WO1998046074A1

WO1998046074A1 - Improving the preservability of plants

Info

Publication number: WO1998046074A1
Application number: PCT/FI1998/000339
Authority: WO
Inventors: Mika Koivistoinen; Kari Jokinen; Robert Rosenqvist; Raija Ahvenainen; Eero Hurme
Original assignee: Cultor Corporation
Priority date: 1997-04-16
Filing date: 1998-04-16
Publication date: 1998-10-22
Also published as: FI971616A; AU6837198A; FI971616A0

Abstract

The present invention relates to improving the preservability of plants, such as vegetables and root crops and fruit with betaine treatment. The invention relates both to the use of betaine for improving the preservability of plants and to a method of improving the preservability of plants by subjecting them to betaine treatment. Betaine compositions suitable for use for the purposes of the invention are also described.

Description

IMPROVING THE PRESERVABILITY OF PLANTS

The present invention relates to improving the preservability of plants by betaine treatment. The invention relates both to the use of betaine for improving the preservability of plants and to a method of improving the preservability of plants by subjecting them to betaine treatment. Betaine compositions suitable for use for the purposes of the invention are also described.

BACKGROUND

Plants are an important part of our diet and have increasing significance as the consumers are paying more attention to the health aspects of food. However, plants are usually cultivated centralized in large farms and in countries suitable for cultivation as to weather and other conditions and energy economics. This often results in longer transportation and storage times and impaired plant quality.

Various methods exist for improving the preservability and storage stability of plants, such as vegetables, root crops and fruit. Plants wilt and age mainly because water evaporates and the plants consequently dry, whereas actual spoilage is usually caused by microbes. On the surfaces of harvested plants appear both micro-organisms that are part of their normal surface flora and foreign micro-organisms originating from e.g. soil, irrigation water and har- vesting. These micro-organisms may be even plant pathogens that contribute to the spoilage of plants. To decrease the number of said micro-organisms, plants may be washed and the storage temperature and humidity controlled. Aqueous solutions which may contain e.g. chlorine, borax or detergents are usually employed in the washing. To improve the storage stability the plants may also be dried, frozen, preserved or subjected to heat treatment to inactivate enzymes. Foliar plants, for example, are often cooled by spraying with cold water to decrease humidity loss. Vacuums, replacing air partly or entirely with e.g. carbon dioxide or ozone, and ionizing radiation have also been used. A mixture of ethylene and chlorinated hydrocarbons is also used, although ethylene is mainly used to produce ripening of harvested raw fruit and to provide desired colour changes. Preservatives, such as hypochlorite, sodium bicarbonate, propionates, biphenyl and borax are used e.g. for surface treatment of fruit. Sodium chloride, i.e. saline, is used e.g. for the preservation of plants by fermentation, such as in preparing sauerkraut, pickles, etc. In accordance with present nutritional norms, the aim is, however, to offer the customers fresh plants without harmful additives. Thus, the drying of plants and the use of preservatives are not considered meaningful, and neither is heat treatment, since they cause negative changes in the appearance and taste of plants. Thus the main means for keeping vegetables and fruit fresh and in good shape is mechanical protection, i.e. packaging. The purpose of packaging is to avoid microbial contamination and to prevent the plants from wilting as water evaporates. At present the most customary packaging material is plastic, but various paper and cardboard products are also used for packaging vegetables. There is, however, a growing tendency to avoid the use of packages for several reasons, e.g. the costs and energy need associated with the manufacture and use of packages, and the legislation in several countries relating to the recycling, reuse and disposal of packages for environmental reasons, setting certain obligations on the manufacturer and user of packages and the consumer of the product. If the packaging procedure is not satisfactory in all respects, resulting in the package being contaminated or dirty or the packaged product being partly of inferior quality or even spoilt, the package can also act as an excellent incubator promoting the growth of microbes and the spoilage of the product. It has been also noted that the consumer prefers to select unpacked vegetables and fruit, which are perceived as fresh and of good quality compared with packaged products. However, the preservability and shelf life of unpacked plants are lower than those of packaged products, and this could affect their price and quality. Thus there is still a distinct need to find new effective means for improving the preservability of plants.

