Controlled atmosphere package for fruit and packaging method

Abstract: A method for packaging and a package of climacteric fruit (2) have been developed, wherein one or more unripe fruit (2) are sealed in a bag (3) of suitable material, having a preselected permeability to gas and aqueous vapour, and sealed hermetically; the bag (3) is filled with a modified atmosphere comprising oxygen in a quantity ranging from 2% to 20% by volume, carbon dioxide in a quantity ranging from 0% to 20% by volume, ethylene in a quantity ranging from 0% to 3% by volume, the remainder being nitrogen.

Description: The present invention relates to a method for packaging climacteric fruit and a package obtained with said method. In the present description and in the claims the expression "climacteric fruit" is used to indicate a fruit the ripening of which comprises a step characterized by the appearance of a breathing peak (climacteric peak) and by an increase in the production of ethylene (C 2 H 4 ). Examples of climacteric fruit are bananas, apples, pears, peaches, plums, nectarines, tomatoes. It is known that bananas arrive on distribution markets a long time after they have been picked. Bananas are picked from the tree while still unripe and are transported by transport means such as ships (banana-boats), cars or containers, toward the countries of the distribution markets. In the transport means, the unripe bananas are kept in a refrigerator and when they are unloaded they are transferred to other refrigeration cells from which they are removed in relation to market demand, when they have to be made to ripen. Their ripening is caused by creating, in ripening cells, suitable conditions of temperature, degree of relative humidity, and, especially, providing them with a suitable quantity of ethylene to trigger their ripening process. In particular, in the ripening cells air is added (about 20% of oxygen (O 2 ) and 80% of nitrogen (N 2 )) with the addition of about 0.1% of ethylene; relative humidity is adjusted to 90-95% and temperature to 20-22°C. The bananas are kept in the ripening cells for about forty-eight hours. Periodically, the air is changed to avoid an accumulation of carbon dioxide (CO 2 ) that would produce fermentation in the bananas. When the bananas have reached the desired degree of ripening, they are distributed in the points of sale to the public. Once put on sale, the bananas must be consumed within the space of a week, at most. In addition to being complex and expensive due to the need to use ripening cells, this process is also fairly rigid in that, once the ripening process has started in the cells, the bananas must be sold and consumed in a comparatively short time interval. Similar problems also occur for other climacteric fruit. The object of the present invention is a method for packaging climacteric fruit and a package containing the same fruit that allow their distribution cycle to be made simpler, flexible and economical. The abovementioned object achieved, according to the invention, with a method for packaging according to claim 1 and a package of climacteric fruit according to claim 6 by means of which the unripe (green) fruit are kept, at room temperature and for a certain period of time, in bags with given characteristics of permeability to gas and aqueous vapour, filled with a modified atmosphere. At the desired moment, the fruit is made to ripen simply by opening the bag and leaving the fruit under environmental conditions for a further given period of time. With the method of packaging and the package according to the invention it is possible to keep unripe fruit at room temperature for periods of about two, three months. After which, in order to trigger the ripening process, it is sufficient to open the bag. About a day and a half, two days, after the opening of the bag, the fruit reaches complete ripening and exhibits organoleptic qualities comparable to those of fruit ripened in the ripening cells. The ripening of the fruit according to the present invention can be activated at any time, by opening the bag that contains them, about two, three days after packaging. The method of packaging and the package according to the invention exhibits several advantages. They simplify the distribution cycle of the fruit, they reduce its costs and they make it more flexible. In fact, they allow the usual ripening cells as well as the refrigeration cells to be eliminated, if the fruit is packaged immediately after being unloaded from the transport means. Moreover, they allow the consumer to keep the fruit without particular precautions up to the end of the storage period (about two, three months) and, especially, they allow the fruit to be consumed at the time that is felt most appropriate. Features and advantages of the invention will now be illustrated with reference to a preferred embodiment represented as a non-limiting example in the enclosed figure which shows a package for climacteric fruit, particularly bananas, according to the invention. In the figure it is shown a package 1 for a banana 2, comprising a bag 3 formed by a film of suitable material having a preselected permeability to gases and to aqueous vapour. The bag 3 is closed hermetically along edges 4. The material of the bag 3 is selected from the group comprising: low-density polyethylene (LDPE), polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), oriented polypropylene (OPP), polyvinylchloride (PVC), oriented polystyrene (OPS), polyethylene terephthlate (PET), polyvinyl acetate (EVA), polyvinyl alcohol (EVOH). The film of the bag 3 has a thickness ranging from 20 to 50 microns, preferably 35 microns. The bag 3 is filled with a modified atmosphere comprising oxygen in a quantity ranging from 2% to 20% by volume, preferably from 2% to 6% by volume, carbon dioxide in a quantity ranging from 0% to 20% by volume, preferably from 6% to 13% by volume, ethylene in a quantity ranging from 0% to 3% by volume, preferably from 0.1% to 1.5% by volume, the remainder being nitrogen. Typically, the bag 3 is formed by a film of LDPE 35 microns thick having permeability to oxygen equal to 6,800 cm 3 /m 2 24 h atm, to carbon dioxide equal to 25,000 cm 3 /m 2 24 h atm, to ethylene equal to 22,000 cm 3 /m 2 24 h atm, where permeability is determined with the method of ASTM-D 1434. Permeability to aqueous vapour is equal to 10 g/m 2 24 h, determined according to the method ASTM 389 83. The bag contains a modified atmosphere comprising 2% by volume of oxygen, 8% by volume of carbon dioxide, 0.1% of ethylene and 89.9% of nitrogen. The package 1 is prepared when the bananas are still unripe (green), after being unloaded from the banana-boats or after a stay in refrigeration cells. The procedure is to insert in the bag 3 one still unripe banana 2, or two or more bananas. Then the bag 3 is filled with the modified atmosphere having the composition indicated above and it is closed hermetically by sealing under heat. Filling the bag 3 with the modified atmosphere and sealing under heat are performed with traditional packaging machines, provided with cylinders for the supply of the required gases. The package 1 can be kept at room temperature for about two, three months. In the bag 3 the composition of the modified atmosphere remains substantially constant. During this period of time, starting with about the second, third day after packaging, the banana can be made to ripen at any time by opening the bag 3 and leaving it under environmental conditions for a day and a half, two days. Tests performed on bananas, kept with the method of the present invention and ripened after opening the bags that contained them, exhibit characteristics that are similar to those of fruit ripened in the ripening cells: weight drop equal to about 1%, refractometric residue (percentage of sugar) equal to about 20%. Moreover, they have the following Cie-Lab colour parameters: "a" (turn from green to red) equal to about 2%, "b" (turn toward yellow) equal to about 45%, "L" (brightness) equal to about 65%.

