Proximate and Functional Properties of Plantain Flour
Aims and Objectives
This study is therefore aimed at providing information on:
- Proximate composition of plantain flour
- Functional properties of plantain flour.
Review on the Taxonomy of plantain
Plantain belongs to the genus Musa of the family musaceae. Nearly all edible plantain cultivar are derived from two wild species, M. acuminate and M. balbisiana (Robinson, 2006). These wild species are classified on the basis of the proportion of the genetic constitution contributed by each parental source (Robinson, 2006). Plantain is a staple crop and an important dietary source of carbohydrate in Nigeria and in the humid tropical zones of Africa, Asia and South America (Robinson, 2006). Plantain is rich in vitamins A, C and B group as well as minerals such as calcium and iron (Marriott and Lancaster, 2003; Robinson, 2006). Plantain provides between 9% and 35% of the total calories in the diets of more than 14 million people in Sub sahara Africa (Robinson, 2006). The contributions of this staple starch crop to the food chains of this region cannot be overemphasized (Robinson, 2006).
Plantains are typical climacteric fruits in that they exhibit a well-defined pre-climateric phase after harvesting during which the fruit remains unripe, the basal respiration rate is low and ethylene production is almost undetectable. The respiratory climacteric commences spontaneously and there is a rapid and well-defined rise in respiratory rate which is closely synchronized with evolution of ethylene, with chlorophyll breakdown in the peel and with starch to sugar conversion and tissue softening in the pulp (Marriot and Lancaster, 2003; Ogazi, 2006). The fruit usually harvested at its mature but unripe stage, ripens within two to seven days, thus making plantain a highly perishable crop, particularly in the overripe stage (Robinson, 2006). An un-ripened banana and the plantain have high starch and low sugar levels plus copious amounts of bitter-tasting latex. Starch is converted to sugar as the fruit ripens, so that bananas can eventually contain about 25% of total sugars. As the banana ripens, the latex is also decomposed. Plantain has the stinging, bitter latex, so the peel is removed with a knife and the pulp is soaked in salt water for 5–10 min prior to cooking. Bananas are harvested unripe and green, because they can ripen and spoil very rapidly (Daniellset al., 2001).
FAO (2004) data sources put the world production of plantains at about 60 million tons (FAO, 2004). In West Africa, plantain production increased at an average annual rate of between 2.3% to 2.6% (FAO, 2004). The level of production of plantains in Africa is comparable with other fruits like grapes (57 million tons); citrus (50 million tons) but much greater than most other important fruits like apples (21 million tons) and mangoes (13 million tons) (FAO, 2004). The higher production figures for plantains has been attributed to the cheaper methods of growing that require few labor inputs, little soil preparation and little weeding are needed once the plant has established vegetative cover (FAO, 2004).
Production of Plantain
The usual method of harvesting plantains is to partly cut through the pseudostem approximately 2 m from the ground or at upper thirds with a machete. This allows the plant to bend over under the weight of the bunch. The bunch is then cut off and taken away while the pseudostem is left in the plot. The pseudostem is then cut into pieces to reconstitute the organic matter. This mode of harvesting exposes the fruits to mechanical damage, especially when no precautions are taken to prevent the bunch from falling on the ground (Wainwright and Burdon, 2001). In the case of dwarf types, bunches can directly be cut off and removed from the pseudostem without cutting it into sections.
The use of plastic forms is recommended to protect bunches of plantain during harvesting and transportation to the packaging site in the same manner as exportation from industrial plantations. This reduces mechanical damage and avoids reduction of fruit quality of plantains for exportation.
In producing zones and at the local distribution market, bunches of plantains are generally stockpiled in bulk. However, simple methods intended to reduce the desiccation and the evapotranspiration rate of fruits are occasionally used within the traditional distribution channel to maintain a certain level of freshness and an acceptable quality for a number of days. These measures include precautions to limit mechanical damage to fruits; stocking bunches under shades shielded from the sun and protection of piles of plantains with leaves of plantain or bags regularly moistened with water. Studies carried out in Côte-d’Ivoire have shown that bunches of plantains (Offoto and Orishele cultivars) harvested at normal maturity stage can be kept green in peasant farms for 14 to 20 days at 302oC and 24 to 27 days at 202 0C. This assumes that bunches are harvested when fingers are well filled or rounded and wrapped in plastic bags (8/100 mm) mixed with powder of dry cocoa leaves or rice husk. They will be preserved without remarkable modifications of their organoleptic characteristics (Agboet al., 2006) Traders who want to sell their plantains at the ripe stage generally induce the ripening process by stocking them in baskets, drums or other containers covered with plastic bags or jute bags to maintain heat among fruits. These containers are ventilated by removing the covers after 2 to 4 days.
Studies carried out on the conservation of plantains recommend that they be packaged in suitable plastic bags to reduce air circulation. In addition, the use of low temperatures (12 to 140C) to extend the green life span and maintain the fresh quality of fruits is advised (Hernandez, 2003; Ngalani, 2006; Marchal, 2000; Collin, 2001). These modern techniques of conservation require an investment (purchase of appropriate plastic bags and storage equipment, installation of positive cold store, electricity bills, etc.). Traditional plantain producers and traders would hardly adopt them.
All storage attempts to prolong the shelf life of mature green plantain should be preceded by an economic analysis of the system in place: network type, stage of harvest, market value and price after conservation (N’daAdopoet al., 2006). The use of refrigerators or appropriate plastic bags would then be necessary only in the long distribution channel to great distances to supply the non-producing zones where selling plantains at a higher price will justify the establishment of such a technology.
MATERIALS AND METHOD
Collection of Sample
Matured, green and wholesome plantains were purchased from local market, near Oba palace in Owo, Ondo State.
Preparation of Plantain Flour
The unripe plantain was processed in the processing laboratory in the department of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Nigeria. The unripe plantains were washed, hand-peeled and manually sliced into cylindrical pieces of 2mm thickness. Blanching was carried out on the sliced samples in hot water at a temperature of 1000C for about 10 minutes, after which it was sundried from morning (9 am) till evening (4 pm) for 7 days. The dried plantains were then milled using attrition mill to obtain the flour followed by sieving to produce flour which passed through a 500 µm sieving bowl. The plantain flour obtained was packaged in polyethylene bags labeled and stored at room temperature for further analysis.
RESULTS AND DISCUSSION
Table 4.1: Proximate Composition of Plantain Flour
CONCLUSION AND RECOMMENDATIONS
This study focused on the proximate composition and functional properties of plantain flour. The proximate composition of plantain flour showed that it is rich in carbohydrate. The result from proximate composition obtained confirm the feasibility of producing starchy flour from plantain was 71.75% of carbohydrate, and with low moisture content with a value of7% for a stable shelf life. Functional properties also indicated there were significant effect in water absorption capacity and swelling index of the plantain flour. It also revealed that bulk density was 0.766%, swelling index found to be0.95%, solubility was given as18.20%, while least gelation was found to be 2.20%.
Based on these findings, the use of plantain flour together with other flour such as wheat flour in bread making and other baked products for diabetic patients and other consumers is recommended. This will help to create variety and improve the utilization of plantain flour in Nigeria.
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