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Genotypic variation in fruit ripening time and weight reduction among a selection of new musa hybrids Adeniji, Tajudeen Adebayo And Barimalaa, Iminabo Samuel Department of Food Science and Technology, Rivers State University of Science and Technology, P.M.B. 5080, Nkpolu, Port Harcourt, Nigeria. e-mail: tiradeniji@yahoo.com Code Number: ja08004 ABSTRACT Thirty different genotypes of plantain and banana hybrids were evaluated for fruit ripening time to provide information on their shelf life, processing, adoption, and marketing potentials. Fruit of many of the plantain and banana hybrids had a significantly longer shelf life (p<0.05) than that of the plantain landraces. Shelf life from green to the attainment of full ripening (16.3 days) was observed in 23688-2, which differed significantly (P<0.05) from all other cultivars investigated. The mean numbers of days before complete ripening in 23977-7, SH 3362 and 25333-S88 were 15.6 days, 13.8 days and 13.4 days, respectively. These clones differed significantly (p<0.05) from the two plantain landraces used in this study. Obino l’Ewai kept for 8.5 days before the attainment of full ripening. Agbagba and 25291-S32 recorded the shortest ripening times of 5.5 and 5.4 days, respectively to attain full ripening stage. Similarly, most of the plantain and banana hybrids differ significantly from the landraces in shelf life prior to senescence (stage 10). Significant difference (P<0.05) was also observed in most of the hybrids compared to plantain landraces in their keeping qualities before senescence. Specifically, hybrids 23977-7 and SH 3362 kept for 25.9 days to stage 10. Fruits of FHIA 3 showed the shortest storage life (13.3days) before senescence. The weight of 25344-18 fruit reduced from 189.6g to 104.5g during ripening from stage 1 to stage 10. The same trend in fruit weight reduction during ripening was observed for all other cultivar, irrespective of their ploidy status. @ JASEM Plantain, banana and cooking banana (Musa spp. themselves. AAB, AAA and ABB respectively) are major starch staple food crops grown throughout the Fruits and vegetables are living, biological entity when humid tropics of the world. Plantains are high attached to the growing parent plant in its agricultural yielding plants, which form an integral component environment. After harvest, produce continues to of the farming systems in tropical Africa (Wilson perform the metabolic reactions and maintain the 1983; Swennen 1990b). The International Institute physiological systems, which were present before of Tropical Agriculture (IITA) have developed harvesting. Losses before harvesting are due to several cultivars of high yielding and disease respiration and transpiration, which are constantly resistant plantain and banana hybrids, which are replaced from the flow of sap, which contains water, being currently disseminated to farmers in Nigeria photosynthates (principally sucrose and acids) and and many parts of West and Central Africa (WCA) minerals (Wills et al. (1989). The process of and East and Southern Africa (ESA). This respiration and transpiration continues after harvest, innovation was aimed to improve socio-economic and since the produce is removed from natural source development of small-holder farmers and generate of water, photosynthates and minerals, it is henceforth raw materials for food industries. The new hybrids dependent entirely on its own food reserves and that are derived from different crosses produced moisture content. Therefore, losses of respirable heavier bunch compared to their parents substrates and moisture are not compensated for and (Vuylsteke et al. 1997). Evaluation of post harvest consequently, deterioration will commence. characteristics, including fruit shelf life and ripening patterns were considered important to A harvested banana or plantain fruit undergoes ensure successful introduction of the new hybrids three physiological developmental stages, which to the farmers and food processors. This is include pre-climacteric or 'green life' stage, the important because the introgression of genes of climacteric and ripening stage, and the eat-ripe and bananas may alter fruit quality characteristics in the senescence stage (Robinson, 1996). Green-life of hybrids, including fruit ripening pattern and shelf climacteric fruit has been defined by Peacock and life, which may in turn affect consumers’ Blake (1970) as the time that elapses between acceptability and consequently result in economic harvest and the onset of the respiratory climacteric, loss. Loss refers to any change in the availability, under defined conditions. During ripening, edibility, wholesomeness or quality of food that plantain and banana peel turns to lighter green, and prevents it from being consumed by people (Ferris, then to yellow as chlorophyll is broken down, and 1991). However, loss can also be