Selected heavy metals content and microbial quality in locally processed Locust beans samples retailed In Ibadan, Nigeria

Abstract

The influence of residual contaminant levels in processing water on the total heavy metal contents and microbial loads in fermented locust bean seeds popularly used as traditional spice was investigated. Twenty five domestically-prepared, fresh locust beans products (iru – Yoruba), produced in Ibadan, Nigeria were selected. Random samples of processing water and iru samples directly procured from each of 25 different local processors were respectively analyzed for microbial loads, total lead (Pb), cadmium (Cd), and arsenic (As) contents. Appropriate laboratory microbiological procedures for microbial assay and standard AOAC analytical methods for total heavy metals’ contents were used to achieve this. The results showed that statistically significant differences were between the Mean total heavy metals contents (MTHMC) in mg/kg of the untreated water types with order of contamination as; Stream (0.77) ˃ Spring (0.50) ˃ Well 0.39) ˃ Borehole (0.27). The MTHMC value in mg/kg for borehole water processed locust beans samples was a minimum of 0.14±0.04, and a maximum of 0.213±0.04 for stream water processed iru samples. The results of microbial analysis showed that ranges for TPC, TVC and TFC were respectively 7.43-7.92 log10cfu/g, 5.00-6.54 log10cfu/g and 6.56-6.91 log10cfu/g. The positive influence of processing water-purity on levels of heavy metals’ contaminants in the final products was confirmed. The use of locust beans as a seasoning, often in little quantities suggests contaminants may not be hazardous to consumers on the long term.