Influence of storage methods on ripening and microbial load of some Musa species Fajinmi, O. B 1*, Akinyemi S.O.S. 1 and Aduramigba-Modupe A. O.

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1 AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: , ISSN Online: , doi: /abjna , ScienceHuβ, Influence of storage methods on ripening and microbial load of some Musa species Fajinmi, O. B 1*, Akinyemi S.O.S. 1 and Aduramigba-Modupe A. O. 2 1 National Horticultural Research Institute, P.M.B. 5432, Jericho Reservation Area, Idi-Ishin, Ibadan, Nigeria 2 Department of Biological Sciences, Redeemer University, P.M.B. 3005, Ogun state, Nigeria. *Corresponding author obfajinmi@yahoo.com ABSTRACT The effect of two storage methods (jute bag and open shelve) on ripening and microbial load of fruits of three cultivars of Musa (PITA 26, cooking banana and agbagba plantain) at different stages of ripening were investigated. There was a significant difference in the fruit ripening rate of the three Musa cultivars kept under the two storage methods. The fruits stored in jute bags ripened within a shorter period of time (8 days for PITA 26 and agbagba plantain; 11 days for cooking banana) compared with those put on open shelf in the laboratory (10 days for PITA 26 and agbagba plantain; 14 days for cooking banana). There was a continuous increase in microbial (bacterial and fungal) count of fruits as ripening process progressed. The identified isolates were Bacillus spp., Staphylococcus aureus, Lactobacillus species, Aspergillus flavus, Aspergillus niger, Fusarium, Saccharomyces and Penicillium species. Key words: Bacterial and fungal count, PITA 26, cooking banana, agbagba plantain. INTRODUCTION Bananas and Plantains (Musa species) are perennials and herbaceous plants belonging to the family Musaceae. Musa is one of the three genera in the family. In popular culture, banana usually refers to soft, sweet dessert Musa cultivars. By contrast, Musa cultivars with firmer, starchier fruits are called plantains. Bananas are grown primarily for their fruits and to a lesser extent to make fiber and as ornamental plants (Frison and Sharrock, 1998). Musa fruits play major roles in the nutrition and well being of people of the tropical and sub tropical regions of the world. They are good source of income to the farmers in their respective growing regions (Bridge, 2000; Akinyemi et al., 2010). In Africa, plantains and bananas provide more than twenty-five percent of the daily energy requirements by the people (Frison and Sharrock, 1998). Fruits of most Musa species are either taken raw or processed into various products at various stages of ripening. (Akinyemi et al, 2010). During natural ripening process, banana produce ethylene also called ethene (C 2 H 4 ), which indirectly affects its flavour due to stimulation of an organic compound called isoamyl acetate (Yiu and Wai-Kit, 2006). Ethylene also stimulates the production of amylase enzyme by microbes, which break down starch to sugar, which influences the taste of banana. Furthermore, ethylene signals production of pectinase, an enzyme that breaks down the pectin between the cells of the banana, making banana to soften as it ripens (Koning, 1994). Activities of pectinase producing micro organisms lead to loss of tissue coherence i.e. tissue maceration (Eckert and Ratnatake, 1983), which undoubtedly facilitates the penetration and invasion of micro organisms (Agoreyo, et al. 2003). Ethylene accelerates aging process and decrease fruit quality and shelf life if it is not controlled. In most parts of sub-tropical Africa where bananas and plantains are grown, they are usually transported in different form of containers from the farmers field to urban areas and from the retailers to the market. A certain degree of hastening of fruit ripeness is done during these stages through the materials used for packaging. However, for retailers to meet the consumers demand of ripe fruits, they use several means and methods to ripen those fruits that remain unripe during transportation. These means and methods include packaging; keeping these fruits in bags (made of jute or polythene) or in pots (made of earth or plastic). At times, banana and plantain fruits are packed with other fruits like arvingia and apple to hasten ripening. It is therefore the objective of this study to investigate the influence of a packaging material (jute bag) on ripening and microbial load of three Musa species at

