title: Aflatoxins, discolouration and insect damage in dried cowpea and pigeon pea in Malawi and the effectiveness of flotation/washing operation in eliminating the aflatoxins.
abstract: Aflatoxin contamination and biodeterioration were examined in 302 samples of dry cowpeas and pigeon peas that were randomly purchased from 9 districts of the Southern Region of Malawi during July and November 2015. Further, the impact of flotation/washing on aflatoxin levels on the pulses was elucidated. Aflatoxin analyses involved immunoaffinity column (IAC) clean-up and HPLC quantification with fluorescence detection (FLD) while legume biodeterioration assessments were done by visual inspection. Aflatoxins were frequently detected in cowpea (24%, max., 66 μg/kg) and pigeon pea (22%, max., 80 μg/kg) samples that were collected in the month of July. Lower aflatoxin incidence of 15% in cowpeas (max., 470 μg/kg) and 14% in pigeon peas (max., 377 μg/kg) was recorded in the November collection. Overall, aflatoxin levels were significantly higher in the pulses that were collected in November. However, there were no significant differences in the total aflatoxin (aflatoxin B1(AFB1) + AFB2+ AFG1+ AFG2) levels between the two types of pulses. Remarkably, in 76.2% of the aflatoxin positive cowpea and in 41.7% of the aflatoxin positive pigeon pea samples, aflatoxin G1concentration exceeded aflatoxin B1.Insect damage percentage averaged at 18.1 ± 18.2% (mean ± SD) in the cowpeas and 16.1 ± 19.4% in pigeon peas. Mean discolouration percentage (number of pulses) of the cowpeas and pigeon peas was found to be at 6.7 ± 4.9 and 8.7 ± 6.2%, respectively. Washing and discarding the buoyant fraction was highly efficient in reducing aflatoxin levels; only 5.2 ± 11.1% of the initial aflatoxin level was found in the cleaned samples. In conclusion, cowpeas and pigeon peas sold on the local market in Malawi may constitute a hazard especially if floatation/washing step is skipped.
authors.affiliation: Food Technology and Nutrition Group, Lilongwe University of Agriculture and Natural Resources (NRC campus), P.O. Box 143, Lilongwe, Malawi. alimbikani@gmail.com.
authors.forename: Limbikani
authors.initials: L
authors.lastname: Matumba
authors.affiliation: Department of Agricultural Research Services, Chitedze Research Station, P.O. Box 158, Lilongwe, Malawi.
authors.forename: Lazarus
authors.initials: L
authors.lastname: Singano
authors.affiliation: Department of Agricultural Research Services, Chitedze Research Station, P.O. Box 158, Lilongwe, Malawi.
authors.forename: Lawrent
authors.initials: L
authors.lastname: Pungulani
authors.affiliation: Food Technology and Nutrition Group, Lilongwe University of Agriculture and Natural Resources (NRC campus), P.O. Box 143, Lilongwe, Malawi.
authors.forename: Naomi
authors.initials: N
authors.lastname: Mvula
authors.affiliation: Department of Agricultural Research Services, Chitedze Research Station, P.O. Box 158, Lilongwe, Malawi.
authors.forename: Annie
authors.initials: A
authors.lastname: Matumba
authors.affiliation: Department of Agricultural Research Services, Chitedze Research Station, P.O. Box 158, Lilongwe, Malawi.
authors.forename: Charles
authors.initials: C
authors.lastname: Singano
authors.affiliation: Veterinary Sciences, Lilongwe University of Agriculture and Natural Resources (NRC campus), P.O. Box 143, Lilongwe, Malawi.
authors.forename: Grey
authors.initials: G
authors.lastname: Matita
mesh_terms: D000348:Aflatoxins / Q000032:analysis* / Q000302:isolation & purification; D036561:Cajanus / Q000033:anatomy & histology / Q000737:chemistry*; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D005470:Fluorometry; D005511:Food Handling / Q000379:methods*; D008295:Malawi; D009183:Mycotoxins / Q000032:analysis* / Q000302:isolation & purification; D012621:Seasons; D000070658:Vigna / Q000033:anatomy & histology / Q000737:chemistry*
chemical_list: D000348:Aflatoxins; D009183:Mycotoxins
keywords: Aflatoxin; Cowpeas; Decontamination; Discolouration; Floatation/washing; Insect damage; Pigeon pea