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Physical and mechanical properties of green banana (Musa paradisiaca) fruit
Journal of Food Engineering 26 (1995) 369.-378 Copyright 0 1995 Else&r Science Limited Printed in Great Britain. All rights reserved 0260~8774/95/$9.50 0260-8774(94)00054-9
ELSEVIER
Research Note Physical and Mechanical Properties of Green Banana (Muss paradisiaca) Fruit R. P. Kachru,” Nachiket Kotwaliwale
& D. Balasubramanian
Division of Post Harvest Engineering, Central Institute of Agricultural Bhopal (MP) 462038, India (Received
Engineering,
20 April 1994; revised version received 9 August 1994; accepted 13 September 1994)
ABSTRACT The physical and mechanical properties of two varieties of green banana fruit, namely, Dwarf Scavendish and Nendran, were determined, The average pulp and peel moisture content were 264.17% (db) and 666.28% (db), respectively for Dwarf Scavendish and 153.39% (db) and 516.41% (db), respectively for Nendran. At these average moisture contents, the average pulp to peel ratios were I .39 and 2.32, and peel thickness were 3.65 mm and 2.95 mm, respectively. The maximum diameter of fruit without peel was 23.34 mm and 37.08 mm, and average pulp specific gravity was 0.993 and 1 .I 10, respectively for the two varieties. The maximum effective length and width of the banana pulp resting at its most stable position was observed to be 137.0 mm and 66.5 mm, respectively for Dwarf Scavendish and 194.5 mm and 50.0 mm, respectively for Nendran. The maximum load required to cut a cross-sectional slice of pulp was 22.4 N and 28.2 N for the two varieties, respectively. Maximum energy of 686.81 J/m’ for Dwarf Scavendish and 724.46 J/m2 for Nendran was required to cut a slice of the fruit. The banana kept in a convex position required the most energy to cut, whereas the plain position was observed to be the best position vis-kvis the energy requirement and consumer preference of chip shape.
*Present address: Indian Delhi 110001, India.
Council
of Agricultural
Research,
Krishi Bhawan,
New
370
R. f! Kachru, N. Kotwaliwale,D. Bafasubramanian
INTRODUCTION Banana (Muss parudisiaca) is consumed directly as raw, ripe fruit or processed into pulp-liquid fruit, canned slice, deep-fried chips, toffees, fruit bars, brandy, etc. Deep-fried chips of raw as well as ripe banana are a popular snack food in southern India. At present, the chips are made by hand peeling raw banana and slicing the pulp portion in a wooden platform type slicer with mild steel blades and then deep frying in oil. The method is cumbersome, unhygienic and does not produce chips of uniform thickness. Besides it may inflict injury to the operator while slicing. To this effect, there is a need to develop a machine which would enhance the capacity and reduce drudgery in making the chips. The design of the machine is to be based on the physical and mechanical properties of raw (green) banana fruit. For making chips of green banana fruit, steel strings are proposed for cutting the fruit. For this, the physical and mechanical properties of banana fruit are required for the selection of size of the steel strings and design of the various parts of the machinery. The objectives of the study were to find the physical properties, namely, size, shape, peel thickness, specific gravity, moisture content, physical constituents (pulp to peel ratio), and mechanical properties, such as total cutting energy, energy requirement per unit area of cut, and maximum load for cutting of the fruit pulp using steel string as a cutting tool. MATERIALS
AND METHODS
Fully mature, unripe (green) bananas of the Dwarf Scavendish and Nendran varieties were procured from Bhopal and Coimbatore markets, respectively. The bananas were separated visually into four groups according to their size. Four bananas were chosen from each group for the determination of physical constituents and properties. The peel and pulp were weighed separately for individual bananas to determine the pulp to peel ratio. The moisture content was determined by placing 35-4-O mm thick banana slices with and without peel in a single layer, in an aluminium dish in a hot air oven, at 130f 1°C for 1.5 h (Rameshbabu & Nayak, 1993). The specific gravity of banana was determined by using the toluene displacement method (Mohsenin, 1980). Specific gravity was measured at three different locations in the fruit, i.e. top, middle and tail end of the fruit (Fig. 1). The top is defined as the end of the fruit which was attached to the plant. The physical properties, size and peel thickness were determined using Vernier calipers having a least count of 0.05 mm. The diameter of the banana with and without peel were recorded at six planes of cut along the longitudinal axis of the fruit, two planes falling in each of the top, middle and tail end of the fruit (Fig. 1). At each plane of cut (Dl-D6), the diameter was measured at four places. The shape of the banana with and without peel was plotted keeping the fruit resting on its most stable position and then the effective length and width were measured (Fig. 1). Stainless steel string was used for banana slicing as proposed for the machine. For proper size selection of the wire,
Physical and mechanical properties of green banana jkuit
(a) with peel
Fig. 1. Longitudinal
(b) without peel section
of banana
fruit: (a) with
peel; (b) without peel.