2 different ripening stages with the aim of coming out with recommendation that will assist Musa merchant in prolonging the shelf life of their produce. MATERIALS AND METHODS Collection of plant materials: This work was carried out in National Horticultural Research Institute (NIHORT), Ibadan, Nigeria. Three Musa cultivars (cooking banana, PITA 26 and Agbagba plantain) used for this study were collected from the banana and plantain orchard of the Fruit Programme of the institute. The bunches of all the Musa cultivars used were harvested at 90 days after flowering. Bunches of each cultivar used were dehanded and separated into three classes based on their position on the bunches (i.e. upper, middle and lower hands). Each of these classes in each cultivar was stored in (a) jute bags and (b) open shelve at ambient conditions. This experiment was a factorial (cultivar, hand position and storage method) and was set up in the institutes laboratory with three replications. Treatment response was determined by observing and recording the number of ripe finger(s) at ripening stage 6 per day. Ripening was monitored by visual change in fruit skin/peel colour using a seven colour scale as highlighted in ( tails_ripeningstages.php.( )). Isolation, enumeration and identification of microbes For each cultivar, fruit samples at different stages of ripening were collected for microbiological analysis of the pulp. The fruits were washed under tap water for about a minute and then surface sterilised by wiping with cotton wool soaked in 70% ethanol. Ten grammes of pulp of each sample was macerated aseptically and mixed with 90mls of sterile distilled water. Serial dilutions up to1:1000 were made. Isolation and enumeration of bacteria and fungi was done using Nutrient agar (NA) and potato dextrose agar (PDA) respectively. One millimetre of each sample dilution was taken aseptically into sterile petri-dishes in triplicates. Nine millimeters of warm sterilised agar (of about 45 o C) was poured into each of the dishes and swirled round gently for even distribution of the inoculums into the medium. Dishes containing NA were incubated at 37 o C for 24 hours while plates containing PDA were incubated at room temperature of 28 ± 2 o C for five days. Uninoculated plates (containing only the media) served as the control. Enumeration was done by multiplying the number of colonies on each plate by the dilution factor. Identification of organisms was done by macro and microscopic examinations and with some biochemical analyses. Statistical analysis: The data collected on ripening were subjected to analysis of variance (ANOVA) using SAS package (2003 version) and the means separated using Least Significant Difference (LSD). Test of significance was done at 5% probability level. RESULTS Ripening of fruits: The results of storage methods on fruit ripening of Musa species showed that there were significant differences between the ripening rate of Musa cultivars and between different hand positions within the bunch of each cultivar (Tables 1 2, 3, 4 ). Generally, all fruits of Musa cultivars stored in jute bag ripened earlier than those put on open shelf in the laboratory (figures 1, 2 and 3). Mean ripening rate of the three cultivars is shown on figure 4. Microbial count: At stages 1 and 2 of all Musa cultivars used, there was no microbial growth noticed on the plates (Tables 5, 6). There was a continuous increase in both bacterial and fungal count/load as ripening process progressed from stage 3 to 7 (Tables 5 and 6). Mean bacterial count/load at every stage of ripening was observed to be higher than the corresponding fungal load (Tables 5 and 6). Identified isolates were Aspergillus flavus, Aspergillus niger, Fusarium sp., Penicillium sp., Saccharomyces spp., Bacillus spp., Staphylococcus spp. Lactobacillus sp., They were majorly the identified spoilage microbes of plantain and banana in this experiment. DISCUSSION Climacteric fruits give off ethylene gas during ripening (Sacher, 1973) and this ethylene increases considerably as the ripening processes advance (Rao & Chundawat, 1986). Once this gas was produced, it was prevented from escape and accumulated in the jute bag around the fruits which caused the fruits stored in jute bags to have a higher percentage rate of fruit ripening. At any given age, the maturity of hands in a bunch varies, those hands at the proximal end of the stem being more mature than those at the distal end (Nelson et al., 2006). This was the reason why the fruits from the upper hands ripened faster than those in the lower hands. Lack of microbial growth noticed at stages 1 and 2 may be attributed to the antimicrobial properties of unripe peel of banana fruit. Mokbel and Hashinaga (2005) reported the antibacterial activities of banana 1202

3 (AAA cv Cavendish) fruit peel against some gram positive and gram-negative bacteria and that green (unripe) banana fruits have less decay due to high concentrations of malic acid, succinic acid and other compounds. Pounded banana fruit peel is used as wound bandage in Pacific cultures as it had been found to contain antibiotic properties (Nelson et al., 2006). Antimicrobial properties of unripe banana (Musa sapientum L.) fruits against some bacteria were also reported by Fagbemi et al. (2009). The continuous increase in both the bacterial and fungal count as ripening process progressed from stage 3 to 7 could be corroborated with the work of Agoreyo et al. (2003) in which the highest microbial counts were at the over-ripe stage and least at the unripe stage of fruits of Musa paradisiaca. Ripening of climacteric fruits like plantain and banana is known to cause decline in pulp firmness or loss of hardness of fruit gradually and this is associated with three main processes, which are the breakdown of starch to sugar, breakdown of the cell walls or the reduction in the middle lamella cohesion due to degradation of pectic substances and the movement of water from the peel to the pulp due to osmosis (Gerard et al, 2009; Esther Sakyi Dawson et al, 2008; Odebode and Sanusi, 1996). These processes encouraged the penetration and growth of micro-organisms and entry of some opportunistic microbes. Higher mean bacterial count than the corresponding fungal count observed at every stage of ripening corroborates the work of Agoreyo et al. (2003), though they enumerated and isolated only from Musa paradisiaca. Higher microbial load/counts observed in fruit samples from jute bags compared with those from the open shelve may be attributed to increase in the temperature provided by the jute bags which encouraged microbial growth. Table 1: Effect of storage methods on ripening of PITA 26 Day 9 Day 10 Day 11 Day 12 Day 13 Day 14 Jute bag Open Shelve CV (%) LSD * 17.52*** 7.71*** 35.34* 10.79** 0.00 Table 2: Effect of storage methods on ripening of cooking banana Day 5 Day 6 Day 7 Day 8 Day 9 Day 10 Jute bag Open Shelve CV (%) LSD NS 20.41* 15.43* 7.71* 6.73 NS 0.00 Day 4 Day 5 Day 6 Day 7 Day 8 Day 9 Day 10 Jute bag Open Shelve CV (%) LSD NS 24.40* 21.82** 20.41** 20.41* 15.43* 0.00 Table 3: Effect of storage methods on ripening of agbagba plantain 1203

4 Table 4: Effect of storage methods on ripening of fruits from different positions on the bunch of three types of Musa species Variety Hand Packaging Day 4 Day 5 Day 6 Day7 Day 8 Day 9 Day 10 Day 11 Day 12 Day Day 14 Position Method Jute bag Jute bag Jute bag Open shelf 16, Open shelf Open shelf Jute bag Jute bag Jute bag Open shelf Open shelf Open shelf Jute bag Jute bag Jute bag Open shelf Open shelf Open shelf Variety 1 PITA 26 2 cooking banana 3 agbagba plantain Hands position 1 upper hand 2 middle hand 3 lower hand 1204

