Inhibition of Listeria innocua in Hummus by a Combination of Nisin and Citric Acid
Authors: Al-Holy, M.1; Al-Qadiri, H.2; Lin, M.2; Rasco, B.2
Source: Journal of Food Protection®, Volume 69, Number 6, June 2006 , pp. 1322-1327(6)
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Abstract:
The effect of nisin or citric acid or combinations of these two inhibitors on the inactivation of a cocktail of three Listeria innocua strains was investigated in a model brain heart infusion (BHI) broth and hummus (chickpea dip). In BHI broth, citric acid had a limited ability to inhibit L. innocua growth. Nisin initially reduced L. innocua concentrations by about 3 log cycles; however, L. innocua reached concentrations similar to those of the control after 5 days at 22°C. In combination, the effects of 500 IU/ml nisin and 0.2% citric acid were synergistic and resulted in complete elimination of L. innocua in the BHI broth. The inhibition of L. innocua by nisin (500 or 1,000 IU/g), citric acid (0.1, 0.2, or 0.3%), or their combinations also was evaluated in hummus. Citric acid alone did not affect L. innocua growth or the aerobic bacterial plate count. A combination of 1,000 IU/g nisin and 0.3% citric acid was somewhat effective (∼1.5-log reduction) in controlling the concentration of L. innocua and the aerobic plate count for up to 6 days. This combination also may be useful, in addition to proper hygienic practices, for minimizing the growth of the pathogen Listeria monocytogenes in hummus.Document Type: Research article
Affiliations: 1: Department of Clinical Nutrition and Dietetics, Hashemite University, Zarqa, Jordan 2: Department of Food Science and Human Nutrition, Box 646376, Washington State University, Pullman, Washington 99164-6376, USA
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