| Affiliation: | Department of Food Science, China College of Marine Technology and Commerce, Taipei 111,;Department of Food Science, National Taiwan Ocean University, Keelung 202,;Department of Hotel &Restaurant Management, Chia-Nan University of Pharmacy &Science, Tainan, and;Department of Food and Nutrition, Providence University, Taichung 433, Taiwan |
| Abstract: | ABSTRACT: Pseudomonas fluorescens MACK-4, isolated from mackerel surface, has an ice-nucleating activity (INA). In addition to bacterial cells, this strain could also produce an extracellular ice-nucleating substance (INS) with a maximal INA at pH 6.0. The extracellular INS (EINS) was stable at pH 6–9 during 1-h incubation with 3–5% of saccharides including maltose, trehalose and sucrose at 15°C. However, glycerol dramatically lowered the INA in both bacterial cells and the EINS. The addition of either the EINS or bacterial cells significantly elevated the ice-nucleating temperatures of pure water, full-cream milk, and 10% starch solution, but not orange juice and mackerel mince. The EINS produced from this strain could serve as crystal nuclei and accelerate ice crystallization during freezing. |
