Tolerance of Bacteria to High Concentrations of NaCl and Glycerol in the Growth Medium

Abstract

When compared at similar levels of water activity, glycerol was more inhibitory than sodium chloride to relatively salt-tolerant bacteria and less inhibitory than salt to salt-sensitive species.

Modelling the growth response of Staphylococcus xylosus to changes in temperature and glycerol concentration/water activity

“…The growth of Staph. xylosus at a lower a, value in NaC1-adjusted media compared with glycerol-adjusted media is consistent with earlier reports that glycerol is more inhibitory than NaCl to relatively salttolerant bacteria (Marshall et al 1971). The results reported above indicate that the growth rate response of Staph.…”

Growth of Staphylococcus aureus as Related to 17O NMR Water Mobility and Water Activity

“…S. aureus has a minimum a w of 0.86 required for growth. However, the minimum growth a w is 0.89 in the presence of glycerol (Marshall et al, 1971). Therefore, some effects of glycerol on growth were apparent.…”

“…3a), samples with raffinose were distinct from those with glycerol or NaCl. Glycerol and NaCl have different minimal water activities affecting growth (Marshall et al, 1971) and glycerol 1.17:1), glycerol (1.80:1) or NaCl (1.08:1) at various moisture contents.…”

“…Comprehensive research with many systems and solute types indicates S. aureus cannot grow at a w Ͻ Ϸ 0.86 (Chirife, 1994;Chirife et al, 1982;Troller, 1986). Minimal a w level which allows growth may be imprecise in some cases and is usually given in a range due to variance in properties of humectants and their effects (Gould and Christian, 1988;Marshall et al 1971). This discrepancy has been a concern and led to questions about the safety of the reformulations of intermediate moisture foods.…”

Fate of Clostridium sporogenes PA 3679 in Fish Sausage Formulations with Adjusted aw using Food Binders

“…Fox and Loncin's (1982) study on the effect of 250 combinations of factors such as heat treatment lethality (F), a,, pH, and Eh to produce a shelf stable product, although comprehensive, did not answer completely the questions related to this vastly complex and challenging area of food preservation. The practical a, limit of 0.95 for stability also raises some concern because C. botulinurn, types A and B, have been reported to grow and produce toxin at an a, as low as 0.94 using salt adjusted growth media (Ohye and Christian, 1967;Marshall et al, 1971). The types of solute or humectant differ in their ability to inhibit germination and growth of the important clostridia and bacilli in growth media (Baird-Parker and Freame, 1967;Jakobsen et al, 1972;Jakobsen and Murrel, 1976;Anagnostopoulos and Sidhu, 1981).…”