Efficacy of Onion (Allium Cepa L.) and Garlic (Allium Sativum L.) Juice as Meat Preservatives
Njue, L. G.
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Meat and meat products are vehicle foods for five million cases of food borne illness. Pathogens such as Bacillus subtilis, Salmonella typhi, Escherichia coli, Listeria monocytogenes, Clostridium perfringens and Staphylococcus aureus are the primary causative agents of illness caused by contaminated meat. This study was carried out between September 2007 and April 2008 to investigate efficacy of onion (Allium cepa L.) and garlic (Allium sativum L.) Juice as meat preservatives. It also sought to determine the effect of garlic, onion juice and combinations on shelf life of meat. The efficacy of equivalent quantities of garlic and onion juice, sodium nitrite and their combinations, were investigated against Bacillus subtilis (ATCC 6633), Salmonella typhi (ATCC 2202) Staphylococcus aureus (ATCC 20591), Escherichia coli (Standard Culture 25922). The results indicated that garlic was significantly, more effective (P < 0.05) in inhibition of microorganisms than all the other test treatments at 0.2 of meat. The inhibition zones of the various preservatives added followed a decreasing order as; garlic (mean, 21.25mm), garlic + onion (12.69mm), garlic + sodium nitrite (I1.88mm), onion (8.50mm), garlic + onion + sodium nitrite (7.44mm), sodium nitrite (7.06mm), onion + sodium nitrite (6.75mm) and Distilled water as a control (6.00mm). The findings from this study also showed that, the number of bacteria significantly increased with an increase in the sizes of the meat used in the experiment. Based on the presence of Salmonella typhi, the shelf life of meat when preserved using garlic alone was detected to be at the 6th hour. With onion, it was the 2°d hour. However meat preserved using sodium nitrite had no shelf life since all the colony forming units were more than 4.30 Loglo cfu/0.2g of meat, when meat is considered to be safe for consumption. Based on the presence of S. aureus, the shelf life of meat when preserved using pure garlic was completely eliminated the 12th hour as well as for B. subtilis. With onion, it was the 2°d hour. However meat preserved using sodium nitrite had a shelf life of 6 hours. Shelf life of meat based on the presence of E. coli was one hour for garlic and onion whereas, sodium nitrite was not an effective preservative as microbial counts were more than 4.30 Loglo cfu/0.2g of meat. Shelf life of meat based on the presence of B. subtilis was 8th hour for Onion and 6 hours for sodium nitrite. However there was a complete elimination of B. subtilis by Garlic on the 12th hour. These results are an important reference that confirms the use of Garlic as meat preservative.