Determination of the effectiveness of fermentation, electrocoagulation, and membrane filtration applications in the separation and purification of D-pinitol from aqueous extracts of carob fruit

Carob fruit is a plant that naturally grows and has been cultivated in tree form since ancient times. In addition to its rich nutritional content, it is also known to be the richest source of D-pinitol, a bioactive compound. Some studies have been conducted on the positive effects of D-pinitol on human health and its isolation, highlighting its therapeutic and disease-preventive effects. One of the most significant of these effects is its positive impact on type 2 diabetes, one of the major health threats of our time, which has been increasing in prevalence. Research has also been conducted on its effects on breast cancer and Alzheimer's disease, with promising results. D-pinitol is a compound that can be synthesized in laboratory conditions, but due to the complexity of the process and its high cost, the isolation from natural sources has become the preferred method. Various methods for isolating D-pinitol from natural sources have been studied for many years. The aim of this thesis is to obtain D-pinitol from carob fruit, which is a low-cost and abundant source of D-pinitol in our country, with acceptable high purity levels (90-99%). In this study, the main process was based on electrocoagulation, a method commonly used for wastewater treatment, supported by membrane filtration and adsorbent applications. Initially, the major components of carob fruit extract—sucrose, glucose, and fructose—were converted into ethyl alcohol through fermentation, and then evaporated to be removed from the extract. Saccharomyces cerevisiae (ATCC 36858) was used for fermentation. After the sugars were removed, electrocoagulation experiments were conducted. Aluminum and steel plates (cathode (-) and steel plates (+) as anode) were used as electrodes, and direct current (DC) was utilized as the power source. The processes were applied in the sequence of fermentation, electrocoagulation, membrane filtration, and adsorption, with each process's final extract serving as the feed for the next step. In the electrocoagulation process, a Box-Behnken experimental design, which is an optimization method, was used, and electrode gap, current density, voltage, and time were selected as independent variables. As a result of the conducted analyses, model fit could not be achieved. Therefore, the first three trials, where the highest D-pinitol amount was obtained, were used in the subsequent steps. As a result, the amount of D-pinitol in the starting material, the 5°Bx carob extract, pinitol concentration increased to 98.62 g/100g dry matter. Additionally, the turbidity of the starting material was 383 NTU, which decreased to 0.5 NTU in the final product. No detectable levels of total phenolic compounds or minerals were found in the final product.