Effects of pH of dipping solutions on the quality of prepeeled potatoes

Summary and Conclusions

Prepeeled French-fry style potato strips were treated with varying concentrations of sodium bisulphite solutions buffered at six pH values from 4 to 10 and stored in polyethylene and Cryovac bags for 10 and 16 days at 32 to 34° F. and 40 to 42° F. Quality factors such as discoloration, softness, exudation, alcohol content and pH value were measured for each sample.

The degree of discoloration was decreased with higher levels of sulphite, lower oxygen tensions, lower pH value and lower temperature, indicating that all four factors were probably acting in conjunction to lower the level of tyrosinase activity.

The degree of softness was increased at the lower pH levels but the effect was relatively small.

The amount of exudation was markedly increased at pH levels below 5 particularly in the presence of high concemtrations of sulphite. This factor alone would preclude the use of dipping solutions buffered below 5 in spite of the advantage in discoloration control. The exudation was also increased with higher concentrations of dissolved salts probably due to osmotic effects.

The alcohol content of the tissue showed a variable effect with different pH values and this may be an indication of tissue injury.

The optimum pH of the dipping solutions for prepeeled potatoes is in the range of 5.5 to 6.5.