WO2014076253A1

WO2014076253A1 - Method and apparatus for identifying, sorting or classifying

Info

Publication number: WO2014076253A1
Application number: PCT/EP2013/073981
Authority: WO
Inventors: Mr Benedict DEEFHOLTS; Mr Timothy KELF
Original assignee: Buhler Sortex Ltd
Current assignee: Buehler UK Ltd
Priority date: 2012-11-15
Filing date: 2013-11-15
Publication date: 2014-05-22
Anticipated expiration: 2015-05-15

Abstract

An apparatus for and method of identifying differing types of unhulled grains (G) in a stream of unhulled grains, such as a stream of paddy rice, the apparatus comprising : a delivery device (3) which delivers the stream of unhulled grains (S) to an identification zone, wherein the unhulled grains (G) in the stream of unhulled grains (S) have no fixed or controlled orient and are of generally different orient from one another at the identification zone, and wherein the stream of unhulled grains (S) has a width (W) at the identification zone across which multiple unhulled grains (G) can be present; an illumination unit (14) which provides an elongate illumination line (19) across the width (W) of the stream of unhulled grains (S) from a first side of the stream of unhulled grains (S) at the identification zone, wherein an intensity or other characteristic of the illumination line (19) is sufficient to cause penetrative transmission of radiation through at least the hull of each unhulled grain (G); and a detector unit (21) which detects radiation transmitted and/or scattered by unhulled grains (G) in the stream of unhulled grains (S) at the identification zone at a second side of the stream of unhulled grains (S), wherein the second side is on the opposite side of the stream of unhulled grains (S) to the first side; whereby different types of unhulled grains (G) are distinguished from one another with reference to differences in light transmission, scatter and/or absorption characteristics of the unhulled grains (G).

Description

M ETH OD AN D APPARATU S FOR I D EN TI FYI N G. SORTI N G OR CLASSI FYI N G

The present invention relates to method and apparatus for identifying, sorting or classifying unhulled grains in a stream of unhulled grains, in particular utilizing a laser line illumination source, and especially in sorting or classifying unhulled rice grains, often being referred to as paddy rice.

Various apparatus exist for identifying, classifying and sorting streams of processed grains in grain-sorting applications, in which the aim is to sort grains from other objects and, as far as possible, to sort 'good' grains from 'not so good' grains. Examples include CA-A- 1009725, J P-A-2003/057187, US-A-1031669, US-A-3197647, US-A-3871774, US-A-4196811, US-A- 4572666, US-A-4666045, US-A-4752689, US-A-4806764, US-A-5245188 and US-A-5524746.

These apparati, however, generally require inter alia stabilized, aligned and singulated streams of grains and a particular arrangement of detectors, in order to image individual grains in the streams of grains.

Many grain sorting systems, for example, as disclosed in WO-A- 2002/031473 and AU-A-654317, use detection of light reflected from a stream of grains which is to be sorted (i.e. the light source and the light sensor are positioned on the same side of the stream of grains) - in some cases against a particular background material and sometimes specified in terms of reflectiveness, translucence and/or colour in order to promote detection in such systems.

Other rice sorting systems, for example, GB-A-2481804 and EP-A-0130715), which are utilized at a stage of grain processing subsequent to milling of the paddy rice to remove rice husks, detect light transmitted by the hulled (i .e. dehusked) rice grains - that is to say, such systems detect differences between grains which are obviously translucent (i .e. semi-transparent) in daylight conditions, based on the transmission of light through the processed grains.

In other, non-grain applications, AU-A-605209 and AU-A-654317 disclose systems for discriminating objects which are themselves obviously translucent (semi-transparent) in daylight conditions, such as broken glass, sultanas, etc, from essentially opaque objects, such as stones, sticks, etc.

WO-A-1995/003139 and EP-A-0633463 disclose sorting systems intended for the colour-sorting of objects which are obviously translucent in daylight conditions (e.g . glass or plastic) for recycling purposes using white light sources (e.g. fluorescent strip-lights) and, in EP-A-0633463, using a line scan camera .

