Method for controlling banana and plantain quality by packaging

Abstract

This invention provides a method to control banana and plantain quality by providing packaging in laser microperforated plastic bags having registered microperforation arrays to allow for transmission of oxygen, carbon dioxide, and ethylene gases into and out. The method improves even ripening of the bananas and plantains, extends green life and yellow life of the bananas and plantains, controls dehydration and reduces crown mold and pedicle withering of packed bananas and plantains during transport and storage.

Claims

1. A method of packing bananas or plantains, said method having means for both ripening and extending the shelf life of said bananas or plantains, the method comprising: selecting a quantity of bananas or plantains to be packaged; providing a box of sufficient capacity to enclose the selected quantity of bananas or plantains; providing a plastic bag having a bottom at a distal end thereof, and a top at an initially open proximal end, said plastic bag being configured to enclose the selected quantity of bananas or plantains; laser microperforating the plastic bag only in a distributed plurality of target areas on the bag, each of said target areas including a plurality of microperforations, each of said target areas being separated from all of its neighbors by distances that are greater than its largest dimension, said target areas including target areas located at both the bottom and the top of the bag, said microperforations allowing a limited gas exchange through the bag; inserting the microperforated bag in the box; inserting the selected quantity of green bananas or plantains into the bag with their concave sides facing down; hermetically sealing the proximal end of the plastic bag; storing the bananas or plantains for a green storage period during which said limited gas exchange through the bag creates a modified atmosphere within the bag; and inducing banana or plantain ripening inside the hermetically sealed bag by exposing the bag to a ripening gas without opening the bag.

2. The method according to claim 1, wherein the bag material is selected from the group of plastics consisting of polyethylene, polypropylene, polyester, nylon, polystyrene, polyvinyl chloride, polylactic acid in monolayers, coextrusions, and laminates.

3. The method of claim 1, wherein the hermetic sealing of the proximal end of the bag is achieved by gathering together a proximal portion of the bag, twisting the gathered portion into a neck, folding over the neck, and securing the neck.

4. The method according to claim 1, wherein there are 4 or 6 target areas on the bag.

5. The method of claim 1, wherein there are at least three target areas on the front side of the bag and in at least three target areas on the back side of the bag.

6. The method of claim 1, wherein the selected quantity of bananas is 401b of bananas, and the target areas include a target area located approximately 2 from the distal end of the bag, and a target area located approximately 26 from the distal end of the bag.

7. The method of claim 6, wherein the microperforations are of a size between 110 and 400 microns.

8. The method according to claim 7, wherein the microperforation size is 150-235 microns.

9. The method of claim 1, wherein the selected quantity of the bananas enclosed in the bag varies between a single banana and more than 40 pounds of bananas.

10. The method of claim 1, wherein a desired O.sub.2 flux is achieved by modifying the number and/or size of the microperforations and the placement and number of target areas of the microperforations according to size of bag and weight of bananas to be packed in the bag.

11. The method of claim 1, wherein the selected quantity of plantains is 50 lb of plantains and the target areas include a target area located approximately 1 from the distal end of the bag, and a target area located approximately 17 from the bottom seal of the bag.

12. The method of claim 11, wherein the microperforation size is 225-230 microns.

13. A method to pack bananas, said method having means for both ripening and extending the yellow life of said bananas, said method comprising the steps of providing a box of sufficient capacity to enclose 40 lbs of bananas, said box having upper vents proximal to a top thereof and lower vents proximal to a bottom thereof; laser microperforating a plastic bag suitable for packing 401b of bananas in at least one upper target area on a front side thereof 26 up from a bottom seal thereof, at least one upper target area on a back side thereof 26 up from the bottom seal thereof, at least one lower target area on the front side thereof 2 up from the bottom seal thereof, and at least one lower target area on the back side thereof 2 up from the bottom seal thereof, each of said target areas including a plurality of microperforations, each of said target areas being separated from all of its neighbors by distances that are greater than its size, said laser microperforation providing microperforations of size 150-235 microns, said microperforations allowing a limited gas exchange through the bag; inserting the microperforated bag in the box so that the upper target areas are aligned with the upper vents and the lower target areas are aligned with the lower vents; inserting approximately 401b of green bananas into the bag; hermetically sealing the bag by gathering together a portion of the bag, twisting the gathered portion into a neck, folding the neck over on itself, and sealing the neck with a rubber band; storing the bananas in an ambient atmosphere for a green storage period during which said limited gas exchange through the bag creates a modified atmosphere within the bag; and inducing banana ripening inside the hermetically sealed bag by exposing the bag to ethylene gas without opening the bag.

