**1. Introduction**

Honey is used as a therapeutic product since ancient times. Its properties are chemically evidenced by its composition. Among features that make this product effective against microorganisms, we can quote high osmotic pressure by low water activity (average 17.2%); low pH because of the presence of organic acids, mainly gluconic acid (average 3.9); the presence of hydrogen peroxide generated by action of enzyme glucose oxidase; low protein content;

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

low redox potential due to the presence of reducing sugars; and chemical agents present as lysozyme, phenolic acids, pinocembrin, terpenes, benzyl alcohol, and volatile substances [1, 2].

High osmotic pressure results from its composition: 85–95% of sugar, of which it has 28–31% of glucose, 22–38% of fructose, 1–4% of sucrose, and 1–9% maltose [3]. Isomaltose and some oligosaccharides are also present in honey and vary according to flowering, climate, and local production [4, 5]. As honey is a product developed from changes in nectar, the bees incorporate the glucose oxidase enzyme that converts glucose into hydrogen peroxide and gluconic acid; this compound is indeed important for the taste of products as well as their bioactivity [5, 6]. The presence of acids and other chemicals varies with the composition of the transformed nectar; for this reason, some honeys have higher antimicrobial activity with respect to other different blossoming [7].

About these conditions, few microorganisms have the capacity to develop or remain in honey. These microorganisms are derived from primary or secondary sources of contamination. The primary sources are related to digestive tract of honeybees, which have natural microorganisms and sources of material collection such as nectar, pollen and propolis, air, flowers, and the environment inside the beehive, while the secondary sources are incorporation of honey microorganisms postharvest, processing plants, and appliances [5].
