Physico-chemical properties and viability of Lactobacillus rhamnosus LGG in inulin-enriched Doineh (a traditional Iranian food) during 21-day storage at 4°C

The aim of this study was to investigate the physicochemical properties and survival of Lactobacillus rhamnosus LGG in synbiotic wet Doineh, a traditional Iranian fermented food enriched with different ratios of inulin. Milk and wheat bulgur were cooked in the conventional method and then mixed with LGG strain and different ratios of inulin (0, 2.5, 5, 7.5, and 10 percent). After 24 h of fermentation at 37ºC, the samples were stored at 4ºC for 21 days. pH, acidity, sensory evaluation, and probiotic culture were measured at 24 h after fermentation and on days 7, 14, and 21, using a pH meter, potentiometric, 5-point hedonic scale, and pour-plate methods, respectively. Protein, fat, solids content, and ash were determined by Kjeldahl, Soxhlet, dry weight at 100–105°C and 550ºC oven methods after 24 h of fermentation. The samples containing inulin showed significantly slower changes in pH and acidity. The viability and survival of LGG increased in the samples with higher amounts of inulin due to its prebiotic effect, and these changes were significant. The 2.5%, 5% and 7.5% inulin models had more acceptable sensory characteristics. Traditional foods and their preparation methods are suitable targets for developing health-oriented products, and functional foods with nutraceutical capabilities can be designed and produced based on them.