Pineapple Wastes 1: Production dynamics and waste generation
Published Date: 7th September 2020
Pineapple (Ananas comosus L.) is a herbaceous perennial tropical plant, belonging to the family Bromeliaceae. It is morphologically characterized by the presence of a stem, leaves, peduncle, crown, shoots, and adventitious roots. The peduncle and inflorescence develop from the apical meristem, while the root system is essentially adventitious, which is typical of monocotyledons, and may spread up to 1 - 2 meters laterally, and 0.85 meters vertically under ideal conditions. At maturity, the plant measures up to 1.8 m high and 1.5 m in diameter. Ideally, the plant produces 68 - 82 sessile leaves arranged in a dense compact rosette around the stem, with the older leaves at the base, and the younger ones in the center of the plant. The leaves can grow up to 100 cm in length and 7 cm in width, and tapers towards the tip, and ends in a sharp point. The short stem is completely concealed by the leaves and measures averagely 35 cm in length, and between 5.5 and 7 cm in diameter. The color of the leaf ranges from green to red, and blue to purple depending on the cultivar. When matured, the pineapple plant produces more than 200 flowers containing both the male and female reproductive organs, and surrounded by thick bracts, which are covered by trichomes, and pointed at the tip. The fruit is scaly outside, and usually contains a tuft of small leaves at the top known as the crown, which may be used for vegetative propagation. Averagely, the plant bears fruit 15 - 22 months post propagation, and it may take more than three months from flowering to fruit maturity. The shoots appear in a variety of forms such as suckers, hapa, slips, and crowns.
Pineapple is originally native to the south American Amazon basin, especially Brazil and Paraguay, where it was first domesticated. It was introduced to India, and the east and west coasts of Africa in 1548, through the trading activities of the Portuguese. Presently, pineapple production is concentrated in more than 82 countries of the tropical, and subtropical regions of the world, with more than 2.1 million acres of land under the fruit cultivation. Many varieties of pineapple exist, although the most widely grown are the Smooth Cayenne and the Queen varieties. A hybrid variety called MD2 was recently introduced, and now commands 80 percent of the global trade in pineapples. The 2018 global production estimate was 27.92 million metric tons, with Costa Rica, Philippine, and Brazil being the top three pineapple producers worldwide (Figure 1). These were followed by Thailand, Indonesia, India, and Nigeria. Nigeria is thus ranked 7th on the list of world pineapple producers and is the leading producer in Africa, followed by Kenya, Democratic Republic of Congo, Ivory Coast, Guinea, and South Africa as other major African producers. Medium- and small-scale producers account for a sizable proportion of the total pineapple production in these African countries.
Pineapple contributes more than 20 percent of the world production of tropical fruits, and as a crop is second only to bananas as the most important harvested fruit. Ninety percent of the global demand for fresh pineapple comes from developed economies like the USA, France, Japan, Belgium, Italy, Germany, Canada, Spain, England, Korea, Netherlands, and Singapore among others. The crop also remains important for local consumption both in the fresh market and as a raw material for local processing industries. The pineapple fruit can be consumed as fresh cuts, cooked, juiced, and dried. In the Philippines, the fermented pulp is made into a popular sweetmeat called nata de pina. In some Africa countries, young, tender shoots are eaten in salads, while the terminal bud or "cabbage" and the inflorescences are eaten raw or cooked. Fresh pineapple is an excellent source of antioxidants and vitamins. For example, 100 g of the fresh fruit contains 47.8 or 80 percent vitamin C and 50 calories equivalent to that of apples. It also contains small amounts of Vitamin A and beta-carotene.
Food and medicinal uses of pineapple
The pineapple fruit is a cherished food in all countries of the world. It also has some medicinal, substances, while the fiber extracted from the leaves is used in making quality textiles, and several other items. Wastes generated from the processing of pineapple fruits, and leaves are converted into animal feed, manure, and biofuel. Ripe pineapple fruit is highly perishable, therefore it is normally eaten fresh in many cultures after removing the crown, rind, eyes, and core. In industrial processing units, these processes are mechanized, and the fruit may be processed into canned fruit, juice, wine, jam, or other products. Pineapple fruit has high moisture, sugars, vitamin C, and low crude fiber contents. The fruit waste also serves as a fermentation substrate for the production of alcohol, and wine. Pineapple has long been used for medical purposes in ethno medicines in several cultures. It has been used as an appetite stimulator, diuretic, contraceptive, worm expeller, and ulcer prevention among other uses. It is high in the proteolytic enzyme bromelain, an anti-inflammatory compound, and vitamin C, an antioxidant that collectively plays important roles in the healing process. Bromelain is also used as a commercial meat tenderizer, and for wound debridement.
Uses of Pineapple biomass wastes
In commercial pineapple plantations, approximately 13 tons per hectare of pineapple residues are produced per cropping season. Traditionally, these wastes are cleared by burning, which not only causes haze, and pollution but also causes peat fire which may be difficult to control. Research on the beneficial alternative uses of these wastes has shown that they could be converted into animal feed or composted to produce organic manure. For example, the organic mass of the pineapple leaf residue can be converted into the vermicompost through a simple biotechnological process of composting, using certain efficient species of earthworm. The process is facilitated by special types of earthworms and microorganisms to achieve a faster rate of biomass degradation than in common composting. Usually, the biomass materials are consumed by the earthworms, and then passed through their guts where they are transformed into manure that is rich in microbial activity, and plant growth regulators, as well as having pest repellent attributes.
