| Aquatic products are widely welcomed by consumers because of their characteristics of delicious meat,low fat content and rich nutrition.However,as an important source of protein,the existence of fishy smell problem has seriously affected the whole industrial chain of aquaculture,processing,sales and consumption,and has long plagued the aquaculture related industries.Therefore,carrying out related research on fishy substances,improving the fishy smell of aquatic products and improving the quality of aquatic products has gradually become a hot research topic in the aquatic industry in recent years.Taking this as a starting point,this experiment studied the two main substances that cause the fishy smell of aquatic products: geosmin(GSM)and 2-dimethylisoborphenol(2-MIB)from three aspects,namely,the establishment of analysis method,the exploration of their change characteristics and reasons in water and the content distribution in fish.The main contents are as follows:1.The contents of GSM and 2-MIB in aquaculture water and aquatic products were determined by headspace solid phase microextraction combined with gas chromatography-tandem mass spectrometry(SPME-GC-MS).In this experiment,four parameters of carrier gas flow rate,microwave power,distillation time and collection method were optimized in the pretreatment process of microwave distillation of aquatic products.Finally,the optimal experimental conditions were determined as follows:carrier gas flow rate of 60 m L/min,microwave power of 400 W,distillation time of6 min and constant volume of 250 m L for distillation collection and quantification.The average recoveries of GSM and 2-MIB in water and aquatic samples were 45.28 %-49.92 % and 82.15 %-87.36 %,respectively.The results showed that the average concentration of GSM was 19.58 ng/L in the water samples of aquaculture ponds and aquatic products in Wuxi area.The mean concentration of 2-MIB was 58.29 ng/L.In aquatic products,only GSM was detected,and the mean concentration was 0.61 μg/kg.2.In this experiment,the content of geosmin(GSM)and 2-methylisoborneol(2-MIB)and harvested aquatic products were detected from May to October,taking the aquaculture water and aquatic products in Wuxi as the research object,and the relationship between the change of their content and the cultivation time and the types of aquatic products was analyzed.The results showed that the concentrations of GSM and 2-MIB in the aquaculture water changed with the cultivation time,among which the concentrations of shrimp and crabs reached the highest in July and August,while the concentrations of Tilapia and Oreochromis reached the highest in May at the beginning,and the mean concentrations of GSM and 2-MIB exceeded the odor threshold.In addition,the concentrations of GSM and 2-MIB in the aquaculture water bodies of different types of aquatic products vary due to different aquaculture times.In May,the concentration of Tilapia aquaculture water bodies is significantly higher than that of shrimp and crab,while in October,the concentration of Tilapia aquaculture water bodies is significantly higher than that of shrimp and crab and fish.However,only GSM was detected in aquatic products,which was different from the content of GSM in water.By calculating the biological concentration coefficient,it was found that the four major fishes had the strongest ability to enrich GSM,which was consistent with the relatively low GSM content in water.3.In order to explore the distribution of the odor substances in different tissues of tilapia and provide dietary suggestions for solving the odor problem of tilapia,the contents of GSM and 2-MIB in intestinal contents,blood,liver and muscle tissues of tilapia were compared.The results showed that the content of GSM in intestinal contents was significantly higher than that in liver,blood and muscle(P < 0.05),while that in liver was significantly higher than that in blood and muscle(P < 0.05).In a word,except for the edible part,the contribution rate of fishy smell was the highest in intestinal contents,followed by liver and blood.Therefore,the distribution of fishy substances in Tilapia varies with different tissues.In the processing of tilapia food,we can fully remove the inedible and high content of fishy substances in tissues,so as to achieve the purpose of reducing fishy substances in aquatic products.In short,this study explores the key issue of fishy substances in aquatic products,hoping to improve the traditional impression of the whole aquatic products in the hearts of consumers,effectively improve the economic value of aquatic products,and provide help for the development of China’s aquatic industry to high quality and high standards,which has certain theoretical significance and practical application value. |
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