Research On The Key Keep Fresh Technologies And Its Quality Changes Of Tilapia Fillets Based On Micro-frozen And Modified Atmosphere

Since the introduction of tilapia?Tilapia?in China,the development speed of breeding and processing has been rapid.Nowadays,the international trade war and the sambal are striking.The tilapia market is in a severe situation.Its products are mainly frozen tilapia fillets.Because of its single product variety,deep-freezing energy consumption,and poor thawing quality,the export industry of superior frozen tilapia fillets has been greatly affected.To alleviate this unfavorable situation,fish fillets can be researched and developed,and the quality of freshness can be improved,energy consumption can be reduced,short-distance transportation can be opened,the domestic demand market can be opened,and economic growth can be driven.Therefore,after investigating the production process of frozen fish fillets,this paper studies the influence of plasma and packaging materials on the quality of fish fillets,and then combines micro-freezing with modified atmosphere to explore the changes in the quality of fish fillets during storage.The picture chooses better tilapia fillet preservation conditions.The test results are as follows:?1?Single factor experiment with different proportion of modified atmosphere.Three types of tilapia fillets are to be selected to determine the freezing curve.The freezing difference between the double helix and ultra-low temperature freezing is compared.Pre-cooling measures are taken to narrow the gap between the quick-freezing and the pre-treatment of the fillets.According to the proportion of CO₂,O₂ and N₂,the processed fish fillets are 40%:30%:30%,50%:30%:20%,60%:10%:30%,70%:10%:20%will be packed with modified atmosphere and stored in a low temperature environment of-8?.Comprehensive quality indicators are available.The high proportion of CO₂ group has a greater impact on the overall quality of the fish fillet.The packaging is easy to sag and texture is softened in the later period of storage,and low oxygen is difficult to inhibit the formation of high iron myoglobin,which can easily lead to dull color.Therefore,the proportion of modified atmosphere in the first three groups was selected for the experiment in?4?.?2?Selection of pretreatment sterilization methods.Choose 3/5 ounce tilapia fillets as raw materials to compare the fresh-keeping effect of four groups of modified atmosphere,modified atmosphere+ozone water?0.6 mg/L,5 min?,modified atmosphere+low temperature plasma?70 KV,60 s?.By measuring the conductivity of fish fillets,texture parameters,fat oxidation value?TBA?,volatile base nitrogen?TVB-N?,p H?p H?,color difference??E?,total bacteria?TVC?,gas content?%?And other indicators,analyze the effects of modified atmosphere,ozone water,and plasma sterilization on the quality of refrigerated?4??modified atmosphere tilapia fillets;with the extension of the storage period,various indicators of fillets have changed significantly?P<0.05?,and the use of plasma treatment can avoid the secondary pollution of fish fillets.Therefore,plasma treatment is the best choice for pretreatment of fillet sterilization.?3?Research on the fresh-keeping effect of modified atmosphere packaging materials.Using unsealed as a control,3/5 ounces of fish fillets were packaged in modified atmosphere using PP+PP film,PP/PE+composite film,PP/EVOH/PE+composite film,and then stored at low temperature,every 14 days to measure the hardness,p H value,color difference,TVB-N value,TVC and other indicators of fish fillets.The sealing of the composite film has a great influence on the quality of the fish fillet,and various indicators show significant changes?P<0.05?,and the p H value and microbial growth and reproduction speed of the composite film packaging group in the later period are slow,and the high barrier composite film group can suppress volatility Basic nitrogen growth,delay color browning and fat oxidation.In summary,the packaging combination of PP/PE+composite film can be used for modified atmosphere packaging of fish fillets,so that the quality of freshness of fish fillets is better.?4?The orthogonal test of the combination of micro-freezing and modified atmosphere.Choose three micro-freezing temperatures of-4,-8,and-12?;three sizes of fish fillets of3/5,5/7,and 7/9 ounces,and?1?three groups of modified atmosphere ratios for L9?3³?positive Submit test.Taking TVB-N value and color difference value?a*?as evaluation indexes,the micro-freezing temperature is-8?,and the modified atmosphere ratio is CO₂:O₂:N₂=60%:10%:30%;the juice loss rate is taken as Evaluation index,that is,the temperature is-12?,the ratio is 60%:10%:30%,the specification is 3/5 ounces;the conductivity is used as the evaluation index,the optimal combination of the optimal combination and the optimal combination of juice loss rate single factor Choose consistent.In summary,the temperature can be selected from-8°C and-12?,the inflation ratio is CO₂:O₂:N₂=60%:10%:30%,and the size of the fillet is 3/5 ounce.?5?Comparison of the quality of micro-frozen modified atmosphere and frozen modified atmosphere fish fillets.Inflate and pack the 3/5 size fish fillets according to the modified atmosphere ratio in?4?,and store them in the low temperature environment of-4,-8,-12,and-18?,respectively.The odor and tissue structure,microorganisms and flora changes were measured.With the extension of storage period,the comprehensive quality of fish fillets showed a downward trend.The combined water in the fish fillet and the difficult-to-flow water are transformed into free water,the fluidity gradually increases,and the free water content increases.At the same time,the electronic nose,circular dichroism chromatography,and scanning electron microscopy were used to detect the odor,protein structure changes,and microstructure changes of modified atmosphere fish fillets under different low-temperature storage.Finally,through high-throughput sequencing,compared with fresh fish fillets,the-8,-12?low temperature group during storage is relatively low in the proportion of the abundance ratio of the-12?group fillet Morganella The abundance ratio of genus,aeromonas,and acinetobacter gradually decreased,and the genus of Providence did not change significantly.Therefore,the micro-freezing temperature can be selected to-12?for fresh storage of fish fillets.