192 Chapter 9
mono - , di - , and triacylglycerols at a lower
rate (Sanz et al. 1998 ), stating their weak
lipolytic system (El Soda et al. 1986 ; Montel
et al. 1998 ; Drosinos et al. 2007 ), whereas
the production of lipolytic enzymes among
staphylococci seems to be a common charac-
teristic (Miralles et al. 1996 ; Coppola et al.
1997 ; Kenneally et al. 1998 ; Mauriello et al.
2004 ; Casaburi et al. 2007 ). Once free fatty
acids are released, they are subjected to
oxidative reactions that give rise mainly to
aliphatic hydrocarbons, alcohols, aldehydes,
ketones, and esters, with the latter being pro-
duced in the absence of nitrite in the recipe.
Excessive oxidation results in the formation
of off - fl avors such as rancidity. The micro-
biota, through the consumption of oxygen,
negatively affects rancidity formation.
Development of Starter Cultures
The concept of starter cultures for fermented
sausages is nearly as old as the product itself.
The rationale is to minimize the variability
quelling from spontaneous fermentation and
to enrich organoleptic quality and safety.
Toward this direction, a huge amount of
research has taken place. Desirable techno-
logical features include acidifi cation, cata-
lase, protease, and lipase activity, as well as
avoidance of possible discoloration phenom-
ena through the production of peroxides
according to Figure 9.2. Regarding the safety
of the product, bacteriocin production is
involved in antibiotic resistance, as well as
the absence of amino acid decarboxylase
activity and transferable genes.
Acidifi cation possesses a key role in fer-
mented sausage manufacture, as it enables
control of spoilage and pathogenic microbi-
ota and affects fl avor, color, and texture
development. It has also been reported that a
rapid decrease of the pH value can prevent
biogenic amine accumulation (Maijala et al.
1993 ). Catalase activity is important, as it
hydrolyses the hydrogen peroxide (producedNO 2-2eH+ OH-NO 3
2H H 2 O-2eNOMyoglobin (purple-red) Fe 2+Myoglobin (brown) Fe 3+Nitric oxide metmyoglobin
(brown) Fe 3+Nitric oxide myoglobin
(bright pink) Fe 2+-O 2Nitrosohemochrome
(pink stable) Fe 2+Cholemyoglobin
(Green)Lactate H 2 O 2 Heat or SmokingHexoseBacterial
actionFigure 9.2. Color development in fermented sausages.