1. Nondestructive Texture Assessment of Fruits and Vegetablesby
Itzhak Shmulevich
Unlimited Postharvesting
Leuven June 11-14, 2002

2. The Department of Agricultural Engineering
Technion-Israel Institute of Technology

3. Technion-Israel Institute of Technology
The Department of Civil & Environmental Engineering, Agricultural Engineering Option

4. Presentation outline
Introduction - firmness quality nondestructive measurements;
Impact technique vs. acoustic technique;
Experimental report on various fruits;
Results;
Discussion;
Conclusions.

5. QUALITY ASSESSMENT

6. Quality Factors of Agricultural Products
Appearance - visual
Texture feel
Flavor taste and smell
Safety
Nutritive Value

7. Texture Texture can be defined by subjective terms such as:
Firmness Mealiness, Hardness, Softness, Brittleness, Ripeness, Toughness, Chewiness, Smoothness, Crispness, Oiliness, Springiness, Toughness, Fibrousness, or Juiciness etc.

8. Quality Sensing in Commercial Settings
Requirements
Nondestructive
External and internal properties
Accuracy
Speed (5-15 fruits/sec)
Recognize inherent product variability

9. NONDESTRUCTIVE
SENSOR TECHNOLOGY

10. Nondestructive Firmness Measurement Techniques
Fruit Response to Force
Detection by Impact Force
Forced Vibrations
Mechanical or Sonic Impulse
Ultrasonic Techniques
Indirect Firmness Measurement

11. Research Objective The motivation of the present work is to develop
a fast nondestructive method for quality firmness
testing of fruit and vegetable. q
The general objective of the research is to
compare sensing the fruit
firmness using low
mass impulse excitation to
the acoustic response
For quality assessment of fruit and vegetable.

12. Texture

13. Relationship between turgor pressure and tissue rigidity
E=3.6 p +2.5 x107 [ dynes/cm2]
Modulus of Elasticity

14. Nondestructive Firmness Measurement
Impact Force Technique

15. Nondestructive Firmness Measurement
Acoustic Technique

16. Method and Materials Mango (210) Kent cultiver;
Shelf life conditions: 20 0C 50%RH;
12 days, ( 10 experiments):
80 fruit were tested daily only nondestructively
130 fruit were tested both nondestructively and
destructively 12 fruit were tested daily;
Special experimental set up for input and output
signals measurements;
Brix by digital refractometer, Atago's Palette 100. .

17. Low-Mass Impact (LMI) Firmness

18. IQ Firmness
Sinclair International LTD
IQ TM Firmness Tester

19. Destructive Firmness Measurement

20. Destructive Tests

21. Destructive Tests

22. Quality Detection by Impact Force
Time [msec]
Force
[N]

23. Delwiche (1989 ,1991), Nahir et al. (1986 )
Quality Detection by Impact Force
Chen. P (1996), Farabee (1991)
Delwiche (1989 ,1991), Nahir et al. (1986 ) d
sec N Fp Tp td

24. The Acoustic Parameters of a Fruit
Natural frequencies and firmness index - FI
FI = f 2 m 2/3 {104 kg2/3 s-2}
where: f - first spherical resonant frequency
m - fruit’s mass.
Damping ratio - z
The centeroid of the frequency response - fc

25. Firmalon Prototype

26. Firmalon

27. Typical Acoustic Fruit Response
Time Domain
Frequency Domain

28. Microphone Based System for Acoustic Firmness Testing
Source: J. De Baerdemaeker

29. Comparison Between Two Acoustic Test Methods
Method-A: Microphone
Method-B: Piezoelectric-Film Sensor
Source: N. Galili & J. De Baerdemaeker

30. Acoustic Firmness Sensor A F S TM
Source: AWETA

31. Method and Materials Mango (319) Tommy Atkins cultivar;
Shelf life conditions: 20 0C 50%RH;
13 days, ( 12 experiments):
25 fruits were tested daily both nondestructively
and destructively;
Three experiment set-up for input and output
signals measurements;
Brix by digital refractometer, Atago's Palette 100. .

32. Quality Detection by Impact Force

33. Correlation Between Firmness Index (FI) and Sinclair (IQ)

34. Results

35. Results

36. Summary
The firmness indices from the two methods gave clear indications of the ripening process of mango fruit during shelf life.
The Sinclair firmness tester (IQ) correlated well to the acoustic and the destructive tests than the low-mass impact (LMI) by pendulum technique.
The good correlation between the firmness index, measured by an acoustic technique (FI) and the IQ firmness by Sinclair indicates that either of the two may successfully be implemented as an on-line sorter for mango fruit.

37. Current Research
Sinclair International LTD
IQ TM Firmness Tester

38. NONDESTRUCTIVE
SENSOR TECHNOLOGY

39. Nondestructive Firmness Measurement Techniques
Fruit Response to Force
Detection by Impact Force
Forced Vibrations
Mechanical or Sonic Impulse
Ultrasonic Techniques
Indirect Firmness Measurement

40. Nondestructive Firmness Measurement
Impact Force Technique

41. Nondestructive Firmness Measurement
Acoustic Technique

42. Relationship between turgor pressure and tissue rigidity
E=3.6 p +2.5 x107 [ dynes/cm2]

43. The Acoustic Parameters of a Fruit
Natural frequencies and firmness index - FI
FI = f 2 m 2/3 {104 kg2/3 s-2}
where: f - first spherical resonant frequency
m - fruit’s mass.
Damping ratio - z
The centeroid of the frequency response - fc

44. Destructive Firmness Measurement

45. Results

46. Parameters extracted from the measurements
Low-Mass Impulse parameters:
C1 = Fp/Tp; C2 = Fp/Tp2 ; w (-20); and fc(in).
Acoustic parameters:
f1 ; FI ; and fc(out);
Destructive parameters:
E ; Pene and Brix.

47. Quality Detection by Impact

48. Summary
The new parameter of the input excitation signal in frequency domain fc(in) can give a clear indication of firmness and ripening degree of mango fruit, independently of fruit size and shape.
Better correlations were achieved between the destructive indices and the input nondestructive parameter, as in compared to the output parameters. This can be explained by the fact that the output acoustic signal gives global indication of fruit properties and is sensitive to fruit shape, while the input signal represents local properties.

49. Summary (Cont. )
The good correlation between the input and output parameters of the nondestructive tests indicates that integration of the two may improve the accuracy of the nondestructive dynamic tests for mango quality assessment.

50. Method and Materials

51. Method and Materials Shelf life conditions: 20 0C 50%RH;
Between 10 and 25 fruits were tested daily both
nondestructively and destructively;
Three experiment set-up for input and output
signals measurements;
Destructive test;
Brix by digital refractometer, Atago's Palette 100. .

52. Results

53. Results

54. Correlation Between Firmness Index (FI) and Sinclair (IQ)

55. Pearson linear correlation between the nondestructive and destructive tests, n=280 Flamekiss-Nectarine, Correlation is significant at the 0.05 level

56. Pearson linear correlation between the nondestructive and destructive tests, n=150 Fuerte-Avocado, Correlation is significant at the 0.05 level

57. Pearson linear correlation between the nondestructive and destructive tests, n=160 Galia-Melon, Correlation is significant at the 0.05 level

58. Pearson linear correlation between the nondestructive and destructive tests, n=309 Tommy Atkins-Mango, Correlation is significant at the 0.05 level

59. Tommy Atkins-Mango n=309

60. Thanks For Your Attention Thanks to the organizer for a great Symposium

61. Pearson linear correlation between the nondestructive and destructive tests, n=205 Tomato, Correlation is significant at the 0.05 level