The rates of ascorbic acid destruction in tomato juice were determined as functions of storage temperature, pH and copper concentration. Ascorbic acid destruction under anaerobic conditions was confirmed to be a first-order reaction with respect to ascorbic acid concentration. The effect of storage temperature on the rate of ascorbic acid destruction was accounted for by the Arrhenius equation. The activation energy of anaerobic destruction of ascorbic acid was 3.3 kcal/mol at pH 4.06, and was shown to change with changes in pH. The rate of ascorbic acid destruction was influenced by pH, reaching a maximum near the pKa of ascorbic acid. The rate of copper-catalysed destruction of ascorbic acid increased as copper concentration in tomato juice increased, and was affected by pH. A mathematical model, which described the rate of ascorbic acid destruction as functions of storage temperature, pH and copper, was developed based on the experimentally derived equations. A computer simulation program was developed using the mathematical model to predict ascorbic acid stability in tomato juice. The computer-aided predictions of ascorbic acid stability in tomato juice was in good agreement with the results obtained from the shelflife tests.

SUMMARY— The phenoloxidase system in the tissues of mushrooms, potatoes, and apples was investigated using a polyacrylamide electrophoretic technique. The enzyme system was shown to exhibit the phenomenon of multiple forms. The multiple form pattern obtained was highly characteristic for each individual species and variety studied, and substrate specificity was evident. The mushroom phenoloxidase system (Agaricus campestris) was shown to consist of at least nine distinct dl‐dopa‐reactive multiple forms, and at least three forms reacting with I‐tyrosine. Potatoes (var. Rural Russet) showed at least 11 bands of dl‐dopa activity, while apples (var. Golden Delicious) had at least three multiple forms of dl‐dopa activity. By introducing the “multiphase” gel electrophoretic technique a better resolution of the multiple forms was obtained. A group of closely related dl‐dopa multiple forms in mushrooms had the unique ability to withstand the temperature of 70°C for one hour. Sulfite, ethylenediamine‐tetraacetic acid (EDTA) and other treatments affected the multiple forms differently. Each multiple form behaved as an individual entity upon repeated elutions and electrophoreses.

Efficient nitrogen-purging systems were developed for maintaining low CO, concentrations in commercial salt-stock pickle fermentations. The successful systems tested were those in which a gas diffuser with a very small pore size was used to purge the brine while the brine was being circulated. The use of these systems dramatically reduced the incidence of severe bloaters in salt-stock pickles of large diameter. Specific recommendations are included for the design and use of a purging apparatus.

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