Ripening chamber and method for ripening fruit

Abstract

The present invention relates to a ripening chamber and a method for fruit ripening. In particular, the present invention relates to a banana ripening chamber and a method for the artificial ripening of bananas (banana ripening technique). In a method according to the invention for ripening fruits, bananas, a respiration of the fruits is measured in a closed chamber containing the fruits to be ripened. A ripening chamber according to the invention is adapted to carry out a method according to the invention for ripening fruit.

Claims

1. A method of ripening fruits, comprising: arranging fruits to be ripened in a gas-tight ripening room; measuring respiration activity of the fruits to be ripened during ripening in the gas-tight ripening room, fumigating with ethylene for a period, in a period the concentration of ethylene is varied in the range of 50 ppm to 300 ppm; and wherein during the period, the concentration of ethylene is actively and continuously varied depending on one or more of an increase in CO.sub.2 concentration or a decrease in O.sub.2 concentration.

2. The method according to claim 1, further comprising guiding or controlling ripening as a function of a respiration of the fruits over a CO.sub.2, an O.sub.2 concentration or an ethylene concentration in the gas-tight ripening room.

3. The method of claim 2, wherein in the ripening room a predetermined ethylene concentration is set or regulated, which is varied over the duration of the ripening process.

4. The method of claim 3, wherein after a predetermined period of time, the ethylene concentration at a lower level is kept constant, at most at a concentration of 50 ppm.

5. The method of claim 1, wherein the ripening process comprises a plurality of phases, which are characterized by their gas concentrations, wherein in a first phase, a steady increase is measurable.

6. The method of claim 5, wherein in an intermediate phase, a fumigation with ethylene takes place, as soon as in the first phase, a constant increase in the CO.sub.2 concentration or a constant decrease in the O.sub.2 concentration is measured.

7. The method of claim 6, wherein in the final phase, the CO.sub.2 or the O.sub.2 concentration is kept constant.

8. The method of claim 1, wherein an absolute CO.sub.2 concentration or a change in CO.sub.2 concentration is regulated by addition of ethylene, addition of O.sub.2, addition of nitrogen, or removal of CO.sub.2 and temperature.

9. The method of claim 1, wherein a guidance or control of the temperature in the ripening room and thus of the fruits takes place.

10. The method of claim 1, wherein the measurement of the parameters is carried out continuously or at intervals.

11. The method of claim 1, wherein the color impression is measured manually or automatically or optionally assigned by means of an algorithm to a degree of ripeness described by a ripening number.

12. The method of claim 11, wherein the measurement of the degree of ripeness is part of a control loop within the method.

13. The method of claim 3, wherein when fumigated with ethylene, the ethylene concentration is set in the range of 80 to 250 ppm.

14. The method of claim 1, wherein after a predetermined period of time, the ethylene concentration at a lower level is kept constant, at most at a concentration of 30 ppm.

15. The method of claim 1, wherein the ripening process comprises a plurality of phases, which are characterized by their gas concentrations, wherein in a final phase, no increase in the CO.sub.2 concentration in the ripening room is measurable.

Description

(1) The invention will be explained below in embodiments with reference to the accompanying drawings. In particular:

(2) FIG. 1 is a schematic representation of a ripening chamber according to the invention in a preferred embodiment of the invention.

(3) FIG. 1 shows a ripening chamber according to the invention with technique 1 comprising a ripening room 2 for containing fruits to be ripened or stored. The ripening room 2 is designed gas-tight in the sense of a so-called CA quality, so that only a very small gas exchange takes place between the interior of the ripening room 2 and an exterior of the chamber 1. This is ensured by the fact that the ripening room 2 is loaded via a CA-Gate 13 with the filling material 3, so the fruits. Only an optimal ripening and storage of fruits and vegetables with absolutely uniform and reproducible gas concentrations ensures uniform ripening or permanently fresh fruits. This is ensured with a CA-Gate 13, which closes, for example, according to the principle of static contact force. The filling material 3 is arranged for example on a so-called port palette. The room volume of a preferred ripening room 2 is usually between 177 m.sup.3 and 266 m.sup.3, depending on the type of chamber. However, the dimensions can be adapted to a desired amount of the filling material 3 and structural conditions. In the preferred standard chamber with 177 m.sup.3 to 266 m.sup.3 room volume 24 so-called harbor pallets are preferably stored in a so-called nine-carton stacking at an utilization of the ripening room of 100%. Based on bananas as fruits, which are packed in a carton of approx. 20 kilos, at full capacity 54 cartons of 20 kg each result, i.e. about 1,080 kg of bananas per harbor pallet. This results for 24 pallets in a total volume of 25,920 kg of bananas per standard ripening chamber 1.

(4) The pallet size, pallet quantity and amount of ripening may vary.

