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Rapid on-line detection and grading of wooden breast myopathy in chicken fillets by near-infrared spectroscopy

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The main objective of this work was to develop a method for rapid and non-destructive detection and grading of wooden breast (WB) syndrome in chicken breast fillets. Near-infrared (NIR) spectroscopy was chosen as detection method, and an industrial NIR scanner was applied and tested for large scale on-line detection of the syndrome. Two approaches were evaluated for discrimination of WB fillets: 1) Linear discriminant analysis based on NIR spectra only, and 2) a regression model for protein was made based on NIR spectra and the estimated concentrations of protein were used for discrimination. A sample set of 197 fillets was used for training and calibration. A test set was recorded under industrial conditions and contained spectra from 79 fillets. The classification methods obtained 99.5–100% correct classification of the calibration set and 100% correct classification of the test set. The NIR scanner was then installed in a commercial chicken processing plant and could detect incidence rates of WB in large batches of fillets. Examples of incidence are shown for three broiler flocks where a high number of fillets (9063, 6330 and 10483) were effectively measured. Prevalence of WB of 0.1%, 6.6% and 8.5% were estimated for these flocks based on the complete sample volumes. Such an on-line system can be used to alleviate the challenges WB represents to the poultry meat industry. It enables automatic quality sorting of chicken fillets to different product categories. Manual laborious grading can be avoided. Incidences of WB from different farms and flocks can be tracked and information can be used to understand and point out main causes for WB in the chicken production. This knowledge can be used to improve the production procedures and reduce today’s extensive occurrence of WB.
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RESEARCH ARTICLE
Rapid on-line detection and grading of
wooden breast myopathy in chicken fillets by
near-infrared spectroscopy
Jens Petter Wold
1
*, Eva Veiseth-Kent
1
, Vibeke Høst
1
, Atle Løvland
2
1Nofima AS, Norwegian Institute for Food and Fisheries Research, Muninbakken 9–13, Breivika, Tromsø,
Norway, 2Nortura SA, Lørenveien 37, Oslo, Norway
*jens.petter.wold@nofima.no
Abstract
The main objective of this work was to develop a method for rapid and non-destructive
detection and grading of wooden breast (WB) syndrome in chicken breast fillets. Near-infra-
red (NIR) spectroscopy was chosen as detection method, and an industrial NIR scanner
was applied and tested for large scale on-line detection of the syndrome. Two approaches
were evaluated for discrimination of WB fillets: 1) Linear discriminant analysis based on NIR
spectra only, and 2) a regression model for protein was made based on NIR spectra and the
estimated concentrations of protein were used for discrimination. A sample set of 197 fillets
was used for training and calibration. A test set was recorded under industrial conditions
and contained spectra from 79 fillets. The classification methods obtained 99.5–100% cor-
rect classification of the calibration set and 100% correct classification of the test set. The
NIR scanner was then installed in a commercial chicken processing plant and could detect
incidence rates of WB in large batches of fillets. Examples of incidence are shown for three
broiler flocks where a high number of fillets (9063, 6330 and 10483) were effectively mea-
sured. Prevalence of WB of 0.1%, 6.6% and 8.5% were estimated for these flocks based on
the complete sample volumes. Such an on-line system can be used to alleviate the chal-
lenges WB represents to the poultry meat industry. It enables automatic quality sorting of
chicken fillets to different product categories. Manual laborious grading can be avoided. Inci-
dences of WB from different farms and flocks can be tracked and information can be used to
understand and point out main causes for WB in the chicken production. This knowledge
can be used to improve the production procedures and reduce today’s extensive occurrence
of WB.
Introduction
During the last five years the muscle syndrome wooden breast (WB) has become a serious
challenge to the poultry meat industry worldwide. WB is a term for abnormal muscle tissue in
the chicken breast, a myopathy, which makes the breasts appear as pale, hard and out-bulging
[1]. Since the appearance of this meat is unpleasant and the functional properties are impaired,
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 1 / 16
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OPEN ACCESS
Citation: Wold JP, Veiseth-Kent E, Høst V, Løvland
A (2017) Rapid on-line detection and grading of
wooden breast myopathy in chicken fillets by near-
infrared spectroscopy. PLoS ONE 12(3):
e0173384. doi:10.1371/journal.pone.0173384
Editor: George-John Nychas, Agricultural
University of Athens, GREECE
Received: November 23, 2016
Accepted: February 20, 2017
Published: March 9, 2017
Copyright: ©2017 Wold et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: All relevant data are
within the paper and its Supporting Information
files.
Funding: This work was partially funded by the
Norwegian Agricultural Food Research Foundation
through the projects Food Imaging (project
number 225347/F40) and Impact of protein
composition for predictable food quality (224820/
F40) and by the Norwegian company Nortura SA.
The funders had no role in study design, data
collection and analysis, decision to publish, or
preparation of the manuscript.
severe cases of WB fillets are downgraded and used to manufacture less valuable products.
With typical incidences of 5–10% of WB in markets with heavy broilers this represents signifi-
cant economic losses for the poultry industry [2]. The causes for WB are still not clear, but are
most likely multifactorial where an important part is related to the fast growth of modern
broiler chickens [3]. With this emerging problem, it is important to find and develop methods
and strategies that can alleviate the situation in the poultry industry.
Some introductory work has been done to identify non-invasive biomarkers based on mass
spectroscopy for diagnostic purposes in live birds [4]. Such markers can contribute to under-
stand the biochemical processes leading to tissue hardening. It might also be used as a trait for
animal selection in breeding work. For effective handling of the problem in the poultry pro-
cessing industry, however, there is a need for rapid on-line detection and grading of WB for
automatic quality grading and sorting. Maybe more important, such a method would also be a
valuable tool for mapping incidences of WB at a large scale and backtrack them in the produc-
tion chain in order detect and remove causes of WB connected to production conditions.
There are some specific features of WB muscle tissue compared to normal muscle tissue
that should enable rapid detection and grading. WB tissue has significantly higher moisture
content and a significantly lower protein content. Soglia et al. [5] reported mean protein and
moisture contents for WB tissue of 21.6% and 77.26%, respectively, compared to 24.65% and
73.78%, respectively for normal tissue. There were also significant higher concentrations of fat
and collagen in WB tissue, but the actual differences were rather small (0.22% and 0.27%,
respectively). The same researchers also measured water holding capacity by the use of low
field NMR and reported that there is a significantly higher share of loosely bound water in the
WB tissue, probably due to muscle fiber degeneration [5]. The characteristic pale color of the
WB tissue due to the degenerative processes is not a unique marker for WB since normal fillets
can also have a similar pale color. The hard texture of the WB meat, however, is notably differ-
ent from normal breast meat and is today the decisive marker used in the industry for detec-
tion by manual palpation.