14. A method to (a) ripen and (b) increase the shelf life of bananas or plantains, the method comprising the steps of selecting a quantity of bananas or plantains to be packaged; providing a box of sufficient capacity to enclose the selected quantity of bananas or plantains; providing a plastic bag having a bottom at a sealed distal end thereof, and a top at an initially open proximal end thereof, said plastic bag being configured to enclose the selected quantity of bananas or plantains; laser microperforating the plastic bag only in target areas, said target areas including at least one upper target area located at the top of the bag on a front side thereof, at least one upper target area located at the top of the bag on a back side thereof, at least one lower target area located at the bottom of the bag on the front side thereof, and at least one lower target area located at the bottom of the bag on the back side thereof, each of said target areas including a plurality of microperforations, each of said upper and lower target areas on the front side of the plastic bag being separated from each other by at least 16 inches, each of said upper and lower target areas on the back side of the plastic bag being separated from each other by at least 16 inches, said microperforations allowing a limited gas exchange through the bag; inserting the microperforated bag in the box; inserting the selected quantity of green bananas or plantains into the bag with their concave sides facing down; hermetically sealing the proximal end of the bag; storing the box in an external ambient atmosphere for a green storage period during which said limited gas exchange through the bag creates a modified atmosphere within the bag; moving the box into a pressurized ripening room; and inducing banana or plantain ripening inside the hermetically sealed bag by exposing the bag to ethylene gas without opening the bag.

15. A method to prevent post-harvest contamination of bananas or plantains with crown mold, said method comprising the steps of selecting a quantity of bananas or plantains to be packaged; providing a box of sufficient capacity to enclose the selected quantity of bananas or plantains; providing a plastic bag having a bottom at a sealed distal end thereof, and a top that is offset from an initially open proximal end thereof so that when the distal end is sealed, the top is at an upper limit of a containing volume created within said plastic bag; laser microperforating the plastic bag only in target areas, said target areas including at least one distal target area on a front side thereof, at least one distal target area on a back side thereof, at least one proximal target area on the front side thereof, and at least one proximal target area on the back side thereof, each of said target areas including a plurality of microperforations, said distal target areas being located at the bottom of the plastic bag, said proximal target areas being located at the top of the plastic bag, each of said target areas being separated from all of its neighbors by distances that are greater than its largest dimension, said microperforations allowing a limited gas exchange through the bag; inserting the microperforated bag into the box; inserting the selected quantity of green bananas or plantains into the bag with their concave sides facing down; hermetically sealing the proximal end of the bag; storing the box in an external ambient atmosphere for a green storage period during which said limited gas exchange through the bag creates a modified atmosphere within the bag; and inducing banana or plantain ripening inside the hermetically sealed bag by exposing the bag to ripening gas in a pressurized ripening room without opening the bag.

16. The method of claim 1, further comprising extracting air from the bag before hermetically sealing the bag.

17. The method of claim 1, further comprising storing the bananas for a yellow storage period without opening the bag after inducing banana or plantain ripening.

18. The method of claim 13, further comprising extracting air from the bag before hermetically sealing the bag.

19. The method of claim 13, further comprising storing the bananas for a yellow storage period without opening the bag after inducing banana or plantain ripening.

20. The method of claim 14, further comprising extracting air from the bag before hermetically sealing the bag.

21. The method of claim 14, further comprising storing the bananas for a yellow storage period without opening the bag after inducing banana or plantain ripening.

22. The method of claim 1, wherein the selected quantity of bananas or plantains is 3 lb of bananas or plantains.

23. The method of claim 1, wherein the box includes upper vents proximal to a top thereof and lower vents proximal to a bottom thereof; and inserting the microperforated bag in the box includes aligning target areas of the bag with corresponding vents in the box.

24. The method of claim 15, wherein the box includes upper vents proximal to a top thereof and lower vents proximal to a bottom thereof; and inserting the microperforated bag in the box includes aligning the distal and proximal target areas of the bag with corresponding vents in the box.

25. The method of claim 15, wherein the selected quantity of bananas or plantains is three pounds of bananas or plantains.

26. The method of claim 9, wherein the microperforations allow a total O.sub.2 flux for packed bananas to be within a range of 1000 cc/day-atm to 500,000 cc/day-atm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings in which:

(2) FIG. 1. Illustrates gas contents (O.sub.2, CO.sub.2, and ethylene) inside microperforated banana bags during storage, before and after ethylene gassing.

(3) FIG. 2. Illustrates ripening cycle of bananas packed in either Polypack bags, Banavac bags or registered microperforated bags after ethylene gas treatment. Day 0 marks the end of ethylene gas treatment. The total O.sub.2 flux of the RMP1 bags was 47,844 cc/day-atm while the total O.sub.2 flux of RMP2 bags was 59,805 cc/day-atm.

(4) FIG. 3 illustrates microperforations registered in a 40-lb polyethylene banana bag according to this disclosure (38.5 wide50.5 long1.5 mil) at 2 and 26 up from the bottom seal and 19 from the edge. Microperforations are in both the front face and the back face so there are 4 locations (2 front, 2 back) per bag.

