Thursday, August 25, 2011

Identifying the Loss of Capsaicin-Induced Heat Sensation in Humans as a Result of Culinary Experimentation

Culinary experimentation can often result in unexpected results. Most recently, an experiment in making a Thai-Mexican pork taco hybrid resulted in a significant reduction in a much-desired capsaicin-induced heat sensation experienced by the human tasters. A simple design experiment was conducted to determine the apparent "loss" of capsaicin when in the presence of citric acids and a fatty acid, in this case canola oil. A review of the literature concerning the chemical properties of capsaicin revealed that the compound is alkaline, highly soluble in vegetable oils, and immiscible in water. The results of the experiment conformed to the known properties of capsaicin.

In the process of creating a new culinary creation, unexpected results can often be achieved without intention. Determining the cause of such unexpected results can be done by random trial and error, or by applying knowledge of chemistry, since the essence of cooking is the combination of various chemical molecules and compounds into a form suitable to both taste and nutrition.

Recently, an experiment conducted to achieve a Thai-Mexican pork taco hybrid marinade resulted in the unexpected loss of the capsaicin-induced heat sensation in the final product. A simple experiment was conducted to determine the cause of the apparent "loss".

Materials and Methods
PhotobucketMaterials used were similar to, or actual ingredients, that would be used in the marinade. A standardized source of capsaicin was used to provide consistency. Two solutions were made, each containing 1 oz. of Sriracha chile sauce dissolved into 4 oz. of reduced sodium chicken broth, and were labeled Solution A and Solution B respectively. Both solutions were tested before the additions of citric or fatty acid by a high sophisticated organic piece of equipment that is known to lack objectivity, but is highly sensitive to the presence of capsaicin, to confirm that they both had a similar capsaicin-induced heat sensation.

Next, 2 oz. of bottled lime juice were added to Solution A. To Solution B, 2 oz. of canola oil were added. Both solutions underwent mechanical agitation (vigorous shaking), then were placed within an environment of approximately 35°F for approximately 4 hours. After the 4 hours, Solution B was observed as being a heterogenous solution consisting of a top oily layer and a bottom aqueous layer. Solution A was observed to be a homogenous solution.

The top oily layer of Solution B was not distinct enough for mechanical extraction by a spoon. A culinary marinade injection syringe with an attached needle was inserted to extract a portion of the bottom aqueous solution below the oily layer. The obtained solution was placed within a spoon to be tested by the highly sophisticated organic equipment. A second sample from Solution B was obtained by using the same syringe apparatus to extract a portion of the top oily later, which was placed in a second spoon to be taste-tested.

A sample of Solution A was obtained by using a third spoon.

Both solutions were returned to the cold environment for approximately another 3 hours before a second extraction was obtained to be tested by a second piece of sophisticated organic equipment.
The sample obtain from the bottom aqueous solution layer from Solution B was found to taste very bland and watery. The distinct absence of a capsaicin-induced heat sensation was very pronounced in comparison to the original solution before the addition of the fatty acid. The secondary tester (without being informed of the first taster's experience) reported similarly that the aqueous solution was bland and had a less than expected heat response.

The sample obtained from Solution A was found to have a very pronounced sour-tang taste at first, then followed by an immediate intense burning sensation that was determined as being near equivalent to the original solution before the addition of citric acid. The second tester was observed not to be expecting such an intense heat sensation from the sample and involuntarily coughed when the capsaicin-induced heat sensation was first experienced. The second tester reported that the heat sensation experienced was intense.

A sample from the top oily layer of Solution B was tested and was found to induce a capsaicin-induced heat sensation, but not as intense or shocking as that of the original solution prior to the addition of the fatty acid. The oil seemed to slightly mitigate the sharp intensity of the heat. The second tester reported the presence of heat as well, but was still recovering from the shock of having sampled Solution A.

Capsaicin is basic in its chemical properties, thus it was expected that the addition of an acid, in the form of citric acid, would neutralize it. While no measurements of the respective pH for any of the solutions were taken, no neutralizing effects were detected by the pieces of sophisticated organic equipment used. It may be that the type of citric acid used was not a strong enough acid, or that a different ratio needed to be used before any neutralizing effects could be detected. It was therefore concluded that the type citric acid used, and the volume and/or ratio that would be used in the marinade had little to no effect of causing any loss of the capsaicin-induced heat sensation experienced by the testers.

Canola oil is a fatty acid derived from a genetically modified species of the rapeseed plant. The modification is to reduce the levels of erucic acid, a known toxin. It could be considered to be part of the generic term "vegetable oil", which according to the literature, is highly soluble with capsaicin. The canola oil did not solidify in the cold environment, which would have made it easier to extract the oily layer from Solution B. The use of extra-virgin olive oil would have been better suited as it would have solidified for removal. The sample of solution that was obtained from the bottom aqueous layer had noticeable minute oil globules, therefore the samples acquired were not of ideal purity. Nonetheless, there was a noticeable lack of capsaicin-induced heat sensation experienced by both testers. The samples tested of the top oily layer were both experienced to contain an expected amount of capsaicin-induced heat sensation, but not as sharp as those samples tested from Solution A.

The samples obtained from the two layers of Solution B most conformed with the expected interaction of capsaicin when dissolved in a fatty acid or "vegetable oil". It was expected that the capsaicins would dissolve into the oil and no longer be present or detectable by the testers in the separated aqueous layer. It was concluded that the unexpected loss of capsaicin-induced heat sensation from the experimental marinades was most likely caused by the omission or removal of the oily layer that formed during the cooking process caused by fat rendering from the meat.

While it was found that the citric acid had undetectable effects on the capsaicin-induced heat sensation, it was realized that the acid could be used to create an unstable emulsion to combine the oily layer and aqueous layer of the marinade mixture, thus preventing the separation and hence loss of capsaicin-induced heat sensation. In other words, the marinade would become like a simple oil and vinegar dressing.

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