A good candidate method for real-time and large scale detection of WB is near-infrared
spectroscopy (NIR). NIR is well suited for on-line grading and sorting of complex foods and is
widely used in the food industry for determination of typically fat, water, protein and carbohy-
drates in products such as meat, fish, cereals and fruits [6]. Studies show that NIR spectroscopy
can be used to determine fat, water and protein in chicken breast meat. Good accuracy has
been obtained for samples of homogenized muscle, while NIR on intact breasts yielded poorer
results with regard to average crude chemical composition [7]. The main reason for this poorer
result was probably that the NIR spectra were collected in reflection mode on the surface of
the breasts and did not capture internal sample heterogeneity. NIR technology has later been
developed to allow improved measurements on intact heterogeneous food products by use of
spectral imaging in combination with so-called interaction measurements. Interaction enables
optical probing of about the upper 2 cm of the samples, which means that more representative
spectral measurements can be obtained. This technical approach made it possible to design
on-line NIR systems for moisture determination in very heterogeneous samples such as dried
salted cod [8] and fat and color in salmon fillets [9]. An illustrative example is an application
where the edible food content in live crabs is measured through the dark brown shell (cara-
pace) [10]. NIR systems like this can also be used to determine fat content in trimmings of beef
and pork [11] and it is demonstrated that this on-line method offers a good basis for real-time
optimization of food processes based on automatic sorting of different qualities [12].
The objective of this work was to elucidate if an NIR imaging system can be used to detect
and grade wooden breast syndrome in chicken fillets in a process line. Two approaches were
tested for discrimination of wooden breast fillets: 1) Linear discriminant analysis based on
Rapid detection of wooden breast syndrome
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 2 / 16
Competing interests: There are no patents,
products in development or marketed products to
declare. Atle Løvland’s employment by Nortura SA
does not alter the authors’ adherence to all PLOS
ONE policies on sharing data and materials.
NIR spectra only, and 2) a regression model for protein content was developed based on NIR
spectra and the estimated concentrations of protein were used for discrimination. We also
included microscopy of some selected normal and abnormal chicken breasts to verify the pres-
ence of wooden breast and to compare with NIR measurements. All NIR measurements were
done in an industrial environment on chicken breasts passing on a conveyor belt at a relevant
speed. The NIR system was finally tested in a real process for massive quality monitoring to
log the occurrence of wooden breast in different broiler flocks.
Materials and methods
Chicken fillets
A total of 197 skinless breast fillets (M.pectoralis major) were taken out for analysis during
three days in a commercial chicken processing facility. Average live bird weight at this plant
was 1.8 kg. The fresh and chilled fillets were taken directly from the processing line approxi-
mately 3 hours after CO
2
-stunning, bleeding and slaughter of the birds. The two first days, 154
fillets were sampled with the aim of spanning all kind of normal quality variation in size, color
and texture. The fillets came from different flocks and farms represented these two days. WB
fillets were not sampled, but when normal fillets among the 154 had possible symptoms of
WB, this was noted in the experimental log. Each fillet was scanned with the NIR system, and
subsequently color and pH were measured. This procedure took about 5 minutes per fillet.
The fillets were then packed in plastic bags and stored over night at 4˚C, before fat, water and
protein content for the whole breast was determined for 99 of these fillets (randomly selected)
by low field nuclear magnetic resonance (NMR).
On day three, 15 normal, 15 moderate WB and 13 severe WB fillets were picked out of the
processing line. The samples were classified by an experienced veterinarian based on visual
inspection and palpation of consistency (normal, hard and very hard). Breast fillets with hard
consistency and limited distribution of very hard parts were classified as moderate WB, while
fillets with extensive areas of very hard consistency, were considered severe WB. WB fillets
were also very pale, but no chicken breasts had significant amounts of serous fluid at the sur-
face described from some studies in markets with higher slaughter weights. The samples were
measured the same way as the first 154 samples. In addition, some muscle samples were
excised for histological evaluation (see below for details). Fat, moisture and protein were deter-
mined the following day in the outer 1-cm layer of the breast fillet.
Industrial testing was performed about one year after the sampling described above. During
these trials 55 normal fillets and and 24 wooden breast were again classified by a trained veteri-
nary. Of the WB fillets, 16 were moderate and 8 were severe WB according to characteristics
described above. They were scanned with the NIR scanner and no further analyses were done
one these. They were used as test set for discrimination models developed based on samples
from day 1–3.
NIR measurements
The on-line NIR system was a QVision500 (TOMRA Sorting Solutions, Leuven, Belgium), an
industrial hyperspectral imaging scanner designed for on-line measurement of fat in meat on
conveyor belts. It was installed in the chicken processing hall at Nortura Hærland (Hærland,
Norway). During the first part of the work it was equipped with a conveyor belt, but was off-
line, i.e. it was not integrated in the commercial processing line. This allowed more flexibility
when conducting the investigation. During the second part of the work, the scanner was
installed above the actual processing line.
Rapid detection of wooden breast syndrome
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The NIR instrument was based on interactance measurements where the light was trans-
mitted into the meat and then back scattered to the surface. Optical sampling depth in the
chicken fillets was approximately 20 mm. Each NIR measurement took less than 1 sec. The
scanner was placed 30 cm above the conveyor belt so there was no physical contact between
samples and the instrument. The scanner collected hyperspectral images of 15 wavelengths
between 760 and 1040 nm with a spectral resolution of 20 nm. The output per sample scan was
an image of the conveyor belt with the sample. Size of the image was 60 pixels in the direction
perpendicular to belt movement and 200 pixels in the direction of belt movement. Each pixel
represented a spatial area of about 7 mm ×5 mm across and along the conveyor direction,
respectively. The imaging capability of the used system was in this work used mainly for effec-
tive sampling, to obtain a representative mean spectrum from each fillet.
Each fillet was scanned three times with skin side of the breast facing the sensor. The repli-
cate measurements were used to test for reproducibility.
Determination of protein, moisture and fat
Of the 154 fillets from day 1 and 2, 99 fillets were thoroughly homogenized and two parallels
of 6 g were subjected to fat and moisture determination. The average values of the parallels
were used in the further work. Fat and moisture content were determined by low field proton
nuclear magnetic resonance (NMR), using a Maran Ultra Resonance 0.5 tesla (Oxford Instru-
ments, UK) equipped with a gradient probe. The method used was “The one-shot method”
developed by Anvendt Teknologi AS (Harstad, Norway) [13]. Operating temperature of the
magnet was 40˚C and the samples were heated up to this temperature before measurement to
ensure that the fat was in liquid form. The weights of all meat samples were measured and cali-
bration was done against a reference meat sample of known weight containing 14.3% fat
(SMRD 2000 Matrix Meat Reference Material, National food Administration, Uppsala, Swe-
den). Protein for each sample was determined as 100%—(fat% + moisture%) since water, fat
and protein make up approximately 100% of the tissue weight.
For the fillets from day three (15 normal and 28 WB) only the outer 1-cm layer of muscle
tissue was used for fat, moisture and protein determination. This was done to study in more
detail the tissue affected by wooden breast syndrome.
pH and color
Color was measured as Labvalues on the surface of the breast fillets at three locations; ros-
tral part (thick part of fillet), middle and caudal part, with a Minolta CR-400 chromameter
(Konica Minolta Sensing, Inc., Osaka, Japan). Each site of measurement covered about 1 cm
2
of the fillet surface. The values from the three sites were averaged before further use. The
instrument was calibrated once every morning with a white reference following the instru-
ment. Lis a measure for lightness, aexpresses degree of redness (or green when values are
negative), while bexpresses yellowness (or blue when values are negative). This kind of color
space is commonly used for food color measurements.
pH was measured with a Knick Portamess 911 pH (Knick Elektronische Messgera¨te,
GmbH & Co. KG, Berlin, Germany) with the electrode InLab1Solids electrode 51343153
(Mettler Toledo, Switzerland). This was an insertion probe that was inserted about 1 cm into
the rostral part of the fillet.
