tajirika had peak carbohydrates at 12 months while the peak for Kibanda Meno was at 9 months. Vitamin C was highest at 6 months for Karembo (6.4 mg/100g) and Kibanda Meno (66 mg/100g). Tajirika had highest vitamin C (7.0 mg/100g) at 9 months. Iron was peak at 3 months for Karembo (3.63 mg/100g) and Tajirika (5.33 mg/100g) but at 9 months for Kibanda Meno (7.12 mg/100g). Peak Zinc was 2.1 mg/100g for Karembo at 6 months while for Kibanda Meno (1.94 mg/ 100g) and Tajirika (1.75mg /100g) at 12 months.  Hydrogen cyanide increased from 8.6 to 9.3 mg/kg in Karembo between 9 and 12 months, it decreased from 7.8 to 5.2 mg/kg and from 5.1 to 4.5 mg/kg in Tajirika and Kibanda Meno, respectively. Harvesting of cassava roots should be staggered across crop ages to maximize on peaks of different root nutrients and processing is important. Keywords: Cassava varieties, roots, nutrients, hydrogen cyanide, months after planting DOI: 10.7176/FSQM/88-04 Publication date:July 31st 201

Molecular characterization of ' Candidatus Liberibacter' species/strains causing huanglongbing disease of citrus in Kenya

This study was undertaken to characterize the alpha subgroup of the proteobacteria causing the huanglongbing (HLB) disease of citrus from three different ecological zones of Kenya namely the Lower highlands (LH2, LH3, 1800-1900 m above sea level); Upper midlands (UM3, UM4, 1390-1475m), Lower midlands (LM5, LM4, LM3 of 1290-1340-1390m), by isolation and sequencing DNA encoding the L10 and L12 ribosomal proteins and the intergenic region. A 7I6-basepair DNA fragment was amplified and sequenced and consisted of 536 basepairs of DNA encoding the L10 protein, 44 basepairs of DNA intergenic region and 136 basepairs of DNA that partially encodes the L12 protein. Sequences of rpL10/L12 protein genes from Kenyan strains were 98% and 81% similar to the South African ' Candidatus Liberibacter africanus strain Nelspruit' and the Asian 'Candidatus Liberibacter asiaticus' strains, respectively. The intergenic rDNA sequence of Kenyan strain from UM and LM showed 84% similarity with 'Candidatus L. africanus strain Nelspruit' and 50% similarity with 'Candidatus L. asiaticus' strain. However, the LH strain had an 11- basepairs deletion, while the LM4 had a 5- basepair deletion in the intergenic region compared to 'Candidatus L. africanus strain Nelspruit'. The L10 amino acid sequence was 100% homologous among HLB bacteria obtained from the agro-ecological zones in Kenya and the L10 protein sequence was also homologus to 'Candidatus L. africanus strain Nelspruit'. Nevertheless, the L10 amino acid sequence of 'Candidatus L. asiaticus' and the 'Candidatus L. africanus subsp. capensis' differed from the Kenyan strains by 18.36% and 11.82%, respectively. Phylogenetic analysis of both the L10/L12 rDNA sequences and the L10 amino acid sequences clustered the Kenyan strains of the 'Candidatus Liberibacter' species with members of alpha subdivision of proteobacteria