BRIEF DESCRIPTION OF THE INVENTION

Thus it is an object of the present invention to find a way to improve the preservability of plants, simultaneously avoiding the use of substances poisonous or harmful to the flora and fauna. It has been surprisingly found that the problem can be solved by subjecting plants to betaine treatment. Betaine is a non-toxic natural product contained in several plant cells and also produced by some animals and micro-organisms. Betaine has no harmful effects on the flora or fauna.

Consequently the invention relates to the use of betaine to improve the preservability of plants. The invention particularly relates to the use of betaine to prevent plants from drying.

The invention also relates to a method of improving the preservability of plants by treating them with betaine.

The invention further relates to a method of preventing plants from drying by treating them with betaine.

The invention still further relates to a combination suitable for improving the preservability and/or preventing the drying of plants and containing a sufficient amount of betaine to achieve the desired effect, in addition to possible other substances.

DETAILED DESCRIPTION OF THE INVENTION

Betaine refers to fully N-methylated amino acids. One of the most common betaines is a glycine derivative wherein three methyl groups are attached to the nitrogen atom of the glycine molecule. This betaine compound is usually called betaine, glycine betaine or trimethyl glycine, its structural for- mula being: (CH₃)₃N⁺CH₂COO\ Other betaines include e.g. alanine betaine, proline betaine and histidine betaine. Wyn Jones R.G. and Storey R. describe betaines in detail in The Physiology and Biochemistry of Drought Resistance in Plants, Paleg, L.G. and Aspinall, D. (Eds.), Academic Press, Sydney, Australia, 1981. The publication is included herein by reference. Betaines are natural products with an important function in the metabolism of both plants and animals. Best known organisms accumulating betaine are plants belonging to the Chenopodiaceae family, such as sugar beet, and some microbes and marine invertebrates. The main reason for betaine accumulation in these organisms is probably that betaine acts as an osmolyte and thus protects the cells from the effects of osmotic stress. Unlike many salts, betaine is highly compatible with enzymes, and the betaine content in cells and cell organelles may therefore be high without having any detrimental effect on the metabolism. Betaine has also been found to have a stabilizing effect on the operation of macromolecules in cell membranes. Betaine has been found to have a protective effect in plant cells, particularly under stress conditions, such as low temperatures or high salinity. The use of betaine in improving the growth yield of plants is described in Finnish Patents 96,111 and 96,112. Betaine has also been added to fertilizers to enhance the growth of plants, as has been described in Japanese Patent Ap- plication 63-31800, Laid-open No. I-208386. To our knowledge, the use of betaine as an agent improving the preservability of harvested or growing plants has not been described or suggested in the literature of the art.

Animals are usually unable to accumulate large amounts of betaine in their cells. However, it has been observed that when betaine is used as an additive in animal nutrition or feed, a similar osmolytically protective effect is achieved as in plants. By using betaine as an additive in animal nutrition, the performance of animals can also be significantly improved. Consequently it has been found that betaine improves bowel movement and increases food intake and growth in animals. Betaine has also been found to decrease body fat in e.g. fish, chicks and pigs. Betaine has also been reported to have pharmacological effects. Hence e.g. proline betaine has been reported to prevent osteomalacia in chicks and glycine betaine the harmful effects of coccidiosis in broilers. Betaine has not been reported to have negative effects on animals.

In accordance with the present invention, betaine is used to im- prove the preservability of plants and to prevent them from drying.