Classification and calibration of NIR spectra
Linear discriminant analysis. From each sample scan we obtained an average intensity
NIR spectrum (T). This spectrum was converted to an absorption spectrum (log10(1/T)) to
Rapid detection of wooden breast syndrome
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 4 / 16
make the data more linear. To remove some of the spectral variation connected to e.g. sample
distance from scanner, light scattering etc., standard normal variate (SNV) was used to nor-
malize the data [14].
A discriminant function was made based on linear discriminant analysis (LDA) [15]. Since
the variables (absorption values at different wavelengths) in the NIR spectra are highly covari-
ant, we used the score values from a partial least squares regression (PLSR) [16] of the NIR
spectra on to the two classes; normal and WB. These score values are orthogonal to each other
and well suited as input variables in LDA.
One NIR scan from each sample from day 1–3 were used to establish a discriminant func-
tion. This function was first validated by full cross validation to determine the optimal number
of PLS factors to use in the function. It was then validated on the test set of 79 samples obtained
under fully industrial conditions one year later.
Regression model
Partial least squares regression was used to make a calibration between NIR spectra and pro-
tein and moisture concentration. Full cross validation was applied to determine the optimal
number of PLS factors and to evaluate the model’s predictive ability. The prediction error was
estimated by the root mean square error of cross validation (RMSECV) where ŷ
i
is the pre-
dicted value from the cross validation, y
i
is the reference value and idenotes the samples from
1 to N.
RMSECV ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
1
NX
N
I¼1ðyi^
yi
sÞ
The calibration was made based on the average of the three spectra from each of the 99 ref-
erenced samples from day one and two. The average spectra were used to establish a best possi-
ble match between spectral data and chemistry. This calibration was then applied to predict
protein in the samples from day three to see if it was possible to discriminate WB from normal
fillets based on these values. Protein values were predicted for each of the three scans per sam-
ple. The regression model was also validated on the test set of the 79 samples obtained under
industrial conditions. The main aim of the calibration model was not necessarily to obtain a
best possible prediction of protein, but to obtain a good discrimination of WB from normal
fillets.
One-way analysis of variance (ANOVA) was performed to analyze group differences
between normal and WB. Two-way ANOVA was used to check for differences between repli-
cate NIR scans. If the p-value was less than 0.05 the differences were considered significant.
The software The Unscrambler ver. 9.8 (CAMO Software AS, Oslo, Norway) was used for
regression analysis. LDA as well as all image processing of multispectral images; sample seg-
mentation, spectral extraction and spectral pre-processing were carried out by the use of
MATLAB version 7.10 (The MathWorks Inc., Natic, MA).
Histological evaluation
Samples for histological evaluation were taken from 10 normal, 10 moderate WB and 10 severe
WB fillets. Samples for transverse sections were excised from the outer layer of the rostral
region, fixed in formalin, and paraffin embedded. Sections were cut (5 μm thickness) perpen-
dicular to the muscle fiber direction and stained using a standard haematoxylin and eosin
stain. Histological evaluations were performed using a light microscope.
Rapid detection of wooden breast syndrome
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On-line testing in industrial line
The classification model based on the protein calibration was implemented in the NIR scanner
so it could detect WB fillets among chicken fillets passing on a conveyor belt. The regression
model was chosen before the LDA discriminant function because it was interesting to monitor
also variation in protein. The scanner was installed in a commercial processing line where the
frequency of fillets was up to 3.5 per sec. Two parallel lines with fillets, separated by about 15
cm, were scanned simultaneously (Fig 1). With the scanner we collected protein values for
batches of fillets belonging to different broiler flocks, and the values were automatically written
to file. We collected data for 66 flocks from different farms and typical number of fillets per
batch was between 6.000–18.000. About 8.500 fillets could typically be scanned per hour
depending on the frequency of fillets on the line. The position of scanning in the line was after
the point were the most severe cases of WB were removed manually by the workers. That
means that the cases of WB that were scanned in these trials were mostly of moderate condi-
tion. Nortura SA gave permission to this field study.
Results and discussion
Fat, water and protein, color and pH
Table 1 summarizes the approximate composition (fat, water and protein) of the fillets. Note
that measurements on normal and WB fillets on day three were done on the outer 1 cm of the
breast to study the region mostly affected by WB. This is also the layer that will have the great-
est impact on the NIR spectra. Water and protein levels for normal fillets day 3 were similar to
corresponding values for the 99 fillets sampled day 1 and 2. Fat content was significantly differ-
ent by 0.25%-points. This means that approximate composition of the outer 1-cm tissue layer
in normal fillets was the same as for the whole fillet as measured days 1 and 2. The WB fillets
had significantly lower protein content compared to the normal fillets, mean differences of
4.6% and 5.1% for moderate and severe WB, respectively. Similar differences (3.8% and 4.3%,
respectively) were found for moisture. Soglia et al. [5] found the same systematic changes in
approximate composition between normal and WB tissue, but they found smaller differences,
probably because they measured the whole fillets and not the outer 1-cm layer in the most
affected part of the fillet, as in this study.
Fig 1. NIR system installed in production line. Illuminating line crosses the entire conveyor belt. All
passing fillets were measured.
doi:10.1371/journal.pone.0173384.g001
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There was a clear tendency that the WB fillets had high L-values, meaning that they were
pale. They also had high bvalues indicating yellowness. Although significant differences in
L, aand bbetween severe WB and normal fillets, the color variation could not be used to
distinguish WB from normal, since many normal fillets were also quite pale.
There were no differences in pH between the groups on day 3, but average pH day 3 was
higher than average pH day 1 and 2. We are not sure of the reason for this. Fillets day 3 were
sampled during a shorter time span compared to fillets day 1 and 2, which were collected over
two full days. The difference might therefore be ascribed to a flock effect.
Histological characterization
In order to verify the presence of wooden breast in the selected fillets on day 3, histological
evaluations of 10 normal and 20 WB fillets were performed. Fig 2 shows representative light
microscopy images of cross sections from normal (a), moderate (b) and severe WB fillets (c).
In the normal fillets, the classical structure of skeletal muscle can be seen, with tightly packed
polygonal muscle fibers of relatively even diameter. Moreover, each muscle fiber is surrounded
by a thin layer of endomysium, and bundles of muscle fibers are surrounded by a slightly
thicker layer of perimysium. In the WB fillets, on the contrary, various signs of myopathy
could be seen. Specifically, the muscle fibers in the WB fillets are rounded and appear to be
more variable in size. Many of the muscle fibers also show signs of degeneration and infiltra-
tion of inflammatory cells, and these features increase in incidence from moderate to severe
WB fillets. In addition, the endo- and perimysium layers have thickened. These findings are in
consistence with earlier reports on myopathy and wooden breast in the pectoralis major mus-
cle of broilers [1,1718], and thus confirms the WB phenotypes in the selected fillets.
