Study On The Changes Of Taste Products In Litopenaeus Vannamei During Ohmic Heating

The Litopenaeus vannamei（L.vannamei）is one of the three largest farmed shrimps in China and has broad market prospects and development value.The preservation and production of the good flavor of vannamei shrimp is an important link in the process of storage.Taste nucleotides and free amino acids are the main flavor components of P.vannamei.Nucleotides and their related products are directly related to the freshness during the processing and storage of aquatic products,and also contribute to the umami taste of aquatic products.Free amino acids can work synergistically with taste nucleotides to make the umami taste of aquatic products stronger.Processing methods,processing and storage temperatures,metal ions and other food additives and microorganisms all affect the content of taste nucleotides and free amino acids in aquatic products,thereby affecting their taste.Ohmic heating is an efficient thermal processing method with high energy conversion rate and uniform heating,and has broad application prospects.At present,the application of electric heating is mainly concentrated on the effects on the texture of aquatic products such as surimi,and the effect of Ohmic heating on the taste of aquatic products needs further research.In order to explore the role and influence of Ohmic heating technology in the development and utilization of P.vannamei,the effects of Ohmic heating temperature on the umami taste of P.vannamei,the degradation pathway of metal ions to nucleotides,and taste nucleosides were investigated The effects of acid and free amino acid content were investigated from two aspects:taste nucleotides and free amino acids.Changes in the taste of P.vannamei during the heating process were provided to provide a theoretical basis for optimizing the processing method of P.vannamei,and to open up The development and utilization of Litopenaeus vannamei provides new ideas.1.Investigated the contents of nucleotides and related compounds at different temperatures（4,25,40,55,65,75,85,and 95℃）under Ohmic heating（50 Hz-20 k Hz）and discussed The effect of heating temperature on the ATP degradation pathway and taste of Penaeus vannamei was studied.Except for ATP and Hx,the contents of nucleotides and related compounds of P.vannamei increased to varying degrees during the heating process.Proper heating will promote the accumulation of nucleotides,but excessive temperature will inhibit the degradation of ATP.There are two ATP degradation pathways of P.vannamei,IMP pathway and Ad R pathway.The IMP pathway is mainly used at low temperature,and Ad R pathway appears at high temperature.The GMP and IMP contents of P.vannamei heated by Ohmic current are large,and the content of Hx R and Hx is low,so it can maintain its umami taste without producing obvious bitterness.In order to obtain a better-tasting product,the temperature of pure shrimp meat heated by Ohmic heating should be controlled between 55?65℃.2.The effects of different metal ions(1,5 and 10 m M Zn²⁺,Cu²⁺,Al³⁺,and Fe³⁺)on ATP degradation and taste nucleotide content and degradation pathways of shrimp surimi in P.vannamei were investigated during the heating process.It was found that the control group（without added metal ions）has the same ATP degradation pathway as the Zn²⁺treatment group with two,IMP pathway and Ad R pathway;and There is only one ATP degradation pathway in the Cu²⁺,Al³⁺,and Fe³⁺treatment groups:IMP pathway.The metal ion-treated shrimp meat increased in nucleotide content,among which the Fe³⁺treatment group had the highest nucleotide level,the Zn²⁺treatment group had the lowest nucleotide level,and the trivalent ion was greater than the divalent ion.Metallic ion-added shrimp meat produced a small amount of Hx and a large amount of IMP at different heating temperatures.There was no significant correlation between the production of IMP and the concentration of metal ions（P>0.05）.When 10 m M Fe³⁺was added and heated to 85°C,P.vannamei tasted best.3.The changes of free amino acids in shrimp minced shrimp treated with different metal ions(1,5 and 10 m M Zn²⁺,Cu²⁺,Al³⁺,and Fe³⁺)during Ohmic heating were investigated.The results show that except for the 10 m M Fe³⁺treatment group,the content of free amino acids in the other metal ion treatment groups decreases with increasing temperature,and heat treatment will cause the loss of free amino acids to a certain extent;5 m M Zn²⁺,Cu²⁺,and Fe³⁺treatment groups The relative content of flavor amino acids was large,and the treatment group with 5 m M Fe³⁺was the largest.The 10 m M Zn²⁺treatment group and the 1 m M Al³⁺treatment group have relatively large amounts of bitter amino acids,which can promote the bitterness of shrimp meat.To some extent,Al³⁺is not very suitable for Ohmic heating of P.vannamei.The metal ions-treated 1 g minced shrimp can produce a umami equivalent to 2.70?5.88 mg of MSG.The EUC in the Zn²⁺and Fe³⁺treatment groups was larger.These two ions can promote the umami flavor of shrimp meat.Fe³⁺is the most suitable ion to add when Ohmic heating P.vannamei.