IMPROVING THE PROBIOTIC EFFECT OF LACTOBACILLUS SALIVARIUS SPP. SALIVARIUS IN MANDARIN JUICE BY ADDING TREHALOSE AND/OR APPLYING HIGH PRESSURE HOMOGENIZATION

Burca C., Barrera Puigdollers C., Betoret Valls N., García Hernández J., Hernández Pérez M., Seguí Gil L.
Instituto Universitario de Ingeniería de Alimentos para el Desarrollo. Universitat Politècnica de València, Spain

Introduction:
Given the high prevalence of infection caused by Helicobacter pylori (Go, 2002) and the side effects associated to its treatment with antibiotics (Graham y Yamaoka, 2000), it becomes interesting to develop natural alternatives to decrease this pathogen colonization. There are clinical studies and in vitro models confirming that Lactobacillus bacteria (particularly L. salivarius spp. salivarius) compete with and inhibit the colonization by Helicobacter pylori (Hamilton-Miller, 2003). However, there is little information about how the antibacterial activity or the survival of this probiotic to the digestion process could be affected by the presence of other compounds such as vitamin C and trehalose, or by the application of food processing unit operations, such as the homogenization, what is the object of this study.

Methods:
Probiotic beverages were prepared by inoculating commercial mandarin juice with 4 mL/L of MRS Broth containing 109 CFU of Lactobacillus salivarius spp. salivarius per mL. Yeast extract (5 g/L) and sodium bicarbonate (9.8 g/L), apart from trehalose of food grade (0, 0.1 and 0.2 g/g), were added to the juice formulation to improve the microbial growing. Once inoculated, the liquids were incubated for 24 hours at 37 ºC and submitted to pressure homogenization (from 0 to 150 MPa) before physicochemical and microbial characterization.

Results:
Among all the physicochemical properties tested, only the particle size was significantly affected by the homogenization pressure. As expected, both the distribution average diameter (D[4,3]) and the average size of 90% of the particles present in the samples decreased significantly with the homogenization pressure. Regarding the trehalose content, increasing its concentration from 0 to 0.2 g/g resulted in a significant decrease in water activity values and a considerable increase in both pH and Brix values. Since Lactobacillus salivarius spp. salivarius are lactic acid bacteria that convert carbohydrates into acids, beverages with no trehalose seemed to be the best for the microorganism growing. However, as the homogenization pressure effect on the number of viable cells was dependent on the threhalose concentration, beverages containing 0.1 and 0.2 g of trehalose per gram and submitted to homogenization pressures below 50 MPa had similar or even greater counts than for the correspondent juice without trehalose. About the other two microbial properties, the antimicrobial activity was evidenced but not improved by the presence of trehalose and/or the pressure homogenization while the probiotic resistance to gastric and intestinal conditions was significantly improved by both adding 0.1 g of trehalose per gram of commercial juice and applying 50 MPa to the fermented juice. The latter could be promoted by the osmotic stress undergone by the probiotic in the presence of trehalose and its increase in hydrophobicity by the homogenization at moderate pressure.

Discussion:
Mandarin juice containing 10% (w/w) of trehalose and homogenized at 50 MPa 24 hours after the inoculation with Lactobacillus salivarius spp. salivarius showed the best microbial properties and changes in its physicochemical properties did not adversely affect its quality.

Keywords: Lactobacillus salivarius spp. salivarius, Homogenization, Trehalose, Mandarin juice, Gastrointestinal simulation, Helicobacter pylori, Probiotic

Citation:
Barrera Puigdollers C., et al. (2016). Improving the probiotic effect of Lactobacillus salivarius spp. salivarius in mandarin juice by adding trehalose and/or applying high pressure homogenization. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 17.). IPC2016

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