the ultimate strength of the wire was determined by using an Instron universal testing machine (model no. 1185). The mechanical properties of raw banana fruit were measured while cutting under shear with the stainless steel string in the Instron machine. For this purpose, a special fixture for attaching to the load cell of the Instron machine was designed and fabricated. This kept the stainless steel string taut while shearing through the banana. The load cell of Instron was calibrated to a full graph scale of 200 N. The crosshead speed was fixed at 10 mm/min. The sample fruit was peeled manually and the pulp portion was kept on the cutting platform in three different positions, i.e. convex, concave and plain, for the Dwarf Scavendish variety. Convex is_ the position when the outer curved side of the fruit is facing the load cell while the concave position is when the inner curved (concave) side of the fruit is facing the compressive load (Fig. 1). Plain is the position when the fruit is resting on its side in the most stable position. Sample fruit at each position were cut under the load at six different locations (Fig. 1). However, the banana of Nendran variety was kept in only the plain position because it was observed that the slices at the top and tail ends would produce oval shaped slices in from the the convex and concave position. This shape is undesirable consumer’s point of view as round chips are preferred. Cuts were performed at three places, i.e. top, middle and tail end. The test was performed with three replications.
R. P Kachru, N. Kotwaliwale, D. Balasubramanian
372
The load against depth of cut was recorded continuously. After shearing of the banana pulp was complete, the plane of cut was plotted on paper and its area was determined by using a graphical method so that mechanical data per unit area of cut could be determined.
RESULTS
AND DISCUSSION
The physical constituents of banana fruit as a per cent weight of whole fruit and the pulp-peel ratio are reported in Table 1. The pulp to peel ratio for Dwarf Scavendish variety of banana varies between 1.18 and 159 with an average value of l-39 at a moisture content of 264.17% (db) and 666.28% (db) of pulp and peel, respectively. These values for the Nendran variety were 2.05 and 2.61, respectively with an average of 2.32 at a pulp moisture content of 153.39% (db) and peel moisture content of 516.41% (db). The peel thickness was measured for both the varieties at the peel moisture content of 666.28% (db) and 516.41% (db) for Dwarf Scavendish and Nendran varieties, respectively. For the Dwarf Scavendish variety, peel thickness varied from 3.38 mm to 4.48 mm, the average being 3.65 mm. For the Nendran variety, these values were found to be 2.55 mm and 3.55 mm, respectively, with an average of 2.95 mm. The banana peel is formed by 3-5 longitudinal planes and the joint of these planes forms a ridge. The thickness of peel is more at these ridges than other places. Figure 2 shows the peel planes, ridges and typical cross-section of raw banana fruit of both varieties. Table 2 shows the range of average diameter at various planes of cut of the banana fruit with and without peel, for both the tested varieties. It can be seen that the diameter of fruit is less at both the ends and maximum in the middle portion. The maximum and minimum observed diameters for Dwarf Scavendish and Nendran banana with peel were 30.86 mm, 18.44 and TABLE 1 Constituents of Banana Fruit tiriety
Total fiuit weight of single fruit
Pulp (%)
Peel (%)
fd
Dwarf Scavendish Average Maximum Minimum Standard deviation Nendran Average Maximum Minimum Standard deviation
Moisture content % (db) Pulp
Peel
Pulplpeel ratio
89.69 97.84 79.97 5.15
58.10 61.35 54.23 2.24
41.90 4577 38.65 2.24
245.7 252.4 239.0
669.8 708.4 599.8
1.39 1.59 1.18 0.13
126.16 201.43 76.25 38.77
69.77 72.32 67.25 l-65
30.23 32.78 27.68 l-65
154,l 168.6 145-l
516.4 542.2 486.2
2.32 2.61 2-05 0.18
Physical and mechanical properties of green banana fruit
(0 Three planes (Dwarf Scavendish)
373
(ii) Five planes (Dwarf Scavendisb)
3.50 mm (iii) Four planes (Nendran)
Fig. 2. Typical cross-section
40.86
(iv) Four planes (Nendran)
(X-X’
of Fig. I) of banana portion.
