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

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

Reduction Of Nitrates, Oxalates And Phenols In Fermented Solar-Dried Stored Cowpea (Vigna Unguiculata L.) Leaf Vegetables

This study was conducted to determine the effect of fermentation, solar drying and storage duration on the levels of anti-nutrients: nitrates, oxalates and phenols, in cowpea leaf vegetables. The rationale was reduction of the anti-nutrients. Reduction of nutritional stress factors in plant foods increases bioavailability of nutrients, hence improving their quality as foodstuffs. The cowpea leaves were purchased from the local markets, sorted to remove blemished leaves and foreign materials, washed in running tap water. Then, the vegetables were drained and divided into three batches of 16 kg each. One batch was heat-treated in hot water for 3 minutes and then cooled to ambient temperatures, drained and solar-dried. The second portion was acidified to a pH of 3.8, heat-treated, and solar-dried. The third portion was fermented for 21 days, heat-treated, and solar-dried. The three batches of vegetables were spread at different times on drying trays at the rate of 4 kg/m2 and dried in a solar drier to an approximate moisture content of 10%. The dried vegetables were packaged in either polyethylene bags or Kraft paper bags and stored for three months at 18°C, 22°- 26°C or 32°C. Fermentation, heat-treatment and drying of vegetables led to significant (P < 0.05) reduction in nitrates compared to fresh cowpea leaves, but the reduction in oxalates and phenols was not significant. Storage for three months led to significant (P < 0.05) reduction in nitrates in the fermented sample compared to the other samples. The acidified sample had significantly (P < 0.05) higher levels of phenols after three months of storage than the other samples. Samples stored at 18oC had higher levels of oxalates and phenols but lower levels of nitrates, compared to those stored at higher temperatures. Packaging material had no significant effect on the level of nitrates, oxalates and phenols. Data obtained in this study reveal a novel technique for the reduction of anti-nutrients in cowpea leaf vegetables, namely; fermentation followed by solar drying. The increased acceptability of these fermented-dried vegetables would help rural communities in providing better foodstuff with fewer anti-nutrients, thus alleviating micronutrient malnutrition. This novel long-term storage technology can greatly help to deal with the issue of seasonality and will increase food security, especially during the dry season

Effect of lactoperoxidase-thiocyanate-hydrogen peroxide system and storage temperature on keeping quality of raw camel milk

The use of lactoperoxidase system (LP-system) in temporary preservation of raw milk has been found useful particularly in places where refrigeration is not feasible. The activity of this system, however, varies from species to species and there are no reports on its effect in camel milk. This study was conducted to investigate the preservative effect of the LP-system on raw camel milk. Camel milk samples were obtained from Kajiado, Isiolo and Nanyuki districts, Kenya and LP-system was activated by the addition of hydrogen peroxide (H2O2) to a concentration of 8.5ppm Changes in total viable bacterial counts and titratable acidity in LP-activated and nonactivated (control) camel milk were then determined during storage at 10, 20 and 30oC. The combined effect of increasing levels of thiocyanate (NaSCN) and hydrogen peroxide (H2O2 ) on antibacterial activity of LP-system in raw camel milk was investigated at 30ºC by monitoring changes in total viable bacterial counts and lactic acid development in raw camel milk at NaSCN:H2O2 concentrations ratios of 0, 10:10, 20:20, 30:30 and 40:40ppms. Natural concentration of thiocyanate occurring in the camel milk from the three districts ranged from 9.7 to 36.4 mg/l and respective districts were significantly different (

Effect Of Lactoperoxidase-Thiocyanate-Hydrogen Peroxide System And Storage Temperature On Keeping Quality Of Raw Camel Milk

The use of lactoperoxidase system (LP-system) in temporary preservation of raw milk has been found useful particularly in places where refrigeration is not feasible. The activity of this system, however, varies from species to species and there are no reports on its effect in camel milk. This study was conducted to investigate the preservative effect of the LP-system on raw camel milk. Camel milk samples were obtained from Kajiado, Isiolo and Nanyuki districts, Kenya and LP-system was activated by the addition of hydrogen peroxide (H2O2) to a concentration of 8.5ppm Changes in total viable bacterial counts and titratable acidity in LP-activated and non-activated (control) camel milk were then determined during storage at 10, 20 and 30°C. The combined effect of increasing levels of thiocyanate (NaSCN) and hydrogen peroxide (H2O2 ) on antibacterial activity of LP-system in raw camel milk was investigated at 30°C by monitoring changes in total viable bacterial counts and lactic acid development in raw camel milk at NaSCN:H2O2 concentrations ratios of 0, 10:10, 20:20, 30:30 and 40:40ppms. Natural concentration of thiocyanate occurring in the camel milk from the three districts ranged from 9.7 to 36.4 mg/l and respective districts were significantly different (p<0.05) from each other. No additional amount of thiocyanate was, therefore, used to activate the LP-system. Microbial growth was halted for 15, 17 and 76 hrs at 30, 20 and 10°C, respectively by activation of the LP-system in raw camel milk at 8.5ppm. Viable counts increased significantly (p<0.05) during storage at 10, 20, 30°C conditions. Shelflife was extended by 19 hrs during storage at 10 and 20°C and 4 hours at 30°C. Increased levels of NaSCN and H2O2 significantly (p<0.05)delayed bacterial growth and lactic acid production. Shelflife of the camel milk as determined by lactic acid production was 4 hrs for control and increased to 6, 12, 16 and 16 hrs for NaSCN: H2O2 ratios of 10:10, 20:20, 30:30 and 40:40 ppm, respectively. The present investigation shows that by activating the LP-System, it is possible to extend the storage period of raw camel milk and that the effect of the LP-System on the microbes varies with temperature of storage and levels of thiocyanate and H2O2. Practical application would be achieved by controlled activation using commercial LP-system kits for pooled camel milk at collection centers and combined with cooling facilities where possible for further extension of keeping quality