| The production of the freshwater fish of our country takes up67%of total output in the world, however, only10%that of freshwater fish were deep processed. The main products are mainly concentrated to the traditional aquatic products, such as dry products, minced fillet products, curing food, canned products and parts of protein feedstuffs. The added value of fish products is not high, especially the ratio of deep processed products of the freshwater is much lower. This study takes Aristichthys nobilis of "four major Chinese carps as the research material for fish protein extraction, fishy smell removing, emulsibility and stability and the spray-drying of fish protein liquid. The aim of this study is to produce a kind of fish protein powder product that can be instant dissolved for ready to eat. The main research results are as follows:1. Taking Aristichthys nobilis meat as raw material, the salt lixiviation at low temperature process method was used for extracting fish protein, and studied the influences of some factors such as solid-liquid ratio (fish:buffer solution), salt concentration dissolving time, and temperature on the lixiviation ratio of fish protein and the the sensory quality. Experimental results showed that the optimum parameters were:solid-liquid ratio of1:9, salt concentration of0.3mol/L, dissolving time of2h at temperature5℃. On these conditions the lixiviation rate of Aristichthys nobilis’s crude protein was91.2%, however, the protein liquid products have fishy smell.2. The fish protein liquid of salt lixiviation method was dealed to remove the fishy smell using activated carbon, β-CD, and active yeast. We valued the fishy smell effect of different materials by TBA index, and the result showed that the optimum conditions of activated carbon to remove fishy smell were3%of activated carbon and incubated for60min at temperature40℃, the TBA value reaches to0.205, and the carp’s protein liquid product smell a little fishy after conduction under these condition. The TBA value reaches to0.108after conduction by β-CD under optimum parameters3%of β-CD and incubated for60min at temperature70℃, and the carp’s protein liquid still have a little fishy smell. The optimum parameters of active yeast to remove fishy smell were4%of active yeast powder followed by incubation at35℃for60min, and the TBA value reaches to0.160, and the carp’s protein liquid product have little fishy smell. Three methods of treatments were compared and the result showed that the best method of removing fishy smell was that of active yeast treatment. We analyzed the changes of sorts and relative contents of flavor substances in the protein liquid treated with active yeast by GC-MS method, and the results showed that the types and relative content of aldehydes were declined obviously in the treated products, and acid increased correspondingly, which indicated that the mechanism of active yeast to remove fishy smell may be the aldehydes in liquid protein was oxidized to the corresponding acid.3. The kinds of the stabilizer and the emulsifier to improve quality of liquid protein product were studied in this paper. We adopted singe factor experiment and orthogonal design to obtain the optimum parameters of treatment. It was concluded that0.05%of xanthan,0.1%of sodium alginate,0.025%of sodium caseinate,0.05%of glyceryli monostearici were added, and the R value of liguid protein reached to0.920, and sensory evaluation and viscosity also achieved the best value.4. We studied the process of spray-drying of the carp’s protein liquid. The optimum conditions were obtained through single factor experiment and response surface analysis. The results showed that the optimum parameters to dry the carp’s protein liquid were18.75%of input concentration,176.66℃of entering air temp,5.75L/h of flow rate. Under these conditions, the yielding rate of the carp’s protein reached to83.87%, and the R value of the stability of fish protein liquid came up to0.890. We concluded that the effect of spray-drying on the stability of fish protein liquid was not obvious by comparing R value before and after spary-drying process. These results suggested that the processing technology of spray-drying developed in this study was feasible at production fishprotein powder... |
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