measured in during colour change the pulp becomes softer and terms of economic, quantitative, qualitative and sweeter as the ratio of sugars to starch increases nutritional terms (NRC, 1978). Losses of food (Robinson, 1996). Fruit also losses its astringency crops are many in kinds and these include weight and develop characteristic flavour (Thompson and loss, loss of food value, loss of quality and Burden, 1995). The respiration rate subsequently consequently loss of acceptability, loss of decreases progressively to reach zero at the economic value and actual loss of produce physiological death of the fruit. Eventually the peel becomes spotted brown or black and the pulp loses its firm texture and white or yellow colouration to become brown and gelatinous (Robinson, 1996). Ripening is a process, which increases the quality of the fruit, and it is part of the same process, which is accelerating the product towards post-market senescence (Ferris, 1991). Reports have implicated plant hormones in the senescence of fruits (Dilley, 1969; Looney, 1970; Vendrell, 1969, 1970a, 1970b). Vendrell (1969) specifically provides good evidence that endogenous auxins may play a key role in fruit ripening. Consumers often decide whether bananas are ripe or unripe solely on the basis of peel colour, which is also used to predict shelf life for retail distribution (Dadzie, 1998). Weight loss in transported or stored fruits could be traced to moisture loss during transpiration (Asiedu, 1987; Burdon et al. 1991). Fruit can sustain a substantial weight loss due to transpiration and respiration with only a minor reduction of food quality. Water loss from plantains is usually through the peel. Water can also migrate from the peel to the edible pulp section, which could be interpreted as a food gain. A substantial moisture loss could hitherto lead to reduction in fruit quality (Ferris, 1991). Such reduction could be detrimental to processing and utilisation, because of impairment in the wholesomeness, nutritional and edibility of the fruit. Banana ripening stages can be assessed by the use of colour charts (Loesecke, 1950; United Fruit Sales Corporation, 1975), carbohydrate and respiratory changes during ripening (Marriott et al, 1981), and firmness or textural changes (Palmer, 1971). Uniformity in fruit ripening patterns, and shelf life are indicators of good quality fruits, which affect consumers’ acceptability and market price. Research is therefore required to investigate the new hybrids for fruit shelf life and weight loss to provide information for future breeding, adoption and marketing. The purpose of this study was to provide information on the ripening pattern and shelf life of new plantain and banana hybrids to complement breeding strategy, post harvest handling and utilization, as well as marketing. MATERIALS AND METHODS Thirty Musa genotypes consisting of plantain and banana hybrids and landraces were used for this study. These included twenty three plantain hybrids: 548-9, 1658-4, 7152-2, 7152-2 OP15, 15108-6, 23688-2, 23898-3, 23977-7, 24044-3, 24364-S10, 25273-1, 25291-S26, 25291-S32, 25291-S41, 25333-S66, 25333-S88, 25333-S90, 25344-18, 25447-S7, 25502-S4, 25729-5, A10-SPS 548-9, A5-SPS 548-9, five banana hybrids: 5295-1, 9128-3, 24408-S22, FHIA 3, SH 3362, and two African plantain landraces: Agbagba, and Obino l’Ewai. Plantain and banana samples were obtained from the experimental station of the International Institute of Tropical Agriculture (IITA), High Rainfall Station, Onne agro ecology, located on Latitude 04o 43' N, Longitude 07o 01' E and 10m Altitude, near Port Harcourt, Nigeria. The nomenclature used for various plantain and banana hybrids were designated by the International Institute of Tropical Agriculture (IITA) where the new varieties were developed. METHOD Plantain and banana bunches were harvested at full maturity and green unripe stage. Ten fruits per bunch were collected from the second and third hands from the proximal end of the bunch for ripening and weight loss assessment, and this was performed in triplicates. Sampling was done following the recommendation of Baiyeri and Ortiz (2000), with slight modification, the same day the bunch was harvested. The maturity of hands in the bunch varies slightly: those at the proximal end of the bunch being mature than those at the distal end. The estimate of maturity is based on the fullness of fruit of the middle hand (Thompson and Burden, 1995). Fruits were arranged in plastic trays on laboratory benches to facilitate movement of samples for assessment and to avoid mechanical injury. The temperature and relative humidity in the laboratory was 25-27oC and 55%, respectively. Three air expellers, GX12 Xpeller manufactured by GEC Xpelair Ltd., UK were installed in the laboratory to remove air, which automatically works for 12 minutes on two hours intervals. This helps to prevent build up of ethylene emanating from ripening