Method for the surface-pasteurization and-sterilization of pieces of food
A process for surface pasteurization/sterilization of particulate food products. Water uptake and qualitative changes of food products are minimized and pasteurization or sterilization conditions are optimized when food products are used preheated, wherein product temperature is selected a few degrees below the evaporation temperature of the pasteurization/sterilization system, in that the preheating temperature of food products is selected lower than the saturated steam temperature, preferably a few degrees below the saturated steam temperature at a predetermined pressure, in that treatment is performed in a moist, air-free atmosphere, wherein pasteurization occurs at temperatures between 55 and 99° C. at a low pasteurization pressure, or sterilization occurs at temperatures between 100° C. and 140° C. at a higher sterilization pressure, in that heat treatment occurs for 1 to 30 mins, and in that the water of condensation is removed from the surface of food products by a subsequent vacuum drying at a further reduced pressure.
1. A method for the surface pasteurization or surface sterilization of pieces of food products with minimized water absorption, the method comprising:
pre-warming the food products to a temperature below an evaporation temperature of pasteurization or sterilization systems, wherein the pre-warming temperature of the food product is selected to be lower than a saturation temperature;
heat treating the food product in a pure steam atmosphere free of air, for performing pasteurization at temperatures between 55 and 99° C. at a pasteurization pressure below atmospheric pressure, or sterilization at temperatures between 100° C. and 140° C. at a sterilization pressure above atmospheric pressure, wherein the heat treatment is performed in the course of 1 to 30 mins; and
removing condensation water from a surface of the food products by subsequent vacuum drying under a reduced pressure wherein a pressure in a treatment chamber is reduced by a vacuum pump and as soon as the pressure falls below a set value, a steam supply valve opens and a steam supply is started.
2. The method in accordance with claim 1 , comprising:
selecting the food product temperature to lie between 0° C. to 8° C. below the evaporation temperature of the pasteurization or sterilization system.
3. The method in accordance with claim 1 , wherein the temperature difference between the pre-warming temperature of the food products and a saturated steam temperature in the moist atmosphere at a given pressure is selected to be 0° C. to 8° C.
4. The method in accordance with claim 3 , comprising:
selecting the pre-warming temperature of the food product to be below the saturated steam temperature at a present pressure.
5. The method in accordance with claim 1 , wherein the pieces of food products are oleaginous seeds, including almonds, hazelnuts, pecans, walnuts, as well as peanuts, bran, cereals, coffee, cocoa.
6. The method in accordance with claim 1 wherein the food products are pre-warmed by at least one of an infrared drum, air and microwaves.
7. The method in accordance with claim 1 wherein the water absorption is limited to less than 0.5%.