Effect of Alkalization With Potassium Carbonate and Ammonium Bicarbonate on the Chemical and Physical Properties of Cocoa Butter: A Factorial and Central Composite Design Approach.
Sadeghzadeh Afghan A, Taghinezhad Maryam M, Pirsa Sajad S
This study investigated the effects of cocoa butter alkalization using potassium carbonate and ammonium bicarbonate (0%-6%) on acidity, peroxide value, iodine value, saponification value, moisture content, slip melting point, pH, and lead content. A factorial design and central composite design (CCD) were employed. The highest peroxide value (0.1 meq O2/kg) was observed in samples containing 3% potassium carbonate +3% ammonium bicarbonate and 6% potassium carbonate +6% ammonium bicarbonate. The highest acidity was related to the control sample (1.77), while the lowest was found in the sample with 6% of both alkalis (0.77). The control sample also showed the lowest saponification value (189.61 mg KOH/g fat), whereas the highest was recorded for the 6% + 6% sample (199.04 mg KOH/g fat). The highest iodine value (35.91 g I2/100 g fat) belonged to the 6% + 6% sample, and the lowest (32.42 g I2/100 g fat) to the sample containing 6% ammonium bicarbonate alone. Minimum moisture content (0.053%) was observed in the sample with 6% potassium carbonate +3% ammonium bicarbonate, and maximum (0.077%) in the sample with 3% + 3%. The lowest pH (5.05) was for the control, and the highest (9.87) for the 6% + 6% sample. The highest slip melting point (30.23°C) was recorded for the control, and the lowest (26°C) for the sample with 3% potassium carbonate +6% ammonium bicarbonate. All samples complied with Iranian national standards for lead content. The results indicated that 3% potassium carbonate alone, 3% ammonium bicarbonate alone, and 3% potassium carbonate +6% ammonium bicarbonate are suitable for cocoa alkalization. Finally, mathematical models were developed using response surface methodology to establish quantitative relationships between the chemical properties of cocoa butter and the concentrations of the alkaline agents, enabling the achievement of desired product characteristics.