Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B13/00—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/02—Food
  • G01N33/025—Fruits or vegetables
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
  • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
  • B07C5/34—Sorting according to other particular properties
  • B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence

Definitions

• the invention relates to a method for determining the quality of fruit and berries by irradiating fruit and berries with electromagnetic radiation.
• the chlorophyll present in the fruit or berries shows prompt fluorescence as a result of this irradiation.
• the present invention also relates to an apparatus for sorting fruit and berries, at least consisting of a feeder part for the fruit and berries, a part for irradiating the fruit and berries with electromagnetic radiation and a part for measuring the chlorophyll fluorescence signal returning from the fruit and berries, and a separation part which operates on the basis of the chlorophyll fluorescence signal returning from the fruit and berries.
• chlorophyll all appearances of the chlorophyll molecule are meant, such as the chlorophyll known as leaf green, protochlorophyll, etc.
• the method of the invention is particularly suitable for determining the quality of blue berries and can especially be used with frozen berries. Below the invention will be described on the basis of blue berries.
• Measuring the amount of chlorophyll of berries is a good method for measuring the maturity and thus the quality of berries. It appears that during the ripening of berries the chlorophyll content of the berry decreases.
• the apparatus known up until now sorts blue berries as to colour. Green berries can be separated from red and blue berries, because the difference in colour is sufficiently evident. However, red berries cannot be separated from blue berries by means of the used method of colour measurement. These red berries are of inferior quality compared to the blue berries, because they have not fully ripened .
• a second problem in colour measurement is that with frozen berries a white frost is created.
• Chlorophyll fluorescence is hardly hindered by the white frost and is much more sensitive than a colour measurement.
• chlorophyll fluorescence chlorophyll can be measured.
• Asian Food Journal (1 987), 3(2), 55-59, R.M. Smillie, S.E. Hetherinton, R.N. Grantley, R. Chaplin and N.L. Wade used the chlorophyll fluorescence technique to measure the photosynthesis activity of fruit. They examined the changes in the photosynthesis activity during ripening and under the influence of low temperatures by measuring the chlorophyll fluorescence signal of the skin.
• the speed with which the chlorophyll fluorescence signal decreased during exposure to low temperatures was used to select varieties that are insensitive to cold. They do not mention the possibility to sort blue berries as to maturity by measuring prompt fluorescence. Neither do they mention the possibility to sort frozen berries as to maturity by measuring prompt fluorescence. In case pf fresh fruit and leafs the chlorophyll fluorescence signal changes during the measurement, because the chlorophyll is photosynthetically active. This as opposed to the chlorophyll in a frozen berry. There is no photosynthesis in a frozen berry. The chlorophyll fluorescence signal is constant over a short period of time of some minutes.
• the prompt quantity of chlorophyll fluorescence is measured, so instantaneous to the irradiation of the berry with electromagnetic radiation.
• the amplitude of the chlorophyll fluorescence signal is now a measure for the quantity of chlorophyll.
• the measuring method of Smillie in total requires one hour because of adjustment to the dark for one hour and some seconds for monitoring the changes in the chlorophyll fluorescence signal.
• the measuring method according to the invention can be carried out in a fraction of a second.
• the usual method for measuring photosynthesis activity in plant material comprises the use of the pulse amplitude modulation (PAM) fluorometer of U.
• PAM pulse amplitude modulation
• chlorophyll fluorescence can be used for determining the quantity- of chlorophyll.
• Reflectance and chlorophyll fluorescence signatures of leaves in Proceedings IGARSS'87 Symp. Ann. Arbor. Ml (USA) 1 8-21 May 1 987, 1 201 -1 206, H.K. Lichtenthaler and C. Buschmann show that around 690 and 730 nm the chlorophyll fluorescence signal of leaves is not linear to the quantity of chlorophyll. It was also demonstrated that a lower quantity of chlorophyll could emit a larger chlorophyll fluorescence signal.
• an object of the present invention is to provide a method which enables one to sort fruit and berries as to maturity and thus quality on the basis of the quantity of chlorophyll.
• Characteristic for the invention are the very high sensitivity and the high speed with which the chlorophyll fluores- cence of fruit and berries can be measured.