The plant to be treated can be any edible plant, a vegetable, root crop, fruit, berry or mushroom. Examples of plants that are suitable for the treatment of the invention include different lettuces, such as green leaf lettuce, arrugula, iceberg lettuce, endive etc., tomato, cucumber, pumpkin, squash, cabbage, sweet pepper, carrot, rutabaga, aromatic herbs, such as parsley, dill, lemon balm, mint, rosemary etc. The invention has been found particularly usable with soft vegetables, such as foliar vegetables and cabbage, and shredded, sliced or grated plants, in which the consequences of water evaporation are usually very rapidly perceptible. The betaine treatment of the invention can be performed on both harvested and growing plants, which are stored or kept on sale in a container maintaining growth, such as a paper container, carton, plastic container, earthen pot or the like. The betaine treatment can be performed as a single treatment, preferably when the merchandise is being prepared, or as a re- peated treatment, e.g. upon harvesting and later when needed. The betaine treatment of the invention is easy to carry out, and can also be performed in the store to freshen up the vegetable or fruit counter.

The betaine treatment of the invention can be performed by any method with which a sufficient amount of betaine can be spread to the differ- ent parts of a plant to achieve the desired effect. Suitable methods include e.g. spraying a plant with solid betaine or a betaine-containing solution, e.g. an aqueous solution of betaine, spreading solid betaine or a betaine-containing solution on the plant, or immersing a plant completely or partly in a betaine- containing solution. Irrespective of the method, the treatment of the invention preferably uses an aqueous solution of betaine, its advantages including easy handling and rapid and even spreading to the different parts of a plant. Other substances, such as surfactants or other detergents, microbicides or deodorizers, can be added to said solution if desired. However, a particularly preferable betaine composition to be used for the purposes of the invention is considered to be an aqueous solution containing solely betaine as the active sub- stance. The most preferable method is considered to be the immersion in a betaine solution of a harvested plant or a plant sold as viable. Another preferable method is spraying with an aqueous solution of betaine.

The amount of betaine used naturally varies according to the particular use, application time and target. Thus, when using an aqueous solution of betaine, a suitable betaine content may be e.g. about 0.001 to 0.2 mol/l, preferably about 0.005 to 0J0 mol/l, most preferably about 0.01 to 0.05 mol/l. With the immersion method a solution of about 0.01 M has been found particularly advantageous. However, the betaine amount may vary considerably and the given amounts are to be understood to be only suggestive; all amounts improving the preservability of plants without causing negative changes in the taste and other properties of the plants are thus within the scope of the present invention.

The effects of betaine and its suitability for the purposes of the invention have been indicated in the following by using as a model glycine betaine, which is considered as a preferable betaine to be used for the purposes of the invention. Glycine betaine is commercially available e.g. as a crystalline anhydrous betaine product from Cultor Oy, Finnsugar Bioproducts. Of the various forms of glycine betaine, this form is considered preferable. Other betaine products, such as betaine monohydrate, betaine hydrochloride and betaine-containing raw solutions, are also commercially available and can be used for the purposes of the present invention. Let it be stated that other betaine compounds, such as alanine betaine, praline betaine, histidine betaine, tryptophane betaine, pipecholate betaine, p-butyro betaine, taurine betaine, carnitine etc., and betaine derivatives and salts with an improving ef- feet on the preservability of plants, can also be used for the purposes of the invention. Thus, betaine is used in the present publication and in the claims as a generic term covering various known betaines which improve the preservability of plants. Let it be stated further that although the term betaine is used in this publication and the claims, it is evident that several different betaines can be used in accordance with the invention, if desired. The invention will be described in greater detail by means of the following examples. These examples are provided only to illustrate the invention and they should not be considered to limit the scope of the invention in any way.

EXAMPLE 1 The purpose of this example was to clarify the effect of betaine treatment on lettuce, particularly the weight and sensory quality of stored lettuce. The lettuce was sold wholesale as potted lettuce in open plastic bags.