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6 Fig 4: Fruit ripening rate of PITA 26, Cooking banana, Agbagba plantain Table 5: Bacterial count (cfu/g) of Musa types at different ripening stages ST1 ST2 ST3 ST4 ST5 ST6 ST7 V 1 X S x x x x x10 3 V 1 X S x x x x x10 3 V 2 X S x x x x x10 3 V 2 X S x x x x x10 3 V 3 X S x x x x x 10 3 V 3 X S x x x x x10 3 V 1 PITA 26 V 2 cooking banana V 3 - agbagba S 1 - jute bag S 2 - open shelve Table 6: Fungal count (cfu g) of Musa types at different ripening stages ST1 ST2 ST3 ST4 ST5 ST6 ST7 V 1 X S x x x x x10 3 V 1 X S x x x x x10 4 V 2 X S x x x x x10 4 V 2 X S x x x x x10 3 V 3 X S x x x x x10 3 V 3 X S x x x x x10 3 V 1 PITA 26 V 2 cooking banana V 3 - agbagba S 1 - jute bag S 2 - open shelve 1206

7 CONCLUSION Keeping banana and plantain fruits in open shelf delayed fruit ripening and reduced the microbial load than keeping in jute bag. Banana and plantain merchants can extend the shelf life of the crops by keeping them in open shelf. This study also supports the reported antimicrobial properties of unripe Musa fruits, because of no microbial growth observed on plates at the unripe stage of the fruit (green stage). REFERENCES Agoreyo,B. O., I. F. Obuekwe and D. O. Edosomwan (2003). Biochemical and microbiological changes in plantain (Musa paradisiaca) at various stages of ripening. Discovery Innovation, 15(3/4); Akinyemi, S.O.S., C. Staver, I. O. O. Ayelaagbe, A. A. Kintomo, and S. O. Babalola (2010). Perspectives of small scale Musa processing firms in Nigeria. Acta Horticulturae No 879: Bridge John (2000). Nematodes of bananas and plantains in Africa: Research trends and management strategies relating to the small- scale farmer. Acta Horticulturae 540. Eckert, J.W. and M. Ratnayake (1983). Host-pathogen interaction in post-harvest diseases. In: Post harvest physiology and crop preservation. Plenum Publishing Corporation. New York. Pp Esther Sakyi-Dawson, Prudence Asamoah-Bonti and Geroge Amponsah Annor (2008). Biochemical changes in new plantain and cooking banana hybrids at various stages of ripening. Journal of the science of Food and Agriculture pp Fagbemi Josephine Ferdinard, Ugogi Ester, Adenipekun Tayo, and Adelowotan Omotoyin (2009). Evaluation of the antimicrobial properties of unripe banana (Musa sapientun L.), Lemon grass (cymbogon vitratus S.) and turmeric (curcuma Longa L.) on pathogens. African Journal of Biotechnology 8(7), Frison E. and S.Sharrock (1998). The economic, social and nutritional importance of banana in the world, pp In: Bananas and Food Security (C. Picq, E. Foure and E. A Frison eds.). INIBAP, International Symposium, Douala, Cameroon. Gerard Ngoh Newilah, Kodjo Tomekpe, Elie Fokou, Frangoid Xarier Etoa (2009). Physicochemical changes during ripening of banana grown in Cameroon. Fresh produce 3(1), Koning, Ross E. (1994). Fruit ripening. Plant physiology information website. plant physinfo/plantshuman/fruitgrowripe.shtml. Matook Saif Mokbel and Fumio Hashinaga (2005). Antibacterial and antioxidant activities of banana (Musa, AAA cv. Cavendish) fruits peel. American journal of biochemistry and Biotechnology 1(3); Nelson S. C., R. C. Ploetz and A. K. Kepler (2006). Musa species (banana and plantain) In: Species Profiles for Pacific Island Agroforestry. Available on traditionaltree.org Odebode, A. C. and Sanusi, J. (1996). Influence of Fungi associated with bananas on nutritional content during storage. Z.Lebsm Unteers Forsc 202: 471 Rao. D. L and B. S. Chundawat (1986). Effect of certain retardants on ripening changes of banana cultivar Laction at ambient temperatures. Progressive Hort., 18: Sacher, J. A. (1973).Senescence and post harvest physiology. Annual Rev. Plant Physiol.24; Yiu H. Hui and Wai-Kit Nip (2006) (ed). Biochemistry and Food Processing. Wiley- Blackwell, pp