fruit showing peel and pulp
mm, 17.01 mm, respectively. These values for the fruit without peel are 23.34 mm, 15.19 mm and 37.08 mm, 11.76 mm, respectively (Table 2). Table 3 gives the specific gravity of various parts of banana fruit, peel and pulp. It is evident, that the pulp portion has the maximum specific gravity for both varieties of banana. The peel of Dwarf Scavendish banana has a higher specific gravity (0.943) than the whole fruit (0.933) containing peel and pulp. This may be because of the presence of air voids in between peel and pulp in this particular variety. However, the peel of Nendran banana has a lower specific gravity (O-948) than the whole fruit (1.005). It was also found that the middle part of the fruit has a higher specific gravity than its top and tail ends, because of its higher moisture content than the other two parts (Table 3). A typical graphical output from the universal testing machine representing load against the depth of cut is shown in Fig. 3. The average, maximum and minimum values (and their standard deviations) of maximum
R. F Kachru, N. Kotwaliwale, D. Balasubramanian
374
TABLE2 Diameter of Banana Fruit at Various Planes of Cut Variety Dwarf Scavendish
Nendran
Condition
With peel Average Maximum Minimum Standard deviation Without peel Average Maximum Minimum Standard deviation With peel Average Maximum Minimum Standard deviation Without peel Average Maximum Minimum Standard deviation
(E)
(tfz,
(rz,
(::)
(rz)
(Lz)
2451 27.18 18.44 2.10
29.46 31.01 27.53 0.93
30.24 30.86 28.76 0.56
29.66 30.60 28.05 0.76
28.36 29.21 27.06 0.68
22.94 25.68 18.74 1.78
17.16 20.54 15.91 1.37
21.54 22.20 20.70 0.49
22.23 23.13 20.79 0.80
21.95 23.34 19.88 0.95
20.82 22.66 18.43 1.08
16.22 19.56 12.84 1.65
21.97 27.68 17.01 2.99
31.71 38.25 28.00 2.75
35.77 40.86 32.11 2.97
36.00 40.86 29.20 3.25
33.10 39.10 24.01 4.55
18.15 22.53 14.41 2.42
27.53 32.58 23.15 2.88
30.44 35.38 26.03 2.81
30.85 37.08 26.83 3.00
2891 36.14 19.66 4.27
*Refer to Fig. 1. TABLE 3 Specific Gravity of Banana Fruit Variety
Dwarf Scavendish
Constituent
Sample position (end) in fruit
Moisture content, % (db)
Specific gravity
Average specific gravity
Whole fruit (peel + pulp)
Top Middle Tail Top Middle Tail Top Middle Tail
338.6 356.0 349.6 599.8 708.4 701.3 239.0 252.4 245.7
0.896 0.982 0.962 0.868 1.007 0.954 0.950 1.030 0.999
0.933
Top Middle Tail Top Middle Tail Top Middle Tail
329.7 341.4 308.7 520.8 542.2 486.2 148.5 168.6 145.1
1.030 1.006 0.980 0.931 0.991 0.921 1.120 1.150 1,060
1.005
Peel only Pulp only
Nendran
Whole- fruit (peel + pulp) Peel only Pulp only
0.943 0.993
0.948 1.110
375
Physical and mechanical properties of green banana fruit
I
I
I
I
i ’ i 4 I I i i i I
Middle
I i 1i i i i i
j
I
,
4
I
--U I I
I I I I I
Top
Middle
’ i ’ % I i i
1 Tail
I
I
I
16 8 Load, N (Var. Dwarf Scavendish) Fig. 3. Graphical
I
1
,
I
8
16
24
32
Load, N (Var. Nendran)
output by lnstron machine for load vs. depth of cut in banana pulp: (a) Dwarf Scavendish; (h) Nendran.
fruit
load, total energy required for cut, and energy requirement per unit area of cut are reported in Table 4. The maximum load required for cutting the banana slice is higher for the Nendran variety (28.2 N) than for the Dwarf Scavendish variety (22.4 N). Similarly, the load required per unit width of cut is higher for the Nendran variety than for the Dwarf Scavendish variety (Table 4). However, the position and the part of fruit does not have any significant effect over the load per unit width. It is observed that the average energy requirement per unit area of cut of banana is maximum when kept in the convex position (Table 4), while the energy requirement per unit area of cut is minimum in the concave position.
