CRANFIELD UNIVERSITY Eleni Anthippi Chatzimichali ...

1.1.3 Microbial Spoilage in Meat
Systems biology has gained in importance in food science and the food industry due
to an increasing focus on food for better health and the demand for products of
consistently high quality (Ellis et al., 2002; Hassani et al., 2010). Out of all foods that
are a vital part of human diet, meat has been described as the most perishable of all.
Muscle foods such as meat or poultry become unacceptable to the consumer when
organoleptic changes occur due to spoilage (Ellis et al., 2002). Spoilage can be
defined as “any change in a food product that renders it unacceptable to the consumer
from a sensory point of view” (Gram et al., 2002; Ercolini et al., 2006)
Meat spoilage may be the result of a plethora of intrinsic and extrinsic factors, the
most significant of which is microbial activity (Gram et al., 2002). Even though
changes of food substances during storage may be the result of endogenous enzymatic
processes within muscle tissue post-mortem, it is generally accepted that detectable
organoleptic spoilage is a result of decomposition and the formation of metabolites
caused by the growth of microorganisms (Ellis and Goodacre, 2001; Ellis et al.,
2002). These organoleptic characteristics usually include the development of
off-odours and off-flavours, the formation of slime in addition to any changes in the
appearance such as discoloration; thus, consumers consider the meat as being
undesirable. Due to its moist highly nutritious surface, meat stored at between -1 and
25°C favours the growth of a wide range of spoilage bacteria. Under aerobic
conditions, spoilage organisms that belong primarily to the genus Pseudomonas attach
more rapidly to meat surfaces than other spoilage bacteria (Ellis et al., 2002). The
organoleptic changes may vary depending on the microbial association contaminating
the meat and the conditions under which it is stored. The development of organoleptic
spoilage is related to microbial consumption of meat nutrients such as sugars and free
amino acids, and the release of undesired volatile metabolites (Ercolini et al., 2006).
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