Apparatus has also been developed which provides for analysis of a well- stabilized and singulated stream of unhulled grains of rice (also known as 'paddy rice', i.e. rice prior to milling to remove rice husks) following launching from a chute, using a line of laser illumination on one side of the stream of grains, in order to allow separation of immature, chalky or internally cracked grains from more 'perfect' grains. Despite the fact that such unhulled rice grains are not obviously translucent in daylight, such apparatus is able to detect defects in the rice grain within the hull using intense laser light which has proven capable of penetrating a rice husk or hull .

To date, for such penetrative-laser-based sorting of seemingly opaque unhulled rice grains, grain-flow stabilization and alignment of the stream of unhulled rice have been understood as essential requirements for functionality, and conventionally, this has been achieved by providing for flow-stabilization and singulation of individual unhulled rice grains through the provision of fixed guide channels for the grains to follow. Grain flow- rates achievable using such techniques are, however, rather low. US-A-5865990, US-A-5986230, CA-A-1009725, JP-A-2003/057187, EP-A- 0086289 and WO-A-1998/050174 disclose such penetrative-light-based apparati, requiring that the streams of unhulled rice be stabilized, aligned in a particular orient and singulated - in other words, presented in a particular, specified, exact position for scanning; this being generally achieved by providing an alignment chute with a stabilizing section, together with, in some cases, the use of photodetectors which have a dimension which is greater than the dimension of the unhulled grain in a direction orthogonal to the stream of unhulled grains. Thus, such systems require (in the words of EP-A-0086289) "precisely scanning each grain particle one after another" for rice grain particles that are "arrayed in a line along the length of the rice feeding trough".

The present inventors have recognized that it would be desirable to achieve sorting of 'more perfect' from Ness perfect' unhulled grains at much higher flow-rates, in order to allow entire harvests (or large parts thereof) of unhulled grains, such as paddy rice, to be sorted prior to further processing in a food supply chain.

The present inventors have now created and implemented a method and apparatus that provides such sorting at much higher flow rates through imaging individual unhulled grains, such as unhulled rice grains, using penetrative light illumination (e.g . laser line) without a need for singulation of the grains or any need for conferring the grains with a common orient.

The present invention has particular application to the sorting of paddy rice, being unhulled rice grains, and especially in the sorting of unhulled chalky grains from unhulled normal, good grains, which allows the unhulled chalky grains to be diverted for parboiling.

The present invention also allows for the identification of peck and colored grains. The identification of discolored grains in the unhulled state is particularly advantageous, as rice milling (to remove rice husks) is an energy-intensive process. Conventionally, the sorting out of colored grains could only be done after milling . By identifying discolored grains in the unhulled state, the milling of these grains can be avoided, which provides for significant energy savings.

In one aspect the present invention provides the apparatus of claim 1.

In another aspect the present invention provides the method of claim 13.

Various optional features of the present invention are disclosed in claims 2 to 12, 14 and 15.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which :

Figures 1 and 2 illustrate a sorting apparatus in accordance with a preferred embodiment of the present invention;

Figure 3 illustrates transmission spectra for normal paddy rice and chalky paddy rice;

Figure 4 illustrates plots of the efficiency, reject quality and the percent in- feed in Accept for tests done using Module 1 in the described Example; and

Figure 5 illustrates plots of the efficiency, reject quality and the percent in- feed in Accept for tests done using Modules 2 and 3 in the described Example.

The sorting apparatus comprises a delivery device 3 for delivering unhulled grains G, in this embodiment paddy or rough rice, from a bulk store. Unhulled grains comprise a body which is surrounded by a hull, whereas hulled grains have had the hull removed. In this embodiment the delivery device 3 comprises a vibrating tray 5, which is fed from a hopper 7, and from which unhulled grains G are continuously delivered.

In other embodiments the delivery device 3 could comprise any delivery system which delivers unhulled grains G, including a stationary tray, a feed belt or a pneumatic transport.