(2)
Convex
(1)
Dlwarf Scavendish
Concave
Position of fruit
Variety
Top Average Maximum Minimum Standard Middle Average Maximum Minimum Standard Tail Average Maximum Minimum Standard Top Average Maximum Minimum Standard Middle Average Maximum Minimum Standard Tail Average Maximum Minimum Standard
(3)
17.60 18.80 16.80 0.68 16.90 18.20 15.80 0.90
788.00 826.00 753.00 25.58 664.33 735.00 570.00 62.20
deviation
deviation
deviation
deviation 16.70 18.60 14.60 1.29
16.77 19.00 14.00 1.96
604.67 705.00 537.00 53.42
deviation
673.50 806.00 545.00 94.64
17.97 19.40 15.40 1.37
716.17 825.00 649.00 65.21
deviation
(5)
Maximum load (N)
Fruit Pulp
17.67 20.40 13.00 2.39
Cross-sectional area of cut (mm2) (4)
of Banana
TABLE4 Properties
640.67 787.00 506.00 86.62
Part of fruit
Mechanical
5 12.93 582.57 424.94 58.44 446.93 541.24 379.44 51.82 508.56 592.11 470.30 40.84
0.351 0.420 0.310 0.034 0.338 0.383 0.285 0.038
548.25 615.02 473.08 48.99
573.48 639.31 490.55 52.70
599.11 686.81 508.89 58.73
Energy per unit area (J/m ‘) (6)
0,342 0.420 0.283 0.043
0.333 0.425 0.285 0.053
0.413 0.525 0.338 0.072
0.386 0.505 0.258 0.075
Total energy for cut (J) (6)
0,583 0.641 0,524 0.037
0.556 0.580 O-532 0.015
0.612 0.528 0,033
0.569
0.604 0.702 0.515 0.063
0.640 0.520 0,037
0.597
0.618 0,716 0.512 0.060
Load per unit width (N/mm) (7)
Y
b 2 E & a 2 3 -. f
5’ k _m b
2
?J 3 x “S f:
d
W
Nandran
TOP Average Maximum Minimum Standard deviation Middle Average Maximum Minimum Standard deviation Tail Average Maximum Minimum Standard deviation
Plain
(3)
Top Average Maximum Minimum Standard deviation Middle Average Maximum Minimum Standard deviation Tail Average Maximum Minimum Standard deviation
(2)
(1)
Part of fruit
Plain
Position of fruit
Variety
Conrd.
19.80 22.00 17.60 2.20 20.70 24.80 16.60 4.10
836.50 927.00 746.00 90.50 704.00 774.00 634.00 70.00
15.60 16.40 12.20 1.53
608.17 695.00 361.00 120.05 23.80 28.20 19.40 4.40
18.60 20.40 16.00 1.70
747.67 770.00 733.00 13.56
702.00 807.00 597.00 105.00
19.07 22.40 16.40 1.83
(5)
Maximum load (N)
668.83 744.00 604.00 51.08
Cross-sectional area of cut (mm”) (4)
TABLE 4
0.365 0.373 0.358 0.007
0.43 1 0.433 0.430 0.001
0.403 0.433 0.373 0.030
0.317 0.385 0.173 0.069
0.386 0.423 0.355 0.023
0.371 0.398 0.345 0.017
Total energy for cut (J) (6)
524.71 587.54 461.89 62.83
521.48 576.41 466.56 54.94
593.02 724.46 461.59 131.43
517.82 555.56 477.84 26.30
5 16.52 564.09 484.3 1 28.18
558.48 658.11 504.20 52.31
Energy per unit area (Jim’) (6)
0.688 0.774 0.602 O.086
0.660 0.701 0.619 0.041
0.725 0.821 0.629 0.096
0.565 0.616 0.547 0.024
0.612 0.659 0543 0.042
0.644 0.754 0,544 0.069
Load per unit width (N/mm) (7)
378
R. P Kachru, N. Kotwaliwale,D. Balasubramanian
However, when the fruit is kept in the plain position, the average energy requirement per unit area is approximately mid-way between the other two positions. In the convex position, some energy is required for bending the fruit prior to piercing. In this position, the fruit is supported at its two extreme ends and the moment arm for bending is positive and maximum, whereas, in the concave and plain positions, the moment arm is zero but the base contact is single point and multi-point, respectively. Therefore, the energy requirement per unit area of cut of the banana pulp is maximum in the convex position followed by the plain and concave positions. It is therefore inferred that plain is the best position for slicing. This provides such advantages as: the fruit remains in the most stable condition, energy requirement for the performance of cut is moderate and the slices of the top and tail ends are not oval shaped.
ACKNOWLEDGEMENTS The authors acknowledge, with thanks, the support and facilities provided by the Director, Central Institute of Agricultural Engineering, Bhopal, India, and the Director, Regional Research Laboratory (CSIR), Bhopal, India, in carrying out this research.
REFERENCES Mohesenin, N. N. (1980). Physical Properties of Plant and Chemical Materials. Gordon and Breach, London. Rameshbabu & Nayak, R. (1993). Moisture content determination of banana and lemon using conventional air oven method. Unpublished report, Post Harvest Tech. and Food Proc. Engng Dept., College of Agricultural Engng, Raichur, Bangalore. India. Sandor, B. I. (1978). Strength of Materials. Prentice Hall, Inc., Englewood Cliffs, NJ.
