Effect of Salt and Liver/Fat Ratio on Microstructure, Emulsion Stability, Texture and Sensory Mouth Feel of Liver Paste

This paper reports the effect of two liver/fat ratios (35/35 and 20/50) and two salt levels (0 and 1.8 %) on the microstructure, emulsion stability, textural and sensorial properties of spreadable liver paste. The conventional liver paste, a hot emulsion, consists of fat globules surrounded by a protein layer and dissolved proteins in a continuous phase forming a gel matrix. Addition of salt led to a microstructure with smaller fat globules and increased fat binding properties, causing more stable emulsions. This was attributed to an increased solubilisation of the liver proteins which are available for gel formation and as emulsifier, resulting in a harder, less spreadable product. The microstructure and emulsion stability were highly influenced by the liver/fat ratio. A lower liver/fat ratio resulted in a more heterogeneous microstructure with bigger fat globules and the formation of fat channels throughout the structure of the product. Less gelling proteins were dissolved in the continuous phase and also a smaller amount of proteins were available to act as emulsifier. Although less stable emulsions were formed, the liver/fat ratio did not affect the hardness of liver paste. These results suggest that both liver protein gelation and fat crystallization contribute to the hardness of liver paste.