Introduction. A comparative study of antinutrients and heavy metals in the peels of five improved varieties of plantain and banana hybrids was investigated. Our aim was to provide information on plantain and banana peels that may circumvent huge losses during fruit processing by converting waste into wealth and health. Materials and methods. Four new plantain hybrids developed at the IITA, Nigeria, named PITA 14, PITA 17, PITA 24 and PITA 26, one cooking banana hybrid (BITA 3) and an African plantain landrace, Agbagba, were investigated. Antinutrient and heavy metal contents of the dried peels from the different cultivars were determined and the data were statistically analyzed. Results and discussion. The plantain hybrid PITA 14 differed significantly from other cultivars in saponin, tannin and oxalate. A significant difference was observed between PITA 17 in phytate compared with other cultivars. Cyanogenic glucosides found in PITA 17, PITA 26 and BITA 3 differed significantly from the values obtained in other cultivars. Both BITA 3 and Agbagba are significantly different from other cultivars in phenolic content, while PITA 24 and Agbagba differed significantly from other cultivars in lead. PITA 24 peels differed significantly from other cultivars in cadmium, but no significant difference was found among the different Musa varieties in mercury. Conclusion. In spite of the antinutritional properties ascribed to the various constituents investigated, the levels found in the peels of new Musa hybrids suggest that new varieties might not constitute a health hazard when ingested. Plantain and banana peels may be converted into livestock feeds, which will eventually provide protein and other nutrients to humans from consumption of meat and other products derived from the animals.

The aim of the present study was to determine, by a field experiment, whether the seasonal variations in the levels of cyanide and rutin in the phloem, secondary compounds potentially implicated in cassava resistance to the cassava mealybug (Phenaccocus manihoti), could be influenced by different kinds of soil fertilisation (manure, NPK, KC1, lime, mulch). It was found that mean cyanide and rutin contents varied significantly with season, soil treatments and infestation. For each soil treatment, the highest contents of these compounds on uninfested plants was registered in the main dry season (Jul-Aug) for cyanide and at the end of the dry season (Jul-Aug) and beginning of the rainy season (Oct-Nov) for rutin. The infestation factor induced an increase in cyanide and rutin contents for 43 combinations of period and soil treatment among 48 in total. For cyanide content (phagostimulant function in mealybug), this increase appeared significant at the end of the rainy season (Apr-May) and in the main dry season (Jul-Aug) for control and KC1 fertilisation. For rutin content (an unfavourable substance for the insect) significant increase was induced by infestation in each period for manure and mulch and especially in the main dry season (Jul-Aug) and at the beginning of the rainy season (Oct-Nov) for other soil treatments. Concerning the seasonal variations in the level of rutin, these results showed that mulch and manure are the best fertilisers to increase cassava resistance against mealybugs.