Study Of Technology Of Liquid Smoked Tilapia Fillets And Changes In Quality Of Products At Stored Different Conditions

Tilapia is one of the most popular fish in the world because its strong productivity, fast growth, mixed food, strong resistance to disease and high output compared to other cultured fish, and has"fish of the 21st century"laudatory name. Now, the quantity and consumption of tilapia increase year by year, but the lever of technology is low, the variety of products are single, and the add-value of products are cheap, the main products involve frozen whole tilapia, frozen tilapia fillets, fresh fillets, canned tilapia food and fishmeal products, so, deep processing of tilapia is necessary, it will impulse the industrial development of tilapia.At present, the technology of liquid smoked tilapia still at pilot study in the world, and china has no report. In this paper, the results of study of technology of liquid smoked tilapia fillets and changes in quality of products at stored different conditions are as follows:1. Firstly, A high performance liquid chromatographic method using fluorescence detection was developed for separation and determination of Bap. Linearity was verified in range from 0.1 to 20μg/L, the correlation coefficient was better than 0.9999. the limit of detection (LOD) in Bap standard was 0.01μg/L , the limit of detection (LOD) in samples was 0.1μg/kg. The analytes were extracted by Triton X-100 and SPE-Florisil, the recoveries were79.6%-83.4% , RSD: 4.41%-4.99%.Compared with Soxhlet method and saponification method, this method was better. Chromatographic conditions were optimized. The column used was Aglient ZORBAX-SXB C-18 ( 5μm ,250 mm×4.6 mm i.d. ) ,with acetonitrile-water(80:20,V:V) as mobile phase. The excitation and emission wavelengths were 294nm and 404nm. This method was sensitive, accurate, simple, and rapid. 2. Secondly, the objective of this study was to investigate the smoking technology of tilapia fillets treated with liquid smoke flavourings. Through the single factor test and the orthogonal experiment, adopted the sensory analysis to confirm the technics conditions of liquid smoked tilapia fillets with spurting and combined dipping. The optimal brining concentration, the brining time, the immersion of liquid smoke flavouring concentration and time, the flux of liquid smoking, the time of liquid smoking, and the time of drying were 15%, 60min, 25%, 5min, 4L/h, 20min and 60min, respectively. Compared with spurting technology and dipping technology, this technology was better, under which the product quality traits, microorganism, the texture variables, the colour variables volatile flavouring compositions and the concentration of Bap were also investigated, and the results provided important theoretical base for evaluating the smoking tilapia fillets.3. Lastly, the storage characteristics of liquid smoked tilapia fillets were studied. The samples were packed in polythene bags sealed and in polypropylene bags vacuumed, than stored at 5℃,15℃and 25℃. The shelf lives of samples stored at different conditions were investigated by studying the growth of microbial flora and changes of TVB-N, pH, colour and texture during storage. The indicators of spoilage were accurately described. The result of experiment showed: at the end of storage, in the polythene packaging at 5℃, the polythene and vacuum packaging at 15℃and 25℃, microbiology growth maximum density was approximately 106-107 CFU/g, TVB-N was about between 29.8～32.9mg/100g. In the vacuum packaging at 5℃, the samples were not deteriorated at all, microbiology growth maximum density was approximately 104-105 CFU/g, TVB-N was about 15.7mg/100g. No matter at what temperature and packaging stored , pH was between 5.3～5.8; the changes of L* and b* was almost sameness, were between 36～50 and 10～30, respectively; a* was between 8～11, but the change was not disciplinarian; the changes of texture was similar, except in the vacuum packaging at 5℃. The shelf life of samples were >150,150,32,20,11 and 4 days, respectively. No matter at what temperature stored, mould was the predominant factor to cause deterioration in the polythene packaging; where as in the vacuum packaging the samples were deteriorated mainly due to enzymatic reaction. However, the two deterioration factors could be effectively inhibited in the vacuum packaging at 5℃storage, and thus the shelf-life was obviously prolonged.