Action of 1-Methylcyclopropene on Postharvest Conservation of Banana ‘Prata-Anã’ Gorutuba Clone

The banana is a highly perishable fruit in which storage and transport for a long period is limited due to the lack of post-harvest technologies that aim to retard fruit ripening. In this regard, the objective of this study was to evaluate the postharvest conservation period of the ‘Prata-Anã’ clone Gorutuba banana using different concentrations of 1-methylcyclopropene (1-MCP), associated with the modified atmosphere and refrigerated storage. Banana bunches (Musa spp. AAB) ‘Prata-Anã’ Gorutuba clone were obtained from Belém farm, located in Janaúba-MG. The pieces were decomposed in bouquets of 4 fruits and submitted to 1-MCP application at concentrations of 0.0; 0.2; 0.4; 0.6; 0.8 and 1.0 ppm for 24 hours and stored refrigerated at room temperature to 13±1 °C. Every 5 days physical and chemical evaluations were performed. There was a delay in the ripening of fruits subjected to refrigeration and treated with 0.6 ppm of 1-MCP and increase in shelf life, due to probable inhibition of ethylene, which showed firmer fruits. Respiratory activity decreased with increasing concentration of 1-MCP. In refrigerated storage, fruits treated with 1-MCP were kept longer than 30 days. For the fruits kept at room temperature shelf life was 21 days for fruit subjected to concentrations of 0.4 to 1.0 ppm. However, the use of 1-MCP associated with the modified atmosphere under refrigeration directly influenced the postharvest conservation of bananas, allowing a longer period of commercialization.


Introduction
The banana tree (Musa spp.) is one of the most cultivated tropical fruit trees in the world. Its cultivation extends to regions of humid climate like the semiarid regions. It is a fruit of great economic and social importance. However, the banana has a quick ripening after harvest with a relatively short shelf life, a high respiration rate, and a highly perishable fruit which limits storage and transportation to distant markets. To this end, the study of technologies that aim to increase postharvest conservation has been evaluated, in order to allow longer storage and transportation of bananas, allowing the production flow and reducing postharvest losses, offering quality products to the final consumer.
According to Santos et al. (2011) the combination of modified atmosphere and low temperature and high relative humidity ensures the preservation of fresh fruits during transportation and storage for domestic market. However for foreign markets it is necessary to associate such techniques to others, aiming to extend the period of transport and storage, enabling exploration of new markets. Therefore, to delay the ripening and prolong the shelf life of fruits, the associated use of 1-MCP with refrigerated storage and packaging has been evaluated as an alternative that allows the increase in exports and marketing of the product to more distant markets, reducing also the postharvest losses. In this regard, the objective of this study was to evaluate the postharvest conservation period of the 'Prata-Anã' banana, Gorutuba clone, using different concentrations of 1-methylcyclopropene, associated with the modified atmosphere and refrigerated storage.

Material and Methods
Bunches of banana (Musa spp. AAB) clone 'Prata-Anã' Gorutuba aged 17 weeks were obtained at Fazenda Belém, located at geographic coordinates: latitude -15°44′45.3″ S and longitude -43°18′40.8″ W, in the municipality of Janaúba, Minas Gerais. The pieces were transported to the Postharvest Fruit Physiology Laboratory of the Montes Claros State University, Janaúba campus, where they were decomposed into four fruit bouquets. The fruits were then washed with water and 0.2% neutral detergent for latex coagulation and surface cleaning. Malformed, diseased or mechanically damaged fruits were selected and eliminated. Subsequently, the bouquets were immersed for five minutes in a 200 mL 100 L -1 Magnate fungicide solution and 10 mL 100 L -1 syrup Iharaguen-s solution and placed to air dry.
After 24 hours, the fruits were removed from the hermetic chambers, packed in low density polyethylene plastic bags (16 µm) and placed in standard cardboard boxes for export of fruits, and stored in a cold chamber at 13±1 °C. and relative humidity of 85±5% for 30 days, and at intervals of five days, a part of the fruits was removed for the physical and chemical analysis, determining the shelf life of the fruits that remained in the refrigeration.
The bananas subjected to 1-MCP treatment were also stored at room temperature at 25 °C without packaging to determine shelf life, being considered a second experiment.
The experimental design of the second experiment was completely randomized (DIC), consisting of four repetitions and each repetition a bouquet with four fruits, being the treatments six concentrations of 1-MCP (0.0; 0.2; 0.4; 0.6; 0.8 and 1.0 ppm).
The fruit firmness was evaluated using a Brookfield CT3 10 KG digital texturometer. Measurements were made in the median region of the fruit, determined by the penetration force, measured in Newton (N). The loss of fresh fruit mass was determined by the difference in fruit mass accumulated during the course of the experiment, considering the difference between the initial fruit mass and that obtained in each sampling period, the result being expressed as a percentage (%).
The pericarp color analysis was performed using a Color Flex 45/0 (2200), stdzMode: 45/0 colorimeter with direct reflectance reading of the L* (luminance) a* (red or green tint) and b* (Hunterlab Universal Software system, measured in the middle region of the fruit. From the values of a * and b*, the hue angle (°h*) and the chroma saturation index were calculated (C*).
The shelf life was determined by fruit acceptance, as a function of appearance, during cold storage and at room temperature. The end of shelf life was determined when the fruit showed signs of deterioration, ie, stage 6 on the Von Loesecke visual maturity scale (CEAGESP, 2006). The shelf life count was determined in days of conservation.
The respiratory rate was determined by the titration method, according to Crispim et al. (1994) adapted by Deliza et al. (2008) and the results expressed in mg CO 2 kg -1 h -1 every assessment day. The percentage of CO 2 was determined by direct measurement using a MOCOM brand carbon dioxide (CO 2 ) meter during the entire cold storage period.
For the analysis of soluble solids, titratable acidity and pH, samples composed of four ground fruits were used. The determination of soluble solids was performed by refractometry, using ABBE benchtop refractometer, with jas.ccsenet. reading in and the re 2008).
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Results
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