The lettuce samples were treated with an aqueous betaine solution in the manner presented in table 1. They were then stored for seven days at a temperature of +5°C and a relative humidity of 60 to 80%. During the preparation of the samples, for 1 to 2 h, they were kept at a temperature of +23°C. The temperature of the betaine solution was +15°C. Two different betaine concentrations, 0.01 mol/l and 0J mol/l, and two different treatment methods, spraying and immersion were used. Spraying was carried out by a fine spray at a spraying distance of about 20 cm (Plastex 671 , Etola). In immersion treatment the amount of betaine solution was 4 I and immersion time 1 min. The number of parallel samples was five.

Table 1. Treatment methods for plant samples

Potted lettuce samples

Unpacked control

Packaged control (open plastic bag normally used for product)

Spraying with 0J mol/l betaine solution. Unpacked

Spraying with 0.01 mol/l betaine solution. Unpacked

Immersion in 0J mol/l betaine solution. Unpacked

Immersion in 0.01 mol/l betaine solution. Unpacked

To determine the changes in weight the samples were weighed before treatment, 3 minutes after treatment, and after a storage of 2 and 7 days using a Precisa 8200D balance at a temperature of +23°C. The results are presented in table 2.

av = average value s_γ = standard deviation

Thus the betaine treatment of the invention provided distinctly better results than the unpacked control. The weight loss of potted lettuce samples immersed in betaine solution in particular was less than the weight loss of other unpacked samples, and the betaine treatment even produces results similar to those achieved by packaging the product in a plastic bag (packaged control). Treating the lettuce with 0.01 mol/l betaine solution was the most efficient way to prevent weight loss.

To perform sensory examination, the lettuce samples treated with betaine solution were stored for 7 days at a temperature of +5°C. After the storage, the whole potted lettuces were estimated by a preliminary jury. The lettuces were estimated shredded to slices by a laboratory jury. The preliminary jury estimated the appearance and odour, and the laboratory jury the appearance, odour, taste and structure by using a nine-step verbally anchored quality scale (method VTT-4440-91 ). Verbal description of the characteristics was allowed. Five (preliminary jury) or ten (laboratory jury) people whose senses had been tested and who were trained for sensory estimation participated in the estimation. The results for whole potted lettuce and shredded potted lettuce are presented in table 3 and 4, respectively.

av = average value s_x = standard deviation md = median v = range of variation

av = average value s_x= standard deviation md = median v = range of variation

Thus the betaine treatment of the invention with a betaine dosage of 0.01 mol/l produced excellent results, the quality of the samples corresponded to that of the packaged control. Particularly the appearance of the potted lettuce immersed in a 0.01 mol/l betaine solution was estimated flaw- less after 7 days' storage, the appearance was good and the odour fresh. Potted lettuce sprayed with a 0.01 mol/l betaine solution was also fully merchantable. The odours of both lettuce samples treated with a 0.01 mol/l betaine solution, but with different methods, were considered flawless. The samples treated with a 0.1 M betaine solution were also merchantable. This example proves that the betaine treatment of the invention protects plants, prevents them from drying and wilting and keeps them crisp and fresh. A preferable treatment is considered the immersion of perishable products in a dilute betaine solution. In addition to the potted lettuce acting as a model, immersion in a dilute betaine solution is also recommendable for other soft whole vegetables, such as cabbages, and shredded, packaged and unpacked plants to decrease drying. After the publication of the present invention, it will be easy for a person skilled in the art to determine the suitable betaine concentration and method of treatment for each particular plant.

EXAMPLE 2 The study described in example 1 was repeated by using carrot instead of lettuce, and a 14 days' storage time instead of 7 days. The carrots used were whole Finnish carrots packaged in a 10 kg perforated plastic sack.

The carrots were thoroughly washed with +5°C water immediately before treatment. The control was packaged in a seamed 260 x 175 mm LDPE bag with four holes having a diameter of six mm. The carrot samples were treated with a betaine/water solution in the same way as is presented for lettuce in table 1. They were then stored for 14 days at a temperature of +5°C and a relative humidity of 60 to 80%. During the preparation of the samples, for 1 to 2 h, they were kept at a temperature of +23°C. The five parallel sam- pies contained several carrots each, the total weight of the sample being about 500 g.