(5) FIG. 4 illustrates microperforations registered in a 40-lb polyethylene banana bag according to this disclosure (38.5 wide48 long1.5 mil) at 4 locations per side: 2 locations at 1.25 up from the bottom seal and 12.5 from each side and 2 locations at 26.5 up from the bottom seal and 12.5 from each side.

(6) FIG. 5. Illustrates microperforations registered in a 50-lb polyethylene plantain bag according to this disclosure (38 wide35 long1.5 mil) at 4 locations per side: two location at 1 up from the bottom seal and two locations 17 up from the bottom seal and 12.5 from the left and right side of the bag.

DISCLOSURE OF INVENTION

(7) Currently available technology for banana and plantain packaging provides solutions that are either expensive (microporous membrane technology) or insufficient to meet the specific needs related to fruit ripening (Banavac bags or Tubopac bags). Therefore, this disclosure addresses these problems and the invention according to this disclosure provides a method to pack bananas and plantains, a method to extend the green life and the shelf live of bananas and plantains, and a method to improve the quality of the bananas and plantains.

Definitions

(8) Green life is defined as the period of time from harvest until ripening is induced (naturally or artificially).

(9) Shelf life of bananas is defined as the time, after ethylene treatment, until the banana peel shows sugar spots (color stage 7).

(10) Banana and plantain color is described in stages by the industry. A color stage of 3.5 to 5 is preferred for bananas placed on sale at retail. At color stage 3, bananas and plantains are 50% yellow and 50% green. At a color stage of 5, bananas and plantains are 95% yellow with slight green color at stem and blossom end.

(11) Registered microperforation means laser perforations registered in a well-defined area(s) of the package. Each microperforation has a preferred average diameter between 110 and 400 microns, and more preferably for bananas between 150-235 microns.

(12) In this disclosure, the units applied to the term used in reference to the O.sub.2, transmission rates of a packaging material, i.e., OTR is expressed as cc/m.sup.2-day-atmosphere (or cc/100 in.sup.2-day-atm) at 25 C., 75% RH. In the pressure units, one atmosphere (atm) is 101,325 kg/ms.sup.2. Another unit describing the flow of a particular gas through a packaging material is Flux, expressed as cc/day-atm. The Total O.sub.2 Flux of a microperforated package is the sum of the O.sub.2 Flux of the base material (e.g. polyethylene) and the O.sub.2 Flux of the microperforations. The moisture vapor transmission rate (MVTR) of a material is expressed as g H.sub.2O/m.sup.2-day-atm or g/100 in.sup.2-day-atm.

(13) The invention is now illustrated further by the non-limiting examples.

Example 1. Registered Microperforations Provide a Package that does not have to be Ripped Open to Initiate the Ripening Cycle

(14) A small scale study was conducted on packaged 40-lb bananas sealed in registered microperforated bags. The 1.0 mil polyethylene (PE) bags were 40.5 wide and 48.5 long. The bag material can also be selected from polypropylene, polyester, nylon, polystyrene, polyvinyl chloride, polylactic acid in monolayers, coextrusions, and laminates. Microperforations (225 microns in diameter) were drilled into the front and back panels of the bags and were registered at 11.5 down from the open end and 19.5 from either side. The total O.sub.2 flux of the bag (base PE film+microperforations) was 61,283 cc/day-atm. The objective was to monitor the gas composition inside the bags during simulated ship transport (3 weeks at 14 C) and after gassing with ethylene for 24 hrs.

(15) FIG. 1 shows the O.sub.2, CO.sub.2, and ethylene (C.sub.2H.sub.4) contents inside these microperforated banana bags. After about 24 hrs, the bananas consumed enough O.sub.2 and produced enough CO.sub.2 to create a modified atmosphere inside the bags, i.e, about 15% O.sub.2 and 3% CO.sub.2. Levels of ethylene before gassing were low; ranging from 1-3 ppm. Within 24 hrs of gassing the fruit with 1000 ppm ethylene (C.sub.2H.sub.4), ethylene content inside the bags rose to about 600 ppm. These data clearly indicate that ethylene can enter the bags via the microperforations, making it unnecessary to rip open the bag to initiate ripening. After the ripening room was vented, the levels of C.sub.2H.sub.4 in the bags rapidly dropped to 150 ppm and then to about 3 ppm during continued storage.

(16) Concomitant with the surge of ethylene into the bags, respiration rate of the bananas increases as evidenced by the decrease in O.sub.2 and increase in CO.sub.2 levels inside the bags. During this ripening process O.sub.2 levels dropped to 5-6% and CO.sub.2 levels rose as high as 14%. These reduced O.sub.2 levels and elevated CO.sub.2 levels will slow ripening rates and account for slower color development in bananas stored in modified atmospheres compared to those stored in ambient air.

Example 2. Green Life of Bananas can be Increased and Ripening Delayed by Packing in Registered Microperforated Bag

(17) In order to test whether packing bananas in registered microperforated bags would increase the green life and delay ripening we conducted this test and compared effects of three package types.

