Germination and False Germination Increase the Levels of Bioactive Steroidal Saponins in Oats

The health benefits of oats, particularly their enhanced nutritional and bioactive properties when sprouted, are well-documented. However, changes in steroidal saponins during germination and false germination are lacking. This study explored the influence of various temperatures (20, 25, and 30 °C) and durations (1, 3, 5, and 7 days) on the steroidal saponin profiles in both germinated and false-germinated oats and assessed their anti-inflammatory activities. The findings revealed that germination at 20 °C for 7 days significantly increased the total steroidal saponin content to 3265.54 μg/g, doubling its original concentration. Notably, avenacoside E (AVE-E), the most potent anti-inflammatory steroidal saponin in oats, increased by an impressive 21-fold from 64.02 to 1421.35 μg/g, becoming the predominant saponin following germination. Furthermore, the hydrolysis of sugar moieties and enzymatic synthesis of steroidal saponins were proposed as plausible secondary metabolic pathways during germination and false germination. This research provides the first evidence that germination and false germination can significantly enhance the steroidal saponin levels in oats and their anti-inflammatory properties, with germination proving more effective than false germination, highlighting the potential of these methods to further enhance the health benefits of oats.