The Reasons And Controlling Measures For Fake Positive Sign Of DSP In Oyster Products

DSP was inspected frequently from export oyster products, however, we found that those oyster products were negative in DSP test, which were still in raw materials and semi-manufactured goods. The key factor due to the fake positive signs for DSP test was that the free fatty acids which produced in the process of oysters'storage. The results showed that the mackerel and salmon of fake negative sign to DSP also could kill the small mouse's; in which the content of the free fatty acids in mackerel and salmon stored for two years was 38.5 times high than that in early period of storage. This result proves our primary conclusion about the fake positive sign for DSP.Our researches found that the conditions of storage, respectively the temperature and the time, affect the quantity and toxicity of free fatty acids in the products of oyster. The longer the products were stored, the more poisonous would be to mouse. But, the content of the free fatty acids of oyster products would be decreased when the temperature of storage was lower.According to the content changes of free fatty acids and the practical technology, the oyster products would be safe under the conditions of the temperature -18℃within 4 months or -25℃within 12 months. To control the risk of free fatty acids poisonous, we suggest that oyster products should be stored under the temperature of -25℃.