Food Engineering and Physical PropertiesMulhouse, France, grinder with different pore size). A mix was made with 75% shoulder, 30% backfat, and 5% salt water solution (Dito-Sama, Montlucon, France, mixer type BM20 AS. The mixing was made in 2 steps : 30 s at speed 1 and 2.15 min at speed 5. After mixing, meat preparation was put in 500-g trays with a calibrated stuffer (Villa) type 50 liters), put under vacuum and stored 24 h at a selected temperature. Samples were frozen at -20 ЊC (d 1) or stored for 3 d at 4 ЊC (d 4) before freezing. In order to avoid structure modifications the samples assigned to be analyzed by electron microscope were frozen for 1 h 45 min in a -20 ЊC ethanol bath and stored at -20 ЊC.
Protein solubilityAfter thawing (12 h at 7 ЊC), 10 g of sausage meat was put on a small bag with 40 ml of salt isotonic solution equal to unsalted meat for estimation of Water Soluble Proteins (WSP) or a isotonic salt equal to salted meat for estimation of Salt Soluble Proteins (SSP). Proteins were then extracted at 7 ЊC by tumbling (Stale injectstar,) micro TC20, 10 rpm for 30 min.). The homogenate was then centrifuged for 15 min at 3500 rpm at 7 ЊC (Heitich, Deutchland, rotanta/RP ). Protein content of the supernatant was estimated using the biuret reagent (Gaspar 1984). For the determination, 0.5 ml of protein solution and 4.0 ml of biuret reagent are mixed and allowed to stand for 30 min at room temperature, the absorbance is then measured at 540 nm against a mixture of 0.5 ml water and 2 ml of biuret reagent. Soluble myofibrillar protein (myo) amount is estimated by the difference between SSP and WSP. Three replicates were made for each sample.
Texture measurementTexture measurements were made on sausage meat standard samples cut after 1 h 30 min of partial thawing at ambient temperature.
Compression measurementsCompression measurements were made with an Instron, Les Ulis, France, Universal Testing Machine (Bourne 1982) on 40 mm diameter and 20 mm height sausage cylinders. The sample was set under the 100 N load cell of the INSTRON, and a 100 mm diameter disk was applied on the sample with a 50 mm/min speed. Forces (N) required to create 60% de-
JFS: Food Engineering and Physical PropertiesABSTRACT Effect of salt content, grinder pore size, and mixing temperature on structure of sausage meat were investigated after 1 and 4 d. Protein solubility, texture characteristics and muscle ultrastructure were measured. Cellular structure is conserved when salt amount is under 0.3% for all temperatures and grinder pore sizes, or when salt amount is of 0.8% for a temperature higher than 6 °C or a grinding size of 10 mm. Cellular structure is modified when salt amount is above 1.3% whatever the temperature and grinding size, or when salt amount is of 0.8% for a temperature below 6 °C or a grinding size of 1.5 mm. The use of statistical tools permitted to distinguish modified meat from intact preparations.
