Electrorheology leads to healthier and tastier chocolate
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Edited by David A. Weitz, Harvard University, Cambridge, MA, and approved May 16, 2016 (received for review April 4, 2016)
Significance
Chocolate is one of the most popular food types and flavors in the world. Unfortunately, at present, chocolate products contain too much fat, leading to obesity. Although this issue was called into attention decades ago, no actual solution was found. To bypass this critical outstanding problem, two manufacturers introduced some low-calorie fats to substitute for cocoa butter. Somehow, their fats are forbidden in most countries. Here we show that, by applying an electric field to liquid chocolate in the flow direction, we aggregate the suspended particles into prolate spheroids. This microstructure change reduces the viscosity in the flow direction and enables us to reduce the fat level by 10–20%. A new class of healthier and tastier chocolate should come soon.
Abstract
Chocolate is one of the most popular food types and flavors in the world. Unfortunately, at present, chocolate products contain too much fat, leading to obesity. Although this issue was called into attention decades ago, no actual solution was found. To bypass this critical outstanding problem, two manufacturers introduced some low-calorie fats to substitute for cocoa butter. Somehow, their products are not allowed in most countries. Here we show that this issue is deeply related to the basic science of soft matter, especially to the viscosity of liquid suspension and maximally random jammed (MRJ) density. When the concentration of cocoa solid is high, close to the MRJ density, removing a small amount of fat will jam the chocolate flow. Applying unconventional electrorheology to liquid chocolate with applied field in the flow direction, we aggregate the cocoa particles into prolate spheroids in micrometers. This microstructure change breaks the rotational symmetry, reduces liquid chocolate’s viscosity along the flow direction, and increases its MRJ density significantly. Hence the fat level in chocolate can be effectively reduced. We are expecting a new class of healthier and tastier chocolate soon.
Footnotes
- ↵1To whom correspondence should be addressed. Email: rtao{at}temple.edu.
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Author contributions: R.T. designed research; R.T., H.T., K.T.-A.-I., E.D., and J.K. performed research; R.T. contributed new reagents/analytic tools; R.T. analyzed data; and R.T. wrote the paper.
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Conflict of interest statement: Temple University holds patents on a methodology to alter the viscosity of liquid chocolate through the application of an electric field. R.T. and H.T. are the inventor of the patents. The authors received funding from Mars Chocolate, Inc.
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This article is a PNAS Direct Submission.
