Analysis of a yogurt containing lacticaseibacillus casei bl23 and omega 3 using a mini-yogurt prototype system

Abstract

Dairy products containing probiotic bacteria are one of the most popular functional foods. To exert their health benefit, probiotics must remain viable throughout the shelf life of the product and throughout the gastrointestinal tract. On the other hand, there is growing evidence that omega 3 have several beneficial health effects as well as a nutritional role. The effect of interactions between probiotics and omega 3 (DHA/EPA) has not been well explored in yogurts, the main vehicle for probiotics. The primary objective of this work was the optimization of an experimental model based on a miniature scale yogurt prototype system (1 mL) where starter and probiotic strains are co-cultivated with or without omega 3. Survival analysis was performed on mini-yogurts with increasing concentrations of EPA and DHA (maximum dose 2500 mg / 200 g yogurt), determining the maximum concentration that can be used without reducing the values required for the probiotic strain to exert its beneficial action. Additionally, characteristics and changes of the bacterial surface in the yogurt medium with or without added EPA /DHA were analyzed. Twenty eight-day survival dynamics of starter strains and probiotic Lacticaseibacillus casei BL23 (L. casei) were consistent with other laboratory-scale reports using volumes from 50 to 200 ml. We found that all bacterial strains survived against the maximum EPA/DHA dose until day 28 of storage. The viability of L. casei from yogurt fortified with EPA/DHA in the presence of gastric and intestinal juices was studied and there was a slight decrease in viability. Yogurt properties, such as syneresis and pH, were measured in the mini-yogurt system. These parameters were not altered by the addition of omega 3 and they were comparable to low-fat yogurts. It is possible to use DHA/EPA concentrations that correspond to 20, 50 and 100% of the recommended daily dose for this L. casei yogurt. The surface properties were analyzed by MATS using xylene and chloroform as solvents. This is the first MATS measurement report from cells grown in milk. Significant differences were observed in the affinity to xylene for L. casei in milk medium (19.70 ± 5.09 %) and omega-3 milk medium (46.50 ± 1.80 %) compared to the MRS medium (16.77 ± 1.11 %). The affinity to chloroform was higher than 95% in all conditions. Higher affinity to xylene, showing increased surface hydrophobicity, could result in better adhesion to the intestinal tract, where L. casei exerts its function. Bacterial adhesion to intestinal cells assay will be carried out to confirm this. The development of yogurt prototypes on a miniature scale proved to be an optimal system to analyze microbiological and biochemical parameters, with the benefit of being able to analyze multiple variables at low cost in a single step, with a greater number of replicates.