# The Effect of Storage on Potentially Synbiotic Emulsion Spread Based on Milk Fat and Inulin
## 3 Results and Discussion  
### Rheological and Textural Properties  
Four weeks of storage did not significantly affect most of the rheological and textural properties of the tested emulsions. Hardness, cohesiveness, and adhesiveness (Figure 1) did not change significantly (\(p\leq 0.05\)). Only in the case of spreadability (Figure 1) was a slight increase in the obtained values noted. This was probably due to the way the samples were prepared and stored, as the emulsions were poured into the target containers as soon as they were obtained. While the containers for measuring hardness, adhesiveness, and cohesiveness were tightly closed with lids, in the case of spreadability, the female cones were only covered with aluminium foil and, despite being placed additionally in a sealed box, some of the water from the samples may have evaporated. This made the spreadability values with longer storage higher, which means the samples were more difficult to spread. Previous studies [19] concerning the effect of storage time on inulin-rapeseed oil emulsions also showed a lack of change in texture during storage. The presence of milk fat does not change the texture properties which is expected from the product designed for spreading on bread. The results obtained during textural analysis confirmed that the studied milk fat-inulin emulsion was easily spreadable immediately after being taken out of the refrigerator because the hardness values were similar to those recorded for soft margarines containing 20-40% fat, and spreadability values were similar to 40-60% fat margarines [22].  
a typical amount of spread on a slice of bread, is enough to achieve therapeutic effects because in such products a minimum level of probiotic bacteria is \(10^{6}\) cfu/g, and daily intake should be about \(10^{8}\) cfu/g [27,28].  
Figure 1: Texture properties of the milk fat-insulin spread. Values are means. Means with different letters for the same texture feature are significantly different (\(p\leq 0.05\)).  
Figure 2: Apparent viscosity. Elastic (G\({}^{\prime}\)) and loss (G\({}^{\prime\prime}\)) moduli of the milk fat-insulin spread. Values are means. Means with different letters for the same rheological feature are significantly different (\(p\leq 0.05\)).  
The emulsion environment was appropriate for the applied bacteria over a longer period. Analysis of pH showed a little, however significant (\(p\leq 0.05\)), decrease after two weeks of storage. This can be an effect of the production of organic acids, mainly lactic acid, by the bacteria [29]. Although, to the best of our knowledge, there are no earlier studies on the effect of storage on the survivability of probiotic bacteria in milk fat-inulin emulsions, other research confirmed that probiotic bacteria can survive in emulsions [21, 30].  
Since there is inulin, a prebiotic compound, in the analysed product, and there are live probiotic bacteria, we can assume that this product can be symbiotic. Additional studies are necessary to show how this product affects consumers in improving the survival and implantation of live health-promoting bacteria [31].