application of alternative food-preservation - Bentham Science

Application of Alternative Food-Preservation Technologies to Enhance Food Safety & Stability, 2010, 17-34 17
Food Spoilage and Safety: Some Key-concepts
Barbara Speranza, Antonio Bevilacqua* and Milena Sinigaglia
Department of Food Science, Faculty of Agricultural Science, University of Foggia, Italy
Antonio Bevilacqua, Maria Rosaria Corbo and Milena Sinigaglia (Eds)
All rights reserved - © 2010 Bentham Science Publishers Ltd.
CHAPTER 3
Abstract: Several mechanisms cause deterioration of food and limit their shelf life: biochemical or microbial
decay, chemical changes - especially oxidation (rancidity of fats, respiration of fruits and vegetables,
discoloration, vitamin loss) -, physical deterioration (moisture migration, water loss or uptake). Therefore,
food spoilage is a complex phenomenon, involving physical, chemical, microbiological and biochemical
changes. As all involved factors and mechanisms operate interactively and often unpredictably, it is very
difficult to predict shelf life of food products precisely. In addition, due to the high diversity of food products,
there is no standard method for determining shelf life.
The sections of this chapter try to supply some key-concepts about food spoilage and food safety with a
particular focusing on the microbiological aspects. A brief synopsis of the bacterial pathogens mostly involved
with foodborne outbreaks and of the main spoiling microflora of foods is given. As there are several ways to
detect microbial spoilage in foods, - i.e. the microbiological methods, chemical/physical/physiochemical
methods, acceptability criteria, including sensory determinations (color, texture, odor, flavor and general
appearance)-, some details for each kind of approach are reported.
Key-concepts: What is food shelf life, Foodborne pathogens, Food spoilage, Food structure.
FOOD SHELF LIFE
There is not a generally accepted definition of the term shelf life; hereby, we can report the most important
definitions. In particular, Hine [1] defined shelf life as “the duration of that period, between packing a product
and using it, for which the quality of the product remains acceptable to the product user”. Another interesting
definition of the term shelf life is that reported by Labuza and Taoukis [2], i.e. “the shelf life is the period in
which the food will retain an acceptable level of eating quality from a safety and organoleptic point of view”.
Focusing on the definition of regulatory agencies, the Institute of Food Science and Technology (UK) proposed
the following definition: the shelf life is “the time during which the food product will remain safe, be certain to
retain the sensory, chemical, physical and microbiological characteristics, and comply with any label
declaration of nutritional data”
FAO (Food and Agricultural Organizations of the United States) and WHO (World Health Organization)
provided a more useful definition, without referring directly to the term shelf life; in particular, they introduced
three basic concepts:
1. the Sell-by-Date, defined as the last date of offer for sale to the consumer after which there
remains a reasonable storage period in the home;
2. the Use-by-Date, defined as the recommended last consumption date;
3. the Best-before-Use (or Date of Minimum Durability), which is the end of the period under any
stated conditions during which the product will remain fully marketable and retain any specific for
which tacit or explicit claims have been made; this definition complies with the generally accepted
meaning of the term shelf life.
The actual shelf life of a product depends generally on four factors: a) formulation; b) processing; c) packaging
and d) storage conditions; these elements can be considered crucial, but their relative importance relies on the
kind of foods.
Several mechanisms cause deterioration of food and limit shelf life, i.e.:
1. biochemical or microbial decay;
2. chemical changes, especially oxidation (rancidity of fats, respiration of fruit and vegetables,
discoloration, vitamin loss);
*Address correspondence to this author Antonio Bevilacqua at: Department of Food Science, Faculty of Agricultural Science, University
of Foggia, Italy; a.bevilacqua@unifg.it; abevi@libero.it