NIR spectra
Fig 3 shows SNV corrected NIR spectra from a normal and two WB fillets of different severity,
the same samples as shown in Fig 2. The main absorption peak for moisture in this spectral
region is at about 980 nm. A close look at the spectra reveals a systematic shift of the peak
towards shorter wavelengths with the severity of WB. This shift was quite prominent and con-
stituted the main variation in the spectra from the chicken fillets. The spectral changes can
most likely be attributed to two phenomena: 1) Protein has an absorption peak at about 1020
Table 1. Approximate chemical composition, color and pH in normal breast muscle and wooden breast muscle.
Normal day 1&2 Normal day 3 Moderate WB Severe WB
Whole fillet Upper 1 cm Upper 1 cm Upper 1 cm
(n = 99) (n = 15) (n = 15) (n = 13)
Moisture % 74.9 ±0.86 75.3 ±0.66 79.1 ±1.49˚*79.6 ±1.49˚*
Protein % 23.5 ±0.89 23.5 ±0.64 18.9 ±1.22˚*18.4 ±1.47˚*
Fat % 1.6 ±0.62 1.25 ±0.50˚ 1.8 ±0.53 2.0 ±0.67˚*
(n = 154)
L*56.10 ±3.70 52.7 ±2.68˚ 60.3 ±1.7 59.8 ±2.3˚*
a*2.97 ±1.32 2.46 ±0.62 2.34 ±0.91 4.56 ±2.9*
b*7.41 ±2.92 5.19 ±1.22 8.84 ±1.48*10.52 ±1.85˚*
pH 5.99 ±0.12 6.3 ±0.10˚ 6.3 ±0.16˚ 6.3 ±0.09˚
Average value ±standard deviation. Values in shaded fields are from outer 1-cm layer of breast fillets.
*indicates significant different from group mean value of normal fillets day 3.
˚ indicates significant different from group mean value of normal fillets day 1&2.
doi:10.1371/journal.pone.0173384.t001
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Fig 2. Morphologic structures in chicken breast muscle. Normal (A), moderate (B) and severe WB (C)
(M. pectoralis major). D = degenerating fibers; E = endomysium; P = perimysium.
doi:10.1371/journal.pone.0173384.g002
Rapid detection of wooden breast syndrome
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nm (not directly discernable in the spectra). A lower protein concentration and a correspond-
ing increase in moisture could contribute to the observed spectral shift. This corresponds with
the systematic differences in water and protein in WB tissue as described above. 2) It is well
known that a shift in the water peak at 980 nm does occur when the water molecules are more
or less bound to other molecules [19]. More loosely bound water creates a shift towards shorter
wavelengths. It has been reported that there is significantly more loosely bound water in WB
compared to normal fillets [5] and it is likely that it will create a shift as observed. The same
characteristic shift in the absorption peak at 980 nm has been proposed as a method to detect
human breast cancer due to a larger share of less bound water compared to normal breast tis-
sue [20]. Thus, both the effects are probably in action and emphasize the differences between
normal and WB muscle tissue.
Classification
Linear discriminant analysis. PLSR score values for all samples measured day 1–3 are
shown in Fig 4. Component 1 expressed 54% of the variation in the NIR spectra, separating
normal and WB fillets quite well. The score values of component 1 correlated closely with the
protein content of the samples (R = 0.90). A cross validated model based on 3 PLSR compo-
nents gave 99.5% correct classification of the 197 samples. All 28 WB fillets were correctly
classified and only one normal fillet was classified as WB. This is a good result taking into con-
sideration that there was a gradual change in muscle tissue from normal to WB. In a system
Fig 3. Typical NIR spectra from chicken fillets. Normal fillet (blue), moderate WB (green) and severe WB (red)
fillets. Spectra were measured on samples A, B and C, respectively, shown in Fig 2.
doi:10.1371/journal.pone.0173384.g003
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with gradual change it will always be some misclassification close to the decision line. The dis-
criminant function did also work very well on the test set recorded under industrial conditions
one year later. All samples were correctly classified, indicating that the NIR spectra contained
systematic and clear differences between the groups of fillets.
Regression analysis. Table 2 summarizes cross validated calibration results for water and
protein in chicken fillets based on the NIR spectra from normal fillets collected day one and
two. The rather low correlations obtained were reasonable since the range in e.g. protein was
short (20.5–25.3%). Prediction errors (RMSECV), however, were quite low and indicated
that protein and moisture could be estimated with an accuracy of approximately ±0.57%
and ±0.58%, respectively. This result is comparable with what was obtained by the use of
reflectance NIR on intact chicken breasts [7].
The regression model obtained for protein (Fig 5A) was used to estimate protein content in
the samples from day 3 (Fig 5B). The normal fillets got estimated protein values above about
Fig 4. PLSR score plot for NIR spectra. Score values for PLSR components 1 and 2 for normal fillets from days 1
and 2 (blue), normal fillets day 3 (red), moderate WB (green) and severe WB (magenta).
doi:10.1371/journal.pone.0173384.g004
Table 2. Calibration results for chemical constituents in whole chicken fillets based on NIR imaging
scanner.
# LV
a
R
b
RMSECV
c
(%)
Protein 4 0.76 0.57
Moisture 6 0.67 0.58
a
# LV—number of latent variables in the PLS regression model.
b
R—Correlation coefficient.
c
RMSECV—Root mean square error of cross validation.
doi:10.1371/journal.pone.0173384.t002
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22% and lied along the target regression line. All WB samples got protein estimates below
22%. Estimated protein values for many of the WB fillets were slightly higher than the mea-
sured protein concentration in these fillets. There are different reasons for this: 1) Protein was
measured in the upper 1 cm layer of the breast, while the NIR system did probably measure
deeper than 1 cm, and the spectra were affected by more normal tissue deeper than 1 cm with
higher protein concentration. 2) The calibration model was not calibrated with samples of
such low protein values, meaning that the model was extrapolating and larger deviations from
the true protein content could be expected. 3) Spectral shifts due to loosely bound water were
not included in the regression model.
Since the regression model did not include WB samples, we can more strictly say that the
WB fillets were discriminated by outlier detection. This approach is in line with established
methodology within statistical process control: The normal variation of samples or process
conditions are modeled, and the models are used to detect deviations from the normal [21].
We did try to include all samples from day 1–3 in the same regression model (normal and
WB), but this approach did not work well with regard to classification. The main point is that
the protein model did clearly separate between normal and WB fillets. A linear discriminant
analysis of the predicted protein values for the groups of normal and WB resulted in an opti-
mal decision limit at 21.9%. The model for moisture could also separate between normal and
WB fillets, but not as clear as the protein model.
The model did also work very well on the 79 test samples from the industrial trial (Fig 5C).
Again normal fillets got protein values above 22% and WB below. Note that there were a few
samples in the calibration set (Fig 5A) with protein content less than 21.9%. Four out of these
samples were listed as “possible WB” in the experimental log during the experimental work.
