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Fruit should be harvested early in the day, when the temperature is low. The fruit can be harvested by cutting the stalk when the bananas are plump but green. For tree-ripened fruit, cut one hand at a time as it ripens. If latter is done, check stalk daily as rodents can eat the insides of every banana, from above, and the stalk will look untouched. Once harvested the stalk should be hung in a cool, shady place.
- The plant has six or less functional leaves.
- Fruits are full, plump, round and light green (index 1).
- Angles in the fingers are rounded.
- Leaves turn yellow.
Latundan | 9 – 11 | Harvest not earlier than 70 hanging days |
Lakatan | 12 – 14 | Harvest not earlier than 80 hanging days |
Saba/Cardaba | 20 – 24 | Harvest not earlier than 118 hanging days |
High humidity reduces water loss, and increases storage life. However, high humidity also encourages fungal growth. A relative humidity of 90% provides the best compromise for storing plantain and banana. Humidity can be raised in a container or room by spraying water in a fine mist. Humidity is reduced by venting. Humidity can be controlled with the help of a humidistat. Traditional methods for increasing the storage humidity include spraying fruit intermittently with water, storing fruit on wet sacking, and storing fruit in boxes filled with moist coir or sawdust. Although effective, these methods can cause excessive wetting, which leads to fruit splitting and reduces market quality. Air circulation is an effective method used to reduce temperature in storage rooms. However, ventilation also increases water loss from fruit, by removing the saturated layer of air that surrounds the fruit. If ventilation is used to reduce temperature, water loss can be reduced by:
- covering fruit with tarpaulins
- packing fruit into bags, boxes, or cartons
- wrapping fruit in polyethylene bags or heat shrink plastic films
At the packing house, the bananas are then separated into hands. The hands are washed in a solution (2% alum, 20% chlorine) to sterilize them, and to prevent latex from cut fruit staining the peel, and then treated with fungicide.
Enzymes sweeten and soften the banana, and change the color of the peel. The enzyme that makes bananas sweet is called amylase. Amylase breaks down the starch in the banana fruit. When the starch is broken into its smaller sugar components, called glucose, the banana tastes sweet. The enzyme that softens the banana is called pectinase. Pectinase breaks down the cell walls in the banana fruit so that it becomes less firm. The peel of the banana also becomes softer as it ripens. Other enzymes break down chlorophyll molecules in the banana. The green pigment of chlorophyll is destroyed and replaced by yellow, red or blue pigments. Depending on the type of banana, the result is either the golden yellow color (dessert banana), or shades of red or purple for other banana varieties. Once the banana peel has been softened, it bruises much more easily. Bruising causes yet another enzyme called polyphenoloxidase to speed up oxidation, which turns a banana peel brown. Eventually the entire peel will turn almost black. Even when a fresh banana is bruised, a brown spot will often develop. The flesh of the banana will also turn brown if the bruising is deep enough. Bananas fresh from the market are often not fully ripe. Green bananas are tougher and therefore easier to ship.
Banana fruit are highly susceptible to chilling injury during low temperature storage. The skins of fruit stored at 3 and 8 °C gradually darkened as storage duration increased. This chilling effect was reflected in increasing membrane permeability as shown by increased relative electrolyte leakage from skin tissue. In contrast, banana fruit stored for 8 days at 13 °C showed no chilling injury symptoms.Exposure of banana fruit to the ethylene binding inhibitor 1-methylcyclopropene (1 l l-1 1-MCP) prevented ripening. However, this treatment also enhanced the chilling injury accelerated the occurrence of chilling injury-associated increased membrane permeability. 14C-ethylene release assay showed that ethylene binding by banana fruit stored at low temperature decreased with reduced storage temperature and/or prolonged storage time. Fruit exposed to 1-MCP for 12 h and then stored at 3 or 8 °C exhibited lower ethylene binding than those stored at 13 °C. Thus, chilling injury of banana fruit stored at low temperature is associated with a decrease in ethylene binding. The ability of tissue to respond to ethylene is evidently reduced, thereby resulting in failure to ripen (Yueming Jiang et al., 2004).
During shipping, the environment of the bananas is carefully controlled so that ripening is slowed. The temperature is kept low, and the concentration of ethylene is controlled so that enzyme activity is minimized.
