Moreover, it should be readily soluble. Glycerol is thus quite effective
(M¼92 Da, eutectic temperature 468 C), but it is not acceptable in
substantial concentrations in most foods. Consequently, sugars and polyols
(e.g., sorbitol) are often used.
Some added solutes can also reduce plasmolysis, because they can
readily pass through the cell membrane. However, there is considerable
variation in permeability for a given substance among species, and even
among specific cells within a species. Most microorganisms let glycerol pass
into the cell; see Section 8.4.3.
FIGURE16.14 Concentration factor due to freeze concentration of a 0.85%NaCl
solution containing various concentrations of glycerol. The numbers near the curves
denote the mass ratio of glycerol to NaCl. (After results by J. Farrant. Lab. Practice
15 (1966) 402.)