QUALITY AND SAFETY CHARACTERISTICS OF CASSAVA CRISPS SOLD IN URBAN KENYA

Cassava ( Manihot esculenta Crantz) crisps are increasingly popular in Kenya\u2019s urban areas. Crisps are popularly consumed as snacks outside homes and in-between meals. However, limited information on the quality and safety of the crisps is available in the country. This study sought to characterise the quality and safety in terms of cyanide levels of cassava crisps commercially traded in Mombasa and Nairobi areas in Kenya. Samples of six commercially traded crisp brands were collected in duplicates, from venders and supermarkets; and evaluated for moisture, oil, cyanide and sodium chloride contents. Product colour and texture were also evaluated. There were significant differences among brand contents of moisture (P=0.0001), oil (P<0.0001) and cyanide content (P=0.026). Levels of sodium chloride were, however, insignificant (P>0.07). Moisture content ranged from 4.3 to 6.77%, oil content 19.17 to 30.68%; and cyanide and salt contents ranged 13.5 to 32.24 ppb and 2.3 to 2.7%, respectively. There were no significant differences (P>0.57) in the texture, as well as in the yellowness (b*) parameter (P>0.137). On the other hand, significant differences were observed on colour. Moisture and cyanide levels exceeded the statutory limits.Le chips de manioc ( Manihot esculenta Crantz) deviant de plus en plus populaire dans les zones urbaines du Kenya. Les chips son generalemant consommes sous forme de gouter en dehors de la maison et au mileu de deux repas. Neanmoins, tres peu d\u2019informations sont disponibles sur la qualite et l\u2019hygienne des chips vendus au Kenya. Cette etude visait a faire le point de la qualite et de l\u2019hygienne en terme de quantite de cyanure du manioc dans les chips commercializes dans les villes de Mombasa et Nairobi au Kenya. Des echantillons de six marques de chips commercializes ont ete collectes chez des vendeurs et supermarches, et ont ete evalues pour leur taux d\u2019humidite, d\u2019huile, de cyanure et de chlorure de sodium. La couleur et la texture ont ete aussi evaluee. Des differences significatives ont ete observes dans les taux d\u2019humidite (P=0,0001), d\u2019huile (P<0,0001) et de cyanure (P=0,026) d\u2019une marque a une autre. Les taux de chlorure de sodium n\u2019etait pas significativement differents (P>0,07). les taux d\u2019humidite varient de 4,3 a 6,77%, ceux d\u2019huile de 19,17 a 30,68%; tandis que ceux de cyanure et de sel varient respectivement de 13,5 a 32,24 ppb et 2,3 a 2,7%. Aucune difference significative n\u2019etait observee dans la texture (P>0.57), ni dans l\u2019inde de teinte jaune (b*) (P>0.137). D\u2019autre part, des differences significatives ont ete observes au niveau des couleurs. Les taux d\u2019humidite et de cyanure depassaient les limites statutaires; d\u2019ou de potentiel dangers pour la sante des populations

