Method for preparing deep-frozen vegetables pieces

Abstract

Method for preparing deep-frozen vegetable pieces, preferably potato pieces such as french fries, comprising of bringing the vegetable pieces into brief contact with an inert substance which has a temperature which is sufficiently low and for a period of time which is sufficiently long to impart to the outer layer of the vegetable pieces a temperature which is <0 C. while an inner part of the vegetable piece has a temperature which is >0 C.; slowly freezing the vegetable pieces until the pieces are fully deep-frozen by bringing the vegetable pieces into contact with air.

Claims

1. A method for preparing deep-frozen potatoes, comprising the steps of: leaching or boiling potato pieces; forming the potato pieces into a shape to obtain French fried shaped potatoes comprising an outer layer with a thickness of less than 1 mm and an inner part; said French fried shaped potatoes being beam shaped with a width and thickness of 7 mm to 14 mm; spraying an inert substance having a temperature lying between 20 C. and 200 C. onto the leached or boiled French fried shaped potatoes, for a period of time which is between 10 seconds and 7 minutes and sufficient to impart to only the outer layer of the French fried shaped potatoes a temperature which is <0 C. and which freezes the outer layer, while maintaining the inner part of the French fried shaped potatoes at a temperature which is >0 C.; and deep freezing the French fried shaped potatoes which have been sprayed with the inert substance by bringing the sprayed French fried shaped potatoes into contact with air until the French fried shaped potatoes are fully deep frozen, wherein said deep frozen French fried shaped potatoes are without fat and are suitable for deep-frying.

2. The method as claimed in claim 1, wherein the inert substance has a temperature lying between 25 C. and 175 C.

3. The method as claimed in claim 1, wherein the contact time between the inert substance and the French fried shaped potatoes is between 1 and 3 minutes and for a period of time sufficient to impart only the outer layer of the French fried shaped potatoes a temperature which is <0 C. and which freezes the outer layer, while maintaining the inner part of the French fried shaped potatoes at a temperature which is >0 C.

4. The method as claimed in claim 1, wherein the inert substance is selected from the group consisting of nitrogen, carbon dioxide and helium.

5. The method as claimed in claim 1, wherein before the spraying, the method further comprises a step of: cooling the leached or boiled potato pieces to a temperature of between 0 and 10 C.

6. The method as claimed in claim 1, wherein the inert substance is liquid nitrogen sprayed at a temperature lying between 25 and 175 C., and wherein the liquid nitrogen becomes gaseous at the moment of contact with the French fried shaped potato.

7. The method as claimed in claim 1, wherein the spraying takes place in a closed space.

8. The method as claimed in claim 1, comprising leaching of the potato pieces, wherein the leaching of the potato pieces takes place in one or more steps in water or steam until the core of the French fried shaped potatoes is between 60 C. and 85 C.

9. The method as claimed in claim 1, comprising leaching of the potato pieces, wherein the leaching of the potato pieces takes place in water, salt water and/or water comprising a preservative.

10. The method as claimed in claim 1, wherein the deep freezing of the sprayed French fried shaped potatoes takes place by placing the sprayed French fried shaped potatoes in a freezing tunnel with a temperature of between 15 and 50 C.

11. The method as claimed in claim 1, wherein during the deep freezing the temperature of the French fried shaped potatoes falls at a rate of between 1 C./1.5 minutes and 1 C./10 minutes.

12. A French fry obtainable with the method as claimed in claim 1.

13. The French fry as claimed in claim 12, wherein the French fry has an underwater weight lying between 360 g and 450 g when potatoes which weigh 5 kg in atmospheric conditions are weighed under water.

