Method For Treating The Surface Of Plant Parts

Abstract

A method for masking corking on the surface of polyphenol-containing plant parts is characterized by contacting the surface of the polyphenol-containing plant parts with one or more iron(III) salts, preferably with an aqueous solution that contains one or more iron(II) salts.

Claims

1. A method of masking corky tissue on a surface of polyphenolic plant parts, wherein the surface of the polyphenolic plant parts is contacted with one or more iron(II) salts.

2. The method as claimed in claim 1, wherein the surface of the polyphenolic plant parts is contacted with an aqueous solution containing one or more iron(II) salts.

3. The method as claimed in claim 1, wherein the plant parts are selected from the group consisting of the fruits of avocados, eggplants, black cherries, figs and blackcurrants.

4. The method as claimed in claim 1, wherein the plant parts are fruits of avocados, selected from the group consisting of Hass, Mendez, Carmen, Lamb Hass, GEM, Puebla, Fuerte, Pinkerton, Reed, Bacon, Zutano, Gwen, Fuentes and Avocadito varieties.

5. The method as claimed in claim 1, wherein the iron(II) salt is selected from the group consisting of Fe(II) gluconate, Fe(II) citrate, Fe(II) lactate, Fe(II) glycinate, Fe(II) salicylate, Fe(II) ascorbate, Fe(II) fumarate, Fe(II) bisglycinate, Fe(II) phosphate, Fe(II) succinate and Fe(II) tartrate.

6. The method as claimed in claim 2, wherein an aqueous solution is used and the iron(II) concentration is 0.01 to 10 g/l.

7. The method as claimed in claim 2, wherein an aqueous solution is used and the pH of the solution is in the range from 2.5 to 9.

8. The method as claimed in claim 1, wherein an aqueous solution is used and the solution additionally contains one or more iron(III) salts.

9. The method as claimed in claim 8, wherein the additional iron(III) salt(s) come from vinasse.

10. The method as claimed in claim 2, wherein an aqueous solution is used and the solution additionally contains plant tannins.

11. The method as claimed in claim 2, wherein an aqueous solution is used and the solution additionally also contains one or more wetting agents.

12. The method as claimed in claim 3, wherein it is performed with harvested fruits.

13. The method as claimed in claim 12, wherein the plant parts, prior to the treatment are subjected to a pre-treatment step, wherein a surface treatment is effected for roughening of the surface.

14. The method as claimed in claim 1, wherein it is performed prior to the harvesting of the plant parts.

15. The method as claimed in claim 1, wherein the plant parts are additionally treated with plant tannins separately from the treatment with iron(II) salt(s), where this treatment can be effected before, during or after the treatment with iron(II) salt(s).

16. (canceled)

17. A polyphenolic plant part containing corky tissue on its surface that has been masked with one or more iron(II) salts.

18. A polyphenolic plant part containing corky tissue on its surface that has been masked with one or more aqueous solutions containing one or more iron(II) salts.

Description

WORKING EXAMPLES

[0062] The invention is further illustrated to the person skilled in the art hereinafter by examples, but these should in no way be considered as a restriction to the embodiments detailed.

Example 1 Masking of Red-Brown Corky Tissue in Commercially Supplied Avocado Fruits

[0063] Commercial avocado fruits of the Hass variety were purchased from a food supplier and made up with a solution of iron(II) gluconate without further additions in tap water. The fruits had the usual black color indicating maturity and taste, and slight (1-2 mm) impressibility. Application was effected outdoors at an air temperature of 18° and 63% humidity in the sun. The fruits were placed in the shade about 10 min after application. The use concentration of iron(II) gluconate was 1 g/l of salt, and about 10 μl of droplets were applied. The test solution was applied with complete coverage of corky areas in some cases, and with only half coverage of these in other cases. The test solution dried out after about 20-30 min. Only about 2 hours after application, the red-brown, corky sites were completely black and were barely distinguishable, if at all, to the naked eye from the rest of the dark shell. The texture of the corky site changed to such a degree that the rough structure of the cork became similarly smooth and shiny to the intact, healthy surface. The black color achieved was completely water-insoluble/water-resistant and could not be wiped off.

[0064] FIG. 1 shows, in schematic form, the fruit with the corky area before treatment and after about 4 hours:

[0065] Top: Fruit before application with corky sites before treatment. Individual droplets were applied in the circled region.

[0066] Bottom: Fruit 4 hours after application.

[0067] The three insets show enlargements of the treatment site before a), during b) and after application c).

Example 2 Masking of Corky Tissue Under Various Conditions

[0068] The abovementioned treatment with iron gluconate was varied, and in all cases the masking shown in example 1 was obtained. This includes:

A) Various types of water, including deionized water, tap water, and CIPAC C standard water (with hardness 500 ppm),
B) Freshly made-up and one-week-old treatment fluid (spray liquor),
C) Treatment and/or drying or storage exposed to the sun or in the dark (box),
D) The use concentration of the iron gluconate solution. The color intensity is independent of the color of the starting solution (clear and transparent to pale yellow to yellow-brown over and above 10 g/l). In the case of avocado, a concentration of 0.5 g/l of salt was needed for the dark color shown in example 1.

Comparative Example

[0069] Other Gluconates

[0070] Sodium gluconate and zinc gluconate had no effect and caused no change in the corky areas.

Example 3 Other Iron(II) Salts

[0071] The following were likewise effective as masking agents, in decreasing order: iron(II) lactate, iron(III) sulfate, iron(III) citrate, iron(III) salicylate, a mixed salt of iron(II) gluconate and nitrate.

[0072] The effect of iron(II) gluconate was the strongest in terms of color and change in texture (smoothing).

Example 4 Green Fruits and Areas without Corking

[0073] Iron(II) gluconate was applied at 5 g/l to various fruits such as apples, avocados, bananas, papayas, grapes or else avocado or apple leaves, and no change in color or any other symptoms of phytotoxicity were observed.

Example 5 Other Fruits with Desirable Color Change Via an Appropriate Concentration of Iron(II) Gluconate are Eggplants, Cherries and Plums

[0074]