PERSISTENCE OF ACTIVE COMPOUNDS OF ESSENTIAL OILS OF CLAUSENA ANISATA (RUTACEAE) AND PLECTRANTHUS GLANDULOSUS (LABIATEAE) USED AS INSECTICIDES ON MAIZE GRAINS AND FLOUR

ABSTRACT Maize occupies an important place in the resolution of food insecurity problems in the sub-Saharan region of Africa. However due to poor post-harvest technologies, more than 35% of annual crop yield is often lost during storage as a consequence of insect attack. While chemical pesticides constitute an efficient tool for reducing these losses, current excessive usage runs the risk of modifying the quality and safety of foods produced from these grains. The use of essential oils of plant origin for grain storage has been advocated as a non invasive method with limited or no effect on the quality and safety of the grains or their products. This study was carried out as an evidence of bioactivity of two essential oils of Clausena anisata (Willd.) Hook and Plectranthus glandulosus Hook F. against adults of Tribolium castaneum Herbst and Sitophilus zeamais Motschulsky, which are two important stored product insect pests in Northern Cameroon. Because of the low persistence of the insecticidal activities of these plants, their essential oils to achieve a complete protection of the stored products must be applied at frequent delays. The present investigation focuses on the occurrence of residues of these oils on treated maize grain and flour. The doses of crude essential oils used to treat adults of S. zeamais and T. castaneum in a contact and inhalation process were their LD 99 s. After the evaluation of their insecticidal activity the persistence of each essential oil was observed every 2 days till 14 days. After the disappearance of their insecticidal activities, essential oil was re-extracted and their residual compounds were identified from treated grain and flour. The major compounds of C. anisata are, estragole, α-humulene, germacrene D and (E)-nerolidol. In P. glandulosus they are: fenchone, α-terpinolene and piperitenone oxide. After 14 days, only 64.24% of compounds of C. anisata were recovered on treated flour and 55.16% on grains. Concerning P. glandulosus, 48.94% was recovered on grains and 61.23% on flour

Drying Kinetics, Physico-chemical and Nutritional Characteristics of "Kindimu", a Fermented Milk-Based-Sorghum-Flour

"Kindimu", a fermented milk-based cereal foods made by sun drying a mixture of fermented milk and cereal flour is a common flour ingredient in the central African region. A study was carried out to evaluate the effect of processing methods on the drying behaviour, functional and nutritional quality of such a food prepared from sorghum flour and fermented milk. A mixture of 1 part sorghum flour (germinated or non - germinated) and the 2 part (w/w) on fermented milk was coated on aluminium trays to a depth of 5mm and dried at 50, 65 or 80°C. Results obtained indicated that a simple mass transfer equation Ln [(C-C*)/(Co-C*)]= -(K/L)t can be used to model the drying behaviour of the fermented milk -sorghum flour mixtures. The magnitude of mass transfer coefficient K, increased with drying temperature and the germination of sorghum. Germination and addition of milk increased the in vitro protein digestibility of sorghum flour by 19.03%, protein solubility by 11.5% and available lysine content by an average of 3.04% and reduced the phytate content by 30%. The water absorption capacity of flours was equally reduced by an average of 4%

The effect of cooking with kanwa alkaline salt on the chemical composition of black beans (Phaseolus vulgaris)

International audienc

PEER REVIEWED ARTICLE No 5 - EFFECT OF PROCESSING AND PRESERVATION METHODS ON VITAMIN C AND TOTAL CAROTENOID LEVELS OF SOME VERNONIA (BITTER LEAF) SPECIES

Vernonia is one of the leafy vegetables that can be used in an attempt to alleviate the problem of micronutrient malnutrition, prominent in tropical Africa. Commonly known as Ndole or Bitterleaf in most Central and West African countries, it is one of the most widely consumed leafy vegetable in Cameroon. Though eaten by a large proportion of the population, cultivation is limited to the southern parts of the country and mostly in the rainy season. In order to ensure availability in nongrowing areas or seasons, the vegetable is usually processed and preserved. Processing and preservation methods used are thought to influence the nutrient content of these vegetables. The study was aimed at determining the effects of processing and preservation methods on vitamin C and total carotenoid levels of some species of Vernonia (V.amygdalina , V.calvoana var. bitter , V.colorata and V.calvoana var. non bitter ) consumed in Cameroon. The processing methods were squeeze-washing, boiling and squeeze-washing with 0N, 1N and 2N concentrations of natron. The methods of preservation were sun drying, oven drying at different temperatures (45, 60 and 75°C) and freezing for 0, 10, 30 60 and 120 days. Results show that these leafy vegetables were good sources of vitamin C and total carotenoid. Vitamin C values vary from 137.5±3.3 in V. calvoana non bitter to 197.5 ± 3.5mg/100g in V. colorata, while total carotenoid levels range from 30.0 ± 1.0 in V. amygdalina to 41.5±0.9mg/100g in V. colorata for the raw samples. Greater losses of both vitamins were observed for the bitter species. Drying caused significant losses, especially in Vitamin C. The best temperature for drying the vegetables to preserve carotenoids and vitamin C was at 45°C, whereas sun drying and oven drying at 75°C caused the highest losses. Freezing for up to ten days had no significant influence on total carotenoids and vitamin C levels. Comparatively, squeezewashing proved to be the best processing method that ensured minimum loss of both vitamins

Influence of technological treatments on bacterial communities in tilapia (Oreochromis niloticus) as determined by 16S rDNA fingerprinting using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)

Food quality and safety are major concern among consumers throughout the world in the context of globalization. Hence, the origin and the history of a food item are of prime interest when food quality is questioned. Precise determination of contamination source relies on the use of efficient and reliable methods. This study was carried out to assess the microbial ecology of fish upon technological treatments using 16S rDNA polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting. Samples of tilapia from Montpellier (South-east of France) and Yagoua (far north of Cameroon) were used for this purpose. The technological treatments applied on fillets were marinade, drying, smoking and deep-freezing. When the 16S rDNA profiles were analysed by multivariate analysis, distinct microbial communities were detected. The band profiles of fish bacteria after each treatment were different and specific. Technological treatments applied on fillets from Montpellier did not have an effect on the biological markers present on the fillets. These bands could be used as specific markers for this region. One of the treatments, the marinade applied on the samples of Yagoua induced the disappearance of some bands on the DGGE profile. In spite of treatment applied on samples, it is possible to recover the geographical origin by using DNA of the bacterial community in fish even if it was treated