Production and evaluation of probiotic brown yoghurt made from buffalo milk as an innovative functional dairy product

Abstract Purpose Brown fermented milk has become more popular with consumers due to its high nutritional value, creamy texture, delicious caramel flavor, and brownish color. Brown yoghurt (BY), made from buffalo milk fortified with probiotic bacteria was evaluated as an innovative functional dairy product. Methods Standardized buffalo milk with a 1:1 protein/fat ratio was homogenized and browned at 97 ± 1 °C for 4 h. At 42 °C, it was inoculated with a 2.0% mixed starter culture and then divided into 4 portions. Bifidobacterium bifidum NRRL B-41410 and Lacticaseibacillus rhamnosus NRRL B-442, as probiotic bacteria, were added individually or in combination at a rate of 1.0% to create three treatments. The last portion without probiotics was served as a control BY. Results B. bifidum showed the highest viable counts when added alone or in combination with L. rhamnosus , particularly on days 7 and 15. However, the addition of B. bifidum did not improve the physical and sensory properties of the BY, which were similar to those of the control. Adding L. rhamnosus , either alone (T3) or in combination with B. bifidum (T4), greatly improved the viscosity, hardness, flavor compounds, and sensory scores of the BY. The antioxidant activity against DPPH and ABTS radicals was also significantly enhanced. T3 and T4 also had a thicker body, a smoother and creamier texture, and a light caramel taste combined with a pleasant sour taste. Hydroxymethylfurfural (HMF) concentration in BY was affected slightly by bacteria strains and storage time. Conclusions Standardized buffalo milk fortified with L. rhamnosus alone or in combination with B. bifidum can produce a higher-quality BY that is more acceptable as an innovative functional dairy product.