Method for roasting and surface-pasteurization of foods products
The disclosure relates to a process for roasting and surface pasteurization of particulate food products. The roasting and surface pasteurization can be combined and united to form one process wherein a treatment is carried out in a moist atmosphere at temperatures <100° C., that the pasteurization treatment is carried out in a roasting system during the roasting operation, that during the pasteurization phase the temperature of the product surface is held a few degrees below the dew point temperature of the atmosphere which is established, that the pasteurization is performed for 1-30 min, and that with advancing or continued roasting the water of condensation on the surface of the food products is removed and the water uptake of the same is minimized.
1. A method for roasting and for surface pasteurization of food product pieces, comprising:
providing a roasting system;
performing a pasteurization treatment during a pasteurization phase in the roasting system during a roasting process, wherein the volume of the air flow through the roasting zone is reduced to 0-20 Nm 3 /h/kg of the product, and steam injection into the hot air is started via a valve and a screen at an order of magnitude of 0.01-15.0 kg steam/h/kg of the food product;
performing the pasteurization treatment of the food product pieces in a humid atmosphere at a temperature <100° C.;
maintaining a temperature on the surface of the food product pieces during at least a part of the pasteurization phase below a selected dew-point temperature of the humid atmosphere;
performing the pasteurization treatment within 1 to 30 mins; and
removing condensation water on the surface of the food product pieces in the course of advancing or continued roasting, and thereby minimizing the water absorption of the food product pieces, wherein following the pasteurization phase the introduction of steam is interrupted.
2. The method in accordance with claim 1 , wherein the pasteurization treatment is performed at temperatures between 50° C. and 99° C.
3. The method in accordance with claim 1 , wherein in the pasteurization phase, the temperature of the product surface is selected to lie between 0° C. to 8° C. below the selected dew-point temperature of the humid atmosphere.
4. The method in accordance with claim 1 , comprising:
preparing a product charge comprising the food product pieces in a preparation container;
introducing the product charge into a roasting zone of the roasting system, wherein the roasting system comprises a ventilator;
aspirating air by the ventilator for generating an air flow;
heating the air flow in a burner by gas for generating a hot air flow;
bringing the hot air flow to a central area of the roasting zone; and
initiating the pasteurization phase as soon as the surface temperature of the product charge to be roasted has reached the pasteurization temperature.
5. The method in accordance with claim 2 , comprising:
preparing a product charge comprising the food product pieces in a preparation container;
introducing the product charge into a roasting zone of the roasting system, wherein the roasting system comprises a ventilator;
aspirating air by the ventilator for generating an air flow;
heating the air flow in a burner by gas for generating a hot air flow;
bringing the hot air flow to a central area of the roasting zone; and
initiating the pasteurization phase as soon as the surface temperature of the product charge to be roasted has reached the pasteurization temperature.
6. The method in accordance with claim 3 , comprising:
preparing a product charge comprising the food product pieces in a preparation container;
introducing the product charge into a roasting zone of the roasting system, wherein the roasting system comprises a ventilator;
aspirating air by the ventilator for generating an air flow;
heating the air flow in a burner by gas for generating a hot air flow;
bringing the hot air flow to a central area of the roasting zone; and
initiating the pasteurization phase as soon as the surface temperature of the product charge to be roasted has reached the pasteurization temperature.
7. The method in accordance with claim 4 , comprising:
providing a flap system comprised in the roasting system;
reducing the hot air flow through the roasting zone during the pasteurization phase with the flap system;
starting steam injection into the hot air flow via a valve and a screen; and
sizing the amounts of hot air flow and steam such that the selected dew-point temperature of the hot air flow mixed with steam lies approximately 0 to 8° C. above the surface temperature of the product charge to be roasted.
8. The method in accordance with claim 5 , comprising:
providing a flap system comprised in the roasting system;
reducing the hot air flow through the roasting zone during the pasteurization phase with the flap system;
starting steam injection into the hot air flow via a valve and a screen; and
sizing the amounts of hot air flow and steam such that the selected dew-point temperature of the hot air flow mixed with steam lies approximately 0 to 8° C. above the surface temperature of the product charge to be roasted.
9. The method in accordance with claim 6 , comprising:
providing a flap system comprised in the roasting system;
reducing the hot air flow through the roasting zone during the pasteurization phase with the flap system;
starting steam injection into the hot air flow via a valve and a screen; and
sizing the amounts of hot air flow and steam such that the selected dew-point temperature of the hot air flow mixed with steam lies approximately 0 to 8° C. above the surface temperature of the product charge to be roasted.
10. The method in accordance with claim 4 , wherein in the course of the pasteurization phase, the product surface temperature is brought to substantially the same temperature as the dew-point temperature on the basis of a selected hot air flow and steam volume flow.
11. The method in accordance with claim 5 , wherein in the course of the pasteurization phase, the product surface temperature is brought to substantially the same temperature as the dew-point temperature on the basis of a selected hot air flow and steam volume flow.
12. The method in accordance with claim 6 , wherein in the course of the pasteurization phase, the product surface temperature is brought to substantially the same temperature as the dew-point temperature on the basis of a selected hot air flow and steam volume flow.
13. The method in accordance with claim 7 , wherein in the course of the pasteurization phase, the product surface temperature is brought to substantially the same temperature as the dew-point temperature on the basis of a selected hot air flow and steam volume flow.
14. The method in accordance with claim 8 , wherein in the course of the pasteurization phase, the product surface temperature is brought to substantially the same temperature as the dew-point temperature on the basis of a selected hot air flow and steam volume flow.
15. The method in accordance with claim 9 , wherein in the course of the pasteurization phase, the product surface temperature is brought to substantially the same temperature as the dew-point temperature on the basis of a selected hot air flow and steam volume flow.
16. The method in accordance with claim 1 , wherein the food product pieces are oleaginous seeds.
17. The method in accordance with claim 16 , wherein the food product pieces are chosen from almonds, hazelnuts, pecans, walnuts.
18. The method in accordance with claim 1 , wherein the food product pieces are chosen from peanuts, bran, cereals, coffee or coca.