The present invention relates to a method for co-extruding an elongated food product wherein the method comprises measuring the product characteristics of the viscous gelling agent provided and wherein the physical state of the collagen is controlled by balancing the process settings of the at least one subsequent processing step based upon the product characteristics measured.

The invention relates to a method of extruding sleeves extruded of collagen for encasing sausages, wherein a collagen fluid is fed to an extrusion head; the collagen fluid is guided through the extrusion head; and the collagen fluid is discharged from the extrusion head. The invention also relates to an extrusion head for performing such a process as well as a co-extrusion sausage line. Finally also the sleeve extruded with this method or devices is part of the invention.

A method is provided for thermal treating a food product in a thermal treatment unit with the food product having a casing comprising a protein, or hybrid casing. The method involves providing the food product, subjecting the food product to a brine solution, conveying the food product into the unit, and subjecting the food product to a thermal treating step. The thermal treating step includes at least: a) drying the food product, and b) subsequently, further thermal treating the food product. The method further involves: determining the denaturation temperature of the protein, and setting the parameters of the climate in the unit such that the dew point of the air of the unit is equal to or lower than the determined denaturation temperature, wherein step a) ends in case the surface temperature of the casing is equal to the dew point of the air of the unit.