Characterization of Bacillus spp. from some spices and assessment of their spoilage potential in various traditional Ethiopian sauces

Abstract

One hundred twenty five samples from five different Ethiopian sauce spices were examined for the incidence and level of contamination of Bacillus species. The spices consisted of fenugreek (Trigenella foenum-graecum), black cumin (Nigella sativa), Ethiopian caraway (Trachyspermum ammi), ginger (Zingiber officinale) and korarim cardamon (Aframomum corrorima). Spore counts ranged from log 1.63 cfu(g)-1 in cumin to log 8.32 cfu(g)-1 in ginger. Of the 781 Bacillus isolates obtained, the most frequently encountered species was Bacillus pumilus (43.7%) followed by B. subtilis (16.6%), B. circulans (11.2%), B. licheniformis (8.2%) and B. cereus (4.9%). The B. pumilus and B. subtilis isolates were active in proteolysis and lipolysis, whereas B. cereus isolates were more proteolytic and amylolytic. All test strains grew well in three different types of traditional Ethiopian sauces, but growth was markedly lower in vegetable-based sauces. Spoilage was manifested only in the form of foul odour, and was noted faster in legume-based sauces (< 24 hours) than in meat-based (24B36 hours) and vegetable-based (48B60 hours) sauces.


SINET: Ethiopian Journal of Science Vol. 23, No. 1 (June 2000), pp. 87-101



Key words/phrases: Bacillus spp., Ethiopia, sauces, spices, spoilage