通电加热过程中凡纳滨对虾虾肉糜核苷酸及关联产物的变化

Study on the changes of nucleotide and related compounds in minced Litopenaeus vannamei during ohmic heating

探究通电加热过程中凡纳滨对虾虾肉糜电导率及呈味核苷酸的变化,考察通电加热对虾肉糜滋味的影响。测定了不同通电加热温度(25、40、55、65、75、85和95℃)和金属离子添加物(1、5和10 mmol/L的Zn^2+、Cu^2+、Al^3+和Fe^3+)下凡纳滨对虾虾肉糜的电导率(50 Hz^20 kHz)以及核苷酸及关联产物的含量。结果表明:其电导率与频率成对数关系,与温度(低于65℃)呈线性关系(P<0.05);添加金属离子会增加凡纳滨对虾虾肉糜的电导率,10 mmol/L Fe^3+是虾肉糜样品的最佳导体。通电加热中,一磷酸鸟苷(guanosine monophosphate,GMP)含量始终处于较高水平(>60 mg/100 g);次黄嘌呤(hypoxanthine,Hx)和次黄嘌呤核苷(inosine,HxR)含量始终处于较低水平(<7 mg/100 g);高温时腺苷(adenosine,AdR)含量更高。通电加热纯虾的温度应控制在55~65℃,有利于其鲜味的产生。金属离子处理的虾肉糜在不同加热温度下均产生少量Hx和大量肌苷酸(inosine monophosphate,IMP),IMP的产生与金属离子浓度之间没有显著的相关性(P>0.05)。添加10 mmol/L Fe^3+并通电加热至85℃时产生的IMP含量最高[(201.39±3.83)mg/100 g]。

The changes in the electrical conductivity(EC)and taste nucleotides of Litopenaeus vannamei shrimp with the treatment of ohmic heating(OH)were investigated in order to investigate the effect of OH on the taste of Litopenaeus vannamei.The EC(50 Hz^20 kHz)and the contents of nucleotides in the shrimp under different temperatures(25,40,55,65,75,85,and 95℃)and metal ion additives(1,5,and 10 mmol/L Zn^2+,Cu^2+,Al^3+,Fe^3+)were measured.The results show that the EC of minced shrimp has a logarithmic relationship with frequency and a linear relationship with temperature(lower than 65℃)(P<0.05).The EC of shrimp with added metal ions was higher than that of pure shrimp and 10 mmol/L Fe^3+ was the best conductor for shrimp.In the treatment of OH,the guanosine monophosphate(GMP)content was always at a high level(more than 60 mg/100 g),while the Hypoxanthine(Hx)and Inosine(HxR)contents were always at a low level(less than 7 mg/100 g).Adenosine(AdR)was accumulated at high temperatures.The best temperature of heating for pure shrimp by OH was between 55~65℃,which was conducive to the production of umami taste.The shrimp treated with metal ions produced a small amount of Hx and a large amount of inosine monophosphate(IMP)at different temperatures.There was no significant correlation between IMP production and metal ion concentration(P>0.05).The IMP content in shrimp was the highest(201.39±3.83 mg/100 g)when 10 mmol/L Fe^3+ was added and ohmic heated to 85℃.This study provided the optimized treatment condition for Litopenaeus vannamei using OH.