To determine weight changes, the carrot samples were weighed before treatment, 3 minutes after treatment, and after a storage of 7 and 14 days using a Precisa 8200D balance at a temperature of +23°C. For carrots, too, the best results were obtained by immersion treatment in a 0.01 mol/l betaine solution. The results are presented in table 5.

av = average value s = standard deviation

To perform a sensory study, whole carrots treated with betaine were stored for 14 days at +5°C. After storage the whole carrots were estimated by a preliminary jury and a laboratory jury estimated them in a grated form. The preliminary jury estimated the appearance and odour, and the laboratory jury the appearance, odour, taste and structure by using a nine-step verbally anchored quality scale (method VTT-4440-91). Verbal description of the characteristics was allowed. Five (preliminary jury) or ten (laboratory jury) people whose senses had been tested and who were trained for sensory estimation participated in the estimation. The results for whole carrots and grated carrots are presented in table 6 and 7, respectively.

av = average value s_x= standard deviation md = median v = range of variation

av = average value s_x= standard deviation md = median v = range of variation

The odour of all whole carrots was estimated flawless and the appearance merchantable. The appearance, odour, taste and structure of all grated carrots were estimated flawless, the best taste score being, however, given to the carrot immersed in a 0.01 mol/l betaine solution and to the pack- aged control. Even here the result achieved with betaine treatment was equally good or even better than that of the packaged control. Thus the treatment of the invention allows packaging of plants to be abandoned or the shelf life of fresh products to be increased further by combining the treatment of the invention with a suitable package.

EXAMPLE 3

The effect of the betaine treatment of the invention on the weight and sensory quality of sweet pepper was studied by repeating the study described in example 1 , but using sweet pepper and a 14 days' storage time. The sweet peppers were first class whole red sweet peppers packaged in shrink film and exported from the Netherlands. In the study, the unpacked control was entirely spoilt, and consequently its results could not be used, the only usable control being the packaged control.

To determine weight changes, the sweet pepper samples were weighed before treatment, 3 minutes after treatment, and after a storage of 7 and 14 days using a Precisa 8200D balance at a temperature of +23°C. The results are presented in table 8.

av = average value s_x = standard deviation

Thus, even for sweet peppers the best results were obtained by immersion treatment in a 0.01 mol/l betaine solution, even through the immersion treatment in a 0J mol/l betaine solution was nearly equally effective. The results were comparable with the result given by the packaged control.

To perform sensory examination, the whole sweet peppers treated with betaine solution were stored for 14 days at a temperature of +5°C. After storage the whole sweet peppers were estimated by a preliminary jury, and the sliced peppers were estimated by a laboratory jury. The preliminary jury estimated the appearance and odour, and the laboratory jury the appearance, odour, taste and structure by using a nine-step verbally anchored quality scale (method VTT-4440-91 ). Verbal description of the characteristics was allowed. Five (preliminary jury) or ten (laboratory jury) people whose senses had been tested and who were trained for sensory estimation participated in the estimation. The results for whole and sliced sweet peppers are presented in table 9 and 10, respectively.

av = average value s_x = standard deviation md = median v = range of variation

av = average value s_x = standard deviation md = median v = range of variation

The odour of all whole sweet peppers was estimated flawless and the appearance merchantable. The appearance and odour of sliced sweet pepper samples were estimated flawless, except for sweet pepper slices prepared of the packaged control, whose odour was estimated only satisfactory. The taste of slices prepared of sweet pepper sprayed with 0J mol/l betaine solution and immersed in 0.01 mol/l betaine solution was estimated flawless. The structure of all sweet pepper slices was estimated flawless.

