The equilibration of solutes between whole cucumbers and the brine in which they were held was found to be consistent with a diffusioncontrolled first-order rate process. First-order rate coefficients for attainment of equilibrium (Ko) for sugar and malic acid (initially in cucumbers) and NaCl and lactic, tartaric, acetic and formic acids (initially in brine) varied up to threefold among four cucumber lots. However, the ratios of Ko values among solutes were not significantly different (P>O.O5). Ko values increased as cucumber size decreased. Peeling increased K, values 3.7-to 11. l-fold. Temperature dependency was greater for solute movement out of [apparent activation energies (E,) of 6.5 and 6.3 kcal/mole for malic acid and sugar] than into (apparent E, of 4.5 and 4.2 kcahmole for NaCl and lactic acid) cucumbers. The equilibration-prediction model used may be helpful in studying rate limiting factors in the fermentation of brined vegetables and in other food preservation processes where solute movement is important.

Proteus mirabilis expressed three superoxide dismutase activities, which depended on the level of soluble iron and dioxygen in the culture medium. Cadmium and lead decreased production of super oxide dismutase in liquid culture and on solid medium. A fourth super oxide dismutase activity appeared in extracts from cells grown in the presence of cadmium. These results support the idea of an interaction between toxic metal ions and putative iron- and redox-dependent regulatory systems.

Mold-induced cucumber softening was prevented in air-purged fermentations by 0.16% acetic acid (equilibrated). Cucumber softening and pectate depolymerase activity increased in air-purged fermentations when the level of acid was decreased to 0.12% and below. Mold-induced softening was prevented in natural (not acidified) fermentations by delaying purging until indigenous microflora had reduced the brine pH to 4.0. Direct contact of air bubbles and cucumbers was not a requirement for subsurface mold growth. In air-purged commercial brines softening was evidenced by soft spots and skin blisters on cucumbers acidified with 0.05 and O.O%, but not with 0.16%, acetic acid. In broth culture, growth of four mold isolates from soft cucumbers was inhibited by 0.3% acetic (pH 4.0) but not by up to 0.9% lactic acid (pH 3.0) at 5.3% NaCl.

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