Unraveling the impacts of germination on the volatile and fatty acid profile of intermediate wheatgrass (Thinopyrum intermedium) seeds

Intermediate wheatgrass (Thinopyrum intermedium, IWG) represents a promising perennial grain currently under investigation for integration into mainstream food applications. Grains have been germinated before consumption for millennia to improve technological and nutritional aspects and overall flavor. However, the effects of germination on IWG flour properties are yet to be explored. This study aimed to investigate the effects of different germination temperatures (10, 15, and 20 ºC) and times (2, 4, and 6 days) on the volatile and fatty acid profile of IWG. An initial fiber coating selection step was performed. The Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) was selected as the fiber of choice due to the significantly higher total area in comparison with the PDMS, and DVB/PDMS fibers. A method based on headspace solid-phase micro-extraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) was optimized by response surface methodology to extract the volatile compounds. The optimum extraction conditions were 61 °C and 56 min. A total of 98 volatile compounds were identified in the IWG samples, especially alkanes (38%), alcohols (19%), aldehydes (14%), ketones (12%), esters (7%), acids (5%) and terpenes (5%). Principal component analysis (PCA) separated the samples as a function of germination, indicating that increased germination time and temperature lead to distinct volatile profiles in IWG. Aldehydes such as hexanal, nonanal, and decanal played an important role in distinguishing the germinated samples from the control. Those aldehydes are secondary products of lipid oxidation and may be related to the rate of oxidation of the polyunsaturated fatty acids of IWG. The fatty acid profile was not affected by germination, and it was composed of linoleic acid (C18:2, 62%), oleic acid (C18:1, 17%), palmitic acid (C16:0, 11%), and linolenic acid (C18:3, 5%). This study significantly contributes to the elucidation of the impact of germination in IWG flour, opening new venues for its end-use applications.