Banana and Plantain Wastes 1: Production dynamics and important uses
Published Date: 10th August 2020
Global banana and plantain production
Bananas are tropical, herbaceous and perennial crops belonging to the Musaceae family, that produces one huge flower cluster and then dies. More than 1000 varieties of bananas (Musa sapientum) produced and consumed in different regions the world have been recognized. However, according to the Food and Agricultural Organization (FAO) estimates, the most commercialized is the Cavendish banana, which accounts for about 47 percent of global production. Cavendish banana crops are able to attain high yields per hectare and are known to be more resilient to natural disasters than other varieties. Plantain (Musa paradisiaca) is the name of a large group of bananas that has about 100 recognized cultivars. Scientifically, however, plantains are a type of cooking banana, which are usually starchy even when ripe, and need to be boiled, fried, or roasted to make them palatable.
Bananas and plantains are produced in 135 countries of the tropics, and subtropics, where they are also consumed, with only about 16 percent of global production being exported to other regions. They represent the world’s second-largest fruit crop. FAO published estimates for 2018 gave a total of 155.2 million tons, made up of 115.7 million tons of bananas (75%), and 39.5 million tons of plantains (25%) as global production. The top 20 banana and plantain producing counties and their production estimates are shown in Table 1. Thus, India is the world’s highest banana producer, followed by China and the Philippines, indicating that the Asian continent is the major producing region. Cavendish is the major types of bananas produced and consumed in China, while they account for 25 percent of the bananas produced and consumed in India. Approximately 50 million tons of Cavendish bananas are produced globally every year.
Cameroon is the highest African producer at a global position of 8, followed by Congo DRC and Uganda, while in West Africa, Ghana tops the chart, followed by Nigeria and Cote d'Ivoire at global positions of 12, 15 and 19. Africa however, leads in plantain production (about 33 million metric tons per annum), with Cameroon, Nigeria, Rwanda, Ghana, Uganda, and Congo DRC being the major producing countries. Ghana is the largest producer of plantain in West Africa, with about 3.95 million metric tons according to FAO (2016) estimates. Although Nigeria is the second-largest producer of plantain, it, however, does not feature among plantain exporting nations because it produces more for local consumption than for export. Indeed, most West African countries produce banana and plantain at subsistence level, except a few Francophone countries that exploit their special relationship with France to export bananas to Europe.
At the global level, the chief banana exporter is Ecuador, which accounted for about 33 percent of total global banana export volume between 2014 and 2018, followed by the Philippines and Costa Rica (13 percent each), Guatemala (12 percent) and Colombia (10 percent) as major exporters. Sub-Saharan Africa estimates show that banana and plantain consumption provides at least 25 percent of the energy needs of 70 million people. They are major staple food crops in the humid forest zones of West Africa and being perishable foodstuffs, they are mostly marketed fresh, while few of the processed products such as chips and flour are sold. They are therefore important for food security and continental economic productivity.
Banana and plantain wastes and their uses
Almost all the parts of the banana plant, for example, fruit, peel, leaf, stem, stalk, and inflorescence (flower), can be utilized in agriculture and cottage industries. They are used in numerous food and non-food-related applications such as thickeners, colorants and flavorings, macro and micro-nutrient sources, livestock feed, fibers, bioactive compound sources, and organic fertilizers. Additionally, all parts of the banana plant have some medical values, for example, the flower can be cooked and consumed by diabetic, respiratory, dysentery, and ulcer patients. The stem sap can be administered orally or applied externally against stings and bites. The roots, ashed leaves, peels, and seeds are equally used for therapeutic purposes in some countries. The banana stem can be processed into pulp and paper raw material, fiber for textiles, and fillers, or structural reinforcement in composites materials. In many banana producing countries, however, bananas are farmed for the fruits only, while the other parts are discarded as waste. This is particularly the case in African countries, although the technology for processing these wastes into valuable products had existed in Asia for centuries.
