Comparative characterization of Hojari and Sha'bi frankincense (Boswellia sacra) with implications for food quality and safety

Introduction Frankincense ( Boswellia sacra ) is a traditional non-timber forest product increasingly incorporated into food and beverage formulations, yet information on the quality attributes and food safety implications of different commercial grades remains limited. This study comparatively characterized the physicochemical, mechanical, and color properties of two commercially important Omani grades of B. sacra frankincense (Hojari and Sha'bi) and evaluated the survival of Escherichia coli in bottled drinking water flavored with frankincense oil as a model food system. Methods Standard analytical methods were used to determine moisture content, solubility, ash, and protein levels, pH, mineral composition, and mechanical properties, while color attributes were assessed using the CIELAB system. E. coli survival was determined via viable count assays. Results Significant grade-dependent differences were observed, with Sha'bi frankincense exhibiting higher weight (3.83 g), moisture content (4.60%), solubility (24.57%), and lower stiffness (Young's Modulus = 2.47 MPa) compared with Hojari, which showed greater brightness ( L * = 56.98) and color saturation (chroma = 6.16). In contrast, length, hardness, ash, protein content, and mineral profiles, including trace and heavy metals, were comparable between grades. Microbiological assessment showed that E. coli survived in commercial water containing 0.05% frankincense oil, suggesting that this concentration does not exert a measurable inhibitory effect on bacterial viability. Conclusion These findings demonstrate that commercial frankincense grades differ in quality-related properties relevant to food formulation and handling, and they highlight the need for appropriate hygiene practices and monitoring of mineral contaminants when incorporating forest-derived resins into food and beverage systems. The study contributes to the sustainable utilization of traditional non-wood forest products by providing evidence-based data to support quality assessment and food safety considerations.