(18) Forty-lb boxes of green bananas packed in one of three types of bags were held at 18 C. The bag types were Polypack bag, Banavac bag and Registered microperforated bag with one location of microperforations per side. Microperforations were drilled into PE bags (40.5 wide48.5 L1 mil thick), registering the microperforations 17 down from the open end and 19.5 from the side. Front and back panels of the bags had the same number and placement of microperforations. Registered microperforated bags tested were one of two total O.sub.2 fluxes: 47,844 cc/day-atm (referred to at RMP1) and 59,805 cc/day-atm (referred to as RMP2). The two different O.sub.2 fluxes were made by varying the number and/or size of the microperforations drilled into the PE, with the average size of microperforations being 225 microns.

(19) The time required for the first cluster to ripen was recorded. This time was considered the end of green life for those bananas. Table 1 shows the green life (days) for bananas packed in Polypack, Banavac, and registered microperforated bags.

(20) TABLE-US-00001 TABLE 1 Green life of bananas packed in different bags. Average Green Green Life Bag Type Life (days) Range (days) Polypack 21 14-26 Banavac 47 32-59 Registered Microperforated 33 27-38 Bags

(21) Banana green life and banana shelf life are two competing physiological conditions. By drastically decreasing the oxygen content in the bag, as the Banavac bag does, green life is greatly increased; 26 days over bananas held in ambient air (Polypack bags) (Table 1). However, unless the Banavac bags are torn open, the bananas will not ripen. In contrast, bananas sealed in registered microperforated bags showed an increase in green life by 12 days (up to 57% increase) compared to Polypack bananas. Bananas in RMP1 and RMP2 bags gave similar green lives.

(22) Unlike unopened bananas in Banavac bags, during the ripening cycle (ethylene gas treatment) bananas in the sealed microperforated bags carried on normal ripening to a color stage of 3.5 without opening the bags while Polypack bags reached a color stage of 4.5 in the same time period as can be seen in FIG. 2 Therefore, it is clear that microperforated bags delayed the ripening of the fruit. Furthermore, unlike the green life results where the O.sub.2 fluxes of RMP1 and RMP2 bags had similar effects on green life even though the RMP2 flux was 20% higher than RMP1, O.sub.2 flux did affect the ripening rate of bananas as can be seen in FIG. 2.

(23) When the gassed bananas were held at 22 C to simulate storage conditions at the retail store, bananas in Banavac bags did not ripen at all. In fact, Banavac bananas produced soft green bananas after 4 days. Polypack bananas reached a color stage of 7 after 4 days post-ripening, compared to bananas in registered microperforated bags which changed to a color stage of 5 after 5 days. Therefore, post-ripening studies show that registered microperforated bags delay ripening, increasing the shelf life of bananas compared to Polypack and Banavac bags.

Example 3. Shipping Test Shows that Microperforations Become Occluded During Pack-Out Procedures

(24) Based on the results of the laboratory tests of Example 1 and 2 above, we designed a shipping test to compare the effects of packing bananas in registered microperforated bags (one microperforation location) versus packing them in Polypack bags. The PE bag composition, dimensions, microperforation number and registration location and the total O.sub.2 flux of the bags were the same as given in Example 1 above.

(25) Four pallets of each bag type were packed out in South America and shipped to a U.S. port for evaluation. Once the bananas arrived at the port, they were placed in ethylene gassing chambers and gassed for 24 hrs and then placed in storage rooms at 14.4 C. for 8 days.

(26) Table 2 shows the gas contents inside the various packages and the color range developed by bananas in those packages 8 days after gassing. There was a wide variability in the oxygen and carbon dioxide contents inside microperforated bags, suggesting that the microperforations were occluded in some bags during the pack-out procedures.

(27) TABLE-US-00002 TABLE 2 Headspace gas content and color development in 40-lb banana bags 8 days after gassing with ethylene. Box # % O.sub.2/% CO.sub.2 Color Range After 8 days 1 12.9/5.7 4.0-5.0 2 0.5/10.3 2.0-2.5 3 2.2/10.4 2.0-2.5 4 1.2/10.0 2.5-3.0 5 1.4/10.2 2.5-3.0 6 0.7/10.2 2.0-4.0 7 6.2/8.6 2.0-3.0 8 0.9/9.9 2.5-4.0 9 5.6/9.1 3.5-4.0 10 1.3/9.3 2.0-2.5 11 0.5/10.2 2.0-2.5 Control Ambient air 5.0-5.5 Control Ambient air 5.0-5.5 Control Ambient air 5.5-6.0

(28) When the oxygen and carbon dioxide contents inside microperforated bags were 12.9 and 5.7%, respectively, the banana color range was 4.0-5.0 which is 1 to 1.5 units lower than the range for banana in control bags. The controls were at a color stage of 5.5 to 6.0. Such reduction in color stage development by the test bags is desirable if these values are consistent. However, microperforated bags with oxygen contents of 1% or less and carbon dioxide contents of 8% or more, produced bananas with color ranges of 2.0 to 2.5, and some bags with carbon dioxide values greater than 10% produced soft green fruit, an undesirable situation. Again, the data suggested that the microperforations were occluded during pack-out.

