Md. Atiqur Rahman*
Horticulture Research Centre, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701, Bangladesh
Md. Miaruddin
Postharvest Technology Division, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701, Bangladesh
M.G.F. Chowdhury
Postharvest Technology Division, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701, Bangladesh
Most. Mahbuba Begum
Tuber Crop Research Centre, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701, Bangladesh
Md. Nazrul Islam
Horticulture Research Centre, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701, Bangladesh
Banana; Postharvest; Firmness; Ripening; 1-MCP; Storage.
Horticulture Research Centre, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701, Bangladesh
Quality and Nutrition
2.1 Fruit materials Locally grown ‘Cavendish’ bananas were used in this experiment. At the time of harvest, the temperature and relative humidity were at 27 ± 2°C and 75 ± 5%, respectively. Hands of mature green bananas obtained from local grower’s field (Gazipur, Bangladesh) were cut into fingers. Fruits were then sorted and grouped based on uniformity of developmental stage, weight and size, and then randomly divided into five treatment groups. 2.2 1-MCP treatment Five groups of 84 fruit each were treated with aqueous 1-MCP (0.18% active ingredient, Nan Ning Oyan Hi Tech Agriculture Co. Ltd. China). Solutions were prepared with 1-MCP powder at 100, 200, 400 and 600 μg L–1 (a.i.) were suspended in 15 L of distilled water in 25 L plastic buckets and swirled gently with a plastic spatula until fully dissolved. Banana fingers were immersed in the solution for 10 min and immediately dried the surface water using fan-forced air. Banana fingers dipped in distilled water only were used as control treatment. The fingers were then placed into perforated (1%) low-density polyethylene bags (0.03 mm thick) each containing four fingers. The treated fingers were then stored for 30 days at 20 ± 2°C and 85 ± 5% RH for ripening. The experiment was laid out in complete randomised design with three replications. Data on the changes in different physico-chemical attributes during storage were collected by examining the fruit at five days intervals after treatment application. At each interval, four fingers per treatment were used to collect the data.
2.3 Assessment of firmness Assessment of pulp firmness was performed using a digital firmness tester (DFT 14, Agro Technologie, France measuring the penetration force reached during the tissue breakage with a 8 mm diameter stainless steel flathead probe, which penetrates the fruit by 5 mm. Round banana slices of 25 mm thick containing both peel and pulp were cut transversely from the stem end, equatorial and blossom end of each fruit with a sharp knife. Measurements were taken at three places of each slice and mean calculated. Results were expressed in kg force cm–2 (kgf cm–2). 2.4 Measurements of surface colour Banana external colour was examined with a chroma meter (Model CR-400, Minolta Corp., Japan). CIE L*a*b* coordinates were recorded using D65 illuminants and a 10° standard observer as a reference system. L* is lightness, a* (–greenness to +redness) and b* (–blueness to +yellowness) are the chromaticity coordinates. The a* and b* values were converted to chroma [C = (a*2 + b*2 ) 1 / 2] and hue angle [h = tan–1(b* / a*)]. Before measurement, the equipment was calibrated against a standard white tile. Three readings were taken at different locations on each finger, taking four fruit from each treatment. Measurements were done in triplicate. 2.5 Measurements of ascorbic acid, total soluble solids, titratable acidity and pH For determination of ascorbic acid, 10 g of fruit tissue was homogenized in 50 mL of 3% cold metaphosphoric acid (HPO3) using a blender for 2 min and filtered through Whatman filter paper No. 2. The clear supernatant was collected for assaying ascorbic acid by 2,6-dichlorophenolindophenol titration following the method of Ranganna (1986). Ten millilitres of aliquot was titrated with 0.1% 2,6-dichlorophenolindophenol solution until the filtrate changed to pink colour persisted for at least 15 seconds and the titration volume of 2,6-dichlorophenolindophenol was recorded. Prior to titration 2,6-dichlorophenolindophenol solution was calibrated by ascorbic acid standard solution. Ascorbic acid content was calculated according to the titration volume of 2,6-dichlorophenolindophenol and results were expressed as mg 100 g–1 fresh weight. Again, 10 g of fruit pulp was homogenised in 50 mL of distilled water for 2 min using a kitchen blender and filtered through Whatman filter paper No. 2. The supernatant was collected in order to determine total soluble solids (TSS) by using hand-held Kruss refractometer (Model HR 900, SN 1200793, brix range 0–90% at 20°C, Germany), pH by glass electrode pH meter (Delta 320, Mettler, Shanghai) and titratable acidity (TA), which expressed as citric acid (%) was determined by titration with 0.1 mol L–1 NaOH to pH 8.1 according to the method by Ranganna (1986).
2.6 Statistical analysis The data were subjected to analysis of variance (ANOVA) using the CropState Statistical Software version 7.2. The results showing significant differences were then subjected to mean separation using Tukey’s studentised range (HSD) test at p < 0.05. Analysed data were graphically plotted using Sigma-plot 8.2 software.
Int. J. Postharvest Technology and Innovation, Vol. 3, No. 3, 2013
Journal