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Title: Characterization of Aerobic Sporeformers from Some Ethiopian Sauce Spices and their Spoilage Potential on Various sauces
???metadata.dc.contributor.*???: Dr. Mogessie Ashenafi
Moges, Feleke
Issue Date: Jun-1998
Publisher: Addis Ababa University
Abstract: One hundred twenty five samples from five different spices namely, Fenugreek (Trigenella foeman-graecum), ‘abish’; Black kumin (Nigella sativa), 'tikur azmud'; Ethiopian caraway (Trachyspermun ammi), nech azmud'; Ginger (Zingiber officinale), 'zingibel' and Korarima cardamom (Aframomum 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 cfu/g) was noted in ginger and this was not significantly different within samples (C.V., <10%). Although black kumin yielded the smallest average count of spores (log 1.63 cfu/g), the counts, in 13 of the 25 samples was below detectable levels (< log 1 cfu/g), resulting quite significant variation within samples (C.V., 117%). The most frequently isolated aerobic sporeformers were Bacillus pumilus (43.7%), B. subtilis (16.6%), B. circulans (11.2%), B. licheniformis (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 active in proteolysis and lipolysis, but amylolysis activity was negative in all isolates. B. subtilis isolates were more proteolytic than lipolysis and amylolysis, while B. cereus showed lower lipolytic activity than proteolytic and amylolytic activity. The growth pattern and spoilage potential of B. pumilus, 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. pumilus 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
Description: A Thesis submitted in (partial) fulfillment for the Degree of Master of Science in Biology
Appears in Collections:Thesis - Biology

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