At maturity, the banana or plantain plant is cut down to harvest the fruit bunch, thus, the trunk (stem) and leaves become waste lingo-cellulosic biomass, which is either left on the ground or taken to open dumps. When the trunk is left on the ground, it decomposes and helps to maintain soil moisture and provide organic matter. The lingo-cellulosic biomass however produces greenhouse gases as they decompose. For every ton of banana fruit harvested, approximately 4 tons of biomass wastes are also produced, indicating that, for every cycle of banana fruit production, four times more biomass wastes are produced. In commercial production units or plantations, the fruit that failed to meet the quality standards is also discarded as waste. At these units, the rejection rate may reach as high as 8 to 20 percent of the harvested banana fruits, and therefore constitute a significant residue from banana or plantain production. Although this residue can be converted to animal feed, for economic reasons, the majority of the producers prefer to allow them to decompose in waste dumps. Banana peels are also regarded as waste, which could be discarded, fed to animals, or burnt to produce edible ash or alkali for local soap production in some cultures. Again, potential waste-to-energy technologies are being researched to achieve the valorization of banana wastes. These include thermal (direct combustion and incineration), thermo-chemical (particularly gasification and pyrolysis), and biochemical (composting, ethanol fermentation, and anaerobic digestion) approach. The basic concept of banana tree waste utilization is shown in Figure 1.
In India, Nepal, and the Philippines, banana wastes are being used to create innovative businesses. These countries are using banana fiber to replace the more expensive cotton that is usually more difficult to grow. African countries like Congo DRC, Cameroon, Ghana, and Nigeria could similarly exploit their abundant banana wastes for the production of beneficial products. Besides, African farmers will be highly interested to cultivate banana for extra income from the currently abandoned wastes.
The trunk or pseudo-stem
The banana or plantain stem is ordinarily a pseudo-stem consisting of an aggregation of leaf stalk bases in cylindrical form. The pseudo-stem is the stem of the banana plant that provides and transports nutrients from the soil to the fruits. It is usually discarded as waste although it could be processed into pulp, fiber, and paper due to its cellulosic content. The height of the banana plant can reach approximately 7.5 m, while the width can reach approximately 30 cm.
The middle of the pseudostem, also known as the core is tender and consumed as a vegetable in many parts of India, due to its richness in edible fiber and fresh juice, which has some medicinal value. Researchers at the Central Institute of Agricultural Engineering, Coimbatore, Tamil Nadu, India, have developed a process for converting the banana center core into rich fiber food grade flour. They removed the outer sheath of pseudostem to obtain the central core, which they washed and sliced into pieces. This was subsequently soaked in a 0.2 percent Potassium Meta bi Sulphate (KMS) for ten minutes in order to control browning. The material was then dried in a cabinet dryer at 50, 60 & 70°C, to reduce the moisture content from the initial 90 percent to 6 percent. The dried samples were ground into fine flour, and on analysis revealed that the sample dried at 60oC produced a better flour in terms of color, crude fiber (23 percent), ash (0.48 g), water holding capacity (10.64 g/g), oil absorption capacity (0.28 ml/g) and bulk density (0.385 g/cm3) than the others. Since such banana stem core flour is rich in fiber, it has been claimed to be useful in the control of obesity, and detoxification of the body. Australian researchers have also successfully converted the banana core into alternatives to forest wood products to be used in paper, packaging, furniture, building, construction, and other industries.
In India and other Asian countries, bananas are not only grown for their delicious fruits but also for textile fiber which is produced from the pseudo-stem. All varieties of bananas (M. sapientum and M. paradisiaca) have fibers in abundance in their pseudo-stem, which can be extracted after the fruit harvest and belong to the group of bast fibers. Bast fibers are classified as soft and flexible fibers that contain a special structure, the fiber node that represents a weak point and gives flexibility to them. Bast fibers occur in bundles that are glued together by pectin and calcium ions in the phloem. Since the valuable fibers are located in the phloem they must be separated from the xylem material (core) through retting processes before use. Banana fiber is also classified as an eco-friendly natural fiber, which can be spun into filaments, threads, and ropes or woven into different articles. Banana fiber is resistant to seawater and also naturally buoyant, properties that have created a ready market for it in the manufacture of ship cables.
