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Storage stability of freeze-dried starter cultures (Streptococcus thermophilus) as related to the physical state of the freezing matrix.

Author(s) : ANDERSEN A. B., FOG-PETERSEN M. S., LARSEN H., et al.

Type of article: Article

Summary

The temperature dependence for loss of acidification activity during storage of a freeze-dried skimmed milk based starter culture of Steptococcus thermophilus in a matrix of ascorbic acid, casein and sucrose or mannitol showed Arrhenius behaviour below the glass transition temperature as determined by differential scanning calorimetry, with an energy of activation depending on the sugar with 57 kJ/mol for sucrose and 40 kJ/mol for mannitol, but not on the initial concentration of sugar before freezing (60 or 120 g/kg of dry matter). For storage at or above transition temperature (around 50 °C), loss of activity increased dramatically with non-Arrhenius temperature dependence. Mannitol based glasses yielded better protection for aerobic storage and this was probably due to better antioxidative properties.

Details

  • Original title: Storage stability of freeze-dried starter cultures (Streptococcus thermophilus) as related to the physical state of the freezing matrix.
  • Record ID : 2000-3108
  • Languages: English
  • Source: Lebensm.-Wiss. Technol. - vol. 32 - n. 8
  • Publication date: 1999

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