Enhanced probiotic viability and aromatic profile of yogurts produced using wheat bran (Triticum aestivum) as cell immobilization carrier

The effect of wheat bran (Triticum aestivum) as a cell immobilization carrier for probiotic yogurt production on cell viability, composition of volatile compounds and sensory characteristics, was studied. Wheat bran was delignified and separately used as a carrier for the immobilization of Lactobacillus casei ATCC393 and Lactobacillus bulgaricus DSM20081. Both biocatalysts were freeze-dried without the addition of cryoprotectants and were used for yogurt fermentation at 40 °C. Their operational stability was evaluated during successive yogurt fermentation batches until they were inactivated. The yogurts fermented using the immobilized biocatalysts were compared with those fermented with free Lactobacillus cells and with conventional yogurt culture (Streptococcus thermophilus and L. bulgaricus). The novel yogurts showed significantly higher cell viabilities during storage at 4 °C. In addition, the immobilized biocatalysts showed higher survival rates during exposure to simulated gastric juice (pH 3.0). The immobilized biocatalysts significantly affected the production of volatile compounds, indicating, in combination with the sensory evaluations, potential for good-quality probiotic yogurt production by freeze-dried ready-to-use immobilized starters.