14. A method for preparing deep-fried French fries, comprising: leaching or boiling potato pieces; forming the potato pieces into a shape to obtain French fried shaped potatoes comprising an outer layer with a thickness of less than 1 mm and an inner part; said French fried shaped potatoes being beam shaped with a width and thickness of 7 mm to 14 mm; spraying an inert substance having a temperature lying between 20 C. and 200 C. onto the leached or boiled French fried shaped potatoes, for a period of time which is between 10 seconds and 7 minutes and sufficient to impart to only the outer layer of the French fried shaped potatoes a temperature which is <0 C. and which freezes the outer layer, while maintaining the inner part of the French fried shaped potatoes at a temperature which is >0 C.; deep freezing the French fried shaped potatoes which have been sprayed with the inert substance by bringing the sprayed French fried shaped potatoes into contact with air until the French fried shaped potatoes are fully deep frozen, wherein said deep frozen French fried shaped potatoes are without fat and are suitable for deep-frying; and deep-frying the fully deep-frozen French fried shaped potatoes to form said deep-fried French fries.

Description

EXAMPLES

Example 1

(1) A potato with an underwater weight of 400 g is peeled and cut into french fries with a thickness and width of about 10 mm. The french fries are leached in salt water to the point where they have a core temperature of about 70 C. by being leached for 10 minutes in water of about 85 C.

(2) The french fries are cooled to about 2 C. and then carried into an almost fully closed space on a conveyor belt. The french fries undergo a flash freezing in that gaseous nitrogen at a temperature of 80 C. is sprayed onto the french fries for 3 minutes.

(3) The average temperature of the outer layer of the french fries is 2 C. and that of the core of the french fries amounts to +2 C.

(4) The french fries are carried into a cooling chamber at a temperature of about 20 C.

(5) The french fries are fried at 180 C. in vegetable oil. The french fries have a crispy crust and have a soft inner part which tastes of potato.

Example 2

(6) The tables below show an overview of different tests which were performed. In table 1 french fries were steamed (leached) and dried. The core temperature of the french fry before the flash freezing is also shown. The temperature of the nitrogen is shown, as is the duration of the contact between the inert substance and the french fry. The temperature of the core of the french fry is then measured, as is that of the outer layer (edge). The french fries were then frozen slowly and deep-fried for about 5 minutes. The best results were achieved by the french fries which, after the flash freezing, had a temperature in the core of more than 0 C. and wherein the temperature of the outer layer is less than 0 C.

(7) TABLE-US-00001 TABLE 1 French French Result fry fry after slow temp temp, freezing Core, Temperature core, and Test before of inert Residence after Edge deep- No. Steamed Dried freezing substance time freezing temp frying 7001 Y Y 15.7 40 1 min 18 2 0 Tasty 7002 Y Y 15.4 40 1 min 35 1 1 Not very tasty 7003 Y Y 20 40 2 min 57 4 2 Not very tasty 7004 Y Y 11.5 60 0.25 sec 2 1 Very tasty and crispy 7005 Y Y 10.8 60 0.39 sec 1 1 Very tasty and crispy outer layer 7008 Y Y 16 80 0.30 sec 2 4 Very tasty and crispy outer layer 7009 Y Y 23 80 1 min 38 0 6 Tasty 7010 Y Y 18 80 2 min 48 2 6.5 Not very tasty 7012 Y Y 10 80 0.45 sec 2 2 Very tasty and crispy outer layer 7013 Y Y 8 70 0.45 sec 2 2 Very tasty and crispy outer layer 7014 Y Y 34 70 1 min 45 0 4 Tasty 7015 Y Y 14 50 3 min 36 2 6 Not very tasty

(8) Table 2 shows the results of french fries which were first steamed (leached), then rinsed with lukewarm water. The temperature of the french fry before the flash freezing is measured. The temperature of the inert substance and the time for which the french fry comes into contact with the nitrogen are also shown. The temperature of the core of the french fry and of the edge of the french fry after the flash freezing are also shown. The french fries are then frozen slowly and deep-fried for about 4 to 5 minutes.

(9) TABLE-US-00002 Result French French after Fry fry slow Rinsed temp temp, freezing with Core, Temperature core, and Test water before of inert Residence after Edge deep- No. Steamed temperature freezing substance time freezing temp frying 7016 Y 45 40 50 1 min 09 2 0 Tasty 7017 Y 38 32 50 l min 48 0 0 Not particularly tasty 7018 Y 36 31 80 1 min 06 2 0 Tasty 7019 Y 34 22 80 1 min 14 0 2 Not particularly tasty 7020 Y 30 25 80 0.54 sec 2 2 Not very tasty