(5) It was found that from a utilization of the ripening room 2 of 60%, i.e. 14 filled pallets in relation to the above example, the concentration values in the method according to the invention do not need to be adapted. At a lower utilization and optionally at each deviating utilization from 100% of the ripening room 2, an adjustment of the monitoring and regulating parameters of the method according to the invention, for example, with the aid of a control program, can take place.

(6) The ripening room 2 has at least one measuring means 4, for example for temperature measurement, or is connected to a device 5+6, which allows a removal, or a diversion of gas located in the ripening room 2 for the measurement of atmospheric parameters. These atmospheric parameters are for example a carbon dioxide concentration, an oxygen concentration and/or an ethylene concentration. In addition, the ripening room 2 is preferably fluidly connected to an ethylene supply 16, an oxygen supply 15, for example as a fresh air supply, and a nitrogen generator 8. These can release an amount of gas defined by the control means into the ripening room 2 by a control means for regulating the gas atmosphere within the ripening room 2. In addition, the ripening room is fluidly connected to a carbon dioxide adsorber 7, which enables a removal of carbon dioxide. In order to avoid an increase in pressure in the ripening room 2 in the case of a gas supply, for example when fresh air supply is required by the adjusting means 15, a required nitrogen supply or due to ethylene fumigation, the ripening room 2 also has a pressure flap 12 which is set up to compensate an over- or under-pressure. Alternatively, or additionally, the ripening room 2 is fluidly connected to a so-called lung 11, in which excess gas can be released or from which gas can flow back from. Thus, certain pressure fluctuations in the ripening room can be compensated.

(7) In addition to the respiration gases ethylene, oxygen and carbon dioxide, the ripening can be influenced by further parameters within the ripening room 2, in particular the temperature. In order to provide an opportunity for intervention here, the ripening room 2 preferably has a heat exchanger in combination with fans, which is fluidly connected to a temperature control, for example a cooling and/or a heater.

(8) The adjusting means and devices 4, 5, 6, 7, 8, 9, 11 suitable for influencing the atmosphere within the ripening room 2 and the ethylene supply 16 are preferably connected to a control device (not shown) in which, for example, an algorithm for controlling a method is stored, which enables an automatic control of the atmosphere within the ripening room 2 as a function of measured values and time parameters. In particular, in this case the method according to the invention is carried out, which can be carried out automatically and/or at least partially manually controlled.

(9) This can preferably be achieved by measuring how much CO.sub.2 develops within about 1 to 2 hours in the ripening room 2 as a result of the ripening processes or by how much the proportion of CO.sub.2 in the ripening room increases (fruits such as bananas absorb oxygen and release the same amount of CO.sub.2). If this respiratory quantity assumes a substantially constant value and is not fluctuating, then the second phase or intermediate phase can already be launched with the ethylene fumigation. In the second phase of ripening, a significantly lower ethylene concentration (80-200 ppm, preferably 150 ppm) is required in comparison with the prior art. Subsequently, the ethylene proportion in the chamber atmosphere is further lowered and kept at a very low level (15-40 ppm, preferably 30 ppm). Furthermore, in this phase, a certain concentration of CO.sub.2 (used here as a ripening factor and not as a storage factor) can be set and preferably kept over a longer period of time.

(10) In order to be able to keep this atmosphere constant over a longer period of time, CA technology is preferably used. An otherwise typically performed flushing of the ripening chamber with fresh air is not intended in the method according to the invention.

(11) A method according to the invention performable with the above-described ripening chamber will be described in detail in a preferred embodiment. In this embodiment, the method comprises a plurality of cycles that substantially correspond to a first phase, an intermediate phase, and a final phase or are included in them.

(12) In the first phase, a comparable state of the individual fruits, based on the ripening stage (degree of ripeness and state of the goods at the beginning of ripening), is set. Then the actual ripening process takes place in the intermediate phase, which is kept constant in the final phase at the gas concentrations. Based on a carbon dioxide concentration, the first phase comprises a comparatively steep increase in the concentration in the range of 0.1 to 5%/h, preferably in the range of 0.2 to 0.35%/h, the second phase—the intermediate phase—a comparatively low increase in the range of 0.05 to 0.2% while in the final phase the CO.sub.2 increase has no longer a relevant significance.

(13) First Phase:

(14) The first phase comprises the setting of a temperature in a temperature range of 13-20° C. and a regular, in particular hourly, measurement of the carbon dioxide production by the fruits. If this has reached a constant value, in other words if the increase in carbon dioxide concentration within the ripening room is linear and uniform, the temperature within the ripening room will be increased slightly. This condition is kept for a few hours and then ripening is initiated by fumigation with ethylene. This involves fumigation with a variable starting set point in the range of 80-300 ppm of ethylene, wherein the actual required value is calculated on the basis of the carbon dioxide concentration increase and the filling amount of the ripening room.

(15) Within the first phase, an increase in the concentration of carbon dioxide in the range of 0.05-0.4% by volume in a time frame of 1.5-3 hours is assumed.