Example 4. Location of Microperforations on the Banana Bag Affects Color Development

(29) In order to solve the problems indicated in the previous example we conducted several studies to determine the effect of microperforation location on banana color development. All bags tested had the same oxygen flux, but different microperforation locations. In some bags, the microperforations were located in one location near the top center of the bag and on both front and back panels. In other bags, microperforations were placed in two locations near the bottom of the bag which would correspond to the location of the side vent holes in the carton. Bananas packed in these bags were held for two weeks at 14.4 C. before exposing to ethylene gas ripening cycle of five days. As was demonstrated before, bananas inside microperforated bags had a color of 2.5 to 3 after the ripening cycle compared to a color of about 4 for Polypack bags and opened Banavac bags. This demonstrated, once more, that the microperforations allowed ethylene gas to penetrate the bags and initiate ripening, although the ripening was delayed compared to controls. Furthermore, Table 3 shows that fruit in microperforated bags developed color more slowly during after-gassing storage studies at 18 C. Polypack and Banavac bananas (after the Banavac bags were ripped open so ripening could occur) changed from a color of 4 to 5 after 1 day to a color of 6 after 6 days at 18 C. Bananas in bags with one microperforation location at the top of the bag had a wide range of colors stages (3.5 to 5 after 6 days), while bananas in bags with two microperforation locations placed at the bottom of the bag near the carton vent holes showed more uniform color development, with colors of 3.5-4.0, than bananas in bags with one microperforation location. In all microperforated bags, shelf life was increased compared to bananas in Polypack and Banavac bags.

(30) TABLE-US-00003 TABLE 3 Color development in banana clusters 1, 4 and 6 days after gassing with ethylene. CLUSTER BAG TYPE DAY % CLUSTERS COLOR Polypack 1 61% 4.0-5.0 4 81% 5.0-5.5 6 64% 6.0 Banavac 1 50% 4.5 4 48% 5.5 6 60% 6.0 RMP*Bags 1 48% 3.0 1 microperf location/side at the top 4 51% 3.0-5.0 6 58% 3.5-5.0 RMP* Bags 1 63% 3.0 2 microperf locations/side at the bottom of the bag at the bottom 4 60% 3.5 6 85% 3.5-4.0 *Registered Microperforated Bag

(31) The need for more than one microperforation location in banana bags was demonstrated in another ship test of 40-lb bananas packaged in S. A. and shipped to the U.S. Whenever the microperforations were located only in the bottom of the bag, the bananas in the bottom portion of the bag (after the ripening cycle) developed desirable color stages while the bananas at the top of the bag (in the same box) remained green. Conversely, when the microperforations were located only at the top of the bag, the bananas at the top developed desirable color stages while those at the bottom remained green. However, with two microperforation arrays per side in the bags, one at the top and one at the bottom, more uniform color development occurred throughout the bag.

(32) When packing the bananas in boxes the bag must be carefully placed in the box so that the microperforation zone will be aligned with the vents in the bottom and top of the box. Importantly, boxes where bananas are packed in bags according to this invention can be stored on pallet for up to two days, because the modified atmosphere in the bags slows the metabolic rate of the bananas and thus reduces generation of heat. In contrast, boxes with bananas in Banavac bags must be depalletized and air-stacked because the heat released by the ripening fruit inside the Banavac bag causes the fruit to become soft.

(33) In order to minimize risk of breaking (puncturing) the microperforated bag, and to provide cushioning for the bananas, the following method was found preferable for packing: A heavy weight piece of paper (tunnel pad) is placed in the bottom of the box followed by the plastic bag.

(34) The tunnel pad is perforated in the area that is placed over the vent hole in the bottom of the box. Banana clusters (concave side down) are arranged in the box in four rows of approximately five clusters per row. The first row is set next to one of the long sides of the box, which allows room for the second row to be put on top of the first row but offset to the opposite long side of the box. The plastic bag is pulled up and over the tunnel pad and this triple layer of packing material is folded over the first two rows of fruit. This folding creates a pocket to hold the third row of fruit as well as creating a cushion that reduces bruising. Similarly, the bag and tunnel pad are pulled over the second and third rows of fruit to create a pocket into which the fourth row of fruit is packed. The remaining bag material is gathered together and pushed through the vent hole in the box lid as the upper half of the box is slipped over the lower half. Air is extracted from the bag with a vacuum cleaner; the bag is twisted, folded over on itself and wrapped several times with a strong rubber band to seal it.

