Water and Fat Mobility in Myofibrillar Protein gels Explored by Low-Field NMR

The physicochemical properties of the lipid phase on the water and fat mobility in gels composed of 2 % myofibrillar proteins (MP) and 15 % lipids were investigated by emulsifying activity, water holding capacity and low field nuclear magnetic resonance (LF-NMR) relaxometry. MP-gels were prepared with lard, diacylglycerols (DAG) or sunflower oil. The differences in the fatty acid composition and acylglycerol structure significantly affected the emulsifying capacity of the MP and increased in the order lard < DAG < sunflower oil. The water holding capacity was significantly lower in gels containing sunflower oil compared to lard and DAG, which was reflected in the NMR relaxation profile. No significant differences in the water and fat mobility were observed between lard and DAG as determined by LF-NMR, which was in agreement with the water holding capacity. The physical state of the lipid at temperatures below the MP-gel setting temperature was found to be determinant for the gel stability.