The sorting apparatus further comprises a chute 8 which receives the unhulled grains G from the delivery device 3 and provides at least one stream S of unhulled grains G as a single layer, in the form of a sheet or curtain, of individual unhulled grains G, this layer having a width W which is much greater than an average dimension of the individual unhulled grains G, such that a plurality of unhulled grains G are present across the width thereof, and a thickness or depth D of only one unhulled grain G.

In this embodiment the unhulled grains G in the stream of unhulled grains S are randomly oriented or have no conferred orientation.

In this embodiment the unhulled grains G within the stream of unhulled grains S are non-overlapping or have substantially no overlap.

In this embodiment a plurality of unhulled grains G are or can be present at any given instance at a location extending across the width of the stream of unhulled grains S.

In this embodiment the chute 8 has a width W of at least 200 mm, preferably at least 300 mm, as compared to the unhulled grains G which have a dimension of approximately 2 to 3 mm .

In this embodiment the chute 8 is a smooth, flat chute, which has no channels across the width thereof. A tiered chute (not shown) having multiple smooth sections with steps between each chute section would also be a desirable alternative. Other smooth, though not flat, chutes that achieve the delivery of a stream of randomly-oriented (or at least not actively-oriented) unhulled grains G would also be suitable. Suitable chutes include, for example, those described in WO-A-2010/046635 or WO-A- 2006/010873 or obvious variations thereof.

In an alternative embodiment the stream of unhulled grains S could be delivered from a belt feed.

The sorting apparatus further comprises a detection system 11 for detecting individual unhulled grains G within the stream of unhulled grains S.

The detection system 11 comprises an illumination unit 14, in this embodiment comprising an illumination source 15 and illumination optics 17, which provides an illumination line 19, which illuminates a narrow, elongate line across the width W of the stream of unhulled grains S from one side of the stream of unhulled grains S.

In this embodiment the illumination source 15 provides visible light, here having a wavelength of from about 630 nm to about 690 nm.

In a preferred embodiment the illumination source 15 provides light having a wavelength of from about 650 nm to about 685 nm, more preferably from about 660 nm to about 685 nm, still more preferably from about 665 nm to about 685 nm .

In another embodiment the illumination source 15 can provide light having a wavelength of from about 765 nm to about 805 nm, preferably from about 775 nm to about 795 nm, and more preferably about 785 nm . The present inventors have determined that light at this wavelength is particularly effective where the requirement is to remove chalky grains from paddy rice with less sensitivity to discolored grains. In an alternative embodiment the illumination source 15 could provide infrared light, including near-infrared light.

The present inventors have recognized surprisingly that it is possible to discriminate between normal paddy rice and chalky paddy rice at high throughput rates by the detection of scattered light which arises from transmissive illumination with light at a selected wavelength in randomly- oriented rice. Paddy rice is unhulled rice which comprises, in its normal state, a translucent body and a surrounding hull. By way of example, Figure 3 illustrates transmission spectra for normal paddy rice and chalky paddy rice, with the chalky paddy rice having a consistently stronger absorption in the red, with a peak absorption around 675 nm.

In this embodiment the illumination source 15 comprises a laser, which provides a laser beam, and the illumination optics 17 comprise one or more lenses which provide the elongate illumination line 19.

In one embodiment the illumination optics 17 comprise a Powell lens, which provides a fixed elongate line of illumination.

In one embodiment the illumination optics 17 comprise a hologram or diffractive sheet, such as a Fresnel lens.

In an alternative embodiment the illumination unit 14 could omit the illumination optics 17, and instead the illumination source 15 would provide a pre-shaped elongate beam.

In another embodiment the illumination optics 17 could scan a point laser beam to provide the elongate illumination line 19, such as by using a polygonal or oscillating mirror. In one embodiment the illumination optics 17 provide a profiled intensity or brightness along a length of the illumination line 19, thereby providing a substantially constant intensity of illumination across the width W of the stream of unhulled grains S, which allows for the use of less complex classification electronics.

