BLBS102-c17 BLBS102-Simpson March 21, 2012 11:52 Trim: 276mm X 219mm Printer Name: Yet to Come
17 Chemical and Biochemical Aspects of Color in Muscle-Based Foods 321it is rapidly oxidized between pH 5 and 7, releasing the different
parts of the Mb (globin, iron, and the tetrapyrrole ring).
From a chemical point of view, it should be borne in mind that
the color of Mb, and therefore of the meat or meat products, not
only depends on the molecule that occupies the sixth coordina-
tion site, but also the oxidation state of the iron atom (ferrous
or ferric), the type of bond formed between the ligand and the
heme group (coordinated covalent, ionic, or none) and the state
of the protein (native or denaturalized form), not to mention the
state of the porphyrin of the heme group (intact, substituted or
degraded) (Perez-Alvarez 1996). ́
During heat treatment of fish flesh, aggregation of denatured
fish proteins is generally accompanied by changes in light
scattering intensity. Results demonstrate the use of changes in
relative light scattering intensity for studying structural un-
folding and aggregation of proteins under thermal denaturation
(Saksit et al. 1998). When fatty fish meat likeTrachurus japon-
icuswas heat treated, MMb content increased linearly, and
the percentages of denatured Mb and apomyoglobin increased
rapidly when mince was exposed to heat, but when temperature
reach 60◦C, the linearity is broken. Results indicated that
stability of the color was higher than that of Mb and that the
thermal stability of heme was higher than that of apomyoglobin
(Hui et al. 1998).
Both Mb and ferrous iron accelerated lipid oxidation of
cooked water-extracted fish meat. EDTA inhibited the lipid oxi-
dation accelerated by ferrous iron, but not that accelerated by Mb.
Also, with cooked nonextracted mackerel meat, EDTA notice-
ably inhibited lipid oxidation. Nonheme iron-catalysis seemed
to be related in part to lipid oxidation in cooked mackerel meat.
Addition of nitrite in combination with ascorbate resulted in
a marked inhibition of lipid oxidation in the cooked mackerel
meat. From these results, it was postulated that nitric oxide fer-
rohemochromogen, formed from added nitrite and Mb, present
in the mackerel meat in the presence of a reducing agent, pos-
sesses an antioxidant activity, which is attributable in part to the
function as a metal chelator (Ohshima et al. 1988).
Tuna fish meat can be improved in its color when the flesh
is treated with CO. The specific spectrum of carboxymyoglobin
(COMb) within the visible range can be obtained. Penetration
of CO into tuna muscle was very slow. After approximately 1–4
hours CO had penetrated 2–4 mm under the surface, and after 8
hours, CO had penetrated 4–6 mm. Mb extracts from tuna muscle
treated with CO exhibited higher absorbance at 570 than at 580
nm (Chau et al. 1997). Jayasingh et al. (2001) reported that CO
(0.5%) can penetrate to a depth of 15 mm (1 week) in ground
beef. These authors also mentioned that when COMb is exposed
to atmospheres free of CO, COMb slowly dissociate from Mb.
In dry-cured meat products, as Parma ham (produced without
nitrite or nitrate), the characteristic bright red color (Wakamatsu
et al. 2004a) is caused by Zn-protoporphyrin IX (ZPP) complex,
a heme derivative. This type of pigment can be formed by en-
dogenous enzymes as well as microorganisms (Wakamatsu et al.
2004b). Spectroscopic studies of Parma ham during processing
all process, revealed a gradual transformation of muscle Mb,
initiated by salting and continuing during aging. Pigments be-
came increasingly lipophilic during processing, suggesting thata combination of drying and maturing yields a stable red color
(Parolari et al. 2003). Electron spin resonance spectra showed
that the pigment in dry-cured Parma ham is at no stage a ni-
trosyl complex of ferrous Mb as found in brine-cured ham and
Spanish Serrano hams (Moller et al. 2003). These authors also
establish that heme moiety is present in the acetone/water extract
and that Parma ham pigment is gradually transformed from an
Mb derivative into a nonprotein heme complex, thermally stable
in acetone/water solution. Adamsen et al. (2003) also demon-
strated that the heme moieties of Parma ham pigments have also
antioxidative properties.COLOR CHARACTERISTICS OF BLOOD
PIGMENTSHb has function carrying oxygen to the tissues. Thus, the oxy-
genated hemoglobin Hb(Fe(II))O 2 is a very stable molecule but
does slowly auto-oxidize at a rate of about 3% per day. This
rate is accelerated at lower oxygen tensions if the Hb is partially
oxygenated. The “blood pigments” chemistry is actually quite
complex (Umbreit 2007).
Nagababu and Rifkind (2000) reported that the auto-
oxygenation generates Hb(Fe(III)), called methemoglobin
(MHb), and superoxide. At least in vitro, the superoxide un-
dergoes dismutation to hydrogen peroxide and oxygen. The hy-
drogen peroxide is rapidly decomposed by catalase. The sixth
coordinate of the MHb is occupied with water. If not immediately
destroyed, the hydrogen peroxide would react with Hb(Fe(II))O 2
to produce ferrylhemoglobin, Hb(Fe(IV))=O, with a rhombic
heme that reacts with further hydrogen peroxide to produce free
Fe(III) and porphyrin degradation products.
Jaffe (1981) reported that the MHb can be reduced by the
NADH-cytochrome b5-MHb reductase or by direct reduction
by ascorbate and glutathione.
The Hb can react with nitrites; the reaction with oxyhe-
moglobin (OHb) limits the half-life of the NO. The reaction
with free Hb is so fast that any NO is consumed immediately
(Vaughin et al. 2000, Huanf et al. 2001). According to Umbreit
(2007), there are two major reactions of the nitrogenous com-
pounds with Hb Fe(II), one binding NO to the heme and the
other reducing nitrite to NO.
Muscles can retain several amounts of blood. Thus, Richard
et al. (2005) reported that dark muscle from Atlantic mackerel
contained roughly equal amounts of Hb and Mb, although in
other fish species such as bluefin tuna (T. thynnus) Hb can be the
major heme compound in dark muscle “sangacho” (S ́anchez-
Zapata et al. 2009a). Niewiarowicz et al. (1986) reported that
in different poultry dark meat species the ratio between Hb and
Mb varies from 20% to 40%. In mammals, this ratio has been
reported to range from 7% to 35% (Han et al. 1994).
Animal blood is little used in the food industry, because of dark
color it imparts to the products to which it is added. Attempts
to solve food color related problems have employed several dif-
ferent processes and means, but they are not always completely
satisfactory. The addition of 12% blood plasma to meat sausages
lead to pale-colored products. Another means of solving color
problems is the addition of discolored whole blood or globin by