Journal of Food Measurement and Characterization

, Volume 9, Issue 4, pp 479–486 | Cite as

The critical water activity from dynamic dewpoint isotherms as an indicator of pre-mix powder stability

  • Brady P. CarterEmail author
  • Mary T. Galloway
  • Gaylon S. Campbell
  • Arron H. Carter
Original Paper


Premix instant powders offer quick, easy alternatives for making common food products such as gravy, muffins, and beverages. To remain viable, premix instant powders must be free of caking while maintaining their wettability, solubility, and dissolution properties. The main extrinsic factors that influence the stability of powders are temperature and water activity. The critical water activity from dynamic isotherms has been demonstrated to be an effective moisture related specification to maintain the stability of glassy powders. Premix instant powders are often primarily wheat flour, which has a high glass transition, so it is questionable if a critical water activity associated with stability can be found. The purpose of this study was to determine if a critical water activity can be determined for premix instant powders using dynamic isotherms and if this critical water activity is associated with product stability. Instant oatmeal muffin powder and instant chicken gravy powder were found to have a critical water activity at approximately 0.70 aw. Samples of the premix powders were then equilibrated to water activities above and below the critical water activity and examined for changes in caking strength. The mean caking strengths at water activities less than the critical water activity were significantly higher than at higher water activities. The premix samples also experienced color and other appearance changes above the critical water activity. The changes in the premix powders’ matrices that occurred at the critical water activity resulted in degradation of the powder, indicating that the critical water activity provides an effective specification to prevent product loss without requiring an extensive stability study.


Premixes Powders Caking Solubility Dissolution Water activity Dynamic isotherms stability 



The authors would like to thank Decagon Devices, Inc. for providing the funding for this study. Also, thank you to Andy Galbraith and other support staff at Decagon Devices for facilitating data collection. Thanks is also given to Dr. Craig Morris and the USDA Western Wheat Quality Lab for use of their equipment. Thanks to Dr. Shyam Sablani for providing feedback.


  1. 1.
    Y.H. Roos, Phase transitions in foods (Academic Press, San Diego, CA, 1995)Google Scholar
  2. 2.
    M. Saltmarch, T.P. Labuza, J. Food Sci. 45, 1231 (1980)CrossRefGoogle Scholar
  3. 3.
    S. Tsourouflis, J.M. Flink, M. Karel, J. Sci. Food Agric. 27, 509 (1976)CrossRefGoogle Scholar
  4. 4.
    S. Jaya, H. Das, J. Food Eng. 63, 125 (2004)CrossRefGoogle Scholar
  5. 5.
    L.E. Chuy, T.P. Labuza, J. Food Sci. 59, 43 (1994)CrossRefGoogle Scholar
  6. 6.
    M. Mathlouthi, B. Roge, Food Chem. 82, 61 (2004)CrossRefGoogle Scholar
  7. 7.
    M. Peleg, C.H. Mannheim, J. Food Process. Preserv. 1, 3 (1977)CrossRefGoogle Scholar
  8. 8.
    G. Roudaut, in Water Activity in Foods, ed. by G. Barbosa-Canovas, A.J. Fontana, S.J. Schmidt, and T.P. Labuza (Blackwell Publishing, Ames, Iowa, 2007). p. 199Google Scholar
  9. 9.
    J.M. Aguilera and J.M. del Valle, in Food Preservation by Moisture Control: Fundamentals and Applications—ISOPOW Practicum II, ed. by G.V.Barbosa-Canovas and J.Welti-Chanes (Technomic Publishing Company, Lancaster, PA, 1995) p. 675Google Scholar
  10. 10.
    J.M. Aguilera, G. Levi, M. Karel, Biotechnol. Prog. 9, 651 (1993)CrossRefGoogle Scholar
  11. 11.
    J.M. Aguilera, J.M. Delvalle, M. Karel, Trends Food Sci. Technol. 6, 224 (1995)CrossRefGoogle Scholar
  12. 12.
    J.J. Fitzpatrick, M. Hodnett, M. Twomey, P.S.M. Cerqueira, J. O’Flynn, Y.H. Roos, Powder Technol. 178, 119 (2007)CrossRefGoogle Scholar
  13. 13.
    J.J. Fitzpatrick, N. Descamps, K. O’Meara, C. Jones, D. Walsh, M. Spitere, Powder Technol. 204, 131 (2010)CrossRefGoogle Scholar
  14. 14.
    K.D. Foster, J. Bronlund, A.H.J. Paterson, J. Food Eng. 77, 997 (2006)CrossRefGoogle Scholar
  15. 15.
    Y. Listiohadi, J.A. Hourigana, R.W. Sleigh, R.J. Steele, Int. J. Pharm. 359, 123 (2008)CrossRefGoogle Scholar
  16. 16.
    R.J. Lloyd, X.D. Chen, J.B. Hargreaves, Int. J. Food Sci. Technol. 31, 305 (1996)CrossRefGoogle Scholar
  17. 17.
    A.H.J. Paterson, G.F. Brooks, J.E. Bronlund, K.D. Foster, Int. Dairy J. 15, 513 (2005)CrossRefGoogle Scholar
  18. 18.
    P. Saragoni, J.M. Aguilera, P. Bouchon, Food Chem. 104, 122 (2007)CrossRefGoogle Scholar
  19. 19.
    H. Levine, L. Slade, Carbohydr. Polym. 6, 213 (1986)CrossRefGoogle Scholar
  20. 20.
    H. Levine and L. Slade, in Physical Chemistry of Foods, ed. by H.G. Schwartzberg and R.W. Hartel (Marcel Dekker, New York, 1992) p. 83Google Scholar
  21. 21.
    M.K. Haque, Y.H. Roos, J. Food Sci. 69, 23 (2004)CrossRefGoogle Scholar
  22. 22.
    Y.H. Roos, Conference of Food Engineering, 14 (1995)Google Scholar
  23. 23.
    R.A. Lipasek, J.C. Ortiz, L.S. Taylor, L.J. Mauer, Food Res Intl 45, 369 (2012)CrossRefGoogle Scholar
  24. 24.
    B.P. Carter, S.J. Schmidt, Food Chem. 132, 1693 (2012)CrossRefGoogle Scholar
  25. 25.
    X. Yuan, B.P. Carter, S.J. Schmidt, J. Food Sci. 76, 78 (2011)CrossRefGoogle Scholar
  26. 26.
    T.A. Shittu, M.O. Lawal, Food Chem. 100, 91 (2007)CrossRefGoogle Scholar
  27. 27.
    A. Savitsky, M.J.E. Golay, Anal. Chem. 36, 1627 (1964)CrossRefGoogle Scholar
  28. 28.
    W. Wang, W.B. Zhou, J. Food Eng. 109, 399 (2012)CrossRefGoogle Scholar
  29. 29.
    Minitab. Minitab 16 Statistical Software. (Minitab, Inc.State College, PA, 2010)Google Scholar

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Brady P. Carter
    • 1
    Email author
  • Mary T. Galloway
    • 1
  • Gaylon S. Campbell
    • 1
  • Arron H. Carter
    • 2
  1. 1.Decagon Devices, IncPullmanUSA
  2. 2.Washington State UniversityPullmanUSA

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