The purpose of this paper is to evaluate from a nutritional, phytochemical, and rheological point of view different varieties/lines of oats cultivated in Romania. In this sense, the proximate composition (proteins, lipids, mineral substances, starch, and carbohydrates), the total polyphenols content (TPC) of individual polyphenols and macro and microelements of 20 oat varieties/lines were determined. In order to evaluate the potential for use in the flour industry (pasta, bread, and biscuits)., a variety of oats with optimal nutritional properties and active principles was used to obtain oat/wheat composite flours in different proportions (10–30% oat flour) and subjected to rheological analysis using the Chopin Mixolab test (Chopin Technologies, Paris, France) The results showed a protein content between 14.36–17.08%, lipid content between 6.01–9.03%, starch between 44.13–52.95%, total mineral substances between 0.93–1.65%, carbohydrates between 65.16–69.32% and energy value between 389.81–409.86 kcal/100 g. The TPC content varied between 614.76–1244.58 µgGAE/g, and the average values of individual polyphenols were between 1.87 μg/g (rosmarinic acid) and 28.18 μg/g (gallic acid). Regarding the macroelements content, potassium (K) was the major element (203.19 μg/g), followed by calcium (Ca) (181.71 μg/g) and magnesium (Mg) (105.79 μg/g). The level of microelements varied between 3.02 μg/g for nickel (Ni) and 60.25 μg/g for iron (Fe). Multivariate data analysis PCA was used to correlate the obtained data. The rheological analysis using the MIXOLAB system proved that, from the point of view of technological properties, composite flours from a mixture of 10–30% oat and wheat flour are the best for obtaining biscuit dough, compared to pasta or pan bread. Following the study and based on nutritional, phytochemical and rheological results, line 2511 was selected as optimal for use in obtaining hypoglycemic flour foods for people with diabetes.

Oat is increasingly recognized as a valuable cereal due to its favorable nutritional profile and potential application in functional foods. This study aimed to provide an integrated nutritional and technological evaluation of black oat (Avena strigosa) and white oat (Avena sativa L.) cultivars Ovidiu, Jeremy, and Sorin, grown under uniform conditions. The chemical composition was assessed by determining proteins, lipids, total mineral and polyphenol contents. Macro- and microelement profiles (Ca, Mg, K, Na, Fe, Mn, Cu, Ni, and Zn) were quantified by atomic absorption spectrometry (AAS), while the technological suitability of black oat flour for bakery applications was evaluated using Mixolab analysis and bread quality parameters. Additionally, Fourier-transform infrared (FTIR) spectroscopy was applied to investigate structural features associated with β-glucans in the oat samples. The results showed that protein content ranged from 12.39 to 13.48%, while lipid content varied between 3.24 and 4.64%. Significant differences were observed in mineral composition among the analyzed samples. Black oat showed a balanced mineral profile, characterized by high levels of K, Mg, Mn, Zn, and Ni, confirming its classification as a mineral-rich cereal, while the Ovidiu cultivar generally presented the lowest concentrations for most elements. Mixolab results revealed that the partial substitution of wheat flour with black oat flour significantly influenced dough rheological behavior, particularly in terms of protein weakening and starch gelatinization, without severely affecting dough stability when applied at moderate inclusion levels. Bread quality evaluation demonstrated acceptable crumb elasticity, porosity, and height-to-diameter ratios, supporting the feasibility of incorporating black oat in bakery products. FTIR analysis revealed characteristic absorption bands associated with β-glucans, supporting their presence and structural integrity in both black oat and cultivated varieties. Overall, this study demonstrates that both black oat and selected oat cultivars represent valuable raw materials for functional food applications, offering enhanced nutritional profiles and suitable technological performance. The combined use of compositional, rheological, and spectroscopic analyses provides a comprehensive approach for evaluating oat-based ingredients in the context of modern cereal science.