Comparison of Physicochemical and Sensory Properties of Freeze-concentrated Milk with Evaporated Milk during Storage

  • Hwang, J.H. ;
  • Lee, S.J. ;
  • Park, H.S. ;
  • Min, S.G. ;
  • Kwak, H.S.
  • Received : 2006.05.09
  • Accepted : 2006.08.22
  • Published : 2007.02.01


This study was carried out to compare the changes of nutrients, sensory and chemical properties of freeze-concentrated and evaporated milks during storage. For pasteurization, the freeze-concentrated milk containing 27% of total solid was treated with 150 rpm ozone for 5 min, and 99% of microflora was eliminated. Also, the activities of protease and lipase decreased 93.31% and 96.15%, respectively, and phosphatase showed negative activity. Total bacteria count was maintained below$2.0{\times}10^4$CFU/ml. During storage, TBA absorbance was lower in freeze-concentrated milk than that in the evaporated milk. The production of short-chain free fatty acids and free amino acids increased proportionally to the storage period in both samples. While the short-chain free fatty acid production was lower in the freeze-concentrated milk compared with that in the evaporated milk, the production of individual free amino acid was similar in both samples. In sensory evaluation, cooked flavor and color were much lower in the freeze-concentrated milk than that in the evaporated milk. Overall acceptability score was higher in the freeze-concentrated than the evaporated milk. Based on above results, ozone treatment for the freeze-concentrated milk pasteurization was positive at the elimination of microflora and enzyme inactivation. During storage, the freeze-concentrated sample minimized the change of color and TBA absorbance, the production of short-chain free fatty acid and vitamins than the evaporated milk. Therefore, the freeze-concentrated milk process in the present study resulted in the positive effect in minimizing nutrient loss and keeping quality of milk during storage.


Freeze-concentrated Milk;Evaporated Milk;Milk Nutrients;Ozone Treatment


  1. Broadwater, W. T., R. C. Hoehn and O. H. King. 1973. Sensitivity of three selected bacterial species to ozone. Appl. Microbiol. 26:391-393.
  2. Graham, D. M. 1997. Use of ozone for food processing. Food Technol. 51:72-75.
  3. Hodgin, J. C., P. Y. Howard and D. M. Ball. 1983. An automated device for in situ pre-column derivatization and injection of amino acids for HPLC analysis. J. Chromatogr. Sci. 221:503- 507.
  4. Hartel, R. W. and L. A. Espinel. 1993. Freeze concentration of milk. J. Food Eng. 20:101-120.
  5. Campbell, J. R. and R. T. Marshall. 1975a. Concentrated and dried milk products. In: The science of providing milk for man. p. 687. McGraw-Hill Book Company, New York, USA.
  6. Speer, E. and A. Mixa. 1998. Milk and dairy product technology, p. 32. Marcel Dekker Inc., New York, USA.
  7. Van Mil, P. J. J. M. and S. Bouman. 1990. Freeze concentration of dairy products. Neth. Milk Dairy J. 44:21-31.
  8. Cochran, W. G. and G. M. Cox. 1957. Experimental designs. John Wieley & Sons.
  9. $SAS^{\circledR}$ 1985. Users Guide: Statistics, Version 5 Edition. SAS Inst., Inc., Cary, NC, USA.
  10. Anema, S. G.., E. K. Lowe and S. K. Lee. 2004. Effect of pH at heating on the acid induced aggregation of casein micelles in reconstituted skim milk. Leben-. Wissen. Technol. 37:779-787.
  11. Mertens, B. and D. Knorr. 1992. Developments of nonthermal processes for food preservation. Food Technol. May, 124-133.
  12. Zhang, Z. and R. W. Hartel. 1995. A multilayer freezer for freeze concentration of liquid milk. J. Food Eng. 29:23-38.
  13. Caric, M. 1994b. Unsweetened condensed milk. In: Concentrated and dried dairy products. p. 8, 9. VCH Publishers Inc., New York. USA.
  14. Cambell, J. R. and R. T. Marshall. 1975b. Assuring high-quality milk for man. In: The science of providing milk for man. p. 522, 525. VCH Publishers Inc., New York. USA.
  15. Caric, M. 1994d. Unsweetened condensed milk. In: Concentrated and dried dairy products. p. 33. VCH Publishers Inc., New York. USA.
  16. Chae, S. K. 2002. Standard Food Analysis, Theory and practice. pp. 675-681. Ji-Gu Publishing Co., Seoul, Korea.
  17. Lindroth, P. and K. Mopper. 1979. High performance liquid chromatographic determination of subpicomole amounts of amino acids by precolumn fluorescences derivatization with ophthaldialdehyde. Anal. Chem. 52:1667-1674.
  18. Miyawaki, O., L. Liu, Y. Shirai, S. Sakashita and K. Kanitani. 2005. Tubular ice system for scale-up of progressive freezeconcnetration. J. Food Eng. 69:107-113.
  19. Kwak, H. S., J. B. Lee and J. Ahn. 2002. Treatment of microencapsulated $\beta$-galactosidase with ozone: Effect on enzyme and microorganism. Asian-Aust. J. Anim. Sci. 15:596- 601.
  20. Caric, M. 1994c. Milk powder: General production. In: Concentrated and dried dairy products. p. 91, 93. VCH Publishers Inc., New York. USA.
  21. Kwak, H. S. and I. J. Jeon. 1988. Comparison of high performance liquid chromatography and enzymatic method for the measurement of lactose in milk. J. Food Sci. 53:975-976.
  22. Owens, S. L., J. L. Brewer and S. A. Rankin. 2001. Influence of bacterial cell population and pH on the color of nonfat milk. Leben. Wissen. Technol. 34:329-333.
  23. Park, S. H., G. P. Hong, H. S. Kwak and S. G. Min. 2006. Effect of ice recrystallization on freeze concentration process of milk in the lab-scale unit. Food Sci. Technol. 15:196-201.
  24. Yang, P. P. W. and T. C. Chen. 1979. Stability of ozone and its germicidal properties on poultry meat microorganisms in liquid phase. J. Food Sci. 44:501-504.
  25. Caric, M. 1994a. Unsweetened condensed milk. In: Concentrated and dried dairy products. pp. 28-30. VCH Publishers Inc., New York. USA.
  26. Ikins, W. G., H. S. Kwak, G. S. Zink and I. J. Jeon. 1988. Comparison of methods for quantitation of free fatty acids in cheese. J. Food Sci. 53:1915-1916.
  27. Driedger, A., E. Staub, U. Pinkernell, B. Marinas, W. Koster and U. Gunten. 2001. Inactivation of Bacillus subtilis spores and formation of bromate during ozonation. Wat. Res. 35:2950-2960.
  28. Hegenauer, J., P. Saltman, D. Ludwig, L. Ripley and P. Bajo. 1979. Effects of supplemental iron and copper on lipid oxidation in milk. 1. Comparison of metal complexes in emulsified and homogenized milk. J. Agric. Food Chem. 27:860-867.
  29. Association of Official Analytical Chemists. 1990. Official Methods of Analysis, Vol. I. 15th ed. AOAC, Arlington, VA, USA.


Supported by : Ministry of Agriculture and Forestry