MICROBIOLOGICAL SAFETY AND QUALITY OF DRIED CASSAVA CHIPS AND FLOUR SOLD IN THE NAIROBI AND COASTAL REGIONS OF KENYA

Cassava ( Manihot esculenta Crantz) is rich in carbohydrates and is the third most important source of calories, in the tropics. The handling and processing practices of cassava roots expose them to microbial contamination. The objective of this study was to assess the level of contamination of cassava products that are in markets so as to establish the safety for human consumption. Samples from Nairobi and Coastal region of Kenya were evaluated for: total count, Staphylococcus aureus , total coliforms, yeast and mould and E. coli to establish their safety and quality for human consumption. Results for dried cassava chips showed; TVC 5.16-8.04 log cfu g-1; 4.81-7.21 log cfu g-1, mould 1.00-3.86 log cfu g-1; 1.00-3.28 log cfu g-1 and Staphylococcus aureus 2.69-4.36 log cfu -1; 2.90-4.71 log cfu -1 for Nairobi and Coastal region respectively. Cassava flour was; TVC 5.66-7.67 log cfu g-1; 5.92-8.12 log cfu g-1, mould 1.00-6.73 log cfu g-1; 2.65-5.08 log cfu g-1, Staphylococcus aureus 3.77-5.79 log cfu g-1; 1.00-5.73 log cfu g-1, and coliforms 0-6.34; 2.00-6.27 log cfu g-1 for Nairobi and Coastal regions respectively. One sample tested positive for presence of E. coli. Eighty seven percent of cassava flour and 77% of dried cassava chips samples were confirmed for presence of Staphylococcus aureus. There was a significant (P<0.05) difference in the microbial counts among the dried cassava chips samples and the cassava flour samples from markets in Nairobi and Mombasa. Results indicate excessive manual and poor post-harvest handling practices of the products hence, their poor quality and non-safety for consumption.Manioc ( Manihot esculenta Crantz) est riche en hydrates de carbone et est la troisi\ue8me plus importante source de calories, sous les tropiques. Les pratiques de manipulation et de traitement des racines de manioc les exposent \ue0 la contamination microbienne. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer le niveau de contamination des produits de manioc qui sont sur les march\ue9s afin d\u2019\ue9tablir la s\ue9curit\ue9 pour la consommation humaine. Les \ue9chantillons provenant de Nairobi et de la r\ue9gion c\uf4ti\ue8re du Kenya ont \ue9t\ue9 \ue9valu\ue9s pour: nombre total, Staphylococcus aureus , coliformes totaux, levures et moisissures et E. coli pour \ue9tablir leur s\ue9curit\ue9 et de qualit\ue9 pour la consommation humaine. R\ue9sultats pour les cossettes de manioc s\ue9ch\ue9es ont montr\ue9; TVC de 5,16 \ue0 8,04 log ufc g-1; 4,81 \ue0 7,21 log ufc g-1, moule de 1,00 \ue0 3,86 log ufc g-1; 1,00 \ue0 3,28 log ufc g-1 et Staphylococcus aureus 2,69 \ue0 4,36 log ufc-1; 2,90 \ue0 4,71 log ufc-1 pour Nairobi et de la r\ue9gion c\uf4ti\ue8re, respectivement. La farine de manioc \ue9tait; TVC 5,66 \ue0 7,67 log ufc g-1; 5,92 \ue0 8,12 log ufc g-1, moule de 1,00 \ue0 6,73 log ufc g-1; 2,65 \ue0 5,08 log ufc g-1, Staphylococcus aureus 3,77 \ue0 5,79 log ufc g-1; 1,00 \ue0 5,73 log ufc g-1, et les coliformes 0 \ue0 6,34; 2.00-6.27 log ufc g-1 pour Nairobi et c\uf4ti\ue8res des r\ue9gions respectivement. Un \ue9chantillon a \ue9t\ue9 test\ue9 positif pour la pr\ue9sence de E. coli. Quatre-vingt-sept pour cent de farine de manioc et 77% des \ue9chantillons s\ue9ch\ue9s chips de manioc ont \ue9t\ue9 confirm\ue9es pour la pr\ue9sence de Staphylococcus aureus. Il y avait une diff\ue9rence significative (P <0,05) dans les comptes microbiens parmi les cossettes de manioc \ue9chantillons s\ue9ch\ue9s et les \ue9chantillons de farine de manioc en provenance des march\ue9s \ue0 Nairobi et Mombasa. Les r\ue9sultats indiquent manuelles et mauvaises pratiques excessives de manutention post-r\ue9colte des produits donc, leur mauvaise qualit\ue9 et non-s\ue9curit\ue9 pour la consommation

Possible influences of water loss and polyphenol oxidase activity on anthocyanin content and discoloration in fresh ripe strawberry (cv. Oso Grande) during storage at 1 degrees C

Fresh‘Oso Grande’strawberries wrapped in polyvinyl chloride stretch film lost 0.7% of their initial weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol oxidase (PPO) activity. Anthocyanin degradation and oxidation of soluble phenolic compounds, caused possibly by increased PPO activity as a result of water loss, contributed to the development of strawberry surface browning during storage. Proper handling to reduce water loss during postharvest operations should be used to maintain acceptable color of strawberries during shipping and retailing

Quality of carrots as affected by pre- and postharvest factors and processing

The aim of this review is to provide an update on factors contributing to quality of carrots, with special focus on the role of pre- and postharvest factors and processing. The genetic factor shows the highest impact on quality variables in carrots, causing a 7–11-fold difference between varieties in content of terpenes, β-carotene, magnesium, iron and phenolics as well as a 1–4-fold difference in falcarindiol, bitter taste and sweet taste. Climate-related factors may cause a difference of up to 20-fold for terpenes, 82% for total sugars and 30–40% for β-carotene, sweet taste and bitter taste. Organic farming in comparison with conventional farming has shown 70% higher levels for magnesium and 10% for iron. Low nitrogen fertilisation level may cause up to 100% increase in terpene content, minor increase in dry matter (+4 to +6%) and magnesium (+8%) and reduction in β-carotene content (−8 to −11%). Retail storage at room temperature causes the highest reduction in β-carotene (−70%) and ascorbic acid (−70%). Heat processing by boiling reduces shear force (−300 to −1000%) and crispiness (−67%) as well as content of phenolics (−150%), terpenes (−85%) and total carotenes (−20%) and increases the risk of furan accumulation. Sensory and chemical quality parameters of carrots are determined mainly by genetic and climate-related factors and to a minor extent by cultivation method. Retail temperature and storage atmosphere as well as heating procedure in processing have the highest impact in quality reduction. © 2013 Society of Chemical Industr