| Decapterus maruadsi, carangidae, decapterus, is of importance inexpensive red flesh fish in Fujian province. In order to enrich its products mix, improve its economic value and make up the shortage of traditional material of frozen surimi, the basic characters of decapterus maraudsi were analyzed, effects of ordinary muscle, dark muscle, mixed muscle on gel properties of decapterus maruadsi surimi were studied, their optimal washing conditions were confirmed, and the cryoprotectant recipe of decapterus maruadsi surimi of the mixed muscle was optimized. The main research results were listing as following:(1) The basic chemical composition of decapterus maruadsi was analyzed and the results showed that its overall muscle content was up to 51.1%, and the ordinary muscle content was 34.4%, its protein 19.7%, fat 2.8%, moisture 75.1%, ash 1.1%, and the dark muscle content was 16.7%, its protein 15.4%, fat 4.1%, moisture 72.1%, ash 1.4%. Compared with dark muscle, the ordinary muscle’s protein, moisture content were higher, and fat, ash content were lower.(2) The frozen storage properties of decapterus maruadsi were analyzed and the results showed that the dissolved load of salt soluble protein and Ca2+-ATPase activity declined quickly at the early stage, declined steadily in the latter period. The dissolved load of salt soluble protein of ordinary muscle, mixed muscle, dark muscle were 35.45%,29.37%,29.02% of chilled decapterus maraudsi’s, and the Ca2+-ATPase activity were 25.86%,20.73%,17.12% of chilled decapterus maraudsi’s after frozen storage for six week. The results showed that the protein freeze denaturalization of decapterus maraudsi was quick, and the measures were necessary to take to restrain that.(3) The gel properties of decapterus maruadsi surimi were analyzed and the results showed that the pH of decapterus maruadsi surimi gel of ordinary muscle, mixed muscle and dark muscle were 6.55,6.48,6.32, water holding capacity were 95.89%,95.57%,93.62%, and whiteness were 46.53,44.86,40.43, separately. Texture properties of decapterus maruadsi surimi gel of ordinary muscle was best: hardness, cohesiveness, springiness, chewiness were 5.12,0.78,1.18,4.58, separately; hardness, cohesiveness, springiness、chewiness of decapterus maruadsi surimi gel of mixed muscle were separately 4.46,0.72,1.01,3.36; decapterus maruadsi surimi gel of dark muscle didn’t display the springiness and chewiness, and it’s hardness and cohesiveness were just separately 2.78,0.42. The results showed that some measures needed to be taken to use dark muscle of decapterus maruadsi as material of frozen surimi solely.(4) Effect of washing conditions and fish composition on the quality of decapterus maruadsi surimi were analyzed and the results showed that the optimum washing conditions of decapterus maruadsi were washing with 0.2% salt water to ordinary muscle,0.3% alkali brine to mixed muscle and 0.4% alkali brine to dark muscle. With the optimum washing conditions, the pH, water holding capacity, whiteness, hardness, cohesiveness, springiness, chewiness of decapterus maruadsi surimi gel of ordinary muscle were 6.68,94.89%,48.29,6.18,0.89,1.52,5.61, separately, that of decapterus maruadsi surimi gel of mixed muscle were 7.01, 94.68%,46.13,5.43,0.78,1.24,4.40, separately, the pH, water holding capacity, whiteness, hardness, cohesiveness of decapterus maruadsi surimi gel of dark muscle were 6.92,92.80%,42.54,3.83,0.46. With washing processing, the quality of decapterus maruadsi surimi gel of dark muscle was worst, and it didn’t display the springiness and chewiness, so it wasn’t fit to use dark muscle of decapterus maruadsi as material of frozen surimi solely.(5) The rheological properties showed that the quality of decapterus maruadsi surimi produced by ordinary muscle was better than mixed muscle, and dark muscle was the worst. The result of temperature scanning suggested the gel process of surimi had three phases:the first phase appeared before 46℃, the second stage, the phase of modori, appeared in 46～52℃, the third phase appeared after 52℃, and protein began to form the final gel.(6) Compound sodium phosphate was optimized to improve water holding capacity of decapterus maruadsi surimi of mixed muscle, measuring with cooking lose. The equation of regression model, Y=28.48-2.79X1-0.89X2-0.70X3+0.60X1X2+ 0.52X2X3+0.54X12-0.97X22, was established, to predict the effect of sodium tripolyphosphate (X1), sodium pyrophosphate (X2) and sodium hexametaphosphate (X3) on the cooking loss of decapterus maruadsi surimi of mixed muscle. The results showed that effectiveness of compound sodium phosphate on water holding capacity was best,with the proportion of tripolyphosphate: sodium pyrophosphate: sodium hexametaphosphate=5:2:3. Under this condition, the cooking loss of decapterus maruadsi surimi of mixed muscle was 24.60%, and lowered 10.24%, comparing with decapterus maruadsi surimi of mixed muscle without compound sodium phosphate.7. Effectiveness of compound antifreeze on decapterus maruadsi surimi of mixed muscle was analyzed. The results showed that effectiveness of compound antifreeze was best, with 4% sorbitol,4% polydextrose and 0.4% compound sodium phosphate. Under this condition, decapterus maruadsi surimi of mixed muscle frozen for six weeks, the dissolved load of salt soluble protein and Ca2+-ATPase activity of decapterus maruadsi surimi of mixed muscle was 31.31mg/g, 0.0883μmolPi/min/mgPro and increased 54.85%,69.48%, separately, comparing with that without compound antifreeze. |
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