The detection system 11 further comprises a detector unit 21 which is disposed to the opposite side of the stream of unhulled grains S to the illumination unit 14, and configured to detect light scattered by illumination transmitted through unhulled grains G in the stream of unhulled grains S.

In this embodiment the detector unit 21 comprises a camera 22 which comprises a plurality of photodetectors, each having a size which is smaller than an average dimension of the unhulled grains G, and detection optics 25 which relay radiation scattered from unhulled grains G to the camera 22.

In this embodiment the photodetectors have a size which is at least 2x, preferably at least 3x, more preferably at least 5x, still more preferably at least lOx, smaller than the average dimension of the unhulled grains G.

In this embodiment the camera 22 comprises a linescan camera, such as a CCD, CMOS or InGaAs linescan camera. Linescan cameras use a single line of sensor pixels (effectively one-dimensional) to build up a two-dimensional image, with the second dimension resulting from the motion of the unhulled grains G being imaged, and two-dimensional images being acquired line by line by successive single lines.

In an alternative embodiment the camera 22 could comprise an area scan camera, such as a CCD, CMOS or InGaAs areascan camera . Area scan cameras have a number of rows of lines of sensor pixels, and are able to build up a picture of an area in one exposure using a matrix of sensor pixels. In this embodiment the optical axes 01, 02 of the illumination unit 14 and the detector unit 21 are offset, such that the optical axes 01, 02, as represented by a projection of one of the optical axes 01, 02, enclose an acute angle β, here an angle of from about 5 degrees to about 35 degrees, typically about 20 degrees.

In one embodiment the optical axis 02 of the detector unit 21 is substantially perpendicular to the stream of unhulled grains S.

With this configuration, by detecting scatter from transmitted illumination, the camera 22 advantageously yields both an intensity signal and spatial information, which allows for improved characterization.

In one embodiment the camera 22 is a single line scan camera which directly detects scattered radiation from unhulled grains G within the stream of unhulled grains S.

In this embodiment the detection system 11 further comprises a reference illuminator 31 which comprises an illumination source 33, optionally in the form of a plate or line illumination source, which illuminates a region or narrow, elongate line across the width W of the stream of unhulled grains S, and which is disposed on the optical axis 02 of the detector unit 21 and to the one side of the stream of unhulled grains S.

In one embodiment the illumination source 33 provides visible light, here having a wavelength of from about 630 nm to about 690 nm.

In one embodiment the illumination source 33 provides light having a wavelength of from about 650 nm to about 685 nm, more preferably from about 660 nm to about 685 nm, still more preferably from about 665 nm to about 685 nm . In one embodiment the illumination source 33 can provide light having a wavelength of from about 765 nm to about 805 nm, preferably from about 775 nm to about 795 nm, and more preferably about 785 nm . As noted above, the present inventors have determined that light at this wavelength is particularly effective where the requirement is to remove chalky grains from paddy rice with less sensitivity to discolored grains.

In one embodiment the illumination source 33 could provide infrared light, including near-infrared light.

In one embodiment the illumination sources 15, 33 could provide light at the same or substantially the same wavelength or with overlapping ranges of wavelengths.

In a preferred embodiment the reference illuminator 31 provides background illumination with an intensity which is similar to an intensity of the scattered illumination from a first type of unhulled grains G, here normal paddy rice, and in this embodiment slightly greater than the intensity of the scattered illumination from the first type of unhulled grains G, whereby a second type of unhulled grains G, here inter alia chalky paddy rice, with a greater scattering factor and higher absorption than the first type of unhulled grains G can be discerned as being darker in the stream of unhulled grains S.

In this embodiment, in the detection of rice grains, in good or normal paddy rice the illumination is transmitted through the hull and internally scattered, but in defective paddy rice, especially chalky paddy rice, part of the illumination is absorbed, leading to detection of a darker region which corresponds to the defective feature. Where the defective grain is chalky, a significant part of the illumination will be reflected or absorbed . Where the defective grain is a darker grain, a significant part of the illumination is absorbed and little or no illumination will be transmitted . Where the defective grain includes a black spot, substantially all of the illumination is absorbed by the spot and little or no radiation is scattered by that region . The sorting apparatus further comprises an ejector 41, in this embodiment comprising an array of ejector nozzles 43, which is operable to provide air pulses in response to one or more characteristics detected by the detection system 11, such to eject unhulled grains G from the stream unhulled grains S and provide a primary stream of unhulled grains SI of a first type or types, here normal paddy rice, and a secondary stream of unhulled grains S2 of a second type or types, here internally-defective paddy rice.

