The preventive effect of carboxylic acids on freezing denaturation at -30°C for 4 to 7 weeks was examined by using an in vitro-model test system. The rate of denaturation was followed by estimating solubility, viscosity, ATPase activity as well as the degree of super-precipitation. The overall results can be summarized as follows:
Additives exhibiting marked effect: malonic, maleic, lactic, malic, tartaric, gluconic, glycolic, methylmalonic, dimethyl malonic and glutaric acid.
Additives displaying moderate effect: adipic, pimelic, formic, acetic and propionic acids.
Additives with little or no effect: oxalic, succinic, fumaric, butyric and valeric acids.
These results suggests that the preventive effect of an additive is influenced by the nature, position, number and configuration of the functional groups of the compounds, and that some physico-chemical properties such as water solubility are closely related to the preventive effect.
The preventive effect of these additives during the thawing process was tested at various concentrations of KCl with results which support the view that additives function indeed during frozen storage.