Claims: A method for packaging climacteric fruit (2) comprising the following steps: a) inserting at least one unripe fruit (2) in a bag (3) of a suitable material; b) filling said bag (3) with a modified atmosphere; and c) hermetically sealing said bag (3); characterized in that d) said material is a film of a plastic material selected from low-density polyethylene (LDPE), polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), oriented polypropylene (OPP), polyvinylchloride (PVC), oriented polystyrene (OPS), polyethylene terephthalate (PET), polyvinyl acetate (EVA), and polyvinyl alcohol (EVOH) having a thickness ranging from 20 to 50 micron, and e) said modified atmosphere comprises oxygen in a quantity ranging from 2% to 20% by volume, carbon dioxide in a quantity ranging from 6% to 13% by volume, ethylene in a quantity ranging from 0,1% to 1,5% by volume, the remainder being nitrogen (N 2 ). A method according to claim 1, characterized in that said oxygen ranges from 2% to 6% by volume. A method according to claim 4, characterized in that oxygen is equal to 2% by volume, carbon dioxide is equal to 8% by volume and ethylene is equal to 0.1%. A method according to any of the preceding claims from 1 to 3, characterized in that said bag is formed by a film of LDPE having permeability to oxygen equal to 6,800 cm 3 /m 2 24 h atm, to carbon dioxide equal to 25,000 cm 3 /m 2 24 h atm, to ethylene equal to 22,000 cm 3 /m 2 24 h atm and to aqueous vapour equal to 10 g/m 2 24 h. A method according to claim 4, characterized in that said film is a film of LDPE 35 microns thick. A package (1) for climacteric fruit (2) comprising at least one bag (3) of suitable material, containing at least one unripe fruit (2), filled with a modified atmosphere and hermetically sealed, characterized in that said material is a film of a plastic material selected from low-density polyethylene (LDPE), polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), oriented polypropylene (OPP), polyvinylchloride (PVC), oriented polystyrene (OPS), polyethylene terephthalate (PET), polyvinyl acetate (EVA), and polyvinyl alcohol (EVOH) having a thickness ranging from 20 to 50 micron, and said modified atmosphere comprises oxygen in a quantity ranging from 2% to 20% by volume, carbon dioxide in a quantity ranging from 6% to 13% by volume, ethylene in a quantity ranging from 0,1% to 1,5% by volume, the remainder being nitrogen. A package (1) according to claim 6, characterized in that said oxygen ranges from 2% to 6% by volume. A package (1) according to claim 6, characterized in that oxygen is equal to 2% by volume, carbon dioxide is equal to 8% by volume ethylene is equal to 0.1%. A package (1) according to any of the preceding claims from 6 to 8, characterized in that said bag (3) is formed by a film of LDPE having permeability to oxygen equal to 6,800 cm 3 /m 2 24 h atm, to carbon dioxide equal to 25,000 cm 3 /m 2 24 h atm, to ethylene equal to 22,000 cm 3 /m 2 24 h atm and to aqueous vapour equal to 10 g/m 2 24 h. A package (1) according to claim 9, characterized in that said film is a film of LDPE 35 microns thick.

Inventors: SCOLARO MAURO, SCOLARO, MAURO
Applicants: SCOLARO MAURO, SCOLARO, MAURO
Application year: 1996
Main classification: B65D81
IPC codes: B65D81