Typically, for rice grains, internally-defective grains include brokens, red kernels, yellow kernels, black kernels, partly-black kernels, peck kernels, chalky kernels, damaged kernels, undeveloped kernels, immature kernels, other seeds and foreign matter.

In addition, the present invention allows for the identification of mouldy or smutty grains, and the selective removal of these grains alone or in combination with other defective or undesired grains. The identification of mouldy or smutty grains is particularly advantageous, as mouldy or smutty grains lead to increased mycotoxin levels, and thus their removal should provide for a reduction in the mycotoxin levels.

In its application to unhulled grains, such as paddy rice, the present invention is particularly advantageous, in providing for an extremely high throughput as compared to existing technologies, which require stabilized, aligned and singulated streams, and also allow for non-destructive characterization of non-physical features of unhulled grains G. In relation to paddy rice, for example, this allows for the identification of chalky grains which can then be diverted for parboiling and not wasted .

In one method of operation, the sorting apparatus can perform a first sorting function to identify good grains from defective grains using a first detection protocol, and perform one or more further sorting functions on the defective grains using second or further, different detection protocols. For example, for rice grains, in the second sorting function, the second sorting function allows for discrimination between dark grains and chalky grains, allowing the chalky grains to be used for further processing, such as in parboiling .

In one embodiment the first detection protocol requires a first predetermined number n of photosites in an image section comprising a predetermined number of photosites as detected by the camera 22, which can be touching or non-touching, to have a defined intensity, typically an intensity lower than a defined threshold, and the second detection protocol requires a second predetermined number m of photosites in an image section as detected by the camera 22, which can be touching or non- touching, and in one embodiment is less than the first predetermined number n, to have a defined intensity, typically an intensity lower than a defined threshold .

In another method of operation, the sorting apparatus can perform a sorting function to identify and selectively remove chalky grains, leaving normal and dark grains together in the main, bulk stream . This can be achieved by using a sorting protocol which characterizes chalky grains as residing in a detection window which sits between a higher (brighter) intensity threshold corresponding to normal grains and a lower (darker) intensity threshold corresponding to dark grains.

The present invention will now be described hereinbelow by way of example only with reference to the following non-limiting Example.

Example

A sample of paddy rice, comprising approximately 80% good grains, 15% chalky grains and 5% dark grains, was tested using the above-described apparatus. Testing was first performed using a first illumination unit (Module 1) under various settings at a throughput of approximately 1.5 tonnes per hour (corresponding to a feed rate of 55%), in order to sort between good grains (Accept) and defective grains (Reject).

After each test, a sample of both Accept and Reject grains was taken, and 100 grains were manually hulled and a subsection of grains analysed; unhulled rice and empty hulls being ignored from the analysis. Each grain was classified as good, chalky, bad or green. The results of these tests are shown in Table 1.

The efficiency (proportion of bad grains removed from the in-feed), reject quality (purity of Reject) and the percent in-feed in Accept are plotted for all tests in Figure 3. The efficiency requires knowledge of the quality of the in- feed, and this was estimated by counting 200 grains from the in-feed.

Further samples were again similarly tested using two further illumination units 14 (Modules 2 and 3). The results of these tests are shown in Table 2, and the efficiency, reject quality and the percent in-feed in Accept are plotted for all tests in Figure 5.

As will be seen, the variations in efficiencies and reject qualities are quite similar between Modules 2 and 3; both producing similar reject qualities; however Module 3 has a 5% better mean efficiency for the same settings. While the tests have been repeated multiple times, in each test the system is recalibrated and then run, so the system never runs continuously over any length of time.