Fig 5. NIR estimated protein in chicken fillets. a) Cross validated predicted versus measured protein in normal chicken fillets. b) Estimated protein in
samples from day 3. Normal (blue), moderate WB (green) and severe WB (red). c) Estimated protein in test samples. Normal (blue), moderate WB (green),
severe WB (red). The dashed red line at 21.9% indicates the decision line between normal and WB.
doi:10.1371/journal.pone.0173384.g005
Rapid detection of wooden breast syndrome
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 11 / 16
In both test sets (Fig 5Band 5C) there was a tendency that the severe WB had lower esti-
mated protein levels compared to the moderate WB group, but there were no significant differ-
ence between the two groups.
Fig 5B shows that the replicate NIR scans resulted in very similar protein predictions. There
was no significant difference between the replicate protein estimates, indicating good repro-
ducibility of the NIR measurements.
The results show that both LDA and the calibration model for protein are very well suited
for classification of WB from normal fillets. The very high percentage of correct classification
obtained in this study is rather optimistic. As noted above, there is a gradual change in muscle
properties from normal to WB. This means that in the region of the decision line there will be
miss-classifications in a grey zone. In a practical industrial setting, different decision limits can
be chosen according to needs and experience. Two limits can for instance be used to separate
the fillets into high, medium and poor quality.
An advantage with the classification model based on protein values is that it gives additional
information. Monitoring the protein content can be of interest in the poultry industry. This
method is also intuitively easy to understand for operators of such a system. Adjusting the
decision line in a LDA model is more complex and less intuitive.
An important reason for the good results is connected to the measurement mode of the
NIR spectra. It seems that for severe cases of WB a thicker part of the breast muscle is affected
by myopathy. An efficient grading based on NIR will therefore require that the light penetrates
rather deep into the muscle, as it did in this study. Reflectance measurements at the surface
might work to separate WB from normal muscle, but would most likely be a less accurate
method. Degree of severity can also be defined by how much of the fillet surface that is
affected. Some fillets are affected on mainly the thick rostral part while on other fillets, the
complete breast fillet is affected. This difference can be captured by the NIR system used in
this study since the entire fillet is measured, not only a limited region.
Industrial on-line measurement trials
Fig 6 shows estimated protein values for all fillets from one flock of birds from farm A (approx-
imately 9063 fillets). Only 8 samples were below the chosen threshold of 21.9%. This was a
flock with very low incidence of fillets with protein estimates typical for WB.
Fig 7 shows similar recordings from two other farms, flock B (6330 fillets) and C (10483 fil-
lets). In those cases the incidence of breast fillets with low protein estimates, indicating WB,
Fig 6. NIR estimated protein in flock A. Red horizontal line indicates the chosen threshold of 21.9% protein.
doi:10.1371/journal.pone.0173384.g006
Rapid detection of wooden breast syndrome
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 12 / 16
was considerable higher. The x-axis in the plots count the numbers of fillets and do also indi-
cate sequence of measurement. The patterns indicate that there were higher incidences of WB
in certain parts of the batch, maybe coinciding with certain houses at the farms or other pro-
duction factors.
Fig 8 illustrates the protein distribution in fillets from the three farms as histograms. Most
values were centered around 24%. Farm A had a more or less Gaussian shape around 24%,
while farm B and C had bigger tails towards lower protein values. Farm B and C had preva-
lences of 6.6% and 8.5% of protein estimates below 21.9%, respectively, which were the highest
incidences of WB in the 66 flocks that were screened in this period.
Conclusion
The results shows that on-line interactance NIR is a well working, practical and useful tool for
detection and grading of WB syndrome. Low protein content is clearly characteristic for WB,
which is shown in this study and also by others [5]. At this point it is not clear if the main vari-
ation in the NIR spectra are attributed to differences in protein and water, or to the amount of
less bound water. The two effects would probably co-vary, but it should be further studied in
order to understand the system in the best possible way.
An on-line system as presented here can be used to alleviate the challenges wooden breast
represent to the poultry meat industry. It can be used for two important tasks: 1) It is possible
to automatically sort chicken fillets of different quality to different product categories. Manual
grading and removal of WB can then be avoided and replaced by a much more rapid and
objective system. 2) It is possible to track incidences of WB in detail from different farms and
use this crucial information to understand and point out main causes for WB in chicken pro-
duction. This knowledge can be used to improve the production procedures and reduce
today’s extensive occurrence of WB.
Fig 7. NIR estimated protein in flock B (upper panel) and C.
doi:10.1371/journal.pone.0173384.g007
Rapid detection of wooden breast syndrome
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 13 / 16
Supporting information
S1 File. Spectroscopic and reference data for all samples.
(XLSX)
S2 File. Description of supplementary data.
(DOCX)
Acknowledgments
This work was partially funded by the Norwegian Agricultural Food Research Foundation
through the projects Food Imaging (project number 225347/F40) and Impact of protein compo-
sition for predictable food quality (224820/F40) and by the Norwegian company Nortura SA.
Karen Wahlstrøm Sanden and Bjørg Narum are thanked for skilled technical assistance. We
are grateful to Dr. Ragni Ofstad, Dr. Ingrid Måge and Dr. Ingunn Berget for valuable
discussions.
Author Contributions
Conceptualization: JPW EVK AL.
Data curation: JPW VH AL.
Formal analysis: JPW.
Funding acquisition: JPW.
Investigation: JPW VH AL.
Fig 8. Histograms showing distribution of estimated protein in the broiler flocks A, B and C.
doi:10.1371/journal.pone.0173384.g008
Rapid detection of wooden breast syndrome
PLOS ONE | DOI:10.1371/journal.pone.0173384 March 9, 2017 14 / 16
Methodology: JPW.
Project administration: JPW.
Resources: JPW AL VH.
Software: JPW.
Supervision: JPW.
Validation: JPW AL VH.
Visualization: JPW AL VH.
Writing – original draft: JPW.
Writing – review & editing: AL EVK VH.
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Supplementary resources (2)

... Severely WB affected pectoral muscles showed higher pH compared to normal pectoral muscles [5,41,42]. In contrast, moderately WB affected pectoral muscle showed no difference (p > 0.05) in pH compared to normal pectoral muscle [42,43]. ...
... Regarding meat color, in agreement with our studies, [43,44] reported an increase in L* and b* in severely WB affected pectoral muscle (p < 0.05), while a* was not affected in moderately [43] and severely [8] WB affected muscle (p > 0.05). On the other hand, several studies reported no changes in L* in moderately [43] and severely [8,41] WB affected muscles compared to normal breast muscle (p > 0.05). ...
... Regarding meat color, in agreement with our studies, [43,44] reported an increase in L* and b* in severely WB affected pectoral muscle (p < 0.05), while a* was not affected in moderately [43] and severely [8] WB affected muscle (p > 0.05). On the other hand, several studies reported no changes in L* in moderately [43] and severely [8,41] WB affected muscles compared to normal breast muscle (p > 0.05). ...
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The effects of guanidinoacteic acid (GAA) supplementation on productive performance, pectoral myopathies, and meat quality of broilers were studied. Treatments consisted of corn/soybean-based diets with a GAA supplement (0%, 0.06%, and 0.12%). A total of 546 one-day-old Ross-308 males were randomly allocated to 42 floor pens with 14 replicates (13 birds/pens) for each treatment. The results showed that GAA at doses of 0.06% and 0.12% improved feed conversion, increased the percentage of normal breast, and decreased the severity of wooden breast. Breast muscle myopathy severity was positively correlated with heavy birds and negatively correlated with breast muscle creatine and glycogen. Breast muscle creatine and glycogen correlated positively with normal, less severe pectoral myopathies and meat quality. In conclusion, GAA supplementation improved broiler performance without exacerbating pectoral myopathy or affecting meat quality.
