In the manufacture of frozen potatoes, raw potatoes are stored under controlled conditions before being processed. However, potato quality gradually changes during storage and this leads to inconsistent quality in the final frozen-potato product. To equalize the quality of frozen potatoes, regardless of the storage period, the processing method must be modified dependant on the period of storage. This study seeks to clarify how selected potato properties change during storage and to develop measures that will equalize the texture of frozen potatoes, regardless of the period over which the raw potatoes have been stored.

The finding of this investigation was that hardness after blanching increased with the duration of storage. The study also suggests that hardness after blanching is related to starch content and to the properties of pectin substances. The effects of various chemical blanchings on potato hardness were tested. Blanching with sodium polyphosphate resulted in a decrease in hardness by rendering the otherwise insoluble pectin soluble. Appropriate sodium polyphosphate concentrations for equalizing hardness after blanching were found to be dependent on the potatoes' specific gravity. For potatoes with a specific gravity of over 1.085, changings odium polyphosphate concentrations to 0.1%, 0.1%, and 0.2% for potatoes in storage for 2, 4, and 6 months, respectively, resulted in potatoes of consistent hardness regardless of the length of storage. For potatoes with a specific gravity of 1.085 or less, the appropriate concentration was 0.1% regardless of the length of storage.