ELSEVIER
Research Note Physical and Mechanical Properties of Green Banana (Muss paradisiaca) Fruit R. P. Kachru,” Nachiket Kotwaliwale
& D. Balasubramanian
Division of Post Harvest Engineering, Central Institute of Agricultural Bhopal (MP) 462038, India (Received
Engineering,
20 April 1994; revised version received 9 August 1994; accepted 13 September 1994)
ABSTRACT The physical and mechanical properties of two varieties of green banana fruit, namely, Dwarf Scavendish and Nendran, were determined, The average pulp and peel moisture content were 264.17% (db) and 666.28% (db), respectively for Dwarf Scavendish and 153.39% (db) and 516.41% (db), respectively for Nendran. At these average moisture contents, the average pulp to peel ratios were I .39 and 2.32, and peel thickness were 3.65 mm and 2.95 mm, respectively. The maximum diameter of fruit without peel was 23.34 mm and 37.08 mm, and average pulp specific gravity was 0.993 and 1 .I 10, respectively for the two varieties. The maximum effective length and width of the banana pulp resting at its most stable position was observed to be 137.0 mm and 66.5 mm, respectively for Dwarf Scavendish and 194.5 mm and 50.0 mm, respectively for Nendran. The maximum load required to cut a cross-sectional slice of pulp was 22.4 N and 28.2 N for the two varieties, respectively. Maximum energy of 686.81 J/m’ for Dwarf Scavendish and 724.46 J/m2 for Nendran was required to cut a slice of the fruit. The banana kept in a convex position required the most energy to cut, whereas the plain position was observed to be the best position vis-kvis the energy requirement and consumer preference of chip shape.
*Present address: Indian Delhi 110001, India.
Council
of Agricultural
Research,
Krishi Bhawan,
New
370
R. f! Kachru, N. Kotwaliwale,D. Bafasubramanian
INTRODUCTION Banana (Muss parudisiaca) is consumed directly as raw, ripe fruit or processed into pulp-liquid fruit, canned slice, deep-fried chips, toffees, fruit bars, brandy, etc. Deep-fried chips of raw as well as ripe banana are a popular snack food in southern India. At present, the chips are made by hand peeling raw banana and slicing the pulp portion in a wooden platform type slicer with mild steel blades and then deep frying in oil. The method is cumbersome, unhygienic and does not produce chips of uniform thickness. Besides it may inflict injury to the operator while slicing. To this effect, there is a need to develop a machine which would enhance the capacity and reduce drudgery in making the chips. The design of the machine is to be based on the physical and mechanical properties of raw (green) banana fruit. For making chips of green banana fruit, steel strings are proposed for cutting the fruit. For this, the physical and mechanical properties of banana fruit are required for the selection of size of the steel strings and design of the various parts of the machinery. The objectives of the study were to find the physical properties, namely, size, shape, peel thickness, specific gravity, moisture content, physical constituents (pulp to peel ratio), and mechanical properties, such as total cutting energy, energy requirement per unit area of cut, and maximum load for cutting of the fruit pulp using steel string as a cutting tool. MATERIALS
AND METHODS
Fully mature, unripe (green) bananas of the Dwarf Scavendish and Nendran varieties were procured from Bhopal and Coimbatore markets, respectively. The bananas were separated visually into four groups according to their size. Four bananas were chosen from each group for the determination of physical constituents and properties. The peel and pulp were weighed separately for individual bananas to determine the pulp to peel ratio. The moisture content was determined by placing 35-4-O mm thick banana slices with and without peel in a single layer, in an aluminium dish in a hot air oven, at 130f 1°C for 1.5 h (Rameshbabu & Nayak, 1993). The specific gravity of banana was determined by using the toluene displacement method (Mohsenin, 1980). Specific gravity was measured at three different locations in the fruit, i.e. top, middle and tail end of the fruit (Fig. 1). The top is defined as the end of the fruit which was attached to the plant. The physical properties, size and peel thickness were determined using Vernier calipers having a least count of 0.05 mm. The diameter of the banana with and without peel were recorded at six planes of cut along the longitudinal axis of the fruit, two planes falling in each of the top, middle and tail end of the fruit (Fig. 1). At each plane of cut (Dl-D6), the diameter was measured at four places. The shape of the banana with and without peel was plotted keeping the fruit resting on its most stable position and then the effective length and width were measured (Fig. 1). Stainless steel string was used for banana slicing as proposed for the machine. For proper size selection of the wire,
Physical and mechanical properties of green banana jkuit
(a) with peel
Fig. 1. Longitudinal
(b) without peel section
of banana
fruit: (a) with
peel; (b) without peel.
