## 3 Nutritional and Bioactive Components of Sprouted Grains
### Increased Bioactive Compounds  
Germination profoundly alters the bioactive compound profile of grains, enhancing both their nutritional value and potential health benefits. Notably, sprouted oat powder from the Meeri variety, obtained after 96 h of germination at 18 \({}^{\circ}\)C, exhibited significant increases in bioactive compounds, including essential minerals, free phenolics, \(\beta\)-glucan, and GABA. These changes were accompanied by increased protease and \(\alpha\)-amylase activity and decreased lipase activity, reflecting a broader reorganization of metabolic processes during germination [26].  
A key bioactive compound enriched during germination is GABA, a non-protein amino acid synthesized from L-glutamic acid via glutamate decarboxylase [42]. GABA has been associated with improved insulin sensitivity, anti-diabetic and anti-inflammatory effects, appetite regulation, and modulation of obesity-related pathways [55; 56; 57].  
Combined germination and fermentation can elevate GABA content up to 674 \(\pm\) 31 ug/g without exceeding safety thresholds for biogenic amines such as histamine or phenylethyl-lamine. Among the tested grains, sprouted oat (_Avena sativa_) exhibited the highest GABA concentration (443 \(\pm\) 34 ug/g), followed by einkorn (_Triticum monoaccount_) (347 \(\pm\) 25 ug/g) and barley (_Hordeum vulgare_) (323 \(\pm\) 24 ug/g). These increases highlight the grain-specific potential of germination to enhance GABA content while maintaining food safety [58]. Animal studies further support the functional relevance of these changes: GABA-enriched germinated adzuki beans (_Vigna anugularis_, cv. 'Pearl Red') helped regulate body weight, stabilize blood glucose, and enhance glycolipid metabolism and gut microbiota composition in diabetic mice [59]. Additionally, maternal intake of GABA-enriched GBR during pregnancy and lactation improved gene expression related to energy balance and insulin sensitivity in offspring, while reducing pro-inflammatory markers [60].  
Polyphenols and flavonoids, known for their antioxidant and anti-inflammatory properties, are also increased during sprouting. For example, the total flavonoid content in red pigmented rice (_Oryza sativa_ L.) increased from 22.89 \(\upmu\)g/g to 27.80 \(\upmu\)g/g after germination, while 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonic acid) (ABTS) radical scavenging activities improved by 1.41-fold and 1.03-fold, respectively [27]. Similar trends have been observed in germinated black soybean (_Glycine max_) genotypes BS1 (Se-Um) and BS2 (Miryang 365), where phenolic and flavonoid levels were significantly elevated. These increases contributed to enhanced antioxidant capacity, as measured by DPPH, ABTS, and ferric reducing antioxidant power (FRAP) assays, as well as improved anti-inflammatory potential [61,62].  
In addition, \(\beta\)-glucan levels in oats (cv. 'Meeri') increased by 14% (dehulled) and 37% (hulled) after sprouting at 14 \({}^{\circ}\)C for 60 h. Even when slightly reduced, \(\beta\)-glucan content remained above 2 g/100 g--sufficient for maintaining physiological benefits [26]. Importantly, \(\beta\)-glucan also exhibits potent metabolic regulatory functions. Recent studies have demonstrated that \(\beta\)-glucan consumption significantly alleviates colonic inflammation and IR by modulating the histone deacetylase 3 (HDAC3)/NF-\(\kappa\)B signaling pathway, thereby highlighting its role in gut-metabolic axis modulation and anti-inflammatory action [43].  
Collectively, these findings highlight germination as an effective strategy to enhance the bioactive compound profile of grains--particularly GABA, \(\beta\)-glucan, phenolics, and flavonoids--all of which are relevant to the prevention and management of IR, oxidative stress, and chronic inflammation.