| In this paper,the quality changes of Takifugu Rubripes under different storage conditions were studied.The total plate counts,pH value,moisture content,water holding capacity,juice loss rate,volatile base nitrogen(TVB-N),thiobarbituric acid(TBARS),texture,tissue microstructure were mensurated to study effects of cold storage(4?),micro-frozen(-3?)and freeze(-25?)on the quality of Takifugu Rubripes.Apparent color,odor composition and moisture mobility were studied to discuss the effects of different freezing methods(-40?,liquid nitrogen,-80?)on the quality of Takifugu Rubripes storing at-20? conditions.The research conclusions are as follows:1.Study on the quality changes of Takifugu Rubripes under cold storage conditions at 4?.Under the conditions of cold storage at 4?,the pH value of Takifugu Rubripes first decreased and then increased.The pH reached a minimum of 6.05 on the 4th day of storage,and the pH rose to 6.69 on the 8th day.The moisture content,juice loss rate,TVB-N,TBARS and the total plate counts showed an upward trend,their values were 84.33 g/100g,4.23 g/100g,7.23 mg/100g,0.434 mg/100g respectively on the 8th day.The total plate counts increased to 5.56 lg(CFU/g)on the 5th day,which exceeded the limit of 5.0 lg(CFU/g)by the national standards for aquatic products.Water holding capacity,hardness,springiness,chewiness,gumminess,cohesiveness,and resilience showed a downward trend.Their values were 71.80 g/100g,4.36 gf,0.257,-23.88 gf,-24.126 gf,-2.693,0.248 on the 8th day.The microstructure observation results of transverse and longitudinal sections of the back muscles showed that the gaps in and between cells gradually increased during cold storage.The quality of Takifugu Rubripes tended to deteriorate during cold storage,and the best edible time is 1?5d.2.Study on the quality changes of Takifugu Rubripes under micro-frozen storage conditions at-3?.During the micro-frozen storage at-3?,the pH value of Takifugu Rubripes first decreased and then increased.The pH reached the lowest value at 6.10 on the 10th day of storage and the pH increased to 6.21 on the 25th day of storage.The moisture content,juice loss rate,TVB-N,TBARS and the total plate counts showed an upward trend,theirvalues were 84.44 g/100g,16.93 g/100g,21.7 mg/100g,0.328 mg/100g on 25d,and the total plate counts increased to 6.54 lg(CFU/g)on the 15th day,which exceeded the limit of 5.0 lg(CFU/g)by the national standards for aquatic products.Water holding capacity,hardness,springiness,chewiness,gumminess,cohesiveness,and resilience showed a downward trend,and their values were 68.62 g/100g?8.18gf,0.76,-40.25 gf,-49.52 gf,-6.85,0.383 until 25d.The microstructure observation results of transverse and longitudinal sections of the back muscles showed that the gaps in and between cells gradually increased during micro-freezing storage.The gaps between the fasciculus gradually became larger and the fasciculus gradually fractured over storage time.The quality of Takifugu Rubripes tended to deteriorate during micro-frozen storage,and the best edible time is 1?15d.3.Study on the quality changes of Takifugu Rubripes under freeze storage conditions at-25?.During the freeze storage at-25?,the pH value of Takifugu Rubripes first decreased and then increased.The pH reached a minimum of 5.95 on the 30th day of storage and rose to 6.90 on the 330th day of storage.Moisture content,juice loss rate,TVB-N,TBARS,and the total plate counts showed an upward trend.Their values were 87.45 g/100g,20.30 g/100g,28.53 mg/100g,and 0.738 mg/100g,and the total plate counts increased to 5.29 lg(CFU/g)on the 270th day,which exceeded the limit of 5.01g(CFU/g)by the national standards for aquatic products.Water holding capacity,hardness,springiness,chewiness,gumminess,cohesiveness,and resilience showed a downward trend,and their values were 67.98 g/100g,6.33 gf,0.15,-19.56 gf,-18.01 gf,-13.184,0.193 until 330d.The microstructure observation results of transverse and longitudinal sections of the back muscles showed that the gaps in and between cells gradually increased during freeze storage.The gaps between the fasciculus gradually became larger.The fasciculus gradually fractured and small fragments appeared over storage time.The quality of Takifugu Rubripes tended to deteriorate during freeze storage,and the best edible time is 1?270d.4.Quality changes of Takifugu Rubripes under different freezing methods storage conditions.The color of Takifugu Rubripes is mainly medium gray and gray-red before freezing(-40?,liquid nitrogen,-80?).The color of Takifugu Rubripes is mainly medium gray,gray-pink and yellow-gray after freezing.There is a significant difference among frozen fish at-40?,liquid nitrogen,-80? and fresh fish.Takifugu Rubripes are similar in color at-40? and-80?,while Takifugu Rubripes at liquid nitrogen was different in color from-40? and-80?.There is a significant difference in odor composition of Takifugu Rubripes among-40?,liquid nitrogen,-80?,and fresh fish,and there was a large difference in the odor composition of Takifugu Rubripes among liquid nitrogen and-40?,-80?.The moisture content of T21,T22,and T23 showed a decreasing trend during storage,and the moisture content of T24 showed an increasing trend,and the peak points of Takifugu Rubripes frozen at-40? were significantly lower than those of frozen at liquid nitrogen and-80?.Takifugu Rubripes frozen at liquid nitrogen had the highest peak point.The proton density in T21,T22 region of the three freezing methods from high to low were liquid nitrogen,-40? and-80?.The proton density in T23 region of the three freezing methods from high to low were liquid nitrogen,-80? and-40?.The proton density in T24 region of the three freezing methods from high to low were-40?,-80? and liquid nitrogen.The results showed that the liquid nitrogen freezing treatment was better than-80? and better than-40?.The results of this study indicate that the storage temperature and freezing method have a significant effect on the quality of Takifugu Rubripes,and the quality of Takifugu Rubripes gradually decreases with the prolongation of storage time;And the lower of the storage temperature,the longer of the storage time of Takifugu Rubripes has.The overall quality of Takifugu Rubripes is not linear with the storage temperature. |
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