高密度CO2处理虾肌球蛋白形成凝胶的临界浓度与凝胶强度

Least gelation concentration and gel strength of myosin from Litopenaeus vannamei induced by dense phase carbon dioxide

为了探讨高密度CO_2(dense phase carbon dioxide,DPCD)诱导蛋白质形成凝胶的机制,以凡纳滨对虾肌球蛋白为研究对象,研究了DPCD处理压强、温度和时间对虾肌球蛋白形成凝胶的临界浓度和对虾肉糜凝胶强度的影响。研究结果表明:DPCD处理压强和温度对虾肌球蛋白溶液形成凝胶的临界浓度有显著影响,处理时间对肌球蛋白溶液形成凝胶的临界浓度无显著影响,但增加处理时间,可以形成更加紧实的凝胶。在40℃和5~30 MPa时虾肌球蛋白溶液形成凝胶的临界质量浓度为14 mg/mL,在50℃和5、10 MPa时虾肌球蛋白溶液形成凝胶的临界质量浓度为12 mg/mL,在50℃和15~30 MPa时虾肌球蛋白溶液形成凝胶的临界质量浓度为11 mg/mL,在60℃和5~30 MPa时虾肌球蛋白溶液形成凝胶的临界质量浓度为10 mg/mL。DPCD处理压强和温度对虾肉糜的凝胶强度也具有显著影响(P<0.05),且随着压强增加和温度升高,虾肉糜凝胶强度呈增加趋势(P<0.05);在50℃和25 MPa下处理虾肉糜20 min,形成的凝胶强度较好,达到了(14.28±0.57)N·mm。DPCD处理温度越高,虾肌球蛋白形成凝胶的临界浓度就越低,而虾肉糜形成凝胶的强度越高;DPCD处理压强越高,虽然对虾肌球蛋白形成凝胶的临界浓度影响较小,但能使虾肌球蛋白和虾肉糜形成凝胶的强度增加。从分析中还可以推断,DPCD低压(5~10 MPa)诱导虾肉糜形成凝胶主要是热效应的作用,DPCD较高压强(>10 MPa)诱导虾肉糜形成凝胶是热和CO_2分子效应的共同作用。研究结果为进一步阐明DPCD诱导蛋白质形成凝胶的机制提供了基础数据。

Dense phase carbon dioxide（DPCD）, also known as high pressure carbon dioxide（HPCD）, is a promising non-thermal food processing technology. DPCD was originally applied to inactivate microorganisms and enzymes in food. However, many researchers found that DPCD could induce some proteins associated with microorganism metabolism inactivation and the change of the secondary structure of enzyme protein when the food was treated by DPCD. Meanwhile, they also found that DPCD could induce some food protein inactivation. DPCD could not only improve the functional properties of protein but also induce protein to form gel. Our previous study results showed that DPCD could induce shrimp surimi to form gel and the microstructure and texture of gel were better than those induced by heat. Myosin is the key protein of forming gel for animal meat. Protein concentration is an important factor affecting myosin to form gel. Generally, the higher the protein concentration, the greater the ability of forming gel, and the better the texture of gel was. In order to clarify the mechanism of shrimp surimi forming gel induced by DPCD, we used myosin fromLitopenaeus vannamei as the subject and researched the effects of DPCD treatment pressure, temperature and time on the least gelation concentration of myosin forming gel and gel strength of shrimp surimi. Firstly, myosin was extracted using the method of reference and the myosin solution with the concentration of 1-14 mg/mL was treated by DPCD, and the least gelation concentration of myosin forming gel was determined. Secondly, shrimp surimi gel was prepared by DPCD and the gel strength was determined using a TMS-PRO texture instrument. The study results were showed as follows： Treatment pressure and temperature of DPCD had a significant effect on the least gelation concentration of myosin forming gel. Though treatment time of DPCD had no significant effect on the least gelation concentration, myosin could form the firm gel by extending treatment time. The least gelation concentration of myosin forming gel was 14 mg/mL at 40 ℃ under the pressure of 5-30 MPa, 12 mg/mL at 50 ℃ under 5-10 MPa, 11 mg/mL at 50 ℃ under 15-30 MPa, and 10 mg/mL at 60 ℃ under 5-30 MPa. Treatment pressure and temperature of DPCD had a significant effect on gel strength of shrimp surimi（P〈0.05）, and gel strength of shrimp surimi increased with the treatment pressure and temperature increasing（P〈0.05）. The gel strength of shrimp surimi induced by DPCD was（14.28±0.57） N·mm at 50 ℃ under 25 MPa for 20 min. The higher the temperature of DPCD treatment, the lower the least gelation concentration of myosin was, and the higher the shrimp surimi gel strength was. The pressure of DPCD treatment had a little effect on the least gelation concentration of myosin, but the higher pressure could increase the gel strength of myosin and shrimp surimi. When DPCD induced the shrimp surimi to form gel at the lower pressure of 5-10 MPa, the heating effect was main and the molecular effect of carbon dioxide was weak. However, when DPCD induced the shrimp surimi to form gel at the higher pressure of above 10 MPa, the heating effect and the molecular effect of carbon dioxide were cooperative. The results will provide the basic data for clarifying the mechanism of forming gel induced by DPCD.