GB2205478A - Method of preserving fresh fruit and vegetables - Google Patents

Abstract

A gas mixture is used for preserving fresh fruit/vegetables (especially potatoes) and comprises about 0.5% to 10.% oxygen and 20% to 50% carbon dioxide, the balance being nitrogen. Preferably the mixture contains 3% oxygen, 31% carbon dioxide, and 66% nitrogen. Fresh fruit/vegetables will first be dipped into an anti-oxidant, preferably a solution of sodium metabisulphite, then stored under the aforementioned gas mixture.

Description

METHOD OF PRESERVING FOOD The present invention relates to a method of preserving food particularly vegetables and more so potatoes, and comprises contacting the food with an antoxident then storing under a gas.

Food is commonly spoiled by oxidation or by the growth thereon of micrcrorganisms. Typically a potato will turn black and spoil if peeled and left untreated.

Present methods'of combatting such spoilage are to add antioxidant to the food, and to design an environment under which the food is stored which is incompatable with the serious growth of dangerous micro-organisms. For example an environment lacking in oxygen is unsuitable for the growth of aerobic micro-organisms while an environment having an abundance of oxygen is unsuitable for growth of anaerobic micro-organisms.

It is an object of the present invention to provide a method of preserving food, particularly potatoes.

According to the present invention there is provided a method of preserving fresh fruit and vegetables comprising contacting therewith an antioxidant, and thereafter storing sealably under a gas of 0.5% to 10% oxygen, 20% to 50% carbon di-oxide, the balance being nitrogen.

The method is particularly suited for the preservation of vegetables, especially potatoes.

The antioxidant is preferably a solution of sodium metabisulphite, the absorbtion of which by the fruit/ vegetable should be as high as possible without exceeding 50 ppm. The criteria for the absorbtion of the sodium metabisulphite is that oxidation of the fruit/vegetable be prevented, which with potatoes causes blackening.

Since different foods will require different amounts of antisxidant and will have varying absorbtion rates, the concentration of and contacting time with the antioxidant will be designed accordingly.

The gas is primarily designed to combat serious growth of aerobic and anaerobic micro-organisms such as will spoil the food. The range of oxygen in the gas mixture could be approximately 0.5% to 10% but preferably is around 3X.

In a preferred embodiment of the invention, peeled potatoes were soaked in a 3000 p.p.m. solution of sodium metabisulphite for five minutes, and thereafter stored under a gas mixture of 3% oxygen, 31% carbon di-oxide and 66% nitrogen.

The invention will now be described by way of example only with reference to the following preparation.

Potatoes are firstly prepared by peeling, eying and removing therefrom all blemishes, before dipping into a solution of sodium metabisulphite for an optimum time of five minutes. In this time each potato will absorb approximately 50 p.p.m. of the sodium metabisulphite (legal limit). Since chips are smaller, they will be dipped in the same solution only for an optimum time of one and a half minutes. The concentration of the solution can of course be varied thereby adjusting the dipping time but for convenience will be between 2000 and 6000 p.p.m.

After dipping, the potatoes are packed into 300 mm guage plastic bags and stored under an atmosphere of gas having the proportions: 3% oxygen, 66% nitrogen and 31% carbon di-oxide. The potatoes will now keep for seven to fifteen days. Although the stated dipping times and proportions of oxygen, nitrogen and carbon di-oxide are ideal for potatoes, the same method can be used for other vegetables and fruit the gas proportions and dipping times being suitably designed.

The gas mixture is designed to prevent the serious growth of aerobic and anaerobic micro-organisms (such as would cause bochulism) and can be varied between approximate limits of 0.5 to 10% of the gas mixture.

Without being bound by theory, the carbon di-oxide is thought to preserve the colour of the potatoes while the nitrogen is thought to prevent the potato drying out.

It is therefore advantageous to have a reasonable proportion of each of these inert gases in any given mixture.

Claims (10)

1. A method of preserving fresh fruit and vegetables comprising contacting therewith an anti-oxidant, and thereafter storing sealably under a gas of 0.5 to 10 oxygen, 20% to 50% carbon dioxide, the balance being nitrogen.

2. A method according to claim 1 wherein the antioxident is a solution of sodium metabisulphite.

3. A method according to claim 2 wherein the absorbtion of the fruit or vegetable is as close as possible to, without exceeding 50ppm sodium metabisulphite.

4. A method according to claims 2 or 3 wherein concentration of sodium metabisulphite is 3000ppm.

5. A method according to any one of the preceding claims wherein the gas mixture contains about 36 oxygen.

6. A method according to any one of the preceding claims wherein gas mixture contains about 31% carbon dioxide.

7. A method according to any one of the preceding claims wherein the gas mixture contains about 66% nitrogen.

8 A method according to any one of the preceding claims wherein the fresh vegetables are potatoes, whole or chipped.

9. A method substantially as described with particular reference to the example.

10. A gas mixture as defined in any one of claims 1,5 6 or 7 whenever used for preserving fresh fruit or eatables.