DE2905575B2 - Method of peeling fruits and vegetables - Google Patents

Description

IO

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. Fruits and vegetables by heating with aqueous solutions of ammonium salts to peel, which are considerably weaker alkalis than » Sodium and potassium hydroxide. However, this procedure is very inconvenient or costly as it is practical can only be carried out in pressure vessels. otherwise ammonia will escape 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 « formation 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 ή 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. 6 »

Fruit and vegetables are usually not peeled 100%, i.e. the peel is not made from 100% of the Surface is removed because this / u take a long time and thereby the inside of the fruit or vegetable would change. Generally one finds a <> '> Degree of peeling from 80 to 100% satisfactory, depending on the type of plant part concerned.

The invention is illustrated below by the following examples, all of which are carried out by immersing the fruit or vegetable in question in the heated aqueous solution of alkali and holding therein until a degree of peeling determined to be acceptable has been achieved. It is then removed from the peeling liquid and rinsed with water, and the peeled area is measured in percent.

example 1 potatoes

Bintje potatoes were peeled while the peeling liquid was kept at 90 ° C. The alkali compounds used were 9 g K ₂ CO ₃ per liter and 56 g KOH per liter of liquid g KOH per liter, a peeling degree 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%, when the appropriate sodium compounds were used in a concentration that is the same Concentration of carbonate ions and hydroxyl ions in the peeling solution guaranteed, namely 7 g Na2COj per 1 and 40 g of NaOH per l (corresponding to 3.9 g / l carbonate ions and 17.0 g / l hydroxyl ions).

Example 2

That the potassium ion is not decisive for the result instead of the sodium ion can be seen from a further comparative experiment in which Bintje potatoes of different origin than those used in Example 1 were used and in which the peeling liquid was again kept at 90.degree. At a concentration of 69 g of K / O ₃ and 42 g of KOH per l, a degree of peeling of 75% was achieved in 6 minutes, whereas a degree of peeling of only 35% was achieved when the concentration was only 74.5 g of KCI per l and 42 g KOH per liter.

Example 3
potatoes

Bintje potatoes were peeled, while the peeling liquid was kept at 90 ⁰ C. The alkali compounds used were 40 g of K ₃ PO ₄ and 46 g of KOH per liter of peeling liquid. As a result, a degree of peeling of 90% was achieved in 6 minutes.

For comparison, a peeling time of 8 minutes was required in order to achieve the same degree of peeling in percent achieve when the appropriate 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 NajPO «per liter and 33 g of NaOH per liter (corresponding to 17.9 g / l phosphate ions and 14 g / l hydroxyl ions).

Example 4
Apples

Spartan apples were peeled, while the peeling liquid at 70 ⁰ C. The alkali compounds used are 35 g of K ^ COj per liter and 21 g of KOH per liter of peeling liquid. As a result, a degree of peeling of 85% was 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 foaming solution, namely 27 g Na ₂ COj and 15 g NaOH per liter (corresponding to 15.2 g / J carbonate ions and 6.4 g hydroxyl ions) were required 10 minutes in order to achieve a degree of protection of 80%.

Example 5

Apples

Spartan apples were peeled, while the peeling liquid at 70 ⁰ C. The alkali compounds used were 35 g of K ₃ PO ₄ and 18 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 53 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 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 KCI and 28 g of KOH per liter Peeling liquid was applied was none at all Peeling effect can be recognized 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 33 g / l carbonate ions and 43 g / l hydroxyl ions).

Example! 8th Onions

Stuttgart onions were peeled, and the 2 ^r . Peeling liquid was kept at 70 ⁰ C. By using 71 g of K ₃ PO ₄ per l, a peel degree of 90% was achieved in 10 minutes Concentration of 60 g / I NaOH under the same time and temperature conditions only an unsatisfactory peel degree of 30% is achieved.

Claims (1)

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