Biomedical Engineering Reference
In-Depth Information
Chapter 2
Natural Antimicrobials for Food
Biopreservation
Biopreservation or biocontrol refers to the use of natural or controlled microbiota,
or its antibacterial products to extend the shelf life and enhance the safety of foods
(Stiles
1996
). Since lactic acid bacteria (LAB) occur naturally in many food sys-
tems and have a long history of safe use in fermented foods, thus classed as Generally
Regarded As Safe (GRAS), they have a great potential for extended use in bio-
preservation. Antimicrobial substances from other natural sources, such as antimi-
crobial proteins or peptides from animal secretions, or bioactive molecules from
plant or animal defense systems have also been exploited in different ways for food
biopreservation.
2.1
Bacterial Antagonism as a Fundamental
for Biopreservation
Microbes often live in complex ecosystems where they must interact with the biotic
and abiotic components of the environment. Bacterial populations must compete for
space and nutrients in order to survive. They have evolved different mechanisms
such as nutrient and space competition, metabolic specialization, o cell differentia-
tion, among others. One of the most common strategies to defend a population ter-
ritory is ammensalism, which is based on the modifi cation of the environment by
the release of antimicrobial substances that inhibit growth or even kill competitors.
Bacteria may release a variety of antimicrobial substances as byproducts of their
normal metabolic activity. They also may produce more specifi c, dedicated antimi-
crobial weapons encoded by specifi c genetic determinants aimed specifi cally at
combating other microbes. Metabolic products as well as antimicrobial peptides
from lactic acid bacteria (LAB) have attracted great attention for food biopreserva-
tion. Being naturally or intentionally present in food fermentations, the lactic acid
bacteria are considered themselves as natural preservatives as well as factories of
