Exploring the dynamics of bioactive metabolites changes in barley grains (Hordeum vulgare L.) during roasting: Insights from UPLC-QqQ-MS/MS analysis combined to chemometrics

This investigation delves into the dynamic metabolic shifts within barley grains during the roasting process, employing UPLC-QqQ-MS/MS analysis. The complex spectrum of metabolites before and after roasting is revealed. The resulting data, unveils substantial transformations in chemical composition during roasting. A total of 62 chromatographic peaks spanning phenolic compounds, flavones, Millard Reaction Products, amino acids, lignans, vitamins, folates, and anthocyanins were annotated. Leveraging UPLC-QqQ-MS/MS analysis, we scrutinized the intricate metabolite profile before and after roasting where the roasting process was found to trigger dynamic changes across diverse metabolite classes particularly Millard Reaction Products, produced through the Maillard reaction, with dihydro-5-methyl-5H-cyclopentapyrazine, maltol and hydroxy maltol emerging as discerning markers of roasting progression. Amino acids and sugars showed degradation, while beta-glucan, a signature barley sugar, experienced notable decline. Folate derivatives witnessed pronounced reduction, aligning with the heat sensitivity of folates. Harnessing the power of multivariate data analysis, the consequences of roasting materialize through distinct clusters in PCA and OPLS-DA plots. Noteworthy, roasting duration governs the trajectory of metabolic divergence, culminating in the identification of roasting-specific markers. Epigallocatechin, procyanidin B, 10-HCO-H4 folate, and hordatine A emerge as pivotal discriminators. Orthogonal Projection to Latent Structure (OPLS) analysis linked anti-inflammatory activity with 30-min, 1-hour, and 1.5-hour roasted samples, with hordatine B in addition to some Millard Reaction Products being correlated with pro-inflammatory marker downregulation.. This study encapsulates the intricate metabolic metamorphosis ignited by roasting in barley grains, offering a holistic comprehension of their potential health-enhancing attributes. Key metabolites act as poignant indicators of these transformations, substantiating the complex interplay between roasting and the barley grain metabolome.