Effect of Drying and Cooking on the Chemical Composition, Phenolic Profile, and Antioxidant Capacity of Chenopodium berlandieri subsp. nuttalliae: A Metabolomic Approach

Traditional edible plants such as quelites are an important component of the Mexican diet due to their nutritional and functional value; however, the effects of postharvest and culinary processing on their phytochemical composition remain poorly understood. This study evaluated the impact of oven-drying and freeze-drying, as well as thermal preparation (raw vs. boiled), on the proximal chemical composition, phenolic profile, and antioxidant capacity of leaves and inflorescences of Chenopodium berlandieri subsp. nuttalliae (huauzontle), using an integrated metabolomic approach. Proximal analysis showed that major macronutrients (protein, dietary fiber, lipids, and carbohydrates) were largely preserved across drying methods, whereas moisture and ash contents differed significantly among tissues and treatments (p < 0.05). Raw freeze-dried inflorescences exhibited the highest total phenolic content and antioxidant capacity. UPLC-DAD-ESI-QToF/MS enabled the identification and quantification of 26 phenolic compounds, predominantly glycosylated flavonols derived from quercetin, kaempferol, and isorhamnetin, while naringin was identified as the main flavanone glycoside present. Quercetin glucuronide was the most abundant compound, particularly in inflorescences. Multivariate analyses (principal component analysis [PCA], permutational multivariate analysis of variance [PERMANOVA], and partial least squares discriminant analysis [PLS-DA]) suggested that the drying method was a major source of variability, followed by thermal treatment and tissue type, although these patterns should be interpreted as indicative rather than conclusive. Overall, freeze-drying appeared to be the most effective method for preserving the phytochemical quality of huauzontle under the conditions evaluated, highlighting its potential as a valuable source of bioactive compounds within the genus Chenopodium.