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Chlorous acid and chlorine dioxide inhibit growth of L. monocytogenes in caviar.

Sturgeon caviar products are prepared by curing them with salt, but they generally receive no heat treatment. The salt concentration and storage temperature are the key factors harnessed to preserve and make caviar products safe. Unlike meat products, it is difficult to pasteurize caviar without damaging its texture.

Scientists at Washington State University evaluated the antimicrobial effect of chlorous acid against L. monocytogenes and endogeneous microflora in caviar held at 3 C and 7 C during one month of storage. In experiments, a cocktail of L. monocytogenes (ATCC 19114, 7644 and 19113) was inoculated onto caviar. The inoculated caviar was dipped into an antimicrobial solution composed of sterile water, 250 ppm of chlorous acid, 100 ppm of chlorine dioxide and 200 ppm of peroxyacetic acid for 30 minutes. The inoculated caviar also was treated with 250 ppm of chlorous acid for 1, 5, 10 and 20 minutes.

After the treatments, the antimicrobial solution was drained, and the product air-dried under asceptic conditions for 30 minutes. The researchers packed the caviar in sealed plastic containers. The containers were stored at 3 C or 7 C for 30 days. L. monocytogenes were recovered by plating onto modified Oxford media. Aerobic microflora were recovered onto plate count agar. The scientists recovered samples at 0, 5, 10, 20 and 30 days after they had treated them.

Treating the caviar with chlorous acid and chlorine dioxide inhibited the growth of L. monocytogenes in caviar samples at 3 C and 7 C. However, sterile water and peroxyacetic acid were not effective in controlling L. monocytogenes. Chlorine dioxide was more effective in controlling total aerobic microbes in caviar than the other antimicrobial agents. It was necessary to dip caviar into chlorous acid for more than 20 minutes to prevent the growth of L. monocytogenes at 7 C.

Further information. Barbara Rasco, Department of Food Science and Human Nutrition, Washington State University, FSHN 106, P.O. Box 646376, Pullman, WA 99164; phone: 509-335-1858; fax: 509-335-4815; email: rasco@wsu.edu.
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Publication:Microbial Update International
Date:Oct 1, 2008
Words:331
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