Proposal for Use of Pseudostem from Banana Tree (Musa cavendish)
D. G. FERIOTTI & A. M. IGUTI

Maua Institute of Technology, Sao Caetano do Sul, Brazil (danygf85@yahoo.com.br)

ABSTRACT
This paper presents a proposal for use of pseudostem from the banana tree (Musa cavendish). After banana harvesting, the pseudostems are cut and left in the fields. In order to add value to banana plantation, the pseudostem could be processed into products. Nowadays, the pseudostem fiber has been used mainly in handicrafts. Although studies have shown that the cellulose fiber has suitable features to industry, the yield is low because pseudostem has about 90% of water. This research presents the physicochemical composition of the liquid fraction extracted from pseudostems and proposes an application for it. The following analyses were performed: sugar, protein, fat, solids, sodium, potassium, calcium, magnesium, chloride, tannin, polyphenoloxidase and peroxidase activity, microbiological and pesticides. Once it contains potassium and sodium, the development of a sport drink seemed suitable. The paper presents some social and economical data of Vale do Ribeira region, the main banana producing region of Sao Paulo State. Additionally, some concepts of the banana plantation are reviewed as well as information about sport drink and the new
Brazilian law on athlete’s food. Data about its market are also included, and the results of analyses. The results showed that the liquid fraction contains 874 mg·L-1 potassium, 88 mg·L-1 sodium, 357.8 mg·L-1 chloride, 130 mg·L-1 calcium and 116 mg·L-1 magnesium. It contains 0.191% total sugar, 0.0141% protein and negligible amount of lipids. It presented 1.32 mg·L-1 tannin, which explains its dark colour. It is susceptible to enzymatic browning catalyzed by polyphenoloxidase. Finally, a sport drink formulation is proposed. Keywords: banana; pseudostem; composition; re-use; sport drink

INTRODUCTION
Brazil harvested 6.78 million tons of banana in 2009 [1] and is one of the greatest world producers [2]. In Sao
Paulo State, Vale do Rio Ribeira do Iguape (Ribeira Valley) region is a great and important producer of this fruit [3].
Ribeira Valley region, which covers 23% of the remaining Atlantic Forest of Brazil; was included by
UNESCO, in 1999, in World Heritage List [4] because of its natural, social, environmental and cultural importance. Contrasting with the rich environmental and cultural heritage, its Human Development Index
(HDI) is one of the lowest of the country, and it has also the higher rates of infant mortality and illiteracy.
Banana plantation occupies large part of the land, but it is a contamination source because after harvest, the tree is cut down and abandoned in the fields, which foments Sigatoka [5], a group of fungal diseases that destroy banana leaves and reduce crop yield. These residues represent 40% of banana production [6].
Research about this waste is important to Ribeira Valley sustainable development, either to raise its population HDI without changing their important economic activity or to avoid Sigatoka spread. There are already some suggestions to its utilization. A study suggested that banana pseudostem core could be turned into heart of palm, recommending that heat treatment temperature should be 120 ºC for 5 to 10 minutes [7].
There is a registered patent that describes a process to use the heart of banana tree for human consumption
[8].
There are also some cooperatives which turn pseudostem fiber into handcrafts. Evaluation of this activity in
Ribeira Valley communities called ‘quilombolas’ was done, and the conclusion was that it is compatible with the concepts of eco-development [9]. Other suggestions for the residue include the manufacture of blades, veneer and plywood [10] and cloth for lampshades, boxes, cases and internal coating of automobiles [11]. In agriculture, it was suggested that pseudostem could be enriched with nitrogen and phosphorus to be used as substrate for growing ferns [12]. In construction, application of the fiber in PVC composites improved tensile strength and resistance against impact [13]. It has been also suggested that biogas could be produced with this

material [14]. To obtain pulp or paper sheet could be a good alternative also because pseudostem fibers have good morphological characteristics, favoring production of cellulose with good mechanical strength. In Itariri city there is a company that already processes pseudostem to produce cellulose pulp and paper [15]. The company technical conditions to process pseudostem is too time and energy consuming though. One of the difficulties lies in its high water content (above 90%).
Therefore, apart from fibers, if heart, juice or other parts of pseudostem could be separated and utilized for goods production, the contribution to people who live in Vale do Ribeira region would be important. The idea of this paper was to study pseudostem sap through chemical and microbiological analyses in order to check the technical feasibility to transform it in a sport drink. It is worth it to keep in mind that there is no published paper in scientific literature about this theme.
MATERIALS & METHODS
Extraction. The pseudostem from banana tree (Musa Cavendish) were from Miracatu city, Vale do Ribeira,
Brazil. Each pseudostem was washed and cut crosswise into three parts. Each third was cut lengthwise into four pieces, discarding the heart. Milling to extract its juice was performed in equipment that presses each piece. After extraction, the juice was filtered and stored at -18 °C until use. Physicochemical analyses were performed in triplicate.
Proximate composition: ash, total solids, nitrogen and sugar were analysed by AOAC methods [16]. For protein content, conversion factor was 6.25. Lipid was analysed by Bligh & Dyer method [17].
Mineral analyses. Sodium and potassium analyses: the readings of this minerals were performed in flame photometer (model B462, Micronal), after standard solutions were used to calibrate the equipment [16].
Calcium and magnesium contents were determined by titration method [18].
Polyphenoloxidase activity analyses were performed too [19]. One unit of enzyme activity was defined as the amount of enzyme which caused an increase of 0.001 absorbance unit per minute.
Microbiological analysis: heat treatment at 85, 90 and 92 °C for 5, 10 and 15 minutes were tested. As control, a sample without heat treatment was analyzed as well. Necessary dilutions were made with 0.85% saline solution. For total plate count of mesophilic aerobic bacteria, 1.0 mL of each dilution described above was inoculated in Petri dishes. 15-20 mL of Count Agar Standard from Oxoid was transferred. Petri plates were moved smoothly on the surface. After agar has solidified, the dishes were inverted and incubated at 35
°C for 48 hours [20]. For enumeration of yeast and mold, Potato Dextrose Agar from Merck acidified with aqueous solution of tartaric acid 10%, pH 3.5 was used. 1.0 mL of each dilution described above was inoculated in Petri dishes. 15-20 mL of potato dextrose agar, previously melted and cooled was added. The dishes were moved gently on a flat surface and after agar has solidified, Petri plates were inverted and incubated at 25 °C for 5 days [21].

