WO1991005479A1

WO1991005479A1 - Preparations for treating fruit

Info

Publication number: WO1991005479A1
Application number: PCT/GB1990/001548
Authority: WO
Inventors: Kenneth James
Original assignee: Surface Systems International Limited
Priority date: 1989-10-10
Filing date: 1990-10-09
Publication date: 1991-05-02
Also published as: GB8922777D0; AU6618190A

Abstract

A preparation for treating apples and pears to protect them against Scald and citrus and other fruits to protect them against cold damage comprises an aqueous solution of a composition comprising sucrose ester(s) and at least one anti-oxidant selected from natural and synthetic agents including tocopherols, ascorbic acid, esters of gallic acid, vitamin E, butylated hydroxy toluene (BHT), butylated hydroxyanisole (BHA), and 6-O-Palmitol-L-ascorbic acid. The sucrose ester(s), composition comprises 50-80 % sucrose ester(s) 5-20 % foam control agent and 15-30 % viscosity modifier. The sucrose ester(s) preferably have a chain length of C?12 to C18¿, the preferred foam control agents are mono-diglycerides and the preferred viscosity modifier is sodium carboxymethyl cellulose.

Description

PREPARATIONS FOR TREATING FRUIT

This invention relates to preparations for treating fruit, and more particularly to preparations for treating apples and pears to protect them against Scald, and citrus and other fruits against cold damage.

Apples and pears which have been cultivated or stored in cold conditions can sometimes become blemished with brown markings which are commonly referred to as Scald. With the advent of refrigeration for the long term storage of apples and pears Scald became a serious problem. As the cause of Scald in apples and pears became better understood so a fairly successful prophylactic treatment was developed which comprises a dip containing either of the chemicals dipheny¬ lamine or ethoxyquin. However, there is now a growing awareness of the toxic nature of these chemicals and increasing pressure, particularly from environmentalists, to reduce or eliminate their use in the treatment of apples and pears. This is causing concern in the fruit trade so that ways of reducing or eliminating the use of these chemicals in the treatment of apples and pears against Scald are being actively sought. Likewise, cold damage to citrus and other fruits is a problem.

It is now generally accepted that the problem of Scald in apples and pears is directly related to an accumulation in the natural surface wax of these fruit of a sesqui- terpene, alpha-farnesene, and that this in turn is controlled by the amount of ethylene which is present. Alpha-farnesene becomes oxidised to form conjugated trienes during cold storage of the fruit and the concentration of these trienes is directly related to the incidence of Scald. Diphenylamine and ethoxyquin act as anti-oxidants to inhibit oxidation of the alpha-farnesene and the formation of conjugated triene systems. Similar oxidative processes are involved in other fruit, like citrus, which develop chill damage as a result of exposure to low temperatures.

It is also known that fruit, including apples, pears and citrus fruits, coated with an aqueous solution of sucrose ester(s), ripen more slowly and have increased shelf-life.

The present invention has as its object to provide preparations for treating apples and pears to protect them against Scald and to avoid the use of diphenylamine and ethoxyquin. It can also be used for treating citrus or other fruits to protect them against cold damage.

The present invention provides a preparation for treating fruit, the preparation comprising an aqueous dispersion of a composition comprising sucrose ester(s) and at least one anti-oxidant selected from natural and synthetic agents including tocopherols, ascorbic acid, esters of gallic acid, vitamin E, butylated hydroxy toluene (BHT), butylated hydroxy anisole (BHA) and 6-0-Palmitol-L- ascorbic acid.

The aqueous dispersion of sucrose ester(s) may be prepared by mixing with water a composition comprising, in weight per cent:

Sucrose ester(s) 50-80%, preferably 60-70% Foam control agent 5-20%, preferably 10-20% Viscosity modifier 15-30%, preferably 18-28% The sucrose ester(s) used in the present invention are preferably those having a chain length of C^**-^**** to C^**"°. The preferred foam control agents are mono/diglycerides and the preferred viscosity modifier is sodium carboxymethyl cellulose.

The mono/diglycerides may be used in an amount from 0-20%. When amounts at the lower end of the range are used, anti- foaming agents such as food-approved silicon anti-foaments may be added to the final formulation before use to achieve the necessary anti-foaming requirements.

The final viscosity of the dispersion is preferably in the range 2.0 - 23.0 P at 20°C and the shear rate is preferably 850 sec-1. By altering the degree of substitution or the polymeric chain length of the sodium carboxymethyl cellulose, the amount needed to achieve the required viscosity may be altered dramatically. This is particularly true if xanthan or guar gum is used. Depending on the formulation requirements, the end product may be either a liquid or a solid.

