Production of Fermented Soy and Soy/Cow Milk Products with Probiotic Lacticaseibacillus rhamnosus GG Strain

Fortifying conventional foods with probiotics is an effective approach for producing functional products. Although Lacticaseibacillus rhamnosus GG (also known as LGG) is one of the most studied probiotics, its application in food bioprocessing remains limited. This study produced probiotic soy and soy + cow milk beverages fermented with LGG. Sixteen samples were prepared with different ratios and different types of milk formulations and fermented with LGG at 37 °C for 30 h. After fermentation, the pH, total acidity, LGG cell count, sensory qualities, and organic acid level were determined. The LGG cell count, total acidity, and pH analyses were performed at various time points during 4 weeks of storage at 4 °C. According to the results, the LGG cell counts did not fall below 7 log CFU/ml in all formulations after 30 h of fermentation and 4 weeks of storage at 4 °C. Samples with glucose added to soy milk caused a decrease in pH after fermentation, leading to coagulation of soy proteins and increasing the sensory quality of the final product. The sensory evaluation results, which included appearance, taste, stability, texture, and general acceptability, revealed that the fermented soy milk with 3% glucose content had the highest score. This study demonstrates the development of probiotic milk beverages—both plant-based and combined plant-based and dairy—fortified with soy milk for a wide variety of consumers seeking a probiotic plant-containing beverage.