358 Chapter 20
free amino acids, and small peptides that
are accumulated by the end of the process,
while aroma is linked to the generation of
volatile compounds with important aromatic
characteristics.
Protein and lipid hydrolysis, also known
respectively as proteolysis and lipolysis,
constitute two of the most important enzy-
matic phenomena, responsible for the gen-
eration of compounds with direct infl uence
on taste and aroma (Toldr á 1992 , 2006c ).
Peptides and free amino acids are generated
in large amounts from the progressive enzy-
matic degradation of major sarcoplasmic and
myofi brillar proteins (Toldr á and Etherington
1988 ; Toldr á 2007b ). Most of the muscle
proteases show very good stability in long
dry - cured ham processes (Toldr á 2004b ), and
the generation rate for free amino acids is
very high, especially up to 9 months (Toldr á
et al. 2000 ). Some free amino acids, such as
glutamic acid, glycine, alanine, valine,
proline, histidine, and leucine, have been
found in savory fractions of ham. More spe-
cifi cally, lysine and tyrosine have been cor-
related with aged taste, and glutamic acid,
aspartic acid, methionine, phenylalanine,
tryptophan, lysine, leucine, and isoleucine
have been correlated with the length of the
drying and the fully ripened ham taste. Bitter
tastes are found in hams with excessive
amounts of tryptophan, tyrosine, and phenyl-
alanine (Toldr á 2002 ).
Free fatty acids are generated from the
progressive enzymatic breakdown of triacyl-
glycerols and phospholipids (Motilva et al.
1992 ; Buscailhon et al. 1994a ). Such lipo-
lytic enzymes are located in muscle and
adipose tissue and also show very good
stability (Motilva et al. 1993a, b ; Toldr á
1998, 2007b ). The released free fatty acids
are then partly oxidized, generating a large
number of volatile compounds with particu-
lar aroma characteristics (Berdagu é et al.
1991 ; Buscailhon et al. 1993 ; Coutron -
Gambetti and Gandemer 1999 ). These vola-
tile compounds, nearly two hundred of them,to initial protein denaturation or partial
degradation of myoglobin, which associates
through noncovalent binding to zinc porphy-
rin (Adamsen et al. 2006a ). In fact, the use
of nitrite as a curing agent has been reported
to inhibit completely the formation of Zn -
porphyrin in hams (Adamsen et al. 2006b ).
When the product is smoked, some surface
dark colors may appear as a consequence of
the pyrolytic decomposition of wood.
Texture
Texture of the product depends not only
on the extent of myofi brillar protein break-
down but also on other factors, such as the
extent of drying, the degradation of the
connective tissue, and the content in intra-
muscular fat, which also exerts a positive
infl uence on some texture and appearance
traits. Proteolysis of key myofi brillar and
associated proteins is responsible for tender-
ization. An intense degradation of the myofi -
brillar structure is observed during dry curing.
Major structural proteins, such as titin,
nebulin, and troponin T, as well as heavy and
light chains of myosin and α - actinin, are
severely proteolyzed (Toldr á et al. 1993 ).
Two clear fragments corresponding to 150
and 85 KDa appear during processing. A
large number of peptides resulting from actin
and titin breakdown have been recently iden-
tifi ed in dry - cured ham (Sentandreu et al.
2007 ; Mora et al. 2009 ). Hams produced
from PSE meats show an absence of these
fragments when compared with normal hams,
and there is a trend toward softer hams. In
fact, the application of a texture analysis
shows that PSE hams have lower hardness,
springiness, cohesiveness, and chewiness
(Tabilo et al. 1999 ).
Flavor
The term fl avor represents the overall percep-
tion of taste and aroma. Taste is mainly asso-
ciated with nonvolatile compounds, such as