Soybeans have long been used as an important component of production animal diets, particularly in the form of soybean meal (SBM), and serve as a high-quality source of protein with a nearly complete amino acid profile. Outside of its primary nutritive fractions, SBM contains a multitude of minor bioactive components that have variable effects on animal health. Soy saponins are one such component that were previously lumped into the category of anti-nutritional factors found in SBM but have more recently been investigated for their potential anti-inflammatory and anti-oxidative properties. Challenges with their isolation have limited research to in vitro or rodent models, which only require small quantities of purified saponins. However, these studies are less applicable to understanding how saponins are affecting larger production animals that are the primary consumers of SBM. In this research, a process for creating greater quantities of saponins was evaluated for its practicality and effectiveness. A total of 10 kg SBM was used as the starting material for the extraction protocol, which initially contained 5.30 mg total saponins/g SBM. The saponin profile of the meal was predominantly made up of group B saponins, at 57.6% of total saponins, with limited quantities of group A saponins at only 7.17% of the total. The SBM was subjected to two consecutive rounds of mixing with 75% undenatured ethanol at 40℃ for 24 hr. After these mixes, remaining SBM solids were removed and ethanol was evaporated to obtain 12.4 kg of a soy molasses product consisting of the carbohydrate, isoflavone, and saponin fractions of the original SBM. This molasses product was then acidified under elevated temperatures (40℃) using concentrated hydrochloric acid to a pH of 3.05. Under these conditions, a precipitate formed and was recovered via centrifugation to obtain 494 g of precipitated solids likely consisting of isoflavones and saponins. This precipitate was combined with 80% American Chemical Society grade acetone at a 10:1 ratio. The pH of the solution was elevated to 6.00 using sodium hydroxide and the solution was heated to reflux at 56℃ for 90 min. The solution was chilled to 4℃ at which time a precipitate formed and was recovered using vacuum filtration. Analyses are currently being performed to determine the total saponin and isoflavone content as well as the saponin profile of this final product to ensure that saponins were adequately extracted from the initial SBM and isolated from other bioactive components like isoflavones. Pending these results, this large-scale saponin extraction protocol may be utilized to create a saponin-enriched product that can be used in future live animal trials using larger production animals.

White, C., R. Dilger, T. McKenna, K. Brownstein and M. Berhow. 2025. Determining the efficacy of a large-scale soybean saponin extraction process. 2025 American Society of Animal Science Midwest Section meeting, Abstract PSIII-16.