Efficacy of Lippia multiflora (Verbenaceae) and Hyptis suaveolens (Lamiaceae) Leaves on Sanitary Quality during the Storage of Maize Grain (Zea mays L.) from Cote D’ivoire

Abstract

The aim of this study was to monitor the sanitary quality during the storage of maize grains for 9 months in polypropylene bags containing leaves of Lippia multiflora and Hyptis suaveolens. It was carried out in the villages of Timbé and Soko respectively in the departments of Katiola and Bondoukou of Cote d'Ivoire in June 2014 to February 2015. The parameters determined were water activity, total aflatoxins, aflatoxin B1, ochratoxin A, zearalenone and fuminosin B1. The water activity was measured using a Hygrometer with the McCormick method and the mycotoxin assay (AFS, AFB1, OTA, ZEA, FB1) was performed using a high performance liquid chromatography with a fluorescence detector. The batches treated with L. multiflora and H. suaveolens recorded the best values compared to the control independently of the study site and of the parameter studied. L. multiflora had a much more marked biopesticidal effect than the leaves of H. suaveolens and the mixture of the two leaves. Indeed, the water activities of the grains varied between 0.80 +/- 0.01 and 0.95 +/- 0.01 for the control batches and the treated batches. For total aflatoxins, the treated batches had maximum levels of 65.48 +/- 0.07 μg/kg and 113.93 +/- 1.23 μg/kg respectively in Timbé and Soko in the departments of Katiola and Bondoukou, while those of the control groups reached 335.98 +/- 2.64 μg/kg and 549.74 +/- 2.81 μg/kg at 9 months of storage. For AFB1, OTA, ZEA and FB1, the treated batches had maximum levels of 4.26 +/- 0.01 μg/kg, 4.87 +/- 0.02 μg/kg, 35.16 +/- 0.06 μg/g and 89.26 +/- 0.48 μg/kg respectively at Katiola and 10.26 +/- 0.11 μg/kg, 7.51 +/- 0.08 μg/kg, 89.25 +/- 0.89 μg/kg and 621.26 +/- 4.73 μg/kg in Bondoukou at 7 months of storage. The recommended standards was respectively 5 μg/kg, 5 μg/kg, 200 μg/kg et 2000 μg/kg for AFB1, OTA, ZEA et FB1 in maize grains. The control batches have very high contents exceeding the recommended standards yet at 4 months of storage. These results indicate that the treatment of maize with leaves of L. multiflora and H. suaveolens inhibits the activity of insects and molds and allows preserving the quality of the grains with a remanence of up to 7 months. This inexpensive and easy-to-use treatment should be popularized among farmers.