Example 5. Importance of Leak-Free (Hermetic) Seals in Maintaining Desired Gas Atmospheres Inside Banana Bags

(35) It is important to have hermetic seals in packaged bananas to attain consistent control of the atmosphere inside. Variable leakage rate at the seal or through punctures in the bags produces variable results. In this study with 3-lb microperforated banana bags, we found that the method used to close the bag greatly affected the O.sub.2 and CO.sub.2 contents inside the bags (Table 4). Bags that were tape-closed using a pressure sensitive adhesive-coated plastic tape, produced mainly leaky bags with O.sub.2 levels averaging 17%. In contrast, a rubber-band closure technique where the neck of the bag is twisted, folded over, and secured with a rubber band yielded an average O.sub.2 content of 14%. Clearly, better control of the atmosphere inside the package was achieved by executing a tight (hermetic) seal using the rubber band technique. Hermetic bag seals can be attained by a number of other methods besides a rubber-band closure technique described here. For example, heat-sealing the bag will provide a hermetic seal.

(36) TABLE-US-00004 TABLE 4 Effect of bag closure method on headspace gas contents (at 13.3 C.) inside 3-lb microperforated banana bags before ethylene gassing. Tape Closure Rubber Band Closure O.sub.2 CO.sub.2 O.sub.2 CO.sub.2 15.6 1.4 15.4 1.5 17.6 0.3 15.0 1.8 17.8 0.2 14.7 2.5 18.1 0.2 13.9 2.1 16.4 1.1 14.3 2.1 16.3 1.2 14.6 2.1 16.0 1.2 9.7 2.3 16.5 1.1 12.4 2.5 17.2 0.4 15.0 2.0 18.8 0.1 15.1 1.9 Mean std. dev. Mean std. dev 17.0 1.0 1.8 0.5 14.0 1.7 2.1 0.3

Example 6. Effects on Ripening and Shelf Life, and Unexpected Effect of Microperforations on Crown Mold and Pedicel Withering

(37) Ship Test: Tubopak v. Registered Microperforated Bags for 40-lb Bananas

(38) The objective of this study was to determine the effects of bag type (registered microperforated v. Tubopack) on the quality of 40 lb bananas, before gassing and after gassing. Tubopack bags have 84, diameter holes. Polyethylene bags (1.5 mil, 38.5 wide50.5 long) were laser microperforated with 225-230 micron holes in specific areas on the bag as depicted in FIG. 3. These microperforated bags had 4 microperforation locations, 2 sets in the front of the bag and 2 sets in the back of the bag. For both the front and the back of the bag, the first set of microperforations was placed 26 up from bottom seal and the second set was placed 2 up from the bottom seal. The total O.sub.2 flux of the bags averaged 82,294 cc/day-atm.

(39) Once the microperforated bags were filled with bananas and the bag was intertwined among the different layers of bananas, the bags were sealed by first gathering all corners of the bag together, twisting them into a neck, folding over the neck, and securing with a rubber band.

(40) Headspace Analysis on Bananas Before Gassing:

(41) The bananas arrived at a California port and were discharged within 1 to 2 days. Headspace (O.sub.2/CO.sub.2) readings were taken on registered microperforated bags approximately 9 days after the bananas' arrival to the port. The bananas were stored at 13.3 C. before measuring the gas contents inside the bag headspace. Headspace analysis (O.sub.2 and CO.sub.2 contents) was done on boxes on two different pallets.

(42) TABLE-US-00005 TABLE 5 Headspace gas readings (at 13.3 C.) in registered microperforated bag containing 40-lb bananas (before ethylene treatment) Location of Box on Pallet Headspace % O.sub.2/% CO.sub.2 4M (front) 15.6/5.9 4L (back) 15.7/5.8 4L (front) 16.3/5.5 5R (back) 16.4/6.1 5R (front) 15.1/6.3 5M (back) 15.5/5.8 5M (front) 15.7/5.6 5L (back) 16.7/5.3 5L (front) 15.1/6.3 6R (back) 15.5/6.3 6R (front) 16.0/5.5 6M (back) 16.5/4.5 6M (front) 13.8/6.8 6L (back) 16.6/4.9 6L (front) 16.5/5.6 7R (back) 16.3/5.0 7R (front) 14.9/6.7 7M (fback) 16.7/5.5 7M (front) 15.4/6.2 7L (back) 16.1/6.1

(43) Table 5 shows the O.sub.2 and CO.sub.2 content of boxes packed with bananas in microperforated bags before gassing. The readings were very consistent with O.sub.2 levels around 16% and CO.sub.2 levels between 5% and 7% before gassing with ethylene.

