Protein “solubilization” and calcium and magnesium precipitation by “chlorinated cleaners"

It has been stated that chlorinated cleansers increase the “protein solubilization” properties of cleanser solutions to which they are added (7). Chlorinated cleansers, however, are alkaline materials which increase the active alkalinity of the solutions to which they are added; this seems to have been overlooked. The study reported here was undertaken to determine whether the added available chlorine or the increase in active alkalinity was responsible for the increase in protein solubilization. Two chlorine sources were employed: Sodium hypochlorite (Chlorox) and chlorinated TSP. The approximate amounts by which these chlorine sources increased the active alkalinity (as % NaOH) at the 100 ppm and 200 ppm levels were: Chlorox, 0.0091% and 0.0199%, and chlorinated TSP, 0.0425% and 0.0800%. When the active alkalinity was the same in two solutions , there was no significant difference in the amounts of protein they would dissolve, even though one of the solutions contained available chlorine and the other did not. However, the pairs of solutions containing the same percentage of active alkalinity as the solution containing 200 ppm available chlorine solubilized significantly more protein (p <0.06) than did the pairs which contained the same active alkalinity as the solution containing 100 ppm; this is attributed to the higher active alkalinity of the former. These results were the same whether Chlorox or chlorinated TSP was the chlorine source, whether the direct or indirect method of determining protein solubilization was employed, and in the direct method, whether skim or homogenized milk was the soiling agent. On the basis of these data, the increase in active alkalinity, not the added available chlorine appears responsible for the increase in protein solubilization when a chlorine source is added to an alkaline cleanser. No calcium remained in any of the spent cleansers from the direct method of evaluating protein solubilization. In general, the amount of magnesium remaining decreased as the active alkalinity of the solution increased. There was no significant difference in magnesium content between the chlorine-containing and chlorine-free solutions having the same active alkalinity. Chlorine sources apparently minimize precipitation of hard water cations onto equipment surfaces.