Microwave-assisted d-pinitol extraction from carob: application of Box-Behnken design

This study investigates the effects of temperature (50-80 degrees C), time (10-60 min), carob-to-solvent ratio (2-8 g/40 mL), and solvent concentration (0-50 ethanol/water%, v/v) on microwave-assisted extraction of d-pinitol compound from carob fruit with optimization using Box-Behnken design. The optimal conditions for maximum d-pinitol yield (64.16 g/kg dry sample) include 50 degrees C temperature, 5.6 g carob/40 mL solvent, water used as a solvent, and an extraction time of 10 min. The fitness of the model was determined by ANOVA analysis with a high coefficient (R-2 = 0.9057). Extraction was performed under optimum conditions for model validation, and 63.89 g/kg dry sample of d-pinitol extraction was achieved. In addition, the effects of the same variables on the total phenolic (TP) content of MEA extraction of carob were also investigated. Extraction efficiency of 426 g/kg was obtained under the optimum conditions determined for TP (80 degrees C, 8 g of carob, 50% ethanol, and 10 min), but it was observed that TP content decreased to 49.7 g/kg under optimum conditions determined for d-pinitol. Sucrose, glucose, and fructose sugar contents of the extract were determined only for optimum conditions for d-pinitol, and the fructose content was found to be the lowest. Determining the d-pinitol, TP, and sugar contents of the extract in optimum condition confirms the direct usability of the extract, because only water is used as a solvent. Conventional extraction method was carried out at 50 degrees C for control purposes, yielding 42.83 g/kg of d-pinitol, thereby supporting the effect of the microwave on extraction.