Dried Probiotics for Use in Functional Food Applications

Abstract

The increasing consumer demand for foods with health benefits has led the food industry to diversify its products. Most of the foods containing probiotic bacteria are dairy products, although there is a rapidly growing demand for incorporating probiotics in other segments of the food industry. According to Food and Agriculture Organization (FAO, 2002), probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits on the host. In order to produce such health benefits, it is essential that live probiotic bacteria survive after passing through the gastrointestinal tract and reach their site of action intact. Foods containing probiotic microorganisms are expected to have a promising future, but will require the development of new technologies, specifically developed to enable their use in innovative products in a wide range of industries. The challenge for the industry is to produce large enough amounts of viable and stable probiotic cultures for use as inoculums or to be introduced directly into a dried food. Although specific numbers are not mentioned at the FAO definition, some studies demonstrated that high levels of viable microorganisms are recommended in probiotic foods for efficacy (Meng et al., 2007). However, maintaining such counts throughout preparation, processing and storage requires constant study by the scientific and industrial community. Drying process are often used as a means to stabilize probiotics and facilitate storage, handling, transportation and subsequent use in functional foods (Santivarangka et al., 2008). Drying by spray-drying and freeze-drying are the most commonly used techniques for dehydrating probiotic cultures and lactic acid bacteria starter cultures (Betoret et al., 2003), although other methods such as vacuum oven drying, fluid bed drying or combinations of these may also be used. Drying processes are a major cause of loss of viability of probiotics, and in the specific case of freeze-drying, the freezing step causes additional stress on the bacterial cells, making the