Food Structure


Cold stage scanning electron microscopy (cryo-SEM), transmission electron microscopy (TEM) and light microscopy (LM) were used to examine the effect of NaCl (2.5%), MgC12 , CaC12 , KCl, LiCl (calculated ionic strength, IS = 0.43) and 1.5% NaCl (IS = 0.26) on the microstructure of comminuted raw meat batters (fat added) and comminuted meat mixes (no fat added). Cryo-SEM revealed that comminuting the lean meat with different chloride salts resulted in the formation of different types of gel structures. Differences were mainly in gel strand thickness, the degree of interlinking between strands and the size of pores within the gels. KCl and 1.5% NaCl formed multi-component, mixed gels in the lean meat system, but formed more uniform gels when fat was added. The other chloride salts produced similar types of gels in both the lean meat mixes and meat batters. Monovalent salts resulted in a good distribution of fat globules in coherent matrices.

The divalent salts were shown to promote protein aggregation in raw batters. The CaC12 batter showed some fat instability but the fat channels were not well interconnected. MgC12 caused widespread fat channelling and matrix disruption which was also visible by LM. The results indicate that some gel formation occurs in meat batters prior to cooking and suggest that the type of gel formed may depend on the relative amounts and type of protein in the aqueous phase. It appears that MgC12 destabilizes batters by causing extensive pre-cooking protein aggregation while CaC12 destabilizes batters by increasing protein-protein interaction during cooking.

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