Color change, meat

GOUTENFONGEA, R., RAMPON, V., NICOLAS, N. and DUMONT, J. P. (1995). Meat color changes under high pressure treatment. 41st Annual International Congress of Meat Science and Technology. San Antonio, Texas, USA, pp. 384-385. 

Besides physicochemical methods, the use of microbiological growth-inhibition assays to test meat and milk for the presence of antibiotics residues is popular over a long period of time. These tests use antibiotic-sensitive bacterial reporter strains, such as Bacillus subtilis and Bacillus stearothermophilus var. calidolactis. These bacteria are inoculated under optimal conditions with and without sample. After culturing, results are read from visible inhibition zones or from the color change of the bacterial suspension in agar gels [6]. 

The scenes to be analyzed are too complex. Except for flat products (e.g., meat slices, fish, biscuits), the third dimension of food products may be relatively odd, with concave areas leading to shadowing and color changes. This is typically the case for the calyx cavity in fruits, which is generally seen as a defect by classical RGB vision systems. Similar problems of misclassiflcation due to concavities occur with chicken carcasses. The use of NIR imaging will allows these effects of shadowing and of depth of field to be reduced. 

With exposure to heat Mb in the center of an intact piece of meat changes from blue-red to red to pinkish to brown due to thermal denaturation of Mb and proteins. Thus, in meat cooked to rare (approximately 50°C) and then sliced open, it is often possible to see the whole range of color changes present, with fully denatured Mb at the outside edges and untouched Mb at the center. 

An unintentional gas-induced color change to meat occurs when it is exposed to sufficiently high levels of nitrogen dioxide (NOj) such as during incomplete combustion of gases in gas ovens. The surface of the meat becomes pink, much like the characteristic pink of cured meat, due to the formation of nitrosylhemochrome (Cornforth et al., 1998). 

Color changes in cured meats are induced by curing and/or drying and during storage (Sebranek, 1988). Depending on the process of preservation, a meat mixture may be subject to temperatures between ambient and... 

Sebranek (1988) has reviewed the effects of heat on denaturation of the proteins. Dehydration by heat denatures the muscle proteins, particularly the sarcoplasmic proteins. This induces a rather dramatic change in meat color. The heme pigments, which provide most of the color of fresh meat, serve as a general indication of doneness or temperature history. In the case of cured products, heme pigments react to form nitric oxide hemochro-mogen, which contributes the characteristic pink cured meat color (Pearson and Tauber, 1984). 

Agar gel immunodiffusion methods have been produced as commercial kits and a further development is dipstick assays for meat species identification. The immunoreagents are immobilized on a dipstick and a color change, occurring in less than 1 h, identifies the presence of a particular meat species, with a detection limit of 1 % lean meat. 

Hall, G. O. 1950. Curing of meat to avoid undesirable color change. U. S. patent 2,513,094. 

Abd El-Khalek and Zahran (2013) evaluated the use of fruit by-products such as mandarin rind powder, orange rind powder, and grapefmit rind powder, with or without y irradiation on color change, microbial growth and lipid oxidation of raw ground beef meat stored at 4 1°C. 

Ahn et al., (2007) studied the effects of 1% grape seed extract on the growth of foodbome pathogens, color changes, and lipid oxidation of cooked ground beef compared to untreated and butylated hydroxyanisole/butylated hydroxytoluene-treated meat. 

A color change to brown is observed when non-cured meat is heated. A Fe + complex is present which has its fifth and sixth coordination sites occupied by histidine residues of denatured meat proteins. 

Heat treatment is an important finishing process and also serves for the production of canned meat. Typical changes involved in heat treatment are development of grayish-brown color, protein coagulation, release of juices due to decrease in water holding capacity (Fig. 12.30), increase in... 

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