Characterization of Aerobic Sporeformers From Some Ethiopian Sauce Spices and Their Spoilage Potential on Various Sauces
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Date
1998-06
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Addis Ababa University
Abstract
One hundred twenty five samples from five different spices namely, Fenugreek (Trigenella
joenulll-graecum), 'abish'; Black kumin (Nigella sativa), 'tikur azmud'; Ethiopian caraway
(Trachyspermllln alllllli), 'nech azmud'; Ginger (Zingiber officinale), 'zingibel' and Korarima
cardamom (Aji'atnolllulIl corrorima), 'korarima' were examined for the incidence and level of
contamination by Bacillus species A total of seven hundred eighty one isolates of Bacillus species were isolated and identified. The
highest average spore count (log 8.32 cfulg ) was noted in ginger and this was not significantly
different within samples (C.Y., <10%). Although black kumin yielded the smallest average count
of spores (log 1.63 cfulg), the counts, in 13 of the 25 samples was below detectable levels « log
1 cfulg), resulting quite significant variation within samples (C.Y., 117%). The most frequently
isolated aerobic sporeformers were Bacillus plllnilus (43.7%), B. sllbtilis (16.6%), B. circuians
(11.2%), B. lichenifonnis (8.2%) and B. cereus (4.9%). B. pumilus was most important in ginger
and korarima than the other spices tested.
The proteolytic, lipolytic and amylolytic activities of B. pumilus, B. subtilis and B. cereus were
assessed. The B. pumilus isolates were a-c--ti-v-e.. -i-n- proteolysis and lipolysis, but amylolysis activity -.-----.---~--.--.------.- .. ---.. - - -- -- . - - .-- .. _._- ------~-.-.
was negative in all isolates. B. subtilis isolates were more proteolytic than lipolysis and
------------------ ---- --' •••• -. -- --- • ---- _ T. _ T' - ••• _. -- --- -- - •• ". _ , _____ • '. ___ --__ ._' -_ •• -- -.---.-- • ..-''''
amylolysis, while B. cereus showed lower lipolytic activity than proteolytic and amylolytic
activity.
The growth pattern and spoilage potential of B. pUlIlilus, B. subtilis and B. cereus isolated from
the above mentioned spices were tested on legume-based, meat-based and vegetable-based
sauces. The growth pattern of B. plimillis followed almost similar growth pattern in all sauces. B.
subtilis showed a sharp increament of growth between 6h and 12h in legume-based and meatbased
sauces. For the B. cereus the highest growth was observed at 18h in legume-based and
meat-based sauces. However, growth rate in was low in all cases.
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Biology