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158 IV.Resultados y discusión. Capítulo II
1. INTRODUCTION
Probiotics are defined as “live microorganisms that when administered
in adequate amounts confer a health benefit on the host” (FAO/WHO,
2001). Within this group, Lactobacillus and Bifidobacterium genera are the
most widely recognised, although Lactococcus, Enterococcus,
Saccharomyces and Propianobacterium genera have been investigated
(Rivera-Espinoza and Gallardo-Navarro, 2010). They should meet several
requirements, such as total safety for the host, resistance to gastric acidity
and pancreatic secretions, adhesion to epithelial cells, antimicrobial activity,
inhibition of adhesion of pathogenic bacteria and immune system and
metabolic activity stimulation, among others (Prado et al., 2008).
The use of probiotics in food product manufacturing dates back to the
ancient world, although the purposes have been changed. Nowadays, not
only are these microorganisms used for food preservation and organoleptic
improvements but also for their nutritional and health benefits: reduction of
hypercholesterolemia, host immune modulation, prevention of urogenital
diseases, alleviation of constipation, protection against traveller’s diarrhoea,
protection against colon and bladder cancer, prevention of osteoporosis and
food allergies, among others (Ferreira et al., 2011; Oelschlaeger, 2010; Saad
et al., 2013). Host benefits, however, are subject to strain type used in
product manufacture (Sharareh et al., 2009). In order to effectively provide
health functionalities, the minimum recommended number of viable
probiotic bacteria is 10 7 -10 8 colony forming per unit (cfu)/g or mL of a