Characteristics and preparation of calcium acetate from butter clam (Saxidomus purpuratus) shell powder by response surface methodology

Abstract

For effective utilization of butter clam shell as a natural calcium resource, the optimal conditions for preparation of calcium acetate (BCCA) with high solubility were determined using response surface methodology (RSM). The polynomial models developed by RSM for pH, solubility, and yield were highly effective in describing the relationships between factors (P<0.05). Increased molar ratio of calcined powder (BCCP) from butter clam shell led to reduction of solubility, yield, color values, and overall quality. Critical values of multiple response optimization to independent variables were 2.70 M and 1.05 M for acetic acid and BCCP, respectively. The actual values (pH 7.04, 93.0% for solubility and 267.5% for yield) under optimization conditions were similar to predicted values. White indices of BCCAs were in the range of 89.7∼93.3. Therefore, color value was improved by calcination and organic acid treatment. Buffering capacity of BCCAs was strong at pH 4.88 to 4.92 upon addition of ∼2 mL of 1 N HCl. Calcium content and solubility of BCCAs were 20.7∼22.8 g/100 g and 97.2∼99.6%, respectively. The patterns of fourier transform infrared spectrometer and X-ray diffractometer analyses from BCCA were identified as calcium acetate monohydrate, and microstructure by field emission scanning electron microscope showed an irregular form. ? 2015, Korean Society of Food Science and Nutrition. All rights reserved.