fruits. Fruit ripening pattern (colour change and weight loss during ripening) were determined on daily basis until the fruit attained satage 10, with pure black peel. Peel colour was scored according to a modification of banana ripening chart developed by the United Fruits Sales Corporation (1975), with scale ranging from dark green to pure black (Table 1). All data analysis was performed using Statistical Analysis Systems (SAS, 1996) software package. Linear (Pearson) correlation and analysis of variance (ANOVA) were used to test for differences among samples. Both the Duncan’s New Multiple Range Test and the Least Significant Difference (LSD) Test were employed to separate sample means that were significantly different at 5%, 1% and 0.1% level of probability. A modification of banana ripening guide adapted from the United Fruit Sales Corporation (1975). RESULTS AND DISCUSSION Fruit shelf life (days to the attainment of colour stages 6 and 10) and weight reduction during ripening were presented in Tables 2 and 3, respectively. Fruit of many of the plantain and banana hybrids had a significantly longer shelf life (p<0.05) than that of the plantain landraces. Hybrid 23688-2 had the longest mean shelf life before complete ripening in 16.3 days. The mean number of days to complete ripening for 23977-7, SH 3362 and 25333-S88 were 15.6 days, 13.8 days and 13.4 days, respectively. These clones differ significantly (p<0.05) from the two plantain landraces used in this study. Obino l’Ewai kept for 8.5 days before the attainment of full ripening. Agbagba and 25291-S32 recorded the shortest ripening times of 5.5 and 5.4 days, respectively to reach completely yellow stage. Similarly, most of the plantain and banana hybrids differ significantly from the landraces in shelf life prior to senescence (stage 10). Hybrids 23977-7 and SH 3362 stored for 25.9 days to reach stage 10, closely followed by 15108-6 and 23688-2 with 24.6 days and 24.3 days, respectively. Fruits of FHIA 3 showed the shortest storage life before senescence. The weight of 25344-18 fruit reduced from 189.6g to 104g during ripening from stage 1 to stage 10. The same trend was observed for all other genotypes, irrespective of their ploidy status. Fruits of most hybrids investigated showed longer shelf life when compared with the landraces. Interestingly, plantain hybrid 23688-2 had the longest shelf life, and also exhibited uniform ripening pattern prior to senescence. The fruits turned completely yellow in 16.3 days, the longest time taken by any of the hybrid considered in this present study. It was also observed that the pulp colours of 23688-2 fruits were comparable to those of Agbagba and Obino l’Ewai. Ferris (1998) have shown that French plantain cultivar, Obino l’Ewai have a high stomata density. A higher density of stomata may cause a higher rate of water loss, which accelerates ripening. Bright yellow and attractive peel colour observed in 25344-18 suggests that this hybrid will constitute a good material for breeding and adoption. Banana Hybrid 5295-1 12.1 20.3 9128-3 8.6 15.2 24408-S22 7.5 18.1 FHIA 3 6.5 13.3 SH 3362 13.8 25.9 Plantain Landrace Obino l’Ewai 8.5 18.1 Agbagba 5.5 15.6 LSD (0.05) 0.64 0.23 CV (%) 12.6 7.5 R2 0.9 0.89 There is no doubt that 25344-18 will attract high premium in the market and may be considered essential raw material in food processing industry. Fruits of most hybrids used had a significantly (p<0.05) longer ripening period than those of the plantain landraces. This observation is consistent with previous studies (PBIP, 1994; PBIP, 1995). An estimate of bunch's maturity can be made using fruit storage life (Dadzie and Orchard, 1997). Burdon et al. (1991) also established evidence that natural variation exist in the storage life of plantain and cooking banana, as reflected in this present study. Experiences have shown that some plantain and banana hybrids with longer shelf life exhibited unacceptable fruit colour changes during ripening. Most often, fruits of some cultivars become difficult to classify in terms of colour change using the colour chart. In this case, fruit colour was obtained by extrapolation. Fruits may develop black spots or even black patches, which may or may not be associated with injury during handling, physiological disorders or diseases. Fruits that have these characteristics consequently fail to attain full ripeness, which is unacceptable to consumers. In addition, ripening may not be noticed at the tips, but rather at the middle of the fruit. Mature banana fruits left to ripen naturally will eventually soften. However, the peel may be dull, pale yellow and unattractive. Robinson (1996) reported that green fruits must be ripened artificially with an injection of ethylene into sealed ripening chambers and at controlled temperatures. This practice ensures fruits with firm pulp texture, good flavour and bright yellow peel colour. Although plantain hybrids, like