(44) After opening representative control and registered microperforated banana bags, we observed that bananas in the registered microperforated bags maintained moisture levels better than bananas in the Tubopack bags. Tubopack bags caused significant moisture loss, and this was expected since they have 84, diameter holes. Banavac bags don't have holes so they would maintain the moisture content. However, they undoubtedly retain too much moisture inside the bag which could lead to crown mold. The moisture vapor transmission rate (MVTR) of the microperforated bags is far greater than that of the Banavac bag. MVTRs of a 1 mil HDPE Banavac bag is less than 1 g H.sub.2O/100 in.sup.2-day while the MVTR of microperforated bags is in excess of 100 g H.sub.2O/100 in.sup.2-day, regardless of bag thickness. Obviously, water vapor can ready pass through the microperforations to reduce the concentration of moisture inside the bag. At the same size hole, the more microperforations, the higher the MVTR. The key is to allow some moisture vapor escape to reduce the growth of mold, but at the same time maintain enough moisture inside the bag to prevent dehydration.

(45) Headspace Analysis on Bananas after Gassing:

(46) Bananas were gassed for 24 hours, at 15.5 C, and headspace readings were taken. Again, readings were taken from boxes on two different pallets.

(47) TABLE-US-00006 TABLE 6 Headspace gas readings (at 15.5 C.) in registered microperforated bags containing 40-lb bananas (after ethylene treatment) Location of Box on Pallet Headspace % O.sub.2/% CO.sub.2 1R (Back) 4.9/21.5 1R (front) 12.8/10.3 1M (back) 3.5/22.3 1M (front) 12.7/11.4 1L (back) 4.1/28.0 1L (front) 11.4/13.4 2R (back) 1.5/23.5 2R (front) 7.2/17.5 2M (back) 2.9/22.8 2M (front) 6.1/19.0 2L (back) 3.0/23.8 2L (front) 5.8/21.2 3R (back) 7.8/15.1 3R (front) 4.8/20.9 3M (back) 3.6/21.3 3M (front) 17.4/3.7 3L (back) 4.8/19.7 3L (front) 2.9/21.5 4R (back) 3.7/22.3 4R (front) 4.5/21.7

(48) Table 6 shows O.sub.2 and CO.sub.2 levels inside the 40-lb microperforated banana bags after gassing with ethylene. The levels of O.sub.2 varied from <1% to 17% with most readings between 3% and 5%. The few unusually high O.sub.2 reading may be due to a poor seal, resulting in an increased flux of O.sub.2 into the bag. Those readings with O.sub.2 less than 1% may be due to microperforation occlusion.

(49) The levels of CO.sub.2 varied from 4% to 24% with the majority of the reading between 20% and 23%. We would expect to see a reduction in O.sub.2 levels and an increase in CO.sub.2 levels after gassing, because ethylene increases the respiration rate of the bananas.

(50) It appears that, in this study most of the seals were good, because they were secured with a rubber band.

(51) After gassing, the bananas in registered microperforated bags were approximately 1.5 stages behind the control (Tubopack) bananas. Bananas packaged in registered microperforated bags were not as ripe as controls, averaging a color stage of 2.5 to 3. In addition, bananas in registered microperforated bags were more uniform in color than control bananas which averaged 3 to 5 color stage (Tables 7 and 8).

(52) More moisture was maintained inside the registered microperforated bags than with the Tubopack bags, and this, undoubtedly, may have helped to prevent withered pedicels during storage (Tables 7 and 8). Bananas in registered microperforated bags showed no withered pedicels while controls averaged 9-11% withered pedicels in the light, moderate and severe ranges.

(53) Based on the data collected during this ship test, the use of registered microperforated bags with microperforations in four locations (2 in front and 2 in back) helped to eliminate the non-uniformity of ripening that was observed when only two microperforation locations were used. The twist and tie rubber band closure technique eliminated many of the leakers that were observed with tape closures. Compared to Tubopack control bags, the benefits of controlling the atmosphere using registered microperforated bags include: a reduction in the rate of color development, a reduction in moisture loss, and a reduction in crown mold and pedicel withering

(54) TABLE-US-00007 TABLE 7 Banana quality in Registered Microperforated Bags after gassing Withered Pedicels Crown Mold (%) (%) Sample OCA Clusters L M S L M S Color Latex 1 2.8 18.0 0.0 0.0 0.0 0.0 0.0 0.0 2.5 33.3 2 2.6 19.0 0.0 0.0 0.0 0.0 0.0 0.0 2.5 10.5 3 2.5 17.0 0.0 0.0 0.0 0.0 0.0 0.0 2.5-3.0 17.6 4 2.5 17.0 0.0 0.0 0.0 0.0 0.0 0.0 2.5-3.0 41.2 Average 2.60 17.8 0.0 0.0 0.0 0.0 0.0 0.0 2.5-3.0 25.4 L: Light, M: Moderate; S: Severe

(55) TABLE-US-00008 TABLE 8 Banana quality in Tubopack (control) after gassing Withered Pedicels Crown Mold (%) (%) Sample OCA Clusters L M S L M S Color Latex 1 3.0 16.0 31.3 6.3 18.8 12.5 6.3 12.5 3-5 43.8 2 2.5 17.0 23.5 11.8 29.4 5.9 17.6 11.8 3-5 23.5 3 3.2 15.0 20.0 20.0 46.7 13.3 20.0 13.3 3-6 33.3 4 2.8 16.0 25.0 12.5 0.0 12.5 0.0 0.0 3-5 25.0 Average 2.88 16.0 25.0 12.5 23.4 10.9 10.9 9.4 3-5 31.3 L: Light, M: Moderate; S: Severe