Normal atmospheric composition is approximately 21% oxygen, 78% nitrogen, and 0.03% carbon dioxide. By reducing the proportion of oxygen and raising the carbon dioxide, the rate of respiration is reduced, and plantain and banana ripening is delayed. For example, bananas stored in 5% carbon dioxide and 3% oxygen at 20 °C have been stored for more than 6 months.
Control of atmospheric composition requires a sealed environment. Sealed storage rooms, where levels of atmospheric gases can be monitored and adjusted, are expensive. A cheaper alternative is a plastic tent. Plastic tents are used in Malaysia and the Philippines to extend the storage life of Pisang Mas (Golden banana).
A simple and cheaper method is to seal fruit in polythene (polyethylene) bags. Plantains sealed in polythene bags remain green for a longer period than fruits stored in perforated polythene bags, paper bags, or wet coir. As the fruits respire, the atmosphere within the bag decreases in oxygen and increases in carbon dioxide. Respiration is then inhibited because of the reduced oxygen.
Plantain and banana may be sealed individually, or several fruits may be bagged together. When several plantains or bananas are stored together in a bag, the first fruit that ripens produces ethylene, and this causes other fruit to ripen. Therefore, only bag together fruit of the same maturity. Although polythene bags can extend storage life, there are a number of problems associated with their use.
In one study, storing bananas in polythene bags at 20 °C delayed ripening by up to 6 days. Also, weight loss was reduced and there was less mechanical damage. High humidity develops in polythene bags. This reduces water loss from fruit, and also has a lubricating effect, which protects fruit from physical damage.
High humidity within bags can result in development of crown rots, caused by Gleosporium musarum. These rots are controlled with fungicides such as benomyl and TBZ.
‘Green soft’ or ‘boiling’ may also occur in fruit stored in polythene bags. The peel remains green, but the pulp becomes soft and develops an off-flavor and odor. This disorder results from storing fruit in high levels of ethylene and carbon dioxide, with low oxygen. ‘Green soft’ can be avoided by including an ethylene absorber in the bag (see below), or using semipermeable polythene.
Polythene bags are now widely used in Australia to extend storage life of fruit. Studies in Sudan and Ghana confirmed the advantage of using polythene bags to extend storage life, but the technology has not been adopted in these countries. Reasons may be lack of information or unavailability of materials. However, it is more likely that polythene bags were not suited to the current system of handling, or that the extra investment in materials and time was not rewarded by higher profit at the market. To avoid high costs, cheap and easily available materials, such as moist jute bags, can also be used.
Reducing ethylene levels delays ripening. Using chemical ethylene absorbents or oxidizers, to reduce ethylene inside polythene bags, is a feasible method for extending storage life. Ethylene can be absorbed by activated carbon, or oxidized by potassium permanganate, ozone, ultraviolet light, or the use of catalysts.
The simplest ethylene absorber consists of an inert carrier, such as vermiculite or rice hulm and ash, impregnated with potassium permanganate. Potassium permanganate absorbs free ethylene. Recently, Japanese researchers have made plastic bags coated with zeolites, which absorb both oxygen and ethylene. Zeolite use is at an early stage, but may eventually result in an appropriate technology for extending storage life of plantain and banana.
Chemical coating of fruit: Researchers have investigated some chemical and physical treatments of fruit, as a cheaper way of extending storage life (Olorunda A.O & Aworh OC. 1984). The main methods investigated so far are
- chemical coating of fruits
- treatment with gibberellic acid
- radiation
There is commercial interest in the use of chemical fruit coatings, such as Prolong and Semperfresh, to delay ripening. These formulations are based on sucrose esters and carboxymethyl cellulose, and they are water dispersable. They provide a microfilm coating on the fruit surface. This film has no effect on water movement, but it may restrict the rate of gas movement through the skin of the fruit, slowing down respiration.Studies have shown that Prolong and Semperfresh delay the ripening of plantains by 8-10 days at 30 °C and low humidity. Hence, chemical coatings have potential use where temperature and humidity cannot be controlled.However, fruit coating has not been accepted in the banana trade, mainly because of high costs. Also, the subsequent ripening of the coated fruit is unpredictable, and uneven.
Several available packaging materials:
- woven large bamboo or rattan baskets lined with dried banana leaves or newsprints
- wooden crates of 30 kg capacity
- 12 kg capacity cartons.