RESULTS & DISCUSSION
The chemical composition of pseudostem sap is shown in table 01. The analysis of pseudostem sap showed low content of solids, consisting primarily of sugars and minerals, which indicated the adequacy of this material to formulate a sport drink. To develop this drink, some requirements must be observed, according to
Brazilian legislation [22].
Bananas are considered a good source of potassium and magnesium. It presents 288 to 485 mg·(100 g)-1 potassium and 32 to 45 mg· (100 g)-1 magnesium [23]. According to a paper published, the composition of banana peel revealed that it is rich in fiber and minerals, particularly potassium, calcium and magnesium
[24]. This information indicated the possibility of presence of these minerals in the sap also. These results, coupled with Brazilian legislation requirements, led us to analyze sodium, potassium, calcium, magnesium and chlorides in pseudostem sap.

Table 1. Pseudostem sap proximate composition
Component
Content (%)
Total solid
Protein
Lipid
Total sugar
Ash

0.308
0.0141
0.005
0.191
0.104

The results of minerals and chlorides are shown in table 02. These results confirmed the initial hypothesis. As expected, pseudostem sap of banana tree has high potassium concentration. Calcium and magnesium are present also, but in lower concentration.
Table 2. Pseudostem sap minerals and chloride.
Component

Content
(mg·L-1)

Sodium
Potassium
Calcium
Magnesium
Chlorides

88
874
130
116
357.8

Although Brazilian law does not impose sugar addition in isotonic drinks, this kind of carbohydrate is commonly found in sport drinks. Pseudostem juice presents only 0.191% of sugar, which is very low content specially if according to the law, the maximum sugar content permitted is 8%.
Coconut water is a natural drink that has also been studied. Popularly it has been considered a natural isotonic beverage because it is rich in sugar and minerals. In Brazil it is very popular, particularly in beach cities. Table 03 presents pseudostem juice minerals compared to coconut water [25, 26].
Table 3. Pseudostem sap and coconut water minerals.
Coconut water

Component (mg·L-1)

Pseudotem sap

[25]

[26]

Sodium
Potassium
Calcium + magnesium

88
874
246

75
1110
241

105
1750
260

The amount of minerals in coconut water is comparable with that of pseudostem sap. Under this aspect, they are very similar. As coconut water, in addition to sodium and potassium, pseudostem juice has calcium and magnesium, which are absent in commercial sports drinks. By the way, pseudostem juice is richer in potassium than commercial sports drinks. About sugar content, coconut water is similar to commercial sports drinks because it has 5% of sugars [26]. According to new Brazilian regulation, addition of sodium to pseudostem sap would be necessary to make pseudostem juice an isotonic because a minimum of 460 mg·L-1 is required. To improve palatability, addition of sugar would be also necessary.
Analyses of polyphenoloxidase (PPO) and peroxidase (POD) activities were performed because they are responsible for enzymatic browning in fruits, especially in banana [27, 28, 29, 30]. Samples before and after heat treatment were analyzed. The sample before heat treatment showed PPO activity of 0.264 EU·mL-1 and after heat treatment, it was reduced to 0.096 EU·mL-1, corresponding to a reduction of about 63% of the PPO activity. The POD activity was not detectable.
Microbiological analysis showed the presence of bacteria in the sap (11,800 CFU·mL-1), but 5 minute heating treatment at 85 °C was enough to eliminate the entire population. Surprisingly, no molds or yeasts were detected. We conclude that the pseudostem sap with no heat treatment may contain bacteria, but they do not survive to mild heat treatment. Therefore, heat treatment is a necessary step in process of turning pseudostem juice into sport drink either to eliminate bacteria population or to denature PPO enzyme.

Pesticides analyses were performed to check if pesticide residues were contaminating the sap. Thirty four pesticides, usually applied in banana plantation were analyzed. Fortunately, no result exceeded the limit stated by Brazilian regulation.

CONCLUSION
The results showed that banana tree pseudostem juice could be raw material to be transformed in isotonic drink. However, water, sodium and sugar addition is necessary. The content of pesticides were below the maximum that is considered safe and under microbiological point of view, heat treatment at 85 °C for 5 minutes is enough to eliminate all the bacteria. To inactivate polyphenoloxidase, a more severe heat treatment is necessary though. Additional studies are needed to complete the study on safety for human consumption. REFERENCES
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Acknowledgement:
The authors thank to CAPES, for scholarship; to Mr. Romeu Grandinetti, for banana pseudostems and to Mr.
Marcello Pilar, for suggestions and support.