Cells of ice nucleation active (INA) bacteria,Pseudomonas syringae, was cultured at 26°C with nutrient agar culture medium and harvested at early stationary phase (20h) for maximum ice nucleation activity.The cells were incorporated into water or solid model food to investigate their effects on degree of supercooling and characteristic freezing time.Two freezing temperatures were used, -15°C and -30°C. It was found that the degrees of supercooling of model foods with INA were reduced by 3°C to 4°C at all freezing temperatures. The characteristic freezing time was shortened. The results imply that the ice nucleation bacteria may be used to modify the freezing process to save energy and the effects will be more obvious for higher freezing temperature and smaller sample size.
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