Prebiotic potential of old and new thickening agents for milk fermented products

Recently, basing on consumer´s requirements, particular attention has been devoted to the development of functional food. Such is the case of food that contains probiotic microorganisms and/or prebiotic compounds that promote the growth of these microorganisms. “Espina Corona” gum (EC) is obtained from the seeds of Gleditsia amorphoides, growing in the north of Argentina. Due to its thickener ability, it is utilized together with gelatin, as additive in the manufacture of dairy products. The interaction between microorganisms and other components of the food matrix may be necessary to understand the inhibition or benefit in the growth of such microorganisms. Other gums (like guar gum) have proven prebiotic activity over different species of bifidobacteria and the great composition similarity between guar gum and EC motivates the study of the latter as a potential prebiotic in food matrices. The aim of this work was to study the ability to ferment commercial prebiotics such as Cup-Oligo® (a galactooligosaccharide, GOS), Actilight®950P (a fructooligosaccharide, FOS), Orafti®Synergy (a high solubility inulin, HSI), Orafti®Raftiline (a high polymerization inulin, HP), EC, and Gelatin (G) by different species of bifidobacteria and lactobacilli isolated from commercial dairy products and others present in the culture collection BUSCOB at Bologna University. The strains were identified according to molecular techniques (species-specific PCR and ERIC-PCR). FOS, GOS and HSI were the substrates fermented by the largest number of species. Lactobacillus casei Shirota and L. rhamnosus isolated from Yakult™ and Yomo™ products, respectively, only grew in the presence of GOS. L. rhamnosus SP1 did not use any substrates. EC and HP did not show significant effects on the growth of lactobacilli species and on the 4 strains of Bifidobacterium animalis ssp. lactis isolated from commercial products. While EC was fermented by B. animalis ssp. lactis DSM 10140T and P23 , B. longum ssp. longum B1835 (deriving from BUSCOB) and DSM 20219T, the gelatin inhibited the growth of all the strains tested. These results point out that EC can be used not only as a thickener additive but that it also has a potential prebiotic activity for some bifidobacteria strains