... Several authors showed that there were no significant differences in moisture content between normal and white striped fillets Kuttappan et al., 2012;Petracci et al., 2014;Soglia et al., 2016a;Soglia et al., 2016b;Soglia et al., 2018). In contrast, several studies showed that WB fillets had significantly higher moisture content than normal (Cai et al., 2018;Soglia et al., 2016a;Soglia et al., 2016b;Wold et al., 2017). Most of studies agreed that white striped meat had lower protein content than normal meat Kuttappan et al., 2012;Mudalal et al., 2014;Petracci et al., 2014;Soglia et al., 2016a). ...
... On the contrary, Soglia et al. (2018) revealed that there were no significant differences in protein content between white striped and normal fillets. WB fillets and WS combined with WB fillets had significantly lower protein contents than normal fillets (Cai et al., 2018;Soglia et al., 2016a;Soglia et al., 2016b;Wold et al., 2017). For the effect of muscle abnormalities (WS and WBs) on lipid content, most of studies were generally in agreement. ...
... For the effect of muscle abnormalities (WS and WBs) on lipid content, most of studies were generally in agreement. Meat affected by severe cases of WS or WB or WS combined with WBs exhibited higher fat content than normal meat Cai et al., 2018;Kuttappan et al., 2012;Soglia et al., 2016a;Soglia et al., 2016b;Soglia et al., 2018;Wold et al., 2017). Some researchers indicated that in moderate cases of WS and WB muscle abnormalities, there were no significant differences in fat content in comparison to normal (Kuttappan et al., 2012;Soglia et al., 2018;Wold et al., 2017). ...
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... These conditions are responsible for detrimental alterations at the microscopic level. Indeed, the affected pectoral muscles exhibit extensive muscle degeneration which results in lower crude protein contents in the forthcoming meat (Wold et al., 2017;Dalle Zotte et al., 2020;Xing et al., 2020;Oliveira et al., 2021). Due to their adverse impact on meat quality and consumer acceptability (Kuttappan et al., 2012;Oliveira et al., 2021), these defects are responsible for significant economic losses for the poultry meat industry (Baldi et al., 2018;Zanetti et al., 2018). ...
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... Some authors reported changes in breast chemical composition by the occurrence of myopathies, such as a significantly higher moisture, lipid and collagen content and a lower protein content, compared to NB [44,28,48]. Changes in the chemical composition of WS and WB chicken breast meat are consistent with the replacement of muscle tissue with adipose tissue (lipidosis), connective tissue (fibrosis) and the accumulation of extracellular water as a consequence of edema and inflammatory processes [11,49]. ...
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... The water absorption peak at around 980 nm is heavily affected by sample temperature, which introduces apparent shifts [16]. Another type of shift and broadening of the water peak is related to how tightly the water is bound to proteins [17,18]. The fourth compound in beef with a strong absorption in this wavelength region is myoglobin, an iron and oxygen binding protein. ...
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... However, the altered aspect of severely affected fillets can negatively influence consumers' acceptance [6], leading to rejection or depreciation of fresh meat due to poor quality. Moreover, these myopathies have been associated with decreased nutritional and organoleptic qualities, such as higher fat and lower protein content compared to normal fillets [3,[7][8][9]. Meat processability issues, such as poor texture, higher drip and cooking losses as well as lower marinade uptake, have also been associated with these myopathies [10][11][12]. The negative impact of breast fillet myopathies has been estimated to be > $1 billion per year in North America alone [13]. ...
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Spaghetti meat (SM), woody breast (WB), and white striping (WS) are myopathies that affect the pectoral muscle of fast-growing broiler chickens. The prevalence and possible risk factors of these myopathies have been reported in other countries, but not yet in Canada. Thus, the objective of this study was to assess the prevalence and risk factors associated with these myopathies in a representative population of Canadian broilers. From May 2019 to March 2020, 250 random breast fillets from each of 37 flocks (total, 9,250) were obtained from two processing plants and assessed for the presence and severity of myopathies. Demographic data (e.g., sex and average live weight), environmental conditions during the grow-out period (e.g., temperature), and husbandry parameters (e.g., vaccination) were collected for each flock. Associations between these factors and the myopathies were tested using logistic regression analyses. The prevalence of SM, severe WB, and mild or moderate WS was 36.3% (95% CI: 35.3–37.3), 11.8% (95% CI: 11.2–12.5), and 96.0% (95% CI: 95.6–96.4), respectively. Most (85.1%) of the fillets showed multiple myopathies. Regression analyses showed that the odds of SM increased with live weight (OR = 1.30, 95% CI 1.01–1.69) and higher environmental temperature during the grow-out period (OR = 1.75, 95% CI 1.31–2.34). The odds of WB increased with live weight (OR = 1.23, 95% CI 1.03–1.47) and when flocks were not vaccinated against coccidia (OR = 1.86, 95% CI 1.51–2.29). This study documents for the first time a high prevalence of myopathies in Ontario broilers, and suggests that these lesions may have a significant economic impact on the Canadian poultry industry. Our results indicate that environmental conditions and husbandry are associated with the development of breast myopathies, in agreement with the current literature. Future studies are needed to determine how risk factors can promote the occurrence of these conditions, in order to implement possible mitigating strategies.
... A bioelectrical impedance analysis method was tested for its potential as a noninvasive biosensor for the WBC in breast fillets [18]. A study with NIR hyperspectral imaging used NIR spectral biomarkers associated with protein and water binding to predict the WBC [19,20]. A spectral domain optical coherence tomography (OCT) technique was used to measure differences in subsurface microstructures of normal and wooden breast fillets, where the epimysium thickness of the fillets with the WBC was about two times larger than the normal fillets [21]. ...
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In recent years, the wooden breast condition has emerged as a major meat quality defect in the poultry industry worldwide. Broiler pectoralis major muscle with the wooden breast condition is characterized by hardness upon human palpation, which can lead to decrease in meat value or even reduced consumer acceptance. The current method of wooden breast detection involves a visual and/or tactile evaluation. In this paper, we present a sideview imaging system for online detection of chicken breast fillets affected by the wooden breast condition. The system can measure a physical deformation (bending) of an individual chicken-breast fillet through high-speed imaging at about 200 frames per second and custom image processing techniques. The developed image processing algorithm shows the over 95% classification performance in detecting wooden breast fillets.
... Although automated systems based on spectrometry have started to appear to selectively remove affected fillets (Wold et al., 2017(Wold et al., , 2019Wold and Løvland, 2020) at the processing plant, breast myopathies are still most commonly identified by visual and tactile inspection by trained personnel. For research purposes, published macroscopic scoring systems divide SM, WB, and WS into three and four tiers of severity (Kuttappan et al., 2013b;Sihvo et al., 2017;Baldi et al., 2018;Malila et al., 2018). ...
