ABSTRACT
Contents 11.1 Introduction ................................................................................................................... 213 11.2 History of Use; First Challenge for Lactic Acid Bacteria: To Be Included in the Diet .... 214 11.3 Challenge of Maintaining Fermentation Cultures and Reward of Fermented Milks ...... 215 11.4 Challenge of Probiotics; Diversity .................................................................................. 217 11.5 Challenge of Probiotic Origin ........................................................................................ 218 11.6 Challenge of Probiotic Survival ...................................................................................... 220 11.7 Challenge of Being Active .............................................................................................. 221 11.8 Challenge of Dealing with Endogenous Microbiota ....................................................... 222 11.9 Probiotic Challenge of Providing a Health Benefit to Humans ...................................... 223 11.10 Final Challenge for Probiotics Exploring Safety ........................................................... 224 11.11 To Conclude ................................................................................................................. 225 References ............................................................................................................................... 225
Milk, the only substance designed by nature specifically to be a food, is a great medium for bacteria to grow, and recent data imply that some bacteria are able to develop in milk even at the source of production (i.e., in the mammary gland) (Martín et al. 2003). This also explains why raw milk is difficult to store: the environment is full of microbes that can grow in milk and spoil it. This is a challenge that humans had faced for ages until pasteurization was discovered. Still today the challenge is to select bacteria in milk that humans can tolerate, and maturation is part of many fermentation processes. One way to select those bacteria is to inoculate them in the milk as soon as possible; fermentation, a controlled use of microbes to preserve foods, is a very old trick humans have been using to prevent microbial spoilage of milk since the ancient times. How did the first controlled fermentation start? Nobody knows. It may have occurred by chance alone, or was the result of either a wise pragmatic observation or a long history of trials and errors, or even an adaptation of consumers to the most frequent microorganisms found in milk.
