FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

In this study, the effects of different capture locations, fishing net operations and operating hours on the freshness of raw Sergestid shrimps (Sergia lucens), and the effects of different drying methods for producing commercial products on the quality of raw Sergestid shrimps were explored. It is expected that the results of the study can be used as a reference for catching and processing raw Sergestid shrimps, thus improving the economic efficiency of such operations. Firstly, raw Sergestid shrimps caught at different working times and with different operating modes off of Yilan and Tungkang were collected and analyzed. The results showed that the Volatile basic nitrogen (VBN) value of the first trawl fishing boats for Yilan was 14.42 mg% higher than that of the first trawl fishing boats for Tungkang (10.43 mg%, 11.75 mg%, and 7.67 mg%). The VBN value analysis results for the different working times of the Yilan fishing boats showed a significant difference (p < 0.05) between the first work time (14.42 mg%) and the second work time (7.83 mg%), results which were consistent with those for three Tungkang boats. These results may have been related to the length of time required for each net to leave the surface of the water, the designs of the nets and the differences among the refrigeration systems and management systems used. In addition, the VBN value of the third trawl had a lower trend than those of the first two trawls, indicating that the raw Sergestid shrimps caught by fishing vessels with shorter return times can have better freshness quality and exhibit lower VBN values. In addition, commercially dried Sergestid shrimp products were randomly collected, and the effects of different processing methods on the quality were compared. The total plate count (TPC) values for the freshness of the raw Sergestid shrimps caught off of Yilan and Tungkang were 3.93–4.71 log CFU/g and 3.99–5.5 log CFU/g, respectively. The TPC values were 4.43–5.8 log CFU/g and 3.62-5.48 log CFU/g for the commercial dried products made from shrimp caught off of Yilan and Tungkang. The coliforms of the raw and commercial dried product samples were both <3 logMPN/g, and E. coli was not detected (-). All the products were in compliance with the relevant regulations. In addition, the average contents of cadmium, lead, and mercury in the fresh raw Sergestid shrimps caught off of Tungkang were 0.09, 0.03, and 0.03 ppm, respectively, while they were 0.06, 0.03, and 0.08 ppm, respectively, for the Yilan shrimp. The average contents of cadmium, lead, and mercury in the commercial dry products made from shrimp caught off of Tungkang were 0.11, 0.01, and 0.02 ppm, respectively, while they were 0.04, 0.03, and 0.03 ppm, respectively for the Yilan products. All the products were in compliance with the relevant regulations. In addition, the results showed for randomly purchased samples showed that the quality levels of the dry products sold in Yilan City were quite different, whereas the quality levels of the samples sold in Tungkang were consistent. Dry products cannot be traced back to the raw materials used to produce them because the sampling was randomly purchased. With respect to the differences in the quality levels of the dried products sold in the Yilan area and Tungkang area, it was speculated that they may have been caused by the differences in the time required for the fresh Sergestid shrimp to reach the processing factories and the heating methods used. Based on the research results, it is suggested that boats catching Sergestid shrimps off of Yilan should strengthen the methods they use for keeping the shrimps fresh while on the boats according to their current operating modes, so that the quality of the Sergestid shrimps will be more stable, which would in turn enhance the boats’ industrial competitiveness.