Variability in Carob Fruit Composition: Geographic and Maturity Stage Effects on Physical and Biochemical Properties

This study investigates the impact of geographic origin and maturity stage on the morphological and biochemical characteristics of immature carob (Ceratonia siliqua L.) fruits collected from three distinct locations in central Morocco. A total of 300 trees were sampled across seven phenological stages (T ₀-T ₇), and various parameters were assessed, including fruit morphology, colorimetric indices, sugar content, total polyphenols, flavonoids, tannins, and antioxidant activities (DPPH, ABTS, and FRAP). Two-way ANOVA revealed that these attributes were significantly influenced by the site, the maturity stage, and their interaction. Morphological characteristics increased significantly throughout fruit maturation, with the most pronounced changes occurring during the advanced developmental stages (T ₅-T ₇). Pod length, width, and thickness exhibited a progressive upward trend, reaching their highest values at late maturity stages. In particular, pod length increased markedly from 4.27 ± 0.45 cm at S ₂-T ₀ to 21.43 ± 2.65 cm at S ₃-T ₅, corresponding to an approximately fivefold increase during fruit development, thereby highlighting the substantial morphological changes associated with pod maturation. Bioactive compounds showed stage-dependent variations, with the highest levels generally recorded at intermediate maturity stages (T ₁-T ₂). Total phenolic content peaked at T ₂, reaching 3342.38 ± 377.96 mg GAE/100 g, while total flavonoid and condensed tannin contents attained maximum values of 1335.42 ± 187.95 mg QE/100 g and 1149.21 ± 55.26 mg CE/100 g, respectively. Principal component analysis accounted for 83.64% of the total variability, highlighting clear groupings based on the developmental stage and site-specific effects. These findings demonstrate that the quality of immature carob fruits is strongly dependent on both environmental and developmental factors. The results provide a valuable basis for the targeted use of carob fruits in food, pharmaceutical, and nutraceutical applications, optimizing their nutritional and functional potential.