X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
2002-04-08
2003-07-29
Dunn, Drew A. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S098900, C378S207000, C250S252100, C702S172000
Reexamination Certificate
active
06600805
ABSTRACT:
TECHNICAL FIELD
The present invention relates to X-ray analysis, and more specifically to the determination of properties of food or feed, such as the fat content of meat.
BACKGROUND ART
X-ray analysis for determining the fat content of meat has been known for several years. Such examples are described in numerous documents. U.S. Pat. No. 4,168,431 (Henriksen) discloses a multiple-level X-ray analysis for determining fat percentage. The apparatus includes at least three X-ray beams at different energy levels. DK PS 172 377 B1 discloses detection means for X-rays as well as a system for determination of properties of an item by use of X-rays. The system operates at a single energy level and applies two detection means separated by a X-ray attenuating material.
WO 92/05703 discloses a method and device for cutting food products. The positioning of suitable cuts are guided by use of X-ray scanning showing the distribution of tissue type in the product. U.S. Pat. No. 5,585,603 discloses a method and system for weighing objects using X-rays. A continuous X-ray analysis for a meat blending system is known from U.S. Pat. No. 4,171,164 (Groves et al).
The percentages of fat in two meat streams are determined by passing a beam of polychromatic X-rays through the streams, measuring both the incident and the attenuated beams. U.S. Pat. No. 4,504,963 discloses an apparatus, system and method for determining the percentage of fat in a meat sample through use of X-ray radiation techniques. An automatic calibration is obtained by use of three incident beams, all at same energy level. Validation of body composition by dual energy X-ray absorptiometry is described in Clinical Physiology (1991) 11, 331-341. (J. Haarbo, A. Gotfredsen, C. Hassager and C. Christiansen). Further studies on bodies are reported in Am. J. Clinical Nutrition 1993: 57:605-608. (Ole Lander Svendsen, Jens Haarbo, Christian Hassager, and Claus Christiansen).
Recently analysis of meat has been reported in Meat Science Vol. 47, No 1/2, 115-124, 1997 (A. D. Mitchell, M. B. Solomon & T. S. Rumsey). A thorough study on pork carcasses by use of dual-energy X-ray absorptiometry was reported by P Elowsson et al (1998) J. Nutr. 128 1543-1549 An Evaluation of Dual-Energy X-Ray Absorptiometry and Underwater Weighing to estimate Body Composition by means of carcass Analysis in Piglets. (p. 1543, l.&r. col.; p. 1544, l.col.; p. 1547, l. col.). Another analysis on pork carcasses is reported by Mitchell et al., J. Anim. Sci. (1998), vol. 76, pp 2104-2113. However, on page 2113 of this analysis it is specifically concluded that the X-ray analysis is too slow for compatibility with on-line processing. None of the above-mentioned prior art has so far lead to an efficient apparatus fulfilling the needs in a slaughterhouse. Generally the prior art shows difficulties when measuring layers of varying thickness, specifically thin layers adjacent to thick layers. Further the prior art is unable to measure and provide results as fast as required to be useful for online processing.
The presently applied apparatus in most slaughterhouses is a Continuous Fat Analyser (Wolfking A/S, Denmark) and Infratec 1265 (Foss Tecator AB, Sweden) using NIR technology. Also applied is Anyl-Ray (The Kartridg Pak Co., Iowa) using a single energy X-ray on a sample of well-defined weight or volume.
It is an object of the present invention to provide a method and apparatus enabling a faster and more accurate determination than hitherto known, of the fat content in a food or feed product, such as a batch of meat trimmings, allowing creation of specific products (such as sausages or minced meat) having a desired content of fat, which is much more accurate than presently possible.
The present invention also applies regression analysis and multivariate calibration. Such analysis is known from e.g. the applicant's own WO 95/16201 disclosing the Determination of extraneous water in milk samples using regression analysis and multivariate calibration. Further, the applicant's WO 98/43070 discloses Measurement of acetone in milk using IR spectroscopy and multivariate calibration. U.S. Pat. No. 5,459,677 discloses a calibration transfer for analytical instruments. The applicant's WO 93/06460 discloses an infrared attenuation measuring system, including data processing based on multivariate calibration techniques, and the applicant's U.S. Pat. No. 5,252,829 discloses a determination of urea in milk with improved accuracy using at least part of an infrared spectrum.
DISCLOSURE OF THE INVENTION
The present invention relates to a method of determining properties a medium of food or feed, such as the fat content of meat, by use of dual X-ray absorptiometry, the medium being a raw material of food or feed, a product or intermediary product of food or feed, or a batch, sample or section of the same, the method comprising—scanning substantially all of the medium by X-ray beams having at least two energy levels, including a low level and a high level,—detecting the X-ray beams having passed through the medium for a plurality of areas (pixels) of the medium,—for each area calculating a value, A
low
, representing the absorbance in the area of the medium at the low energy level,—for each area calculating a value, A
high
representing the absorbance in the area of the medium at the high energy level, characterised by for each area generating a plurality of values being products of the type A
low
n
*A
high
m
wherein n and m are positive and/or negative integers or zero, and predicting the properties of the medium in this area by applying a calibration model to the plurality of values, wherein the calibration model defines relations between the plurality of values and properties of the medium.
The advantage over the prior art is a more accurate determination of the properties, such as the fat content in the medium. The accuracy is specifically improved over the prior art when measuring layers of varying thickness. A further advantage is due to the fact that using the method according to the invention almost the whole product is measured instead of a sampling. Generally, when using sampling in an inhomogeneous medium the extraction of a sample will introduce an error, because the sample may not be representative.
Preferably the plurality of values includes values A
low
n1
/A
high
m1
, wherein n1 and m1 are positive integers. Further on it is preferred that the plurality of values includes the values A
low
, A
high
, A
low
2
, A
high
2
, and A
low
/A
high
and/or at least one of the values A
low
*A
high
; A
low
2
*A
high
; A
low
*A
high
2
and/or at least one of the values A
low
*A
high
; A
low
2
*A
high
; A
low
*A
high
2
; A
low
*A
high
4
and A
low
2
*A
high
4
and/or at least one of the values A
low
2
/A
high
; A
low
/A
high
2
and A
low
2
/A
high
2
; A
low
3
/A
high
2
; A
low
4
/A
high
2
; 1/A
high
4
; A
low
4
/A
high
3 ; A
low
3
/Ahigh4 and A
low
4
/A
high
4
.
Practical experiments have proved that such values contribute considerably to improve the accuracy.
Preferably the calibration model is obtained by use of a regression method being included in the group comprising Principal Component Regression (PCR), Multiple Linear Regression (MLR), Partial Least Squares (PLS) regression, and Artificial Neural Networks (ANN).
The present invention further relates to an apparatus for the determination of properties of a medium, such as the content of a component in the medium, the medium comprising a raw material of food or feed, a product or intermediary product of food or feed, or a batch, sample or section of the same, the apparatus comprising means (
12
,
14
) for emitting at least two X-ray beams (
16
,
18
) at two different energy levels, means for directing the at least two X-ray beams towards and through the medium, X-ray detection means (
22
,
24
) covering a plurality of areas for detecting the two beams (
16
,
18
) after passing through the medium, means (
27
,
28
,
34
,
35
) for transferring and converting output signals from the detection means (
22
,
24
)
Birch & Stewart Kolasch & Birch, LLP
Dunn Drew A.
Foss Electric A/S
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