the ultimate strength of the wire was determined by using an Instron universal testing machine (model no. 1185). The mechanical properties of raw banana fruit were measured while cutting under shear with the stainless steel string in the Instron machine. For this purpose, a special fixture for attaching to the load cell of the Instron machine was designed and fabricated. This kept the stainless steel string taut while shearing through the banana. The load cell of Instron was calibrated to a full graph scale of 200 N. The crosshead speed was fixed at 10 mm/min. The sample fruit was peeled manually and the pulp portion was kept on the cutting platform in three different positions, i.e. convex, concave and plain, for the Dwarf Scavendish variety. Convex is_ the position when the outer curved side of the fruit is facing the load cell while the concave position is when the inner curved (concave) side of the fruit is facing the compressive load (Fig. 1). Plain is the position when the fruit is resting on its side in the most stable position. Sample fruit at each position were cut under the load at six different locations (Fig. 1). However, the banana of Nendran variety was kept in only the plain position because it was observed that the slices at the top and tail ends would produce oval shaped slices in from the the convex and concave position. This shape is undesirable consumer’s point of view as round chips are preferred. Cuts were performed at three places, i.e. top, middle and tail end. The test was performed with three replications.
R. P Kachru, N. Kotwaliwale, D. Balasubramanian
372
The load against depth of cut was recorded continuously. After shearing of the banana pulp was complete, the plane of cut was plotted on paper and its area was determined by using a graphical method so that mechanical data per unit area of cut could be determined.
RESULTS
AND DISCUSSION
The physical constituents of banana fruit as a per cent weight of whole fruit and the pulp-peel ratio are reported in Table 1. The pulp to peel ratio for Dwarf Scavendish variety of banana varies between 1.18 and 159 with an average value of l-39 at a moisture content of 264.17% (db) and 666.28% (db) of pulp and peel, respectively. These values for the Nendran variety were 2.05 and 2.61, respectively with an average of 2.32 at a pulp moisture content of 153.39% (db) and peel moisture content of 516.41% (db). The peel thickness was measured for both the varieties at the peel moisture content of 666.28% (db) and 516.41% (db) for Dwarf Scavendish and Nendran varieties, respectively. For the Dwarf Scavendish variety, peel thickness varied from 3.38 mm to 4.48 mm, the average being 3.65 mm. For the Nendran variety, these values were found to be 2.55 mm and 3.55 mm, respectively, with an average of 2.95 mm. The banana peel is formed by 3-5 longitudinal planes and the joint of these planes forms a ridge. The thickness of peel is more at these ridges than other places. Figure 2 shows the peel planes, ridges and typical cross-section of raw banana fruit of both varieties. Table 2 shows the range of average diameter at various planes of cut of the banana fruit with and without peel, for both the tested varieties. It can be seen that the diameter of fruit is less at both the ends and maximum in the middle portion. The maximum and minimum observed diameters for Dwarf Scavendish and Nendran banana with peel were 30.86 mm, 18.44 and TABLE 1 Constituents of Banana Fruit tiriety
Total fiuit weight of single fruit
Pulp (%)
Peel (%)
fd
Dwarf Scavendish Average Maximum Minimum Standard deviation Nendran Average Maximum Minimum Standard deviation
Moisture content % (db) Pulp
Peel
Pulplpeel ratio
89.69 97.84 79.97 5.15
58.10 61.35 54.23 2.24
41.90 4577 38.65 2.24
245.7 252.4 239.0
669.8 708.4 599.8
1.39 1.59 1.18 0.13
126.16 201.43 76.25 38.77
69.77 72.32 67.25 l-65
30.23 32.78 27.68 l-65
154,l 168.6 145-l
516.4 542.2 486.2
2.32 2.61 2-05 0.18
Physical and mechanical properties of green banana fruit
(0 Three planes (Dwarf Scavendish)
373
(ii) Five planes (Dwarf Scavendisb)
3.50 mm (iii) Four planes (Nendran)
Fig. 2. Typical cross-section
40.86
(iv) Four planes (Nendran)
(X-X’
of Fig. I) of banana portion.
