THE MYTHS OF PINEAPPLE JUICE and PAPAYA

The pH of a rabbit’s stomach is   ~  1.5 to 2.2  ~  highly acidic

Bromelain (the enzyme in pineapple juice that is capable of dissolving hair) cannot survive the extremely acidic environment of a rabbit’s stomach and thus cannot help with dissolving the hair.

The purpose of the following experiment was to determine at what pH the jello would solidify (because the bromelain was denatured/destroyed/rendered ineffective).  Similar experiments with Papain (the enzyme in papaya) yielded like results.

You will see that the jello did solidify at pH ~ 1, 3, and 12.5, 14  ~ indicating that at those pH’s bromelain was denatured and thus rendered ineffective. This backs up the argument that a pH less than 3 (which a rabbit’s stomach pH is) would denature the bromelain and render any hair dissolving effects useless.

This experiment was conducted by Tessa Motz and Katherine Kulp, University of Colorado at Boulder ~ at ~ http://spot.colorado.edu/~basey/motz.html

Here is that experiment:  pH and its Affects on Bromelain and Solidification

Many people enjoy pineapple in gelatin salads. However, it is difficult to enjoy fresh pineapple in gelatin because of bromelain, the proteolytic enzyme found in pineapples that prevents gelatin from solidifying. ~ the enzyme, Bromelain ~ will prevent gelatin from solidifying because of its chemical nature. If an enzyme is denatured it will not function as it normally would. Several factors may cause bromelain to become denatured, such as increasing its temperature, altering its concentration in a solution, or by adjusting its pH.

Our experiment investigated the problem: what is the optimum functioning pH level for bromelain?

Based on our knowledge of enzymes and a previous experiment in General Biology Lab, we hypothesized and predicted that if the functioning point of bromelain is directly related to the pH, then the rate of solidification will vary after altering of the pH.

Bromelain is found in pineapple juice, and as we saw in a previous lab, pineapple juice would not solidify in gelatin. Based on these results, I predicted that bromelain’s optimum functioning point would be somewhere high on the acidic side of the pH scale where most citrus juices are found.

The results of our experiment did not illustrate the outcome we had expected. We found that the solutions with the highest and lowest pH levels solidified and the solutions with pH levels in the middle of the scale did not solidify at all.

The solutions with a pH of 1,3,12.5, and 14 all solidified, showing that the most acidic and the most basic were not affected by the bromelain. This was consistent with my idea that a high acidic pH wouldn’t solidify, but we did not expect the lower basic pH to not solidify.

Our conclusion is that strong acids and bases counteract the affects of bromelain, allowing solutions to solidify in gelatin.


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