低场核磁共振分析猪肉宰后成熟过程中的水分变化

Analysis of moisture changes of pork during postmortem aging by low-field NMR

以三元杂交猪为对象,利用核磁共振技术分析猪肉不同相态水分的弛豫时间和含量比例,研究了不同保水性猪肉在宰后成熟过程中水分变化情况。结果表明:猪肉成熟过程中的核磁共振T_2弛豫谱显示3个峰,横向弛豫时间分别为T_(21)(2.127～2.541 ms)、T_(22)(31.248～48.817 ms)和T_(23)(167.086～275.782 ms)。宰后同一时间下低、中、高三组保水性猪肉T_(21)及P_(21)均无显著性差异,与低保水性组相比,高保水性猪肉T_(22)及T_(23)均显著降低,P_(22)显著升高,自由水比例P_(23)显著低于低保水性组(p<0.05)。宰后成熟过程中各组肉样T_(21)变化不大,T_(22)和T_(23)均呈现先上升后下降的趋势,并在宰后8 h达到最高值。成熟时间对P_(21)无显著性影响,但对P_(22)和P_(23)影响显著(p<0.05)。核磁成像图显示肉样亮度随着成熟时间的延长而增加。该实验结果对于研究肉品成熟过程中的水分变化具有重要意义,同时为解释肉品保水性机理提供理论依据。

In order to in,Jestigate the moisture changes of pork with different water holding capacity during aging, a total of thirty Duroc x Large White x Landrace pigs were used in this study by using low-field nuclear magnetic resonance （LF-NMR）, and transverse relaxation time and water propotion of different phase water were analysed.In the present investigation, three peaks were identified in pork during aging through the multi-exponential fitting of the bulk NMR T2 transverse relaxation time data.The peaks were directly related to three water components Tn （2.127~2.541 ms ）, T22 （31.248~48.817 ms）and T23 （167.086~ 275.782 ms）. Compared with low WHC group ,T22 ,T23 and P23 decreased significantly in high WHC group ,while P22 inereased dramatically ,T2~ and P2~ was not significantly different from the three groups.During postmortem aging,the general trend of T22 and T23 increased firstly and declining, and reached the highest value at 8 h postmortem, the water molecules mobility of immobilized water and free water had the same trend,while T21 changed little.The proportion of free water P22 increased initially and then decreased during aging,while the opposite trend was detected for the proportion of free water P23.The NMR images showed that the brightness of pork increased during aging.The results was of important significance to study the moisture changes of pork during postmortem aging, and it could provide theoretical basis for explain the mechanism of water holding capacity of meat.