A further test was subsequently performed on the sorted grains, as a resort, using the first illumination unit 14 (Module 1).

This test was run at a lower feed rate, here using a channelled chute, translating to 0.8 tonnes per hour, and using a spot defect of size 2 pixels at two sensitivities. The results of these tests are shown in Table 3.

It will be noted that the definitions of efficiency and reject quality are different as the system is accepting good, chalky and green grains and rejecting bad ones. These tests indicate that the re-sort can be setup effectively to reject most of the bad grains and collect a good proportion of the good and chalky grains.

Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appendant claims.

In one embodiment the second characterization can be performed prior to the ejection step, either by utilizing the already-acquired image or capturing a second image, such as by a second linescan camera, and then ejecting into two auxiliary streams, such as by using two sets of ejectors or a single set of ejectors which can eject into two streams.

The present invention also extends to sorting dehulled grains, which are non-translucent or essentially opaque or fully opaque, under daylight conditions, (i.e. not obviously translucent dehulled grains - as opposed to, for instance, de-husked rice grains which are obviously translucent) into different types.

For example, the present invention is, surprisingly, capable of being used to sort vitreous dehulled grains from starchy dehulled grains, optionally wheat grains, through penetrative transmission of radiation through the differently oriented dehulled grains.

Table 2

Defect

45% feed, in

From M2 Good Chalky Bad Green -0.8 t/hour Infeed

(%)

Infeed 50 28.4 20.6 1 79.4

Table 3

Claims

CLAI M S

1. An apparatus for identifying differing types of unhulled grains (G) in a stream of unhulled grains, such as a stream of paddy rice, the apparatus comprising :

a delivery device (3) which delivers the stream of unhulled grains (S) to an identification zone, wherein the unhulled grains (G) in the stream of unhulled grains (S) have no fixed or controlled orient and are of generally different orient from one another at the identification zone, and wherein the stream of unhulled grains (S) has a width (W) at the identification zone across which multiple unhulled grains (G) can be present;

an illumination unit (14) which provides an elongate illumination line (19) across the width (W) of the stream of unhulled grains (S) from a first side of the stream of unhulled grains (S) at the identification zone, wherein an intensity or other characteristic of the illumination line (19) is sufficient to cause penetrative transmission of radiation through at least the hull of each unhulled grain (G); and

a detector unit (21) which detects radiation transmitted and/or scattered by unhulled grains (G) in the stream of unhulled grains (S) at the identification zone at a second side of the stream of unhulled grains (S), wherein the second side is on the opposite side of the stream of unhulled grains (S) to the first side;

whereby different types of unhulled grains (G) are distinguished from one another with reference to differences in light transmission, scatter and/or absorption characteristics of the unhulled grains (G).

2. The apparatus of claim 1, wherein the delivery device (3) comprises a chute (8) having smooth, non-channelled chute sections, from which the stream of unhulled grains (S) falls in an unsupported manner.

3. The apparatus of claim 1 or 2, wherein the illumination line (19) is a laser illumination line, optionally having a profiled intensity along a length of the illumination line (19).

4. The apparatus of any of claims 1 to 3, wherein the illumination line (19) has a wavelength of from about 650 nm to about 685 nm, from about 660 nm to about 685 nm or from about 665 nm to about 685 nm, or the illumination line (19) has a wavelength of from about 765 nm to about 805 nm, from about 775 nm to about 795 nm or about 785 nm, optionally where discriminating chalky grains from paddy rice with less sensitivity to discolored grains.

5. The apparatus of any of claims 1 to 4, wherein the detector unit (21) comprises a camera (22) having a plurality of photosites or pixels, each having a dimension which is less than an average or smallest dimension of the unhulled grains (G).

6. The apparatus of claim 5, wherein the photosites have a dimension which is at least 2x, optionally at least 3x, optionally at least 5x, optionally at least lOx, less than an average or smallest dimension of the unhulled grains (G).