• a further object of the invention is to provide an apparatus with which fruit and berries can quickly and accurately be sorted as to quality.
• the method according to the invention is characterized in that the electromagnetic radiation has such a wavelength that the chlorophyll present in the fruit and berries shows prompt fluorescence, which fluorescence is measured.
• the method according to the invention can very well be performed in an apparatus as mentioned in the preamble, which is characterized in that the electromagnetic radiation has such a wavelength that the chlorophyll present in the fruit and berries shows prompt fluorescence, which fluores- cence is measured in the measuring part.
• the present invention is based on a fluorescence measurement which is very specific to the chlorophyll present. Other substances which influence the colour of the blue berries but do not fluoresce, will not contribute to the fluorescence signal. Also according to the invention small differences in the quantity of chlorophyll in the blue berries can be shown, because of the principle that a fluorescence measurement is very sensitive.
• a suitable method for measuring the chlorophyll contents comprises irradiating at least a part of the chlorophyll molecules with electromagnetic radiation, preferably with a wavelength between 400 and
• the excited molecules mainly loose their energy by heat dissipation and for about 3% by emission of fluorescence which preferably is measured between 600 and 800 nm.
• the blue berries can be sorted as to the stage of maturity and quality.
• the invention is very sensitive, entirely non-destructive and very quick. These are the characteristics of the invention which make it possible to manufacture a sorting apparatus with which blue berries can be selected on the basis of the quantity of chlorophyll fluorescence. Because the quantity of fluorescence by chlorophyll has a direct relation to the maturity of the blue berries sorting as to quality is possible.
• the present invention can also be used for many kinds of fruit, such as many other kinds of berries (for instance red berries), blackberries, cherries and strawberries.
• the invention also works for fruit in which the quantity of chlorophyll changes during ripening.
• the light source has a spectral distribution of the light between 400 and 660 nm. This light is directed to the blue berries. At least a part of the chlorophyll molecules is electronically excited. At least a part of the excited chlorophyll molecules falls to the ground state while emitting fluorescence. At least a part of the chlorophyll fluorescence is captured with a lens. The filter ensures that predominantly fluorescence is detected by the CCD camera.
• a valve After measuring the chlorophyll fluorescence for instance a valve can subsequently be operated with an electronic circuit such as a micro processor, which valve takes out the blue berries from the main stream that have a higher or lower signal than a pre-determined value.
• the sorting from the main stream with a valve can take place with any known principle, such as an air stream, liquid pulse or mechanical valve. It is pointed out that sorting can be performed on berries which are in the air, but also for berries that are contained in a liquid. Sorting in a liquid can for instance take place in order to minimize the possibility of damage of very delicate fruit.
• the light source could be a lamp with optical filters, a LED or a laser.
• the light source could be a lamp with optical filters, a LED or a laser.
• the invention can also be used in any fruit sorter apparatus. It can be built in in all kinds of sorter apparatus.
• the invention can particularly be used in the known colour sorter apparatus.
• the light source can be replaced by. a light source in the described spectral range and the CCD camera can be provided with an optical filter so that predominantly the chlorophyll fluorescence is measured.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Biochemistry (AREA)
• Food Science & Technology (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• Engineering & Computer Science (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Medicinal Chemistry (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Investigating Or Analysing Biological Materials (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19767422

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (14)

Family Cites Families (4)

• 1998
  • 1998-07-03 NL NL1009556A patent/NL1009556C2/nl not_active IP Right Cessation
• 1999
  • 1999-07-01 NZ NZ509205A patent/NZ509205A/xx unknown
  • 1999-07-01 WO PCT/NL1999/000411 patent/WO2000002036A1/en not_active Application Discontinuation
  • 1999-07-01 AU AU48034/99A patent/AU4803499A/en not_active Abandoned
  • 1999-07-01 EP EP99931583A patent/EP1095263A1/de not_active Ceased
  • 1999-07-01 PL PL99345405A patent/PL345405A1/xx unknown
  • 1999-07-01 BR BR9911822-0A patent/BR9911822A/pt not_active Application Discontinuation
  • 1999-07-01 CA CA002337903A patent/CA2337903A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events