Effects of Organic Acids, Sodium Chloride, Amino Acids and Sugar on Calcium Release from Calcium Alginate

Effects of Seasonings on Softening of Dried Kelp, Laminaria sp., Part IV

Abstract

To elucidate the mechanism of softening of dried kelp Laminaria sp. by seasonings during processing, calcium release from calcium alginate (Ca-Alg) immersed in organic acid, sodium chloride, amino acid and sugar solutions was examined. Regardless of the kind and concentration of seasonings, calcium release from Ca-Alg reached equilibrium within a few minutes after immersion. Organic acids, sodium chloride and monosodium glutamate resulted in a rapid increase below 0.2M and a slight increase to 1M in the rate of calcium release, followed by leveling off. Glycine as well as alanine, showed a gradual increase from 0.2M to 1M in the rate of calcium release followed by a rapid increase at concentrations higher than 1M. A rise in immersion temperature increased the rate of calcium release with increasing in concentration. The effects of seasonings on the rate of calcium release with increasing in concentration. The effects of seasonings on the rate of calcium release were in the order of tartaric acid_??_citric acid>malic acid>lactic acid>monosodium glutamate>succinic acid_??_sodium chloride>acetic acid>alanine>glycine_??_sucrose. Ion exchange selectivity coefficient for exchanging Ca²⁺ for H⁺ was proportional to the dissociation constants of organic acids at low concentrations. In the case of sodium salt, the selectivity coefficient for exchanging Ca²⁺ for Na⁺ of monosodium glutamate was considerably larger than that of sodium chloride. These results clearly show the type of seasonings, concentration and temperature which are most effective for release of calcium from Ca-Alg.