Article
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Spaghetti meat (SM), woody breast (WB), and white striping (WS) are myopathies affecting breast muscle of broiler chickens, and are characterized by a loss of myofibers and an increase in fibrous tissue. The conditions develop in intensive broiler chicken production systems, and cause poor meat processability and negative customer perception leading to monetary losses. The objectives of the present study were to describe the physical and histological characteristics of breast myopathies from commercial broiler chicken flocks in Ontario, Canada, and to assess the associations between the severity of myopathies with the physical and histological characteristics of the affected breast muscle fillets. Chicken breast fillets (n = 179) were collected over three visits from a processing plant and scored macroscopically to assess the severity of myopathies, following an established scoring scheme. For each fillet, the surface area, length, width, thickness, weight, and hardness (compression force) were measured. A subset of 60 fillets was evaluated microscopically. Multinomial logistic regression models were built to evaluate associations between physical parameters and macroscopic scores. The odds of SM co-occurring with severe WB (SM1WB2) were significantly associated with increased fillet thickness (OR = 1.59, 95% CI 1.31 – 1.94) and weight (OR = 1.06, 95% CI 1.03 – 1.09). Histologically, myopathies had overlapping lesions consisting of polyphasic myodegeneration, perivascular inflammatory cuffing and accumulation of fibrous tissue and fat. The pairwise correlation between macroscopic and microscopic scores was moderate (rho 0.45, P < 0.001). This is the first study to characterize breast myopathies in Canadian broiler flocks. Results show that the morphologic and microscopic changes of fillets from this cohort are similar to data from other countries, and provide database to benchmark these parameters in future studies. Our standardized categorization can be applied to broiler breast fillets in other regions of the world.
... Apart from that, it is able to aid in the prediction of salted meat composition at different temperatures [121] and in the prediction of sodium contents in processed meat products [122]. The detection and grading of the wooden breast syndrome in chicken fillet in the process line was also able to be performed by using the NIRS technique [123]. Not only that, it is proven to be efficient in determining the maturity of the avocado based on their oil content [124], predicting the acrylamide content in French-fried potato and in the potato flour model system [125], and determining the composition of fatty acid in lamb [126]. ...
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Artificial intelligence (AI) has embodied the recent technology in the food industry over the past few decades due to the rising of food demands in line with the increasing of the world population. The capability of the said intelligent systems in various tasks such as food quality determination, control tools, classification of food, and prediction purposes has intensified their demand in the food industry. Therefore, this paper reviews those diverse applications in comparing their advantages, limitations, and formulations as a guideline for selecting the most appropriate methods in enhancing future AI- and food industry–related developments. Furthermore, the integration of this system with other devices such as electronic nose, electronic tongue, computer vision system, and near infrared spectroscopy (NIR) is also emphasized, all of which will benefit both the industry players and consumers .
Thesis
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La filière avicole est confrontée à des défauts musculaires qui impactent la qualité de la viande de poulet. Des analyses génétiques et génomiques ont été menées en complément de mesures histologiques afin de mieux comprendre l’étiologie de ces défauts et contribuer au développement de nouveaux indicateurs et biomarqueurs utiles au diagnostic et à la sélection. L’étude a porté sur deux modèles génétiques complémentaires : (1) deux lignées divergentes de poulets sélectionnées sur le pH ultime du filet, et (2) une lignée à fort développement musculaire plus sévèrement affectée comparée avec une souche à croissance lente indemne de lésions. La thèse a permis de décrire les modifications métaboliques et structurales induites par la sélection à long terme sur la croissance et le rendement en filet ainsi que les dérégulations biologiques observées en cas de myopathies sévères. Elle a aussi conduit à l’identification des premières régions QTL contrôlant les défauts chez le poulet et à l’établissement d’un set de marqueurs géniques corrélés aux mesures histologiques des myopathies, qui une fois validé, servira d’outil d’aide à la sélection et à l’élevage.
Article
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Myopathies are gaining the attention of poultry meat producers globally. White Striping (WS) is a condition characterized by the occurrence of white striations parallel to muscle fibers on breast, thigh, and tender muscles of broilers, while Woody Breast (WB) imparts tougher consistency to raw breast fillets. Histologically, both conditions have been characterized with myodegeneration and necrosis, fibrosis, lipidosis, and regenerative changes. The occurrence of these modern myopathies has been associated with increased growth rate in birds. The severity of the myopathies can adversely affect consumer acceptance of raw cut up parts and/or quality of further processed poultry meat products, resulting in huge economic loss to the industry. Even though gross and/or histologic characteristics of modern myopathies are similar to some of the known conditions, such as hereditary muscular dystrophy, nutritional myopathy, toxic myopathies, and marbling, WS and WB could have a different etiology. As a result, there is a need for future studies to identify markers for WS and WB in live birds and genetic, nutritional, and/or management strategies to alleviate the condition.
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This study was conducted to characterize metabolic features of the breast muscle (pectoralis major) in chickens affected with the Wooden Breast myopathy. Live birds from two purebred chicken lines and one crossbred commercial broiler population were clinically examined by manual palpation of the breast muscle (pectoralis major) at 47-48 days of age. Metabolite abundance was determined by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using breast muscle tissue samples from 16 affected and 16 unaffected chickens. Muscle glycogen content was also quantified in breast muscle tissue samples from affected and unaffected chickens. In total, levels of 140 biochemicals were significantly different (FDR < 0.1 and fold-change A/U > 1.3 or < 0.77) between affected and unaffected chickens. Glycogen content measurements were considerably lower (1.7-fold) in samples taken from Wooden Breast affected birds when compared with samples from unaffected birds. Affected tissues exhibited biomarkers related to increased oxidative stress, elevated protein levels, muscle degradation, and altered glucose utilization. Affected muscle also showed elevated levels of hypoxanthine, xanthine, and urate molecules, the generation of which can contribute to altered redox homeostasis. In conclusion, our findings show that Wooden Breast affected tissues possess a unique metabolic signature. This unique profile may identify candidate biomarkers for diagnostic utilization and provide mechanistic insight into altered biochemical processes contributing to tissue hardening associated with the Wooden Breast myopathy in commercial chickens.
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Due to their importance for the control of meat quality in broiler chickens, the present study aimed at identifying the factors associated with the occurrence of myopathies and characterizing the meat properties when affected by myopathies. To this aim, a total of 768 broiler chickens were reared until slaughter (46 d) to evaluate the effect of genotype, gender, and feeding regime (ad libitum vs. restricted rate, 80% from 13 to 21 d of age) on performance and meat quality. Standard broilers were heavier (3,270 vs. 3,139 g; P < 0.001) and showed lower feed conversion (1.56 vs. 1.61; P < 0.001) than the high-yield broilers. Males showed higher final live weight (3,492 vs. 2,845 g) and lower feed conversion (1.54 vs. 1.63) than females (P < 0.001). Feed restriction decreased final live weight (3,194 vs. 3,142 g; P < 0.01) and feed conversion (1.60 vs. 1.57; P < 0.01) compared to ad libitum feeding. At gross examination, feed restriction tended to increase white-striped breasts (69.5 vs. 79.5%; P < 0.10), whereas females showed less wooden breasts than males (8.0 vs. 16.3%; P < 0.05). White-striped fillets had higher pHu (5.87 vs. 5.83), and lower a* (−0.81 vs. −0.59) and b* color indexes (13.7 vs. 14.5) (P < 0.05), whereas wooden breast fillets exhibited higher cooking losses (25.6 vs. 22.1%) and AK-shear force (4.23 vs. 2.84 kg/g) compared with normal fillets (P < 0.001). At histological examination, 3.1% of pectoralis major were normal, 26.6% mildly degenerated, 45.3% moderately degenerated, and 25.0% severely degenerated. In conclusion, genotype had a moderate effect on growth without modifying myopathy occurrence. In contrast, gender and feed restriction affected performance, meat quality, and breast abnormalities.