fruit showing peel and pulp
mm, 17.01 mm, respectively. These values for the fruit without peel are 23.34 mm, 15.19 mm and 37.08 mm, 11.76 mm, respectively (Table 2). Table 3 gives the specific gravity of various parts of banana fruit, peel and pulp. It is evident, that the pulp portion has the maximum specific gravity for both varieties of banana. The peel of Dwarf Scavendish banana has a higher specific gravity (0.943) than the whole fruit (0.933) containing peel and pulp. This may be because of the presence of air voids in between peel and pulp in this particular variety. However, the peel of Nendran banana has a lower specific gravity (O-948) than the whole fruit (1.005). It was also found that the middle part of the fruit has a higher specific gravity than its top and tail ends, because of its higher moisture content than the other two parts (Table 3). A typical graphical output from the universal testing machine representing load against the depth of cut is shown in Fig. 3. The average, maximum and minimum values (and their standard deviations) of maximum
R. F Kachru, N. Kotwaliwale, D. Balasubramanian
374
TABLE2 Diameter of Banana Fruit at Various Planes of Cut Variety Dwarf Scavendish
Nendran
Condition
With peel Average Maximum Minimum Standard deviation Without peel Average Maximum Minimum Standard deviation With peel Average Maximum Minimum Standard deviation Without peel Average Maximum Minimum Standard deviation
(E)
(tfz,
(rz,
(::)
(rz)
(Lz)
2451 27.18 18.44 2.10
29.46 31.01 27.53 0.93
30.24 30.86 28.76 0.56
29.66 30.60 28.05 0.76
28.36 29.21 27.06 0.68
22.94 25.68 18.74 1.78
17.16 20.54 15.91 1.37
21.54 22.20 20.70 0.49
22.23 23.13 20.79 0.80
21.95 23.34 19.88 0.95
20.82 22.66 18.43 1.08
16.22 19.56 12.84 1.65
21.97 27.68 17.01 2.99
31.71 38.25 28.00 2.75
35.77 40.86 32.11 2.97
36.00 40.86 29.20 3.25
33.10 39.10 24.01 4.55
18.15 22.53 14.41 2.42
27.53 32.58 23.15 2.88
30.44 35.38 26.03 2.81
30.85 37.08 26.83 3.00
2891 36.14 19.66 4.27
*Refer to Fig. 1. TABLE 3 Specific Gravity of Banana Fruit Variety
Dwarf Scavendish
Constituent
Sample position (end) in fruit
Moisture content, % (db)
Specific gravity
Average specific gravity
Whole fruit (peel + pulp)
Top Middle Tail Top Middle Tail Top Middle Tail
338.6 356.0 349.6 599.8 708.4 701.3 239.0 252.4 245.7
0.896 0.982 0.962 0.868 1.007 0.954 0.950 1.030 0.999
0.933
Top Middle Tail Top Middle Tail Top Middle Tail
329.7 341.4 308.7 520.8 542.2 486.2 148.5 168.6 145.1
1.030 1.006 0.980 0.931 0.991 0.921 1.120 1.150 1,060
1.005
Peel only Pulp only
Nendran
Whole- fruit (peel + pulp) Peel only Pulp only
0.943 0.993
0.948 1.110
375
Physical and mechanical properties of green banana fruit
I
I
I
I
i ’ i 4 I I i i i I
Middle
I i 1i i i i i
j
I
,
4
I
--U I I
I I I I I
Top
Middle
’ i ’ % I i i
1 Tail
I
I
I
16 8 Load, N (Var. Dwarf Scavendish) Fig. 3. Graphical
I
1
,
I
8
16
24
32
Load, N (Var. Nendran)
output by lnstron machine for load vs. depth of cut in banana pulp: (a) Dwarf Scavendish; (h) Nendran.
fruit
load, total energy required for cut, and energy requirement per unit area of cut are reported in Table 4. The maximum load required for cutting the banana slice is higher for the Nendran variety (28.2 N) than for the Dwarf Scavendish variety (22.4 N). Similarly, the load required per unit width of cut is higher for the Nendran variety than for the Dwarf Scavendish variety (Table 4). However, the position and the part of fruit does not have any significant effect over the load per unit width. It is observed that the average energy requirement per unit area of cut of banana is maximum when kept in the convex position (Table 4), while the energy requirement per unit area of cut is minimum in the concave position.
