Food or edible material: processes – compositions – and products – Contacting food in liquid or solid state with exteriorly... – Including packaging of contacted food or treatment of...
Patent
1987-12-03
1989-05-30
Czaja, Donald E.
Food or edible material: processes, compositions, and products
Contacting food in liquid or solid state with exteriorly...
Including packaging of contacted food or treatment of...
426319, 426320, A23B 7152
Patent
active
048349976
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of treatment of foodstuffs, particularly, but not exclusively, fruit such as apples, to prolong their shelf life. The process will be described with reference to apples, although it may be applied to other fruits.
The use of sulphur dioxide as a preservative for apple pulp to be used in manufacture is a long established and well known and documented practice. The addition of sulphur dioxide to apples at the rate of 350 mg/liter is permitted by the Preservative in Foods Regulations. At that level, thought necessary to preserve the apple pulp, the apple has a characteristic smell and flavour of sulphur dioxide and is, therefore, unsuitable for eating without further cooking and consequent softening to drive it away.
However, it is desired to preserve peeled apples in segments, slices or dice for storage at room temperature for several months. The apples should retain the crisp crunchy texture associated with fresh apples throughout that storage period. It has been found that this may be achieved by ensuring penetration of sulphur dioxide into the cell structure. The process uses much lower levels of sulphur dioxide than the established method, and therefore the product is acceptable without further cooking, thus retaining the firm texture of a raw apple.
Accordingly, the invention provides a method of extending the shelf life of foodstuffs which comprises the steps of evacuating gas from the foodstuff, treating the foodstuff with carbon dioxide and sulphur dioxide either in admixture or sequentially, evacuating said gases from the foodstuff and sealing the foodstuff into a container under an inert gas.
In cases where the preserved foodstuff is likely to exude moisture during storage, the method comprises an additional step of removing water from the product.
In the case of apples or eggs the additional step preferably comprises the step of blowing cold or ambient air over the foodstuff, after having treated the foodstuff with the gases. The amount of moisture removed in this manner may be in the region of 10% to 25% by weight of the total weight of foodstuff.
In the case of foodstuffs for human consumption, and particularly delicately flavoured foodstuffs such as apples, the amount of sulphur dioxide after processing, is for example a maximum of 250 mg/liter.
One danger in preservation methods of the present type is the development of the bacteria Clostridium botulinum which is a major pathogenic bacteria as regards humans and can prove fatal. Of course, it is advisable to minimise the danger of this bacteria developing and accordingly, the amount of sulphur dioxide preferably used is somewhat in excess of that needed for normal preservation techniques. In the case of apples, the acidity of the preserved product should ensure that the bacteria does not develop.
The container into which the foodstuff is sealed is preferably a tray, although other containers such as pouches may be used. The preferred material is a laminated plastics material with high barrier properties to oxygen, for example nylon/polyethylene.
The gas treatment step may be performed by admitting sulphur dioxide to an evacuated chamber containing the foodstuff, measuring the pressure difference to determine the level of sulphur dioxide, and then admitting carbon dioxide until atmospheric pressure is reached.
Alternatively, the sulphur dioxide and carbon dioxide may be mixed beforehand and the mixture admitted to the chamber.
The method may comprise an additional step, after evacuating said sulphur and carbon dioxides from the foodstuff, of flushing the foodstuff with carbon dioxide.
The invention will now be more particularly described with reference to the following non-limiting Examples.
EXAMPLE 1
Preservation of raw apples
This Example was carried out twice, once with Bramley cooking apples and once with Granny Smith eating apples (chosen because of their firm texture). In each case the results were comparable.
The process included the following steps: Immediately before treatment the apples
REFERENCES:
patent: 3975551 (1976-08-01), Shatila
patent: 4454945 (1984-06-01), Jabarin et al.
Czaja Donald E.
Pratt Helen
Vetostar Limited
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