Example 7. Effects of More than Two Microperforation Locations in Banana Bags on Uniformity of Banana Ripening

(56) The effects on uniformity of banana ripening of including more than 2 microperforation locations per bag side was studied in a large ship test from South America. Forty-lb banana bags (1.5 mil PE, 38.5 wide48 L) were microperforated with 225 micron holes at 4 locations in the front panel and 4 locations in the back panel. The total 02 flux of these bags was the same as the bags in Example 6 above, i.e., 82,294 cc/day-atm. However, the total flux was divided into 4 microperforation locations/side rather than 2/side as in the previous example. FIG. 4 gives the target area locations of the microperforations in these bags.

(57) Using 4 microperforation locations/side improved the uniformity of banana ripening compared to only 2 microperforation locations/side. Bananas in bags with two microperforation locations/side showed color stages from 2.5-4.0 after ethylene ripening (Table 9). In contrast, bananas in bags with 4 microperforation locations/side showed a narrower color range of 3.0-4.0 after ripening. The data also show that color development during storage at room temperature was delayed by 1 to 1.5 stages for bananas packaged in microperforated bags compared to control packaged (Tubopack) bananas. Furthermore, bananas packaged in microperforated bags, unlike those packed in Tubopack bags, did not show dehydration, crown rot, yellow crown and withered pedicels during storage, indicating an improved shelf life for bananas stored in microperforated bags.

(58) TABLE-US-00009 TABLE 9 Banana color after ripening and storage at room temperature Days after ripening Bag Type 0 1 2 3 4 Tubopack (SOP) 4.0 (Range = 3-5) 5.0 5.5 6.5 MP-2 locations 3.0 (2.5-4.0) 3.5 4.0 5.0 6.5 MP-4 locations 3.5 (3.0-4.0) 4.0 4.5 5.5 7.0 *Note: Dehydration, crown rot, yellow crown and withered pedicel were observed in SOP bag but not in the MP (microperforated) bags

Example 8. The Weight of Bananas to be Enclosed in the Bag Determines the Number of Microperforations in the Bag and Microperforation Locations

(59) For some retail applications, it may be desirable to market a single banana (a finger) enclosed inside a small microperforated bag. The number of microperforations needed to control the quality of a single banana in a bag is far less than required by 40-lbs of bananas in a bag.

(60) A study was conducted to determine if registered microperforated bags would be useful in controlling the quality of single bananas in a 1.25 mil PE bag 3 wide11.25 long. Four, 150-micron microperforations were drilled into each side of the bag at a location of 5 up from the bottom seal. The total O.sub.2 Flux of the bag was 1920 cc/day-atm.

(61) Naked (no packaging) single finger bananas showed a color stage of 5.0 after the ripening cycle (Day 0) compared to a color stage of 4.0 for those packaged in the microperforated bag (Table 10). In addition, there was delayed color development for bananas packaged in the microperforated bag compared to the naked bananas after 2 and 4 days storage at room temperature. Therefore, the microperforated bags extended the shelf life of the single finger bananas compared to no packaging.

(62) TABLE-US-00010 TABLE 10 Banana color after ripening and storage at room temperature Days after ripening Type of Packaging 0 1 2 3 4 No Packaging- Naked 5.0 6.5 Single Finger Banana Single Finger Banana 4.0 5.0 6.5 in MP Bag

Example 9. Plantain Fruits Ripen Uniformly in 50-lb Microperforated Bags

(63) Green plantain fruits were packed in microperforated bags designed for 50 lb of plantains. The bag material was 1.5 mil thick PE Blend with an oxygen transmission rate of 350 cc O.sub.2/100 in.sup.2 day-atm. Bag dimensions were 38 wide and 35 long. Each bag had four positions of microperforations on each side of the bag. FIG. 5 shows the locations of the microperforations. Two set of microperforations were drilled into the front and back panels of the plantain bag at the following locations: 1 up and 17 up from the bottom seal of the bag and 12.5 from each bag side (FIG. 5). Each microperforation had an average diameter of 225-230 microns. The total O.sub.2 Flux of the bag was 82,294 cc/day-atm, which is the same O.sub.2 Flux that was used for 40 lbs bananas. Besides the differences in the fruit weight going into the bag (50 lbs plantain v. 40 lbs bananas), there is a difference in microperforation placement on the bag (cf. FIGS. 4 and 5). With the appropriate microperforation number and placement, plantain fruits ripened uniformly in these hermetically closed bags to color stage 3-4. Plantains in registered microperforated bags did not show crown rot, yellow crown or withered pedicels during storage, indicating an improved shelf life for plantains stored in microperforated bags.