Quality Parameters and 5-Hydroxymethylfurfural Levels in Hazelnut-Based Dulce de Leche With Orange Essential Oil Infusion

The purpose of this study is to investigate the influence of orange essential oil on the rheological, physicochemical, and sensory properties of jam formulations, with the aim of enhancing product quality and consumer acceptance while exploring its potential for industrial application. Rheological analysis revealed that the consistency index (k) values ranged from 28.17 to 31.47 Pa.s, and the flow behavior index (n) values were between 0.21 and 0.33, indicating pseudoplastic flow behavior. The high determination coefficients (R2 = 0.96–0.99) confirmed the reliability of the rheological model applied. The concentration of 5-hydroxymethylfurfural (HMF), a thermal degradation marker, varied from 16.30 to 44.65 mg/kg, reflecting differences in heat treatment. Colorimetric parameters showed significant variation, with L* values between 35.3 and 53.2, a* values from −0.84 to −1.34, and b* values ranging from 3.78 to 11.3. Textural analysis presented a statistically significant interaction between formulation (p < 0.05), with the control sample exhibiting superior firmness, consistency, and cohesiveness. Samples A and C were most preferred in terms of sensory attributes due to their balanced flavor profiles, desirable texture, and enhanced overall acceptability. These findings highlight the potential of orange essential oil as a natural flavoring and functional ingredient in jam production. Furthermore, strategic optimization of formulation processes to facilitate high-quality production should also be a primary focus of industrial research in the food field. © 2026 Wiley Periodicals LLC.