Optimization Research On Low-Temperature Drying Technology Of Cultured Pseudosciaena Crocea

Pseudosciaena crocea is a kind of drum fish, artificial breeding is successful in 1990s, then it becomes one of China's major cultured marine fish. However, cultured Pseudosciaena crocea's fat content is higher than the natural Pseudosciaena crocea, the high content of unsaturated fatty acids in the fat makes it more easily to oxidize. The traditional drying methods are room drying and tunnel drying, but the temperature of the two drying methods is high, which makes a high degree of oxidation. So low-temperature drying method can be used to avoid fat oxidation, and it becomes a effective way to reduce the fat oxidation. In addition, the proper use of antioxidants can not only maintain the original quality of Pseudosciaena crocea, especially can reduce the deterioration caused by fat oxidation, but also can extend the storage life of the products, it also can inhibit the softening and the flavor deterioration of meat, so it can keep the fish fresh. Although the domestic low-temperature drying equipment is exist, the study on the deep processing of the Pseudosciaena crocea and the optimization research on low-temperature drying technology of Pseudosciaena crocea have not been reported abroad.In this paper, low-temperature drying method was used to research the fat oxidation changes in the drying processing. The effects of different drying temperatures, time and humidities on the drying result of the Pseudosciaena crocea were investigated. Finally we get the best drying conditions for Pseudosciaena crocea.In this article we chose three kinds of anti-oxidants:Erythorbic Acid Monosodium Salt, TBHQ and Tea Polyphenols, we compared their antioxidant effect and ultimately chose the TBHQ. The effects of different concentration, immersing time and ratio of material to liquid on the drying result of the Pseudosciaena crocea were investigated, and we found the best condition. Then the low-temperature dried Pseudosciaena crocea were in cold storage, and we study the changes in quality during storage. The results are as follows:1. We analysis the basic components of the cultured Pseudosciaena crocea. The results are as follows:the content of crude protein is 12.40%; the content of crude fat is 12.09%; the content of 1.02%; the content of water is 73.91%; the content of the others is 0.58%.2. To establish an low-temperature drying method of Pseudosciaena crocea. The single factor test and the Response Surface Method were used to optimize the drying conditions. The effects of different drying temperatures, time and humidities on the drying result of the Pseudosciaena crocea were investigated. The Acid Value,peroxide value and thiobarbituric acid value (TBA) were taken as evaluating markers in the single factor test, and the thiobarbituric acid value was taken as evaluating markers in the Response Surface Method. The result was as follows:The optimum drying conditions were drying 7.5h under the temperature 24℃and humidity 36%. Above selected condition may be the best way to dry Pseudosciaena crocea.3. In this paper, we contrast the anti-oxidant effect of the Erythorbic Acid Monosodium Salt, TBHQ and Tea Polyphenols, experimental results show that TBHQ can play a good antioxidant activity at a low concentration, then we determined the best conditions through orthogonal experiment. The results are as follows:the concentration of TBHQ is 0.06 %; the immersing time is 60min and the ratio of material to liquid is 1:1.4. The compared terms of the appearance and color, acid value, peroxide value and TBA value were studied among Pseudosciaena crocea with three different technological processions, which were hot-air drying process, low-temperature drying process and combining the antioxidants in the low-temperature drying process. The results were as follows:the products showed obviously better according to all the above items'results through the low-temperature drying process. And as the extent of fat oxidation, adding the TBHQ could be more effective in the dying processing.5. In this chapter, we take cultured Pseudosciaena crocea adding TBHQ and not adding TBHQ as research objects, compare their changes and differences in acid value, peroxide value, TBA value and total number of bacterial. The results showed that:the acid value, peroxide value and TBA value increased as the time increased, acid value changed slowly, peroxide value and TBA values significantly accelerated after 12 weeks. The total number of bacterial changed slowly in first 8 weeks, then have a accelerated growth as time increased.