On the Optimization of Carob Seed Peel Extraction Using Aqueous-Based Acidic Systems

Carob fruit utilization remains limited, with most of their commercial value derived from locust bean gum, which is obtained from seed endosperm. Efficient extraction requires dehusking, which is traditionally performed under harsh conditions. This study aims to develop and optimize a milder, more sustainable dehusking method while preserving seed quality for industrial applications. Various aqueous-based solvents were tested, leading to the selection of metanesulfonic acid (CH₄O₃S). A Box-Behnken design with response surface methodology optimized the process, using husk removal efficiency as the response variable. The optimized conditions were 24.5 g of seeds treated in 50 mL of a solvent mixture (41% CH₄O₃S and 59% H₂SO₄) at 90 °C for 10 min, followed by washing by 5 min with water (87 mL). The treated seeds were analyzed using colorimetry assays and diffusive reflectance spectroscopy and benchmarked against both pristine and dehusked seeds from a local company. The resulting seeds remained morphologically intact and exhibited appealing color characteristics comparable to commercial samples. The optimized method ensured intact seed morphology and color characteristics comparable to commercial standards, offering a viable alternative to conventional H₂SO₄-based dehusking. Furthermore, this study also highlights for the first time the effectiveness of diffusive reflectance spectroscopy as a rapid and straightforward tool for assessing the dehusking process.