| Symlectoteuthis oualaniensis in the South China Sea was commonly known as red squid, it had hard meat and heavy odor, and always received less attention. But the resource survey in recent years showed that its annual catch amounted was 147-195 million tons and it had great potential for development. Currently the domestic and international study on Symlectoteuthis oualaniensis was less, so the white and delicious Loligo duvauceli was as a reference in this paper, the characteristics of nutrition, protein and texture from Symlectoteuthis oualaniensis were analyzed and compared, to provid theoretical basis for its processing and utilization. The main results are as follows:1. The nutritional compositions of the two kinds of squid was analyzed and evaluated, the results showed that the mass fraction of moisture, crude protein, crude fat, ash, total sugar in the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis were 82.68%, 15.72%, 0.27%, 1.05%, 0.61% and 81.83%, 16.46%, 0.30%, 1.03%, 0.32%, respectively. On dry basis, the mass fraction of crude protein were 90.76% and 90.58% in the cephalopodium and mantles muscle, respectively, higher than that of Loligo duvauceli. The mass fractions of crude fat were 1.56% and 1.63%, respectively, lower than that of Loligo duvauceli. The first limited amino acid in the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis were valine, the amino acids score values were 85, 76, respectively. The mass fractions of unsaturated fatty acids in the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis were high up 68%, slightly higher than that of Loligo duvauceli. Compared with Loligo duvauceli, DHA was rich in the Symplectoteuthis oualaniensis. Symplectoteuthis oualaniensis was rich of Mg and Zn. The results show that the Symlectoteuthis oualaniensis was a kind of marine resource with high protein, low fat, rich mineral content.2. The protein composition and properties of the two kinds of squid were studied, the results showed that the mass fraction of water-soluble protein(WSP), salt soluble protein(SSP)and insoluble protein(ISP)component accounted for 19.01%, 52.21%, 13.23% and 10.83%, 58.68%, 10.03% of total protein in the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis, respectively. The mass fraction of SSP in the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis was higher than that of Loligo duvauceli. The essential amino acids content in WSP and SSP in the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis accounted for 40% of total amino acid, had little difference with that of Loligo duvauceli. SDS-PAGE pattern showed that the molecular weight distribution of WSP, SSP and ISP were 14~200 KDa,29~200 KDa and 29~200 KDa, respectively, and were similar to that of Loligo duvauceli. As demonstrated by DSC, the denaturation temperature of WSP, SSP and ISP from the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis were 64.02 ℃, 58.04 ℃, 68.91 and 81.93 ℃ ℃, 62.18 ℃, 68.54 ℃, respectively, and were lower than of Loligo duvauceli. The solubility of WSP and SSP from the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis reached minimumat pH 3 and pH 5, respectively. The solubility of SSP from the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis had maximum when the NaCl concentration were 1.0mol/L and 0.5mol/L.3. The chapter analyzed the effect of different heat treatments on the texture of the cephalopodium and mantles muscle from the two kinds of squid, the results showed that the heat treatment at 40 ℃ had little effect on the two kinds of squid. Heat treatment at 80 ℃, 90 ℃ and 100 ℃ can reduce the hardness and increase the flexibility of the two kinds of squid, and the hardness and flexibility from the cephalopodium and mantles muscle of Symplectoteuthis oualaniensis were higher than that of Loligo duvauceli. From the result of microstructure of electron microscope scanning, the membrane structure from the cephalopodium of Symplectoteuthis oualaniensis and the cephalopodium and mantles muscle of Loligo duvauceli were destroyed at 80 ℃, and obvious phenomenon of granulation were occurred. While the mantles muscle of Symplectoteuthis oualaniensis didn’t appear the phenomenon. From the result of the rheology, the changes of the G ’, G " and tanδ curve of the muscle from the two kinds of squid heated at 40 ℃ had little difference with that of untreated, the initiation of G ’, G " of the muscle heated at 80 ℃, 90 ℃, 100 ℃ increased, and the G ’, G " and tanδ of the muscle had little changes in the temperature scanning. The salt soluble protein content of the meat heated at 80 ℃ for 5 min changed little in the mantles muscle of the two kinds of squid, and the salt soluble protein heated for 7 min were near to complete degeneration in the cephalopodium of the two kinds of squid.4. The effect of Ca++ concentration in the rinse water, TGase addition amount and heating conditions on the gel properties of the surimi of the mantles muscle in the Symplectoteuthis oualaniensis. The results showed that salt soluble protein content was the highest in the surimi when concentrations of CaCl2 was 0.1%(w/v) in the rinse water, the gel strength of the surimi under this conditions was 2.48 times of that with water rinsing. When the surimi was added 1.0% TGase, the gel strength of the surimi was in the maximum 1.31 times of that without TGase, and the water loss rate was the lowest. The experimental results showed that the gel of the two section heating method was better than that of one section heating method. When the heating method was that firstly heating at 50℃for 30 min, and then heating at 90 ℃ for 30 min, the water loss rate of the gel was the lowest, that was 9.76%. And the gel grade was B, which wass higher than that of C with one section heating method. The optimum conditions of the mantles muscle from Symplectoteuthis oualaniensis to gel were as followed: they were rinsing with 0.1% CaCl2, 1.0% TGase was added to the surimi to grind, then use the two heating method. The surimi gel had high gel strength and low water loss rate.In summary, Sthenoteuthis oualaniensis was the aquatic products with high protein, high minerals, low fat, balanced nutrition. It had high salt soluble protein content, and was a good raw material for surimi, and should be reasonable development and application. |
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