Impact of seven conservation methods on the nutritional value, phytochemical composition, and chemical antioxidant capacity of Terfezia boudieri and Tirmania nivea from Southeastern Tunisia

Introduction Desert truffles ( Terfezia boudieri and Tirmania nivea ) are edible fungi valued for their nutritional and nutraceutical properties. However, the effects of post-harvest preservation on their bioactive composition and health-related quality remain poorly understood. This study evaluated the influence of seven conservation methods on the nutritional and functional properties of both species collected from the arid regions of southeastern Tunisia. Methods Seven preservation techniques (sun drying, oven drying, deep freezing, lyophilization, chips processing, marination, and olive‐oil preservation) were assessed. Nutritional composition, mineral content, vitamins, carotenoids, phenolic compounds, and antioxidant activity were determined using standard analytical methods. Data were analyzed by two-way ANOVA to evaluate the effects of preservation method, species, and their interaction. Results Preservation method was the main source of variation, explaining up to 99.06% of protein, 95.65% of carbohydrate, 94.88% of antioxidant activity, 88.19% of potassium, and 87.07% of total phenolic variability (all P < 0.0001), whereas species effects were comparatively minor. Oven drying and lyophilization best preserved protein content (≈27–28%) and antioxidant activity (87–89% radical scavenging activity). Lyophilization and marination retained the highest mineral concentrations, while lyophilization also preserved the greatest riboflavin (2.69–3.94 ppm) and lycopene (0.15–0.16 ppm) contents. Oven drying produced the highest phenolic acid levels, whereas chips processing consistently reduced proteins, minerals, vitamins, and bioactive compounds. Discussion Preservation method is the principal determinant of the nutritional and nutraceutical quality of desert truffles. Oven drying and lyophilization were the most effective strategies for maintaining health‐promoting compounds, supporting their application as optimal post‐harvest technologies to maximize the functional food value and commercial potential of T. boudieri and T. nivea .