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pp.343-350
Effects of high pressure processing on physicochemical and microorganisms properties in birch sap were investigated using variable high pressure processing conditions. The viable cell counts of untreated birch sap was 4.0 log CFU, whereas high pressure processed sap were not detected. In birch sap was treated with 450 to 550 MPa, microorganisms were not detected during storage period, and physicochemical properties as well as color were slightly changed. The more processing time and pressure, its quality variations were more stable and then its optimum processing condition was determined with 120 sec at 550 MPa. The microorganisms and physicochemical properties of treated birch sap were investigated during storage at 5℃ and 10℃ for 45 and 28 days. Changes of physicochemical properties of treated birch sap were smaller than those of the untreated, but viable cell count were not detected during storage period. As for pH, °Brix, and turbidity result of birch sap, quality shelf life of control and treatment were 4 and 24 days, respectively. Especially, ΔE value of instrumental color was untreated birch sap 4 days similar with the high pressure processed it for 28 days. These results indicated that the high pressure processing can be used as an effective method to improve the shelf life of birch sap.
