Food Biochemistry and Food Processing (2 edition)

BLBS102-c15 BLBS102-Simpson March 21, 2012 13:21 Trim: 276mm X 219mm Printer Name: Yet to Come

15 Biochemistry of Raw Meat and Poultry 299

Figure 15.9.Classification of pork carcasses in the slaughterhouse.

(Courtesy of Industrias Carnicas Vaquero SA, Madrid, Spain.) ́

first, and a number for the fat level. In some countries, additional

grading systems may be added. For instance, in France, the color

is measured and rated 1 to 4 from white to red color.

New Grading Systems

New grading systems are being developed that take advantage of

the rapid developments in video image analysis and other new

physical techniques as well as those in biochemical assay tests.

New methodologies based on physical methods for the online

evaluation of meat yield and meat quality, applied as schematized

in Figure 15.10, include near infrared reflectance (NIR), video

image analysis, ultrasound, texture analysis, nuclear magnetic

resonance, and magnetic resonance spectroscopy techniques.

Physical Techniques

NIR is applied for the rapid and nondestructive analysis of meat

composition in fat, protein, and water (Byrne et al. 1998, Rod-

botten et al. 2000). This technique has also been applied to

aged meat, giving a good correlation with texture, and thus

constituting a good predictor for meat tenderness. In addition,

NIR spectroscopy allows for a minimal or nonnecessary sample

preparation (Niemoller and Behmer 2008). Video image analysis ̈

is very useful for the measurement of carcass shape, marbling,

and meat color. Conductivity has been in use for several years

to predict meat composition and quality.

Ultrasounds are based on the measurement of different param-

eters such as velocity, attenuation, and backscattering intensity

and may constitute a valuable tool for the measurement of meat

composition (Got et al. 1999, Abouelkaram et al. 2000). Texture

Figure 15.10.Example of application of physical-based methods

for the online evaluation of meat yield and quality. At the

slaughterhouse, the hand-held devices are applied to the carcass

between the last three and four ribs (place marked with anarrow).

The signal is then received in the unit and computer-processed. The

carcass quality is estimated and, depending on the technique, is

also classified by yield. (Courtesy of Industrias Carnicas Vaquero ́

SA, Madrid, Spain.)

analysis, as the image processing of the organization of gray

pixels of digitized images, can be used for the classification

of photographic images of meat slices (Basset et al. 2000). This

technique appears to give good correlation with fat and collagen,

which are especially visible under ultraviolet light, and would

allow classification according to three factors, muscle type, age,

and breed (Basset et al. 1999).

Nuclear magnetic resonance has good potential as a nonin-

vasive technique for better characterization and understanding

of meat features. Thus, magnetic resonance imaging can give

a spatial resolution that characterizes body composition. This

technique is well correlated to important meat properties such

as pH, cooking yield, and water-holding capacity (Laurent et al.

2000). Magnetic resonance spectroscopy may be useful to de-

termine the fatty acid composition of animal fat. This technique

may have further applications; for example, in the possible use

of^23 Na imaging to follow brine diffusion in cured meat products

(Renou et al. 1994).

The use of bioimpedance spectroscopy has shown good per-

formance for the assessment of meat quality, especially to dis-

tinguish among PSE, DFD, and normal pork meats (Castro-

Gir ́aldez et al. 2009, 2010a). The amount of ATP is character-

istic for each type of pork meat quality and the ion activity of

ATP may be correlated with the ionic dispersion in the dielectric

spectra (Castro-Giraldez et al. 2010b). ́