Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Reexamination Certificate
2000-03-03
2001-08-21
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
C209S556000, C209S592000, C209S590000, C073S579000, C073S653000, C073S657000, C073S659000, C702S194000, C702S056000, C702S075000, C702S076000, C702S077000
Reexamination Certificate
active
06276536
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for measuring the ripeness and the physical characteristics (hereinafter referred to as texture) such as hardness, resistance to teeth and glutinousness of fruits such as a kiwifruit, an apple, a melon, a tomato and the like, and vegetables, without damaging the fruits to be measured. More particularly, the present invention relates to a technology for finding the ripeness and the texture of a fruit from the relation between the elasticity value and the damping ratio, and, from the relation between the viscosity value and the elasticity value of the fruit.
BACKGROUND OF THE INVENTION
For measuring the ripeness of a fruit without damaging the fruit, a method of measuring the change of the color of the fruit and a method of measuring the hardness of the surface of the fruit are tried. However, the former can not be applied for a kiwifruit, a pear and the like whose color does not change in the process of ripening, and, in the latter, there is big discrepancy between the measured result and the actual ripeness of the fruit because the hardness of the surface of the fruit does not represent the hardness of the flesh of the fruit.
Also, a method for measuring the sugar content of a fruit by using the technology of the spectral diffraction of near infrared rays is launched for practical use in sorting fruits such as melons, peaches and the like by ripeness. However, in this method, a just ripe fruit and a rotten fruit can not be discriminated because both have similarly high content of sugar, though the sugar content increases in the process of changing from unripe to ripe.
In the quality of a fruit, texture is an important factor as well as taste. In the United States, the judgment of the texture of an apple is performed by the panel test of experienced judging members. However, in this method, an objective judgment of the texture is hardly obtained because the judgments of the respective members are subject to the respective experiences and the likes of the members.
In plant physiology, it is known that the texture, i.e., the physical characteristics such as hardness, resistance to teeth, glutinousness and the like of a fruit relate to the viscosity value and the elasticity value of the fruit.
The softening of a fruit is caused by the change of the characteristics of the viscosity and the elasticity of the cell wall of the fruit. The mechanical structure of the cell wall of a fruit is maintained in such a manner that bundles of crystalline cellulose surrounded respectively by highly polymerized polysaccharides (i.e. matrix gel) are united by winding each other. The softening of a fruit is caused by the loosening of the winding of the bundles of the crystalline cellulose, which is caused by the low polymerization of the matrix gel. The polysaccharides which compose the matrix gel comprise various substances, and the substance which is low polymerized in the softening is different depending on the kind of fruit. As a result, the state of the matrix gel of a ripe fruit is different depending on the kind of fruit. The rough taste in the flesh of an apple or the like and the thick taste in the flesh of a berry such as kiwifruit or the like are caused by the different state of the matrix gel of each. The state of the matrix gel of a fruit represents the glutinousness of the fruit. In other words, the viscosity value of a fruit represents the feeling in eating such as the glutinousness, juiciness and the like of the fruit. Also the elasticity value of a fruit represents the elasticity force of the cell wall of the fruit, i.e. the hardness of the flesh of the fruit.
B. Drake designed a viscosity measuring apparatus for objectively measuring the texture of foodstuffs such as fruits by utilizing the fact that the texture can be shown by the characteristics of the viscosity and the elasticity of the foodstuffs (J. Food Sci. 27. P182-188:1962). The method is to compute the damping ratio &eegr; of the foodstuff to be measured by an equation &eegr;=&Dgr;f/f
0
, in which f
0
is the intrinsic resonance frequency of the foodstuff, which is obtained by measuring the rectangular slice of the foodstuff, on which a vibration is applied, and &Dgr;f is a half-power bandwidth. And the damping ratio &eegr; thus computed is deemed as the viscosity value of the foodstuff.
However, in this method also, the foodstuff to be measured is damaged because the rectangular slice has to be taken from the foodstuff for the measurement.
SUMMARY OF THE INVENTION
A method for measuring the ripeness and the texture of a fruit in the present invention, for addressing the above conventional problems, comprises a step for applying a vibration having sequentially changing frequencies to a fruit to be measured, a step for measuring the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, a step for measuring the weight of the fruit, a step for finding the transfer functional characteristic of the fruit by performing frequency analysis based on the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, and computing the secondary resonance frequency f
0
(i.e., frequency of secondary resonance peak) of the fruit and the frequencies f2 and f1 which represent the frequencies of the fruit, at which respective gains are 3 dB lower than the gain at the frequency f
0
of the secondary resonance peak, a step for computing the damping ratio &eegr; defined by an equation &eegr;=(f2−f1)/f
0
and the elasticity value E defined by an equation E=m
⅔
·f
0
2
, of the fruit, in which m represents the weight of the fruit, a step for determining the ripeness of the fruit by using the elasticity value E when the elasticity value E is larger than a predetermined value and by using the damping ratio &eegr; when the elasticity value E is not larger than the predetermined value, a step for computing the damping ratio &eegr; defined by the equation &eegr;=(f2−f1)/f
0
, the viscosity value c defined by an equation c=k·f
0
·m·&eegr; and the elasticity value E defined by the equation E=m
⅔
·f
0
2
, of the fruit, and a step for determining the texture and the ripeness of the fruit from the relation between the viscosity value c and the elasticity value E.
Also, an apparatus for measuring the ripeness and the texture of a fruit in the present invention comprises a vibration applying unit for applying a vibration to a fruit to be measured, a second vibration detecting unit for detecting the intensity of a vibration applied to the fruit and generating the signal of the vibration detected, a first vibration detecting unit for detecting the intensity of the vibration of the fruit to which the vibration is applied by the vibration applying unit and generating the signal of the vibration detected, a weight gauge for measuring the weight of the fruit and generating the signal of the weight measured, a secondary resonance point computing unit having functions of finding the transfer functional characteristic of the fruit by performing frequency analysis based on the output signals of the first vibration detecting unit and the second vibration detecting unit, and computing a secondary resonance frequency f
0
(i.e., frequency of secondary resonance peak) of the fruit and frequencies f1 and f2 which represent the frequencies of the fruit, at which respective gains are 3 dB lower than the gain at the frequency f
0
of the secondary resonance peak, based on the transfer functional characteristic of the fruit, and, functions for computing the damping ratio &eegr;, the elasticity value E and the viscosity value c of the fruit from the output signal of the weight gauge and the frequencies f
0
, f1 and f2, outputting the signals of the results computed, and also displaying the output signals of the results.
In the present invention, the elasticity value E, the damping ratio &eegr; and the viscosity value c of the fruit are computed based
Terasaki Shoji
Wada Naoki
Matsushita Electric - Industrial Co., Ltd.
Miller Jonathan R.
Walsh Donald P.
Wenderoth , Lind & Ponack, L.L.P.
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