Effectiveness of Calcium Preparation to Control Microbial Growth in Food.

Abstract

Inhibitory effects of a calcium preparation on the growth of food-borne bacteria and yeast were investigated, and its application to food was advanced. The calcium preparation was made from oyster shells, and then treated electrically with ohmic heating. This product has been already used as a nutrient supplement. Chemical analysis showed that this preparation contained mainly calcium and other minor elements. The minimum inhibitory concentration (MIC) to bacterial growth was measured. This preparation and its major component Ca(OH)2 showed almost the same MICs in the range of 0.07 to 0.1%. Both Gram-positive and negative bacteria were inhibited at the same concentrations. In the case of NaOH or KOH, MICs ranged from 0.09 to 0.15% or from 0.15 to 0.24% , respectively. Yeasts were inhibited at the lower concentrations than bacteria. Viable cell number in food decreased or did not increased by addition of the calcium preparation. Bacillus , Escherichia, Salmonella and Staphylococcus inoculated to food were suppressed their growth by the calcium preparation. The calcium preparation was more effective than Ca(OH)2 to get the same effects. It was shown that the calcium preparation used as a nutritional additive could be applied to control the microorganisms in food. Also, the possibility of utilizing the alkaline range to keep the quality of food was suggested.