by Michael Cammer
Director of Light Microscopy and Image Analysis Albert Einstein College of Medicine
Yeshiva University, The Bronx, New York
(Image credit: Flickr user Nathan LeClair)
We investigated the morphological behavior of chocolate chip cookies as reported by previous investigators.
We were unable to effectively challenge their results.
(Image credit: Flickr user Nathan LeClair)
To challenge the results, we prepared the Toll House formulation in its standard form.1,2
To assess area and shape continuity or flux over a ten-minute heat stress condition, we employed an endpoint assay. Morphology and area, measured from a vantage normal to the plane of plating, were quantified before and after baking conditions using the powerful image analysis package.3 Index of roundness is measured as a ratio of perimeter to the square root of area with an adjustment by a constant based on 4 * pi to yield 1 for a perfect circle.
We confirm the qualitative analysis that dough both spreads and loses integrity of hard corners due to heat shock (see Figures 1a and 1b).
The dough is a suspension of starch, sucrose and lipid-based chips in butterfat, which is subjected to pretreatment and post-treatment by heat. Application of heat appears to alter morphology of the suspension, resulting in more spread and smoother-edged objects.
In addition, quantification of changes in absolute area and circularity confirm that dough loses its morphometric integrity when heated to 375 degrees F. Absolute area change is an index of spreading. All specimens spread typically by more than 100 percent each. Circularity is an index of variation from a perfect circle where 1 = perfect circle and, for our uses as it is known that area increases over time, 0 = perimeter approaching infinity. Circularity increases by approximately 25 percent which indicates the smoothing and loss of detailed edge features. Unfortunately, we were unable to establish a 1:1 correlation between area change and increase of circularity in individual specimens; however, the population study of each parameter isolated from the other is compelling (see Figures 2a and 2b).
The de facto final arbiter on all things cooking in the United States, the Culinary Institute of America, says nothing in its popular press regarding the chemistry or stability of drop-cookie dough under heat stress conditions.4 Therefore, we established definitively that drop-cookie dough loses its morphometric integrity when subjected to heat.
Area as measured by 2D projection from directly above. The thick colloid increases by 2X due to treatment by heat in standard convection oven.
However, the mechanisms of action have not been identified. Yet to be determined is the cascade of chemical events leading to collapse, spreading and subsequent cessation of flux. What roles do sugar and starch suspended in lipid play to slow the spread of the fat, which loses viscosity when heated? Do chocolate chips play a significant role as physical barriers to heat and gravity induced flow? Does protein in flour crosslink to provide stability and at what point does protein in egg crosslink due to heat? Cookies develop crisp outer shells which may be involved in the cessation of flux. The relative roles dehydration or other chemical reactions contribute to this exoskeleton have yet to be investigated.
Our investigation lays a firm foundation for further study. It should also be especially noted that cookies are three- dimensional constructs and, therefore, need more rigorous study as objects in space.
Approximate 25 percent loss of unique edge variation of features as measured by circularity of 2D projection from directly above due to treatment by heat in standard convection oven.
Special thanks to Dr. Dianne Cox for tolerating this research and not complaining excessively about the laboratory being too messy or the results too crispy.
1. R. Wakefield’s 1930 Toll House Cookie recipe as published by Nestlé, http://www.verybestbaking.com/recipes/detail.aspx?ID=18476
2. How does the Cookie Crumble?, C. Deane and R.C. Cammer, 2005, Webster, New Rochelle, N.Y.
3. Image J 1.34g, W.S. Rasband, National Institutes of Health, Bethesda, Md., http://rsb.info.nih.gov/ij/, 1997-2005.
4. Baking and Pastry: Mastering the Art and Craft, Culinary Institute of America, John Wiley and Sons, Inc., Hoboken, N.J., 2004.
This article is republished with permission from the July-August 2005 issue of the Annals of Improbable Research. You can download or purchase back issues of the magazine, or subscribe to receive future issues. Or get a subscription for someone as a gift!
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