Morphological, physical and chemical analysis of acorns from three oak species from Durango, Mexico

Introduction: In Mexico, there is a lack of information on morphological, physical and chemical characteristics of acorns of Quercus, which makes it difficult to make decisions on the use that can be made to the fruits. Objectives: To identify the morphological, physical and chemical characteristics of Quercus rugosaNée, Q. sideroxyla Humb. & Bonpl. and Q. deserticola Trel. acorns. Materials and methods: From each species, 10 trees were selected and 30 acorns per tree were collected. Mature acorns were characterized morphologically (polar and equatorial diameter, shell weight and total weight) and in physicochemical characterization (moisture, dry matter, ash, crude fiber and protein, ethereal extract and tannins) green and mature acorns were used. Differences among species and among maturity stages were determined with an analysis of variance (P ≤ 0.05) and subsequent Tukey’s test. Results and discussion: Morphology varied among species and among trees of the same species (P < 0.05); Q. deserticola had the largest acorn size (15.69 mm) and weight (1.94 g), and Q. sideroxylaproduced the smallest acorns. Maturity stage and species significantly (P < 0.05) influenced chemical composition; mature acorns had higher content of ethereal extract (8.88 %) and protein (8.40 %). Pearson’s correlation indicated that acorn weight was strongly associated with crown diameter and diameter at breast height. Conclusion: Significant differences were found in morphology and chemical composition of acorns of each species, although they inhabit sites with similar characteristics.