(16) Intermediate Phase:

(17) The intermediate phase takes a period of about 1 to 3 days during which the temperature is kept stable within a range of 15-20° C. In this process, the carbon dioxide concentration is measured at regular time intervals, for example in the range of 1.5-2.5 hours, to determine how much carbon dioxide is produced by the fruits, as this allows a conclusion on the ripening process. The increase in carbon dioxide concentration in this phase should describe a substantially linear function with a low increase, in particular with a lower increase than in the first phase, preferably an increase of less than 1%, preferably less than 0.5%. If the carbon dioxide concentration, in particular its increase, deviates from the setpoint value, readjustment is made by the adjusting means of the ripening chamber 1. If, for example, an increase in the carbon dioxide concentration is too high, therefore the fruit is ripened too quickly, the setpoint value for an ethylene supply can be lowered or the ripening room can be flushed with nitrogen in order to reduce an oxygen content within the ripening room. Conversely, for example, an ethylene supply may be increased to stimulate the ripening process.

(18) The intermediate phase essentially lasts until a desired degree of ripeness of the fruits has been set. For this, the fruit is checked regularly. The ripening indicator used is, for example, the color or the properties of the fruit. Especially with bananas, the color of the fruit is also an expression of the degree of ripeness. Increasing yellow coloring correlates with a progressive degree of ripeness of the banana. For fruits that allow such a correlation of the degree of ripeness with the external appearance, the monitoring of the degree of ripeness or the detection of the final state can be automated, for example by means of photometric measurements of the degree of ripeness. For this purpose, for example, a color impression of the fruits as definitions for the predetermined degree of ripeness, in particular as ripening number (as typical for bananas) stored in the program. If the color impression is achieved with at least one measured fruit, the intermediate phase is ended, and the final phase is launched, if not another ripening cycle takes place within the intermediate phase.

(19) Thus, as an alternative or in addition to the concentration of a respiration gas, it is preferred to use the determination and monitoring of the ripening number as a measure of a color impression as a control parameter for the method according to the invention. As well as the measurement of the respiration parameters, the measurement of the color impression and/or the assignment of the ripening number is carried out manually and/or at least partially automated, wherein the last case of the automated measurement and assignment is preferred for the purpose of process simplification and process reliability.

(20) Final Phase:

(21) In the final phase, the temperature, starting from the temperature value of the intermediate phase, is lowered slowly, i.e. in particular over several hours, in particular over 5 to 30 hours, to a value of below 15° C. In addition, the gas atmosphere is frozen, meaning another respiration is prevented. The carbon dioxide concentration and the ethylene and the oxygen concentration remain substantially constant in this phase, wherein a comparatively high carbon dioxide concentration of more than 1%, preferably more than 1.5%, is set. The oxygen concentration in this phase should be in a range of 10 to 30% by volume, in particular not more than 25% by volume.

(22) In a preferred embodiment, the ripening program according to the invention comprises nine cycles, which can be assigned to the above-mentioned three phases. These are shown in Table 1. In principle, the method according to the invention is carried out with a number of cycles in the range from 4 to 12.

(23) After completion of the final phase, the actual ripening process is completed. The ripening room can be opened and does not have to be gas-tight anymore. The goods can either be further be ripened in a controlled manner in the chamber to desired color or further ripen or develop outside under different temperatures according to the desired color.

(24) TABLE-US-00001 TABLE 1 Parameters of the method according to the invention in a preferred embodiment in an embodiment of 9 cycles. Phase Cycle t in h T in ° C. c(CO.sub.2) c(O.sub.2) c(N.sub.2) c(C.sub.2H.sub.4) First phase 1 3-6 12-20 measured 2  3-18 15-20 0.2-0.4 vol %/h 80-300 ppm  Intermediate phase 3 11-13 15-19 Setpoint: regulated 0.1-0.2%/h Max: 2.5% 4 6-8 12-17 2% 15-20   As 10-30 ppm required Final phase 5 4-6 T lowered by 2% 15-20% 10-30 ppm 0.5-2.5° C. 6 2-4 T lowered by 2% 15-20% 10-30 ppm 0.5-2.5° C. 7 2-4 T lowered by 2% 15-20% 10-30 ppm 0.5-2.5° C. 8 5-7 T lowered by 2 17-20% 15-25 ppm 0.5-2.5° C. 9 2-4 10° C. < T < 15 2% 20%   20 ppm

REFERENCE LIST

(25) 1 ripening chamber with technology 2 ripening room 3 transport aids with goods 4 temperature sensor 5 adjusting means gas metering pump 6 control means 7 CO.sub.2-Adsorber 8 N.sub.2-Generator 9 apparatus for transferring cold and heat to a liquid medium 10 heat exchangers air/liquid medium for temperature control (cooling/heating) 11 lung 12 pressure flap 13 CA-Gate 14 flexible air foreclosure system 15 Oxygen aeration device with fan 16 ethylene gas mixture