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An online NIR interactance imaging instrument was tested for fat distribution analysis in raw and salted salmon fillets. Approximately 3000 spectra were collected for each fillet when passing under the instrument on a conveyor bell (approximatety 1 s exposure). The instrument was calibrated using five cylindrical plugs (15mm diameter) from each fillet. The fat content was measured for each of these plugs using (1)H-NMR spectrometry and the spectra from each plug region were averaged and used for calibration and validation. It was found that online NIR interactance imaging is well-suited for distributional fat analysis in raw and salted intact salmon fillets. The local sampling and calibration strategy using 15mm diameter plugs for reference analysis and spectral averaging was found to provide relevant information and robust models. The average prediction errors (root mean square error of cross-validation) for raw and salted fillets in combination were approximately 2% fat for local plug regions.
Article
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A myopathy affecting the pectoralis major muscle of the commercial broiler has emerged creating remarkable economic losses as well as a potential welfare problem of the birds. We here describe the macroscopic and histologic lesions of this myopathy within 10 pectoralis major muscles of 5- to 6-week-old broilers in Finland. Following macroscopic evaluation and palpation of the muscles, a tissue sample of each was fixed in formalin, processed for histology, and histologically evaluated. The muscles that were macroscopically hard, outbulging, pale, and often accompanied with white striping histologically exhibited moderate to severe polyphasic myodegeneration with regeneration as well as a variable amount of interstitial connective tissue accumulation or fibrosis. All affected cases also exhibited perivenular lymphocyte accumulation. The etiology of this myodegenerative lesion remains yet open. Polyphasic myodegeneration is associated with several previously known etiologies, but palpatory hardness focusing on the pectoralis major, together with perivenular lymphocytes, has not been described in relation to them. The results of this study provide the pathological basis for further studies concerning the etiology of the currently described myopathy.
Article
In the past few decades, a remarkable increase in the incidence of breast muscle abnormalities termed as White-Striping (WS) and Wooden-Breast (WB) (normally downgraded by the poultry industry and used as raw materials to produce processed products) was observed. Thus, the present study aimed at evaluating the effect of WS and/or WB abnormalities on main compositional traits, lipid and protein oxidation and physicochemical state of water assessed by time domain nuclear magnetic resonance. Overall, if compared with controls, WS and WB groups revealed an increased (P < 0.05) moisture, fat and collagen contents coupled with reduced protein and total heme pigments levels. Otherwise, negligible modifications in fatty acid profile were found. Moreover, higher carbonyls (P < 0.05) were measured in WB and WS/WB samples if compared to normal and WS ones, and WB group also exhibited higher (P < 0.05) TBARS values. Abnormal samples showed a remarkable increase in proportion and mobility of extra-myofibrillar water fraction especially in WB and WS/WB groups. As a result, both functional and quality issues might arise when processed products are formulated including raw meats affected by WS and/or WB.
Article
Near infrared (NIR) spectroscopy represents an emerging analytical technique, which is enjoying increasing popularity in the food processing industry due to its low running costs, and since it does not require sample preparation. Moreover, it is a non-destructive, environmental friendly, rapid technique capable for on-line application. Therefore, this technique is predestined for implementation as an analytical tool in industrial processing. The different fields of application of NIR spectroscopy reported in the present review highlight its enormous versatility. Quantitative analyses of chemical constituents using this methodology are widespread. Moreover, a wide range of qualitative determinations, e.g. for authenticity control, sample discrimination, the assessment of sensory, rheological or technological properties, and physical attributes have been reported. Both animal- and plant-derived foodstuffs have been evaluated in this context. Highly diverse matrices such as intact solid samples, free-flowing solids, pasty, and fluid samples can by analysed by NIR spectroscopy. Sophisticated conditions for the application in industrial scale comprise among others measurements on moving conveyor belts, in continuous flows in tubes, and monitoring of fermentation processes. For such purposes, different construction designs of NIR spectrometers for hyperspectral imaging, portable devices, fibre optical and direct contact probes as well as tube integrated probes measuring through windows, and automated sample cell loading have been developed. In the present review, emphasis was put on studies dealing with on-line application of NIR spectroscopy for industrial processes in the food industry, which were categorised according to their application conditions into semi-industrial scale and industrial scale.
Article
SUMMARY The wooden breast condition is a myopathy affecting the pectoralis major (p. major) muscle in fast-growing commercial broiler lines. Currently, wooden breast–affected birds are phenotypically detected by palpation of the breast area, with affected birds having a very hard p. major muscle that is of lower value. The objective of this study was to compare the wooden breast myopathy in two fast-growing broiler lines (Lines A and B) with incidence of wooden breast to a slower growing broiler Line C with no phenotypically observable wooden breast. One of the characteristics of the wooden breast condition is fibrosis of the p. major muscle. Morphologic assessment of Lines A and B showed significant fibrosis in both lines, but the collagen distribution and arrangement of the collagen fibrils was different. In Line A, the collagen fibrils were tightly packed, whereas in Line B the collagen fibrils were diffuse. This difference in collagen organization may be due to the expression of the extracellular matrix proteoglycan decorin. Decorin is a regulator of collagen crosslinking and is expressed at significantly higher levels in Line A wooden breast–affected p. major muscle, which would lead to tightly packed collagen fibers due to high levels of collagen crosslinking. Furthermore, expression of the muscle-specific transcriptional regulatory factors for proliferation and differentiation of muscle cells leading to the regeneration of muscle in response to muscle damage was significantly elevated in Line A, and only the factor for differentiation, myogenin, was increased in Line B. The results from this study provide initial evidence that the etiology of the wooden breast myopathy may vary between fast-growing commercial broiler lines.
Article
Spectra of water have been acquired in the mid-infrared (MIR) and the near-infrared (NIR) region in the temperature range 2–96°C and 4–52°C, respectively. Loading plots from partial-least-squares regression were used to locate isosbestic points in the spectra bands of water. By means of least-squares, the original spectral profiles have been resolved into two spectra, one increasing and the other decreasing with temperature. Concentration profiles of the two structurally different water associations, for the investigated temperature range, were obtained by use of evolutionary curve resolution and first-order differentiation of the MIR spectra. Utilising information from the concentration profiles obtained in the MIR, the NIR spectra were resolved. Relative concentrations were obtained using spectral intensities from the isosbestic points. The complexity in both the fundamental and overtone region of the spectra shows that both structures of water are involved in H-bonding. This result indicates a pseudo-first-order reaction in water, either between an open and a more dense state, or between a rigid, strongly H-bonded state and a more loosely H-bonded state. The cross-correlation pattern between the two regions can be ascribed to the temperature-induced variation in the concentration of the two associations.