EXAMPLE 4

The effect of the betaine treatment of the invention on improving the preservability of raw shredded iceberg lettuce, particularly on preventing it from drying and colour and odour defects from appearing was studied by the use of two different betaine concentrations, 0.01 mol/l and 0.02 mol/l, and a non-betaine-containing control. Other parameters included treatment time, 60, 120 and 180, area of micro perforation in the packaging film, 0, 0.31 mm² and 0.62 mm²/package, and storage time, 4, 6 and 8 days.

The iceberg lettuce, packaged in plastic wrappings, was supplied by Tuoretukku Oy on the day preceding the preparation of the samples, and stored at a temperature of +5°C and a relative humidity of 60 to 80%.

For the experiment the iceberg lettuce was sliced into about 5-mm slices, which were then immediately immersed in water (3 I water/kg of product) containing 100 mg/l of active chlorine (sodium hypochlorite solution) at +5°C for 60 s. Immediately thereafter the sliced iceberg lettuce was immersed in another washing water (3 I water/kg of product) containing 0, 0J or 0.2 mol/l betaine for 60, 120 or 180 s, and centrifuged. The sliced iceberg lettuce was then packaged in a polypropene film (OPP film, bag 16 x 23 cm, thickness 25 μm, Akerlund & Rausing Oy, Lieksa, Finland) which was intact or perforated in two different manners, in an amount of 250 g/package, and the packages were stored in the dark at +5°C and at an RH of 50 to 70%. Sliced iceberg lettuce, which was washed twice with pure water (60 s + 60 s) and packaged into an intact polypropene film acted as the control.

To determine weight changes, the samples were weighed at the beginning of storage and during storage (Precisa 8200D). The weight changes observed were not statistically significant.

At the end of each storage period, the oxygen and carbon dioxide contents of the gas space in the package were also measured (PBI Dansensor Combi Check). According to the results, only the perforation significantly af- fected these parameters.

The bags were then opened and a sensory test was performed as described in example 1 , the preliminary jury first estimating the appearance and odour, and the laboratory jury the appearance, odour, taste and structure. Of the variables, betaine was the only one with a distinctly positive effect on the preservability of shredded lettuce.

Betaine had the most significant effect on the appearance of the lettuce, which is also one of the most critical factors as far as shelf life is concerned. If the limit for the acceptability is considered to be an appearance score of 3, the statistical appearance model employed gave a shelf life of 10.5 days without betaine addition. A 0J mol/l betaine addition gave a shelf life of 12.4 days and a 0.2 mol/l betaine addition 14.3 days. Thus the shelf life increased by 4 days on the basis of the appearance of the lettuce. On the basis of the results of the test, the optimum betaine concentration may very well be more than 0.2 mol/l. According to the evaluation given by the preliminary jury, betaine addition impaired the odour of lettuce immediately after the package was opened, although the result was not statistically significant. However, the defective odour evaporated rapidly, and the laboratory jury evaluated the effect of betaine addition as positive. Betaine was also found to have a distinctly positive effect on the taste and structure of lettuce. The effect of betaine treatment on the appearance, structure, odour and taste of lettuce, as evaluated by the laboratory jury, is presented graphically in Figure 1. The variables were: storage time 6 days, treatment time 120 s, area of microperforation of packaging film 0.31 mm².

The results of this experiment, too, show that the betaine treatment of the invention is effective and particularly suited to grated fresh vegetables.

Claims

1. The use of betaine to improve the preservability of plants.

2. The use according to claim 1, characterized in that betaine is used to prevent plants from drying.

3. The use according to claim 1 or 2, characterized in that the betaine is glycine betaine, alanine betaine, proline betaine, histidine betaine, tryptophane betaine or pipecholate betaine or any other betaine compound having an improving effect on the preservability of plants.

4. The use according to claim 3, characterized in that the betaine is glycine betaine, preferably anhydrous glycine betaine.

5. The use according to any one of claims 1 to 4, characterized in that the plant is a vegetable, root crop, fruit, berry or mushroom.