About 1.5 million tons of quality dry banana fiber can be produced from the outer sheath of the pseudo-stem, annually, while the biomass waste derived from the process can be profitably applied to other uses. The major challenge to the adoption of banana fiber extraction technology has been a low fiber recovery rate resulting in high transportation costs. These challenges are however being overcome by mechanizing the processes through the use of more modern equipment capable of increasing fiber recovery and extraction rate.
During fiber extraction from the banana pseudo-stem, a considerable quantity of residue is generated as unsuitable products, which has been estimated at 30 to 35 tons/hectare. The fiber residue can be subjected to vermicomposting by adding animal dung or other essential components to produce organic manure. The sap extracted from pseudo-stem during fiber production can serve as liquid fertilizer and has been used to replace 20 to 30 percent of inorganic fertilizer in tree crop farming. Whole banana stem and leaves can also be processed into animal feeds. In small-scale farms, the pseudo-stem may be sliced into small pieces by mechanical or manual means and fed to pigs after heat treatment. In Cambodia, the banana pseudostem is extensively utilized as pig feed after harvesting the fruit. It can be mixed with cereal bran and kitchen wastes prior to feeding. Fermentation of macerated banana pseudo-stem with yeast solution has been shown to produce a more nutritive product than direct feeding.
Banana/plantain leaves and peels
The banana leaf is frequently used in food processing, food esthetics, and food packaging, in some Asian countries, like Indonesia and India. The young leaf can be used for the treatment of skin irritations (as a poultice). Farmers also feed the leaves to ruminants and pigs. Researchers have also incorporated banana leaves in chicken diets after fermentation with Trichoderma viride. Large quantities of peels are generated during the processing or direct consumption of banana and plantain. Traditionally, banana peels are widely fed to livestock by small-scale farmers in banana producing regions. In some cultures, it is burnt to produce ash which could be used in preparing special dishes or used in soap making because of its high content of potash. Although low in protein content, the unripe peels are moderate in their energy values, while their crude fiber values range from 14.9 to 50.0 percent. They are however rich in macro-and micro-minerals, crude fat, and polyunsaturated fatty acids (linoleic and α-linolenic acids). In addition, the peels contain high levels of antioxidants, anti-cholesterolemic, and antimicrobial compounds, while tannins have been reported to be the major anti-nutritional factor in banana peels. Several studies have been carried out on the nutritional value of plantain peels for chicken, pigs, rabbits, ruminants, and even fish, with relatively good results. However, the major concerns have been the impact of tannins contained in the peels on animals that consume them. Studies have therefore been carried out to improve the nutritive value of banana peels, either by additive inclusion or by other treatments before incorporation in animal diets.
Banana peels have also been used in the production of highly insoluble dietary fiber and antioxidant compounds both for health benefits and functional foods development. Studies have shown that plantain peels can be reused for industrial production of cost-effective carbon black and ink for printers, with a lot of positive environmental benefits. For example, peel flour is a very rich source of antioxidants, dietary fiber and has been used to produced acceptable cookies by replacing wheat flour with 10 percent banana peel flour. Other benefits of banana peels include its recent use in the preparation of nano-fertilizer blends to improve the germination percentage of crops like tomato, pepper, and garden egg.
Banana and plantain are exceptionally useful tropical crops that have been farmed mostly for their edible fruits. Innovative approaches to the conversion of banana and plantain waste into value-added products for industrial application a veritable waste management options. In pursuit of this, banana pseudo-stem-based cottage industries could be established in rural African communities to create employment opportunities, especially, for women and youths, and to increase their family income. A video on the production of different articles from the banana plant can be viewed at https://youtu.be/JBX3Y0xXMFo
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