Impact of ultrafiltrated whey powder and lactulose on survival of Bifidobacterium bifidium and color and sensory characteristics of ultrafiltrated synbiotic cheese

During last decades, consumer awareness in importance of healthy intake has led their tendency towards the potential health benefits of particular foods and food ingredients. These conditions resulted in development of functional foods. In the current research, the effect of different concentrations of demineralized ultrafiltrated whey powder (DUWP) at levels of 0, 1 and 2% (W/V) and lactulose at levels of 0 and 1% (W/V) on symbiotic ultrafiltrated cheese were evaluated as a functional food. The color values, total acceptability and survival ability of Bifidobacterium bifidium during 60 days of storage at 4 °C were studied. Results showed that as the amount of lactulose and DUWP powders increased, the number of probiotics enhanced meaningfully, while the number of probiotic bacteria deceased with passing the storage time (p<0.001). However, the count of probiotic bacteria in samples containing lactulose and 1 or 2% DUWP at the end of 60 days of storage time were in the standard range of probiotic foods (>107 Log cfu/g). The colorimetric results showed that as the amount of DUWP and the storage time increased, the lightness (L*) decreased significantly (p<0.001); but addition of both powders had no significant effect on a* and b* values. Based on the obtained results, the synbiotic cheese containing 1% DUWP and 1% lactulose powder as compare to control sample had a higher count of probiotic bacteria. Meanwhile, no differences in color quality and total acceptability were found between these two samples. Therefore, this synbiotic ultrafiltrated cheese was determined as the best functional cheese sample.