The processing of pineapple fruits into canned products generates large quantities of waste products include 44.36 percent peel/skin and 15 percent core with respect to the total raw materials (Figure 2). The peel/skin has been used as a potential substrate for methane, ethanol, and hydrogen generation, while the core the second biomass waste from the fruit processing has been used for the production of pineapple juice concentrates, alcoholic, non-alcoholic beverages. Pineapple peel as a solid waste has also been fermented successfully to produce biogas containing up to 48 percent methane using the indigenous microorganisms. The outer peel and core also called bran, are produced during industrial processing of the pineapple fruit, and have been processed into animal feed. Similarly, the leaves and crown have been ensiled, and fed to ruminants, while the dried and ensiled bran has been used as supplemental feedstuff to replace up to 50 percent roughage in rations for dairy cattle.
Pineapple bran contains some juice rich in flavor similar to the pineapple fruit. The juice is also rich in sugar, protein, vitamins, and nutrients essential for microbial growth. Its crude protein and ash contents are 2.5 times more than that of the fruit pulp. Pineapple bran has therefore been used to produce vinegar beverages in some Asian countries. This is achieved by fermenting the pineapple bran so as to produce some fruit vinegar rich in both amino acids, and essential trace elements. Pineapple peel/skin because of its high content of glucose, fructose, and other essential nutrients, has successfully been used to produce poly 3-hydroxybutyrate, a potential replacement of synthetic plastics due to its biodegradability, and sustainability. Bromelain is a strong commercially available proteolytic enzyme extracted from the pineapple stem, core, and peel, using different extraction, and purification techniques. Pineapple waste has served as a substrate for the production of lactic, and citric acids using submerged, and solid-state fermentation.
Fiber extraction from pineapple leaves
Every year, tons of pineapple leaves are produced as part of the pineapple farming operation, with only a very limited quantity of these being utilized, while the rest is discarded as waste. In its raw form, the leaves are not suited for ruminant feeding, and hence after harvest of the fruits, their disposal creates a big problem. Pineapple leaves are however known to yield a strong, white, and silky fiber, and therefore can be grown solely for fiber production. The potential of the leaves, as a major part of the pineapple plant which is currently virtually unexploited, is however gaining global attention. The fiber is extracted from the leaves either by mechanical means or by retting the leaves in water. Although the fiber possess silky luster, creamy color, finer than jute, good antibacterial, and dyeing properties, the yield is comparatively low at about 2.5 - 3.5 percent only of total leaf biomass. Thus, farming pineapple solely for fiber extraction may not economically viable, and therefore may not be readily adopted by rural farmers.
In Asia, the traditional methods of pineapple leaf fiber extraction are laborious and involve manual or machine decortication followed by retting and/or washing. Research into modern methods of fiber extraction has however increased in recent times. Specifically, in India, pineapple fiber derived thread is used in shoemaking, while in West Africa, the pineapple fiber has been used to string jewels, and also to weave caps. Pineapple leaf fiber has been used in making heavy fabrics such as upholstery materials, and curtains, and in industrial appliances like tires, and conveyor belts. Again, fabrics made from pineapple leaf fibers are valued as superior fabrics in many cultures, especially the Philippines, where it has been utilized as raw material for producing high-quality textiles. It has been blended with jute, wool, and cotton in different proportions to produce composite materials of varying quality.
Use of pineapple biomass waste as animal feed
In India, the residual biomass debris obtained during the extraction of pineapple leaf fiber has been used in vermicomposting and preparation of animal feeds as additional income generation avenue by the pineapple growers. Research has also shown that pineapple leaves, crown, residual pulp, skin, and peels can be processed by microbial fermentation into a ruminant, pig, and poultry feeds. The proximate composition of pineapple leaves on analysis have been shown to be 8.47 percent crude protein, 17.89 percent crude fiber, 25.87 percent acid detergent fiber, and 42.28 percent neutral detergent fiber among others. Therefore, in several studies, varying mixtures of pineapple leaves, and high protein leaf meals like Leucaena have been co-ensiled to improve its nutrient value for high-performance animals. Other studies have reported that pineapple leaves can be used as a component in the total mixed ration for dairy cattle, with a substantial reduction in feed cost, and no deleterious effect on milk production.
Different types of pineapple wastes such as fermented pineapple fruit waste meal, leaf powder, and bromelain extract have been fed to poultry with varying effects on growth, laying performance, and meat quality. For example, a study at Ataturk University, Erzurum, Turkey reported that bromelain supplementation in the diet of laying hens resulted in improved antioxidant defense, and better health. Again, studies on the use of ensiled waste pineapple leaf residues as feed for growing pigs showed good growth performant, and meat quality.
Available information shows that the large number of wastes produced during pineapple fruits harvest, and processing into food items, which are currently regarded as waste material could be converted into valuable products. The leaves could be processed into fiber, while the crown, peels, and stem could be processed into animal feed, manure, biofuel, and several industrial products. These technologies have been developed in Asian countries, and need to be adopted by African pineapple producers in order to enhance the profitability of pineapple farming in the continent. A video on pineapple waste processing into livestock feed can be viewed at https://youtu.be/-Lf-g6QY7Ng
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