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Published on: August 18, 2015
Toxicity and Sorbate Sensitivity of Molds Isolated from Surplus Commodity Cheeses 1
Wei-Yun J Tsai1, Michael B Liewen1, Lloyd B Bullerman1
1Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska 68583-0919.
Abstract:
A total of 263 mold isolates were obtained from moldy surplus cheese released from government storage for distribution in the surplus commodity food distribution program in 1984. All of the molds belonged to the genus Penicillium , and consisted of four species, P. roqueforti (176), P. cyclopium (46), P. viridicatum (32) and P. crustosum (9). About 10% of the isolates were capable of producing known mycotoxins on laboratory media. The mycotoxins detected were patulin, penicillic acid and ochratoxin. Patulin was detected most often followed by penicillic acid and ochratoxin. When tested in chicken embryos, 10.1% of the isolates were toxic (causing 50% mortality or more) when grown on cheese, and 29.7% of the isolates were toxic when grown on rice. There was no correlation between having the ability to produce known mycotoxins and toxicity to chicken embryos. None of the isolates when grown on cheese contained any mutagenic activity in the Salmonella mutagenesis (Ames) test. The percentage of isolates showing a high or medium degree of resistance to sorbate were 77, 45, 3.6 and 0 at sorbate concentrations of 0.30, 0.45, 0.60 and 0.90%, respectively. There was no apparent relationship between sorbate resistance and toxigenic properties of the molds.
Insights
Mold isolates from surplus cheese included four Penicillium species. Some produced mycotoxins like patulin, but no mutagenic activity was found in Ames tests.
Area of Science:
- Food Microbiology
- Mycology
- Food Safety
Background:
- Surplus cheese from government storage may harbor mold contaminants.
- Understanding mold populations and their potential toxicity is crucial for food safety.
Purpose of the Study:
- To identify and characterize mold species in surplus cheese.
- To assess the mycotoxin production and toxicity of these mold isolates.
Main Methods:
- Isolation and identification of mold species from cheese.
- Detection of mycotoxins (patulin, penicillic acid, ochratoxin) using laboratory media.
- Toxicity testing in chicken embryos and mutagenicity testing (Salmonella mutagenesis/Ames test).
- Assessment of sorbate resistance in mold isolates.
Main Results:
- 263 mold isolates identified, all belonging to the genus Penicillium (P. roqueforti, P. cyclopium, P. viridicatum, P. crustosum).
- Approximately 10% of isolates produced mycotoxins; patulin was most common.
- Toxicity observed in chicken embryos (10.1% on cheese, 29.7% on rice), with no correlation to mycotoxin production.
- No mutagenic activity detected in the Ames test when grown on cheese.
- Significant variation in sorbate resistance among isolates, unrelated to toxigenicity.
Conclusions:
- The study identified Penicillium species in surplus cheese, with some exhibiting mycotoxin production and toxicity.
- No mutagenic potential was found in the Ames test for these isolates on cheese.
- Sorbate resistance varied, but did not correlate with toxic properties.
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