Food Biochemistry and Food Processing

328 Part III: Muscle Foods

found, depending on the batch and the presence of
specific strains (Molly et al. 1997). Other authors
have also observed that fatty acids are released in
higher amounts when starters are added, but that
there is significant lipolysis in the absence of micro-
bial starters (Montel et al. 1993, Hierro et al. 1997).
When pH drops during fermentation, the action of
muscle lysosomal acid lipase and acid phospholi-
pase becomes very important. Some strains are se-
lected as starters based on their contribution to lipol-
ysis. So, Micrococacceaepresent a highly variable
amount of extra- and intracellular lipolytic enzymes,
dependant on the strain and type of substrate. The
action of the extracellular enzymes on the hydroly-
sis of tri-acylglycerols becomes more important
after 15–20 days of ripening (Ordoñez et al. 1999).
Other microorganisms used as starters are Staphy-
lococcus warneri,which gives the highest lipolytic
activity, and S. Saprophyticus; S. carnosusand S.
xylosuspresent poor and variable lipolytic activity
(Montel et al. 1993). Lactic acid bacteria have poor
lipolytic activity, mostly intracellular. Many molds
and yeasts such as Candida, Debaryomices, Crypto-
coccus,and Trichosporumhave been isolated from
fermented sausages, and all of them exhibit lipolytic
acivity (Ordoñez et al. 1999, Ludemann et al. 2004,
Sunesena and Stahnke 2004).
The increases in the levels of free fatty acids show
a great variability depending on the raw materials,
type of sausage, and processing conditions (Toldrá

et al. 2002). The increase may reach 2.5–5% of the

total fatty acids, and the rate of release decreases in

the following order: oleic palmitic stearic 

linoleic (Demeyer et al. 2000). The release of poly-

unsaturated fatty acids from phospholipids is more

pronounced during ripening (Navarro et al. 1997).

Some short-chain fatty acids such as acetic acid may

increase, especially during early stages of ripening.

The generation of volatile compounds with impact

on the aroma of fermented sausages depends on the

type of processing and the starter culture added

(Talon et al. 2002, Tjener et al. 2004). Some of the

most important are aliphatic saturated and unsaturat-

ed aldehydes, ketones, methyl-branched aldehydes

and acids, free short-chain fatty acids, sulfur com-

pounds, some alcohols, terpenes (from spices), and

some nitrogen-derived volatile compounds (Stahnke

2002).

LIPOLYSIS INDRY-CUREDHAM

The generation of free fatty acids in the muscle is

correlated with the period of maximal phospholipid

degradation (Motilva et al. 1993b, Buscailhon et al.

1994). Furthermore, a decrease in linoleic, arachi-

donic, oleic, palmitic, and estearic acids from phos-

pholipids is observed at early stages of processing

(Martin et al. 1999). This fact corroborates muscle

phospholipases as the most important enzymes in-

volved in muscle lipolysis. The amount of generated

Figure 14.11.Evolution of muscle lipases during the processing of dry-cured ham.(Toldrá, unpublished data.)