7. The apparatus of any of claims 1 to 6, further comprising :

a reference illuminator (31) on the first side of the stream of unhulled grains (S), which provides background, reference illumination on an optical axis (02) of the detector unit (21), wherein the reference illumination has an intensity or other characteristic sufficient to cause penetrative transmission of radiation through each unhulled grain (G) of a first type or types, whereby unhulled grains (G) in the stream of unhulled grains (S) with a greater scattering factor and/or higher absorption than the first type or types of unhulled grains (G) can be identified.

8. The apparatus of any of claims 1 to 7, wherein, with a first type or types of unhulled grains (G), the radiation is transmitted through the hull and internally scattered, and, with a second type or types of unhulled grains (G), optionally chalky, mouldy and/or coloured grains, a component part of the radiation is absorbed by the grain or other contents within the hull.

9. The apparatus of any of claims 1 to 8, wherein the detector unit (21) is operative to identify a first type or types of unhulled grains (G) where an image section for the unhulled grain (G) has a first predetermined number of photosites with a defined intensity, optionally an intensity lower than a first defined threshold, and to identify a second type or types of unhulled grains (G) where an image section for the unhulled grain (G) has a second predetermined number of photosites with a defined intensity, optionally an intensity lower than a second defined threshold.

10. The apparatus of any of claims 1 to 9, wherein the stream of unhulled grains (S) has a thickness or depth (D) which is orthogonal to the width (W) thereof and the unhulled grains (G) in the stream of unhulled grains (S) have substantially no overlap in a direction extending through the depth (D) thereof, optionally the depth (D) is substantially that of a single unhulled grain (G).

11. The apparatus of any of claims 1 to 10, wherein the unhulled grains (G) in the stream of unhulled grains (S) can adopt any random orientation and/or have no singulation or alignment.

12. A sorting apparatus, comprising :

the apparatus of any of claims 1 to 11 ; and

an ejector (41), optionally comprising an array of ejector nozzles (43), which is operable to provide air pulses in response to identification of unhulled grains (G) in the stream of unhulled grains (S), so as to eject unhulled grains (G) of a particular type or types into a separate stream of unhulled grains (S2).

13. A method of identifying different types of unhulled grains (G) in a stream of unhulled grains (S), such as a stream of paddy rice, the method comprising the steps of:

delivering the stream of unhulled grains (S) to an identification zone, wherein the unhulled grains (G) in the stream of unhulled grains (S) have no fixed or controlled orient and are of generally different orient from one another at the identification zone, and wherein the stream unhulled grains (S) has a width (W) at the identification zone across which multiple unhulled grains (G) can be present;

providing an elongate illumination line (19) across the width (W) of the stream of unhulled grains (S) from a first side of the stream of unhulled grains (S) at the identification zone, wherein an intensity or other characteristic of the illumination line (19) is sufficient to cause penetrative transmission of radiation through at least the hull of each unhulled grain (G); and

detecting radiation transmitted and/or scattered by unhulled grains (G) in the stream of unhulled grains (S) to a second side of the stream of unhulled grains (S), wherein the second side is on the opposite side of the stream of unhulled grains (S) to the first side; whereby different types of unhulled grains (G) are distinguished from one another with reference to differences in light transmission, scatter and/or absorption characteristics of the unhulled grains (G).

14. A method of processing paddy rice, the method comprising the steps of:

applying the method of claim 13, wherein the stream of unhulled grains (S) is a stream of paddy rice, to identify at least a first type or types of paddy rice and a second type or types of paddy rice;

based on such identification, and optionally using the apparatus of claim 12, sorting the stream of paddy rice into a first stream of the first type or types of paddy rice and a second stream of the second type or types of paddy rice;

processing the first type or types of paddy rice using a first process comprising a hull-removing or milling step;

processing the second type or types of paddy rice using a second process, which is different from the first process, optionally the second type or types of paddy rice being chalky rice and the second process comprising a parboiling step.

The method of claim 13 or 14, wherein the unhulled grains (G) in the stream of unhulled grains (S) can adopt any random orientation and/or have no singulation or alignment.