DE2905575C3 - Method of peeling fruits and vegetables - Google Patents

Description

The present invention relates to a method for peeling fruits and vegetables by heating with them aqueous alkali.

In the known method for peeling fruits and vegetables by heating with aqueous alkali one has Sodium hydroxide or potassium hydroxide was used as the alkali because it was believed to be the strongest possible alkali was necessary to remove the peels. The procedure shows however considerable Disadvantages that are due to the fact that it takes too long a heating period to produce a satisfactory one To ensure the degree of peeling. For this reason, the method concerning thermal energy is expensive and it is therefore only suitable for peeling fruit and vegetables that are not cooked or softened may, e.g. B. because after peeling mechanical treatments such. B. Chopping onions and Cutting potatoes for chips, intended to be subjected to a soft material, is difficult are executable.

It is also known to produce fruits and vegetables by heating them with aqueous solutions of ammonium salts to peel, which are considerably weaker alkalis than sodium and potassium hydroxide. This procedure is but very inconvenient or expensive, since in practice it can only be carried out in pressure vessels, as ammonia otherwise escapes during heating.

It has now been found according to the invention that the disadvantages of the known methods for Peeling of fruits and vegetables by using all or part of potassium carbonate and / or Can eliminate potassium phosphate as alkali. This enables faster peeling than when using it of sodium or potassium hydroxide, and thereby a better utilization of the performance of the Apparatus. Open containers can also be used.

In the present context, the peeling of fruit and vegetables is the removal of the Outer layer of cells from the plant part in question to understand whether this outer layer is an actual one Shell that is clear from the rest of the fruit or vegetable such. B. with potatoes or Apples is different, or whether the outer layer is in principle of the same character as that of the rest Part of the plant such as B. onions, where there is no sharp transition between dry and juicy Shells

Fruits and vegetables are usually not 100% peeled, i.e. that the peel is not removed from 100% of the surface because this takes too long and thereby changing the interior of the fruit or vegetable. Generally one can find one Degree of peeling from 80 to 100% satisfactory, depending on the type of plant part concerned.

The invention will hereinafter be explained with reference to the following

Examples demonstrates all of which to run through be that the fruit or vegetable in question is immersed in the heated aqueous solution of alkali and held therein until one judged acceptable Degree of peeling has been achieved. Then it is removed from the peeling liquid and rinsed with water, and the peeled area is measured in percent.

example 1
potatoes

Bintje potatoes were peeled and in the process the peeling liquid was kept at 90 ° C. The alkali compounds used were 9 g K2CO3 per liter and 56 g KOH per 1 liquid As a result, a peeling degree of 85% was achieved in 6 minutes. In the case of potassium hydroxide used alone, in a concentration that ensures the same concentration of potassium ions, namely 63 g of KOH per liter, a degree of peeling of only 65% is achieved in 6 minutes

For comparison, a peeling time of 8 minutes was required to achieve the same degree of peeling in% if the corresponding sodium compounds were used in a concentration that ensures the same concentration of carbonate ions and hydroxyl ions in the peeling solution, namely 7 g Na ₂ CO ₃ per liter and 40 g of NaOH per liter (corresponding to 3.9 g / l carbonate ions and 17.0 g / l hydroxyl ions).

B e i s ρ i e 1 2

That it is not the potassium ion instead of the sodium ion that is decisive for the result becomes another matter Comparative experiment can be seen in which Bintje potatoes of different origins than those used in Example 1 are used were used and in which the peeling liquid was again kept at 90 ° C. With a concentration of 69 g of K2CO3 and 42 g of KOH per liter, a degree of peeling of 75% was achieved in 6 minutes, whereas one Peel degree of only 35% was achieved when the concentration was only 74.5 g KCl per 1 and 42 g KOH per 1 fraud.

Example 3 potatoes

Bintje potatoes were peeled while the peeling liquid was kept at 90 ° C. The used Alkali compounds were 40 g of K3PO4 and 46 g of KOH per liter of peeling liquid. This resulted in a degree of peeling of 90% achieved in 6 minutes

For comparison, a peeling time of 8 minutes was required to achieve the same degree of peeling in percent when the corresponding sodium compounds were used, in a concentration that ensures the same concentration of phosphate ions and hydroxyl ions in the peeling solution, namely 31 g Na ₃ PO ₄ per 1 and 33 g NaOH per 1 (corresponding to 17.9 g / l phosphate ions and 14 g / l hydroxyl ions).

Example 4
Apples

Spartan apples were peeled and the Peeling liquid kept at 70 ° C. The used

•> 5 alkali compounds were 35 g K2CO3 per 1 and 21 g

KOH per 1 peeling liquid. This became a Peel degree of 85% achieved in 6 minutes. If the corresponding sodium compounds

were used in a concentration that ensures the same concentration of carbonate ions and hydroxyl ions in the peeling solution, namely 27 g N 32CO ₃ and 15 g NaOH per liter (corresponding to 15.2 g / l carbonate ions and 6.4 g hydroxyl ions) were required 10 minutes to achieve a peeling degree of 80%.

Example 5

Apples

Spartan apples were peeled while the peeling liquid was kept at 70 ° C. The alkali compounds used were 35 g of K ₃ PO ₄ and 13 g of KOH per liter of peeling liquid. This achieved a degree of peeling of 90% in 6 minutes

For comparison, a peeling time of 10 minutes was required to achieve a peeling degree of 85% if the corresponding sodium compounds were used in a concentration that ensures the same concentration of phosphate ions and hydroxyl ions in the peeling solution, namely 27 g Na ₃ PO ₄ and 13 g NaOH per 1 (corresponding to 15.7 g / l phosphate ions and 54 g / l hydroxyl ions).

Example 6

Apples

Springrove apples were peeled and the peeling liquid kept at 70 ⁰ C. If the alkali compounds used contained 69 g of K ₂ CO ₃ and 28 g of KOH per liter, a degree of peeling of 100% was achieved in 6 minutes. If, on the other hand, 74.5 g of KCl and 28 g of KOH per 1

Peeling liquid was applied, no peeling effect at all could be seen after 6 minutes.

Example 7
Onions

Zittau onions were peeled, and the peeling liquid was kept at 8O ⁰ C. If the alkali compounds used contained 9 g of K ₂ CO ₃ and 14 g of KOH per liter of peeling liquid, a degree of peeling of 85% was achieved in 6 minutes

In order to achieve the same degree of peeling, a treatment time of 10 minutes was required if the corresponding sodium compounds were used in a concentration that ensures the same concentration of carbonate ions and hydroxyl ions in the peeling liquid, namely 7 g Na ₂ CO ₃ and 10 g NaOH per liter (corresponding to 3.9 g / l carbonate ions and 4.3 g / l hydroxyl ions).

Example 8
Onions

Stuttgarter onions were peeled, and the peeling liquid was kept at 70 ⁰ C. By using 71 g of K ₃ PO ₄ per liter, a degree of peeling of 90% was achieved in 10 minutes. At a concentration of 84 g / l KOH, a peel rate of 97% is achieved under the same time and temperature conditions, while with a concentration of 60 g / l NaOH under the same time and temperature conditions, only an unsatisfactory peel rate of 30% is achieved.

Claims (1)

Patent claims: 1. Process for peeling fruits and vegetables by heating with aqueous alkali, thereby gekennzeichne; that the alkali wholly or partially potassium carbonate and / or potassium phosphate be used.