The microbiota of dried traditional vegetables produced in the Sudan Savannah and Guinea Savannah agro-ecological zones of Ghana

Abstract

Traditional vegetables are an important article of diet of the ethnic groups from the northern parts of Ghana. Such vegetables are preserved by sundrying and consumed throughout the year. These are mostly leafy vegetables and include Hibiscus sabdariffa (sorrel), Bomtax costatum (kapok), Ceratotheca sesamoides, Adansonia digitata, and Hibiscus esculentus (okro), respectively called by the local names shure or sobolo, daala, yaudo, kuuka, and okro (common name). The dominant microbiota of ten common dried traditional vegetables were investigated by enumerating total bacteria, yeasts and moulds, lactic acid bacteria, Bacillus species and coliform bacteria. Isolates were characterized by colony and cell morphology, and by biochemical tests. The water activities of all the dried vegetables were between 0.513 and 0.539. Shuri and bisap had low pH values, between 2.6 and 2.71, whilst the other vegetables had relatively higher pH values ranging from 5.21 to 6.39. Moulds and Bacillus spp. dominated the biota of all the dried vegetables although lactic acid bacteria and coliforms were also isolated in most of these products. Bacterial counts of the dried vegetables were between 103 and 107 CFU/g. Aspergillus spp, Rhizopus spp, Eurotium spp, Penicillium spp and Aureobasidium spp. were the major genera of moulds identified in the dried vegetables. The dominant Bacillus species in all samples was Bacillus subtilis except in the okro pods and leaves where Bacillus cereus was dominant. The dominant lactic acid bacteria were Lactobacillus plantarum and pediococci. Escherichia coli was not detected in any of the dried vegetables, however, Enterobacter aerogenes was detected in most of the samples. Because of the high microbial levels in the dried vegetables, it is recommended that handling procedures be improved by primarily sanitizing the fresh vegetables prior to drying in solar dryers