6. The use according to any one of claims 1 to 5, characterize d in that the plant is a vegetable, root crop or fruit.

7. The use according to claim 6, characterized in that the plant is a soft vegetable, particularly a foliar vegetable.

8. The use according to any one of claims 1 to 7, characterize d in that the plant is a harvested or growing plant.

9. The use according to any one of claims 1 to 8, character- i z e d in that the plant is a grated, sliced or shredded vegetable, root crop or fruit.

10. The use according to any one of claims 1 to 9, characterized by the use of an aqueous solution of betaine containing 0.001 to 0.2 mol/l betaine and possibly other substances.

11. The use according to claim 10, characterized in that the aqueous solution preferably contains about 0.005 to 0J0 mol/l betaine.

12. The use according to claim 10, characterized in that the aqueous solution most preferably contains about 0.01 to 0.05 mol/l betaine.

13. The use according to any one of claims 1 to 12, charac- t e r i z e d by the use of an aqueous solution containing solely betaine as the active substance.

14. A combination suitable for use for improving the preservability of plants, characterized in that it contains betaine and possibly other conventional substances.

15. A combination according to claim 14, c h a racte rize d in that it contains betaine and water.

16. A combination according to claim 15, characterized in that it is an aqueous solution containing 0.001 to 0.2 mol/l betaine, preferably about 0.005 to 0J0 mol/l, most preferably about 0.01 to 0.5 mol/l, or is diluted with water to said betaine content when used.

17. A combination according to claim 14, characterized in that it is a solid product.

18. A combination according to any one of claims 14 to 17, characterized in that the betaine is glycine betaine, alanine betaine, proline betaine, histidine betaine, tryptophane betaine or pipecholate betaine or any other betaine compound having an improving effect on the preservability of plants.

19. A combination according to claim 18, characterized in that the betaine is glycine betaine, preferably anhydrous glycine betaine.

20. A method of improving the preservability of plants, characterized in that the plants are treated with betaine.

21. A method of preventing plants from drying, characterized in that the plants are treated with betaine.

22. A method according to claim 20 or 21, characterized in that the plants are treated with glycine betaine, alanine betaine, proline betaine, histidine betaine, tryptophane betaine or pipecholate betaine or any other betaine compound having an improving effect on the preservability of plants.

23. A method according to claim 22, characterized in that the plants are treated with glycine betaine, preferably anhydrous glycine betaine.

24. A method according to any one of claims 20 to 23, c h a r a c - terized in that the plant is a vegetable, root crop, fruit, berry or mushroom.

25. A method according to claim 24, characterized in that the plant is a vegetable, root crop or fruit, particularly a soft vegetable, particularly a foliar vegetable.

26. A method according to any one of claims 20 to 25, c h a r a c - terized in that the plant is a harvested or growing plant.

27. A method according to any one of claims 20 to 26, c h a r a c - terized in that the plant is a grated, sliced or shredded vegetable, root crop or fruit.

28. A method according to any one of claims 20 to 27, c h a r a c - terized by the use of an aqueous solution of betaine containing 0.001 to 0.2 mol/l betaine and possibly other substances for the treatment of plants.

29. A method according to claim 28, characterized in that the aqueous solution preferably contains about 0.005 to 0J0 mol/l betaine, most preferably about 0.01 to 0.05 mol/l betaine.

30. A method according to any one of claims 20 to 29, c h a r a c - terized in that the betaine treatment is performed once or repeatedly.

31. A method according to any one of claims 20 to 30, c h a r a c - terized in that betaine is applied together with a detergent, surfactant, pesticide, microbicide or deodorizer.

32. A method according to any one of claims 20 to 31 , c h a r a c - terized in that the treatment is performed by spraying, spreading or immersion.

33. A treatment according to claim 20, characterized in that the plants are treated with betaine by immersing the plants into an about 0.01 to 0.05M betaine solution.