1. Local Market:
The fruits are packed in bamboo baskets, wooden crates and corrugated cartons. These containers are lined with newspapers, banana leaves or polyethylene sheets. The linings are used to prevent the fruits from injuries during further handling.
As much as possible bamboo baskets are avoided, for they can easily be deformed. The baskets are also unstable and can easily roll off during transport. The sharp edges of the baskets may also puncture the fruit. The collapsible wooden crates with veneer slots functions better.
2. Export Market:
Export bananas are picked green, and then usually ripened in ripening rooms when they arrive in their country of destination. These are special rooms made air-tight and filled with C2H4 gas to induce ripening. Bananas can be ordered by the retailer “ungassed”, however, and may show up at the supermarket still fully green. While these bananas will ripen more slowly, the flavour will be notably richer, and the banana peel can be allowed to reach a yellow/brown speckled phase, and yet retain a firm flesh inside. Thus, shelf life is somewhat extended. The flavour and texture of bananas are affected by the temperature at which they ripen. Bananas are refrigerated to between 13.6 and 15 °C during transportation. At lower temperatures, the ripening of bananas permanently stalls, and the bananas will eventually turn grey.
Bananas being exported are packed in cartoon boxes with fiber boards at the bottom. These boxes are lined with thin polyethylene films. Holes, 2.5 cm in diameter on the sides of the boxes are provided for ventilation.
Optimum storage temperature for some banana cultivars
Cultivars | Optimum Temperature °C | Storage Period (days) |
Saba/Cardaba | 10 | 35 |
Latundan | 14 | 21-28 |
Lakatan | 13 | 28 |
Source: Banana Production by : Rene Rafael C. Espino, Ph. D., et al, 2001
- Englberger, L. 2003. Carotenoid-rich bananas in Micronesia. InfoMusa 12(2): 2–5.
- “FAOSTAT: ProdSTAT: Crops”. Food and Agriculture Organization. 2005.
http://faostat.fao.org/site/567/DesktopDefault.aspx?PageID=567. Retrieved on 09-12-2006. - http://agroforestry.net/tti/Musa-banana-plantain.pdf
- http://www.ctahr.hawaii.edu/nelsons/banana/
- Kepler, A.K., and F.G. Rust. 2005. Bananas and Plantains of French Polynesia. Part I Traditional Non-Fe‘i Bananas: Descriptions, color photographs, status, and possible kinships with Hawai‘i’s ancestral bananas. Part II Color photographs of Western introduced Varieties. Part III Names & Synonyms of Extant and Recently Extirpated Varieties, Tahiti & the Marquesas Islands. Part IV Traditional Non-Fe‘i Banana Varieties, Society and Marquesas Islands: Known Historical Names, Meanings, and Locations dating back to the mid-19th Century. Part V Appendices. Unpublished.
- Lassoudiere, A., 1974. La mosaïque dite a tirets du bananier Poyo en Cote d’ Ivoire. Fruits,. 29: 349-357. Page 4. Int. J. Virol, 3 (2): 96-99.
- Lockhart, B.E. 1986. Occurence of canna yellow mottle virus in North America. Phytopathology 76: 995.
- Nelson, S.C., R.C. Ploetz, and A.K. Kepler. 2006. Musa species (bananas and plantains), ver. 2.2. In: Elevitch, C.R. (ed.). Species Profiles for Pacific Island Agroforestry. Permanent Agriculture Resources (PAR), Hōlualoa, Hawai‘i. <http:// www.traditionaltree.org>
- Olorunda AO, Aworh OC. 1984. Effects of Tal Prolong, a surface coating agent, on the shelf life and quality attributes of plantains. Journal of the Science of Food and Agriculture 35: 573-578.
- Rene Rafael C. Espino, Ph. D., et al, 2000.Banana Production.“Tracing antiquity of banana cultivation in Papua New Guinea”. The Australia & Pacific Science Foundation.http://apscience.org.au/projects/PBF_02_3/pbf_02_3.htm. Retrieved on 2007-09-18
- Yueming Jiang1, , Daryl C. Joyce3, Weibao Jiang4 and Wangjin Lu. 2004. Effects of Chilling Temperatures on Ethylene Binding by Banana Fruit Plant Growth Regulation 43: 109–115, 2004.Kluwer Academic Publishers. Printed in the Netherlands.