other Musa fruits may be sold at all stages of ripeness, depending on locality or countries, this study provides an idea of market life. Fruit ripening period is of considerable commercial interest to farmers, retailers, wholesallers and the ultimate consumers alike (PBIP, 1995). Ripening in Musa sp. fruit has a fundamental effect on fruit quality characteristics (PBIP, 1994). For these reasons, the ripening period of the hybrid should be consistent with that of their parental plantain and banana cultivars. Transportation of new plantain hybrids to distance markets may prove practicable. Moreover, variation between genotypes is apparently large enough to justify the use of shelf life of a genotype (e.g. 23688-2) and ripening pattern observed in 25344-18 as a criterion for crop selection. Genotypes with short shelf life may be exploited for various food processes such as flour from green fruit, and beverage production from ripe fruit. Generally, bananas are either eaten raw as dessert bananas or prepared by cooking, fermenting, or drying, according to the cultivar (Wainwright and Burdon, 1991). Plantain on the other hand are traditionally grown for cooking as part of a staple diet, or for processing into products such as flour with longer shelf life compared to fresh fruit (Dadzie, 1995; Wainwright and Burdon, 1991). Fruits are eaten in many forms in Nigeria including frying into chips and dodo, roasting, boiling, porridge making, steaming to make moin-moin and in flour production (Agbor, 1996; Echibiri, 1996). During the senescent phase, metabolic activity decreases, fruit quality deteriorates and pathogens develop (John and Marchal, 1995). However, overripe fruit are not left out in food product development. In some parts of Nigeria for instance, overripe plantain is fermented to produce a cloudy beverage, which is locally referred to as “agadagidi”, pleasing, low alcoholic beverage considered as health drink (Abiose and Adedeji, 1992). Dodo Ikire, a fried traditional snacks made from overripe plantain mixed with ingredients is a delicacy in Ikire town in Osun state, Nigeria. One advantage of this snack over regular fried ripe plantain is its longer shelf life. Adeniji (1995) investigated the use of ripe or over ripe plantain and banana pulps and peels in winemaking. Processing of alcoholic beverages is a feature of the banana-based highland cropping systems of six East African countries, including Kenya, Tanzania, Uganda, Rwanda, Burundi, and Zaire (Davies, 1995). In such areas, fruit preservation may not be necessary since large quantities of harvested bananas are required in ripe form. For instance, Davies (1995) reported that processing, distribution and sale of traditional banana beer contribute to domestic income in both rural and urban areas in East Africa. To achieve this, fruit are forced to ripen traditionally to provide uniformly ripe fruit for beverage production. In West Africa, wide ranges of food products are prepared from plantain involving boiling, roasting or baking, frying and drying (Dadzie, 1992; Dadzie and Wainwright, 1995). The variety of plantain and the level of fruit ripeness depends on the specific dish to be prepared. Following increasing urbanisation in Africa, new products should be developed that take into account the different tempo of urban compared with rural life. Fruits with uneven and unpredictable ripening patterns would definitely not meet consumer demand. This can be a major problem in the marketing of plantain and banana in industrialized importing countries. Superficial peel discolouration is of less significance in domestic marketing in producing countries where the eating quality of the fruit is more important than its appearance (Thompson and Burden, 1995). Conclusion Certain post harvest characteristics affecting the quality and marketability of plantain and banana was appraised. The export of banana fruit from the tropics to remote destinations has been in progress for over 100 years (Thompson and Burden, 1995). The extension of this trade to include plantains has developed only since 1960’s, primarily in response to the demand by ethnic migrant populations in importing countries. Generally, the practices used in banana marketing are, with minor exceptions, applicable to plantains. Understanding of fruit ripening patterns and their shelf life is therefore necessary to provide information on the extent to which fruit could be kept during the marketing phase, and this will depend on the market and uses for which it is intended. Cultivars with good ripening pattern and extended shelf life may also provide materials for future breeding. Acknowledgement: The authors wish to express our profound gratitude and appreciation to the International Institute of Tropical Agriculture IITA for providing experimental materials and laboratory facilities used for this study. REFERENCES
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