A preferred composition for mixing with water to form the aqueous dispersion comprises, in weight percent:

C^**-° unsaturated sucrose ester 26%

C^1*c"-° saturated sucrose ester 36%

Mono/diglycerides 15-

Sodium carboxymethyl cellulose 23% The composition is preferably mixed with water to produce a 1% solution, although different solutions may be used if desired.

The anti-oxidant(s) used in the preparation of the present invention may be present in the aqueous dispersion in an amount of from 125 to 10,000 ppm, preferably from 250 ppm to 5000 ppm and more preferably from 500 ppm to 1500 ppm, although the amount used will vary according to the particular anti-oxidants used.

A preferred embodiment of the invention will now be discussed with reference to the accompanying drawings in which:-

Figure 1 shows the effect of mixtures of diphenylamine and an aqueous dispersion comprising sucrose esters on the symptoms of Scald in apples;

Figure 2 shows the effect of a mixture of a 0.62% aqueous dispersion comprising sucrose esters and 1500 ppm of either butylated hydroxy toluene or propyl 3,4,5- trihydroxybenzoate on the symptoms of Scald in apples compared with the effect of diphenylamine alone;

Figure 3 shows the effect on Scald in Granny Smith apples of a 0.62% aqueous dispersion comprising sucrose esters and increasing concentrations of BHT; and

Figure 4 shows the effect on Scald symptom of a 0.62% aqueous solution comprising sucrose esters and increasing concentrations of 6-0-Palmitol-L-ascorbic acid (ascorbyl palmitate) . ---. Although the anti-oxidants used in the preparation of the present invention are approved for food use and suitable for use in food, including fruit, they have not previously been used under commercial conditions to control Scald in apples and pears or cold damage in citrus or other fruits because of their poor solubility in water which has required the use of an organic solvent, such as a vegetable oil, as a carrier for the anti-oxidan . Suitable vegetable oils are, however, phyto-toxic and cause severe burning to the skin, which makes them unsuitable for use with fruit. In the present invention the aqueous solution of sucrose ester(s), which is itself non-toxic and suitable for food use, acts as an emulsifier for the anti-oxidant and as an enhancer of the anti-oxidant effect.

In the preferred composition of the present invention, the unsaturated sucrose ester is water soluble and may also be organic soluble, the saturated sucrose ester is water soluble or water suspendable and organic soluble, the mono/diglycerides are organic soluble and the sodium carboxymethyl cellulose is water soluble. A composition for mixing with water to produce the aqueous solution can be produced by emulsifying the mono/diglycerides into an aqueous solution of unsaturated sucrose ester followed by addition of the saturated sucrose ester to complete emulsification. The anti-oxidant may be dissolved in the liquid mono/diglycerides, with warming if required, prior to adding to the aqueous solution of unsaturated sucrose ester. The sodium carboxymethyl cellulose can be added at any convenient stage. As an alternative to the above mono/diglycerides anti-foam agents may be added to the final formulation prior to use. The resulting emulsion is dried to produce a powder which when dispersed in water yields a dispersion containing no visible particles and which can be used to coat fruit, yielding a coating which is not visible to the naked eye and which does not cause phyto-toxicity. The coating is, moreover, non-toxic and suitable for use on fruit, e.g., as a dip or spray for coating fruit.

Laboratory tests have indicated that synergism may well exist between the sucrose ester(s) and the anti-oxidant in the control of Superficial Scald in apples and pears. It is believed that this may be due to the fact that the sucrose ester(s) control ethylene production in the fruit whilst the anti-oxidant controls alpha-farnesene breakdown.

Figure 1 shows the effect on the symptoms of superficial Scald in apples of solutions of diphenylamine alone and diphenylamine in a 1% aqueous solution of sucrose esters. The black areas represent severe Scald symptoms and the white areas represent mild Scald symptoms. Column A shows the amount of Scald in untreated apples, B shows apples treated with a 500 ppm solution of diphenylamine, C shows apples treated with 500 ppm diphenylamine in a 0.62% aqueous dispersion of sucrose esters and D shows apples treated with 2500 ppm diphenylamine. It can clearly be seen from a comparison of columns B and C that the use of diphenylamine together with the solution of sucrose esters drastically reduced the amount of Scald from that obtained with the same amount of diphenylamine alone. Thus, as mentioned previously the use of diphenylamine is undesirable due to its toxicity the use of 500 p.p.m. of diphenylamine in 0.62% dispersion of sucrose esters can be seen as a more desirable alternative.