(2)
Convex
(1)
Dlwarf Scavendish
Concave
Position of fruit
Variety
Top Average Maximum Minimum Standard Middle Average Maximum Minimum Standard Tail Average Maximum Minimum Standard Top Average Maximum Minimum Standard Middle Average Maximum Minimum Standard Tail Average Maximum Minimum Standard
(3)
17.60 18.80 16.80 0.68 16.90 18.20 15.80 0.90
788.00 826.00 753.00 25.58 664.33 735.00 570.00 62.20
deviation
deviation
deviation
deviation 16.70 18.60 14.60 1.29
16.77 19.00 14.00 1.96
604.67 705.00 537.00 53.42
deviation
673.50 806.00 545.00 94.64
17.97 19.40 15.40 1.37
716.17 825.00 649.00 65.21
deviation
(5)
Maximum load (N)
Fruit Pulp
17.67 20.40 13.00 2.39
Cross-sectional area of cut (mm2) (4)
of Banana
TABLE4 Properties
640.67 787.00 506.00 86.62
Part of fruit
Mechanical
5 12.93 582.57 424.94 58.44 446.93 541.24 379.44 51.82 508.56 592.11 470.30 40.84
0.351 0.420 0.310 0.034 0.338 0.383 0.285 0.038
548.25 615.02 473.08 48.99
573.48 639.31 490.55 52.70
599.11 686.81 508.89 58.73
Energy per unit area (J/m ‘) (6)
0,342 0.420 0.283 0.043
0.333 0.425 0.285 0.053
0.413 0.525 0.338 0.072
0.386 0.505 0.258 0.075
Total energy for cut (J) (6)
0,583 0.641 0,524 0.037
0.556 0.580 O-532 0.015
0.612 0.528 0,033
0.569
0.604 0.702 0.515 0.063
0.640 0.520 0,037
0.597
0.618 0,716 0.512 0.060
Load per unit width (N/mm) (7)
Y
b 2 E & a 2 3 -. f
5’ k _m b
2
?J 3 x “S f:
d
W
Nandran
TOP Average Maximum Minimum Standard deviation Middle Average Maximum Minimum Standard deviation Tail Average Maximum Minimum Standard deviation
Plain
(3)
Top Average Maximum Minimum Standard deviation Middle Average Maximum Minimum Standard deviation Tail Average Maximum Minimum Standard deviation
(2)
(1)
Part of fruit
Plain
Position of fruit
Variety
Conrd.
19.80 22.00 17.60 2.20 20.70 24.80 16.60 4.10
836.50 927.00 746.00 90.50 704.00 774.00 634.00 70.00
15.60 16.40 12.20 1.53
608.17 695.00 361.00 120.05 23.80 28.20 19.40 4.40
18.60 20.40 16.00 1.70
747.67 770.00 733.00 13.56
702.00 807.00 597.00 105.00
19.07 22.40 16.40 1.83
(5)
Maximum load (N)
668.83 744.00 604.00 51.08
Cross-sectional area of cut (mm”) (4)
TABLE 4
0.365 0.373 0.358 0.007
0.43 1 0.433 0.430 0.001
0.403 0.433 0.373 0.030
0.317 0.385 0.173 0.069
0.386 0.423 0.355 0.023
0.371 0.398 0.345 0.017
Total energy for cut (J) (6)
524.71 587.54 461.89 62.83
521.48 576.41 466.56 54.94
593.02 724.46 461.59 131.43
517.82 555.56 477.84 26.30
5 16.52 564.09 484.3 1 28.18
558.48 658.11 504.20 52.31
Energy per unit area (Jim’) (6)
0.688 0.774 0.602 O.086
0.660 0.701 0.619 0.041
0.725 0.821 0.629 0.096
0.565 0.616 0.547 0.024
0.612 0.659 0543 0.042
0.644 0.754 0,544 0.069
Load per unit width (N/mm) (7)
378
R. P Kachru, N. Kotwaliwale,D. Balasubramanian
However, when the fruit is kept in the plain position, the average energy requirement per unit area is approximately mid-way between the other two positions. In the convex position, some energy is required for bending the fruit prior to piercing. In this position, the fruit is supported at its two extreme ends and the moment arm for bending is positive and maximum, whereas, in the concave and plain positions, the moment arm is zero but the base contact is single point and multi-point, respectively. Therefore, the energy requirement per unit area of cut of the banana pulp is maximum in the convex position followed by the plain and concave positions. It is therefore inferred that plain is the best position for slicing. This provides such advantages as: the fruit remains in the most stable condition, energy requirement for the performance of cut is moderate and the slices of the top and tail ends are not oval shaped.
ACKNOWLEDGEMENTS The authors acknowledge, with thanks, the support and facilities provided by the Director, Central Institute of Agricultural Engineering, Bhopal, India, and the Director, Regional Research Laboratory (CSIR), Bhopal, India, in carrying out this research.
REFERENCES Mohesenin, N. N. (1980). Physical Properties of Plant and Chemical Materials. Gordon and Breach, London. Rameshbabu & Nayak, R. (1993). Moisture content determination of banana and lemon using conventional air oven method. Unpublished report, Post Harvest Tech. and Food Proc. Engng Dept., College of Agricultural Engng, Raichur, Bangalore. India. Sandor, B. I. (1978). Strength of Materials. Prentice Hall, Inc., Englewood Cliffs, NJ.