Figure 2 shows the effect of treatment of apples with a 0.62% aqueous dispersion of sucrose esters and 1500 ppm either butylated hydroxy toluene or propyl 3,4,5- trihydroxybenzoate compared with the effect of treatment with diphenylamine alone. Column A shows the amount of Scald in untreated apples ten days after removal from approximately 6 months storage. B shows apples treated with 2500 ppm diphenylamine, C shows apples treated with 1500 ppm of propyl 3,4,5- trihydroxybenzoate in a 0.62% dispersion of sucrose esters and D shows apples treated with 1500 ppm butylated hydroxy toluene in a 0.62% dispersion of sucrose esters. The level of Scald is clearly reduced in columns C and D over that of columns A and B. Thus, treatment of the apples with a 0.62% dispersion of sucrose esters containing 1500 ppm of either propyl 3,4,5-trihydroxybenzoate or butylated hydroxy toluene produced a greater reduction in the level of Scald than treatment with 2500 ppm diphenylamine. The present invention therefore provides an improved alternative to the use of diphenylamine.

Figure 3 shows the effect of increasing concentrations of butylated hydroxy toluene (BHT) in a 0.62% dispersion of sucrose esters on the percentage of Scald in Granny Smith apples. The percentage of Scald is reduced proportionally with the increase in concentration of BHT,^' 1500 ppm BHT reducing the Scald to almost 0%.

Figure 4 shows the effect of increasing concentrations of 6-0-Palmitol-L-ascorbic acid (ascorbyl palmitate) on the level of Scald, the dotted line showing the level of Scald in untreated apples. Here it can be seen that with concentrations less than 1500 ppm, the Scald is worse than that of untreated apples, the low levels of ascorbyl palmitate exacerbating the Scald. In these conditions therefore, the concentration of anti-oxidant must be at least 1500 ppm to achieve control of Scald. This demonstrates the difference in amounts of the different anti-oxidants which are required for effective control of the Scald. Laboratory tests have produced the unexpected result that apples treated with the preparation of the present invention lasted much longer at room temperature than either untreated apples or apples treated with an aqueous dispersion of sucrose ester(s) without the anti-oxidant. Thus, Granny Smith apples treated with the preparation of the present invention lasted much longer at room temperature in terms of green colour, flesh pressure and internal white flesh colour than either untreated apples of the same variety or apples of the same variety treated with an aqueous dispersion of sucrose ester(s) without the anti- oxidant, thus unexpectedly indicating that fruit treated with the preparation of the present invention will have a longer shelf life than either untreated fruit or fruit treated with an aqueous dispersion of sucrose ester(s) alone.

Claims

1. A preparation for treating fruit characterised in that it comprises an aqueous dispersion of a composition comprising sucrose ester(s) and at least one anti-oxidant selected from natural and synthetic agents including tocopherols, ascorbic acid, esters of gallic acid, vitamin E, butylated hydroxy toluene (BHT), butylated hydroxyanisole (BHA), and 6-0-Palmitol-L-ascorbic acid.

2. A preparation according to claim 1 , characterised in that the composition comprising sucrose ester(s) comprises 50-80% sucrose ester(s), 5-20% foam control agent and 15-30% viscosity modifier.

3. A preparation according to claim 2, characterised in that the sucrose ester(s) have a chain length of C¹² to C¹⁸.

4. A preparation according to claim 2 or 3, characterised in that the foam control agent is a mono/diglyceride.

5. A preparation according to any of claims 2 to 4, characterised in that the viscosity modifier is sodium carboxymethyl cellulose.

6. A preparation according to any preceding claim, characterised in that the aqueous dispersion comprises 1% of the composition comprising sucrose ester(s).

7. A preparation according to any preceding claim, characterised in that the at least one anti-oxidant is present in the aqueous dispersion in an amount from 125 ppm to 10,000 ppm.

8. A preparation according to claim 1 characterised in that it is a viscosity in the range 2.0 - 23.0 P as at 20°C and a shear rate of 850 sec-1.

9. A method of protecting apples and pears against Scald and citrus and other fruits against cold damage characterised by coating the fruit with an aqueous dispersion of a composition comprising sucrose ester(s) and at least one anti-oxidant selected from natural and synthetic agents including tocopherols, ascorbic acid, esters of gallic acid, vitamin E, butylated hydroxy toluene (BHT), butylated hydroxy anisole (BHA), a d 6-0-Palmitol-L- ascorbic acid.