For the Love of Chocolate

A Short History

The art of making chocolate is chemistry exemplified. Historians traced the origins of chocolate 4000 years ago to a small village in Honduras, where it is believed the first hot chocolate drink, Xocolati, or bitter water was made. Cacao beans remained a prized, native possession in Central American cultures for 2000 years before becoming introduced in Europe around 1500 AD.

Even so, chocolates did not become affordable for the middle-class until sugar and cocoa prices had dropped enormously around 1900AD. Also, the liberalization of the cocoa trade and the elimination of government taxes on cocoa beans led to a growing commercialization of chocolate. In Italy, Francesco Buitoni of the ‘Buitoni’ pasta making family, started developing small chocolates wrapped in silver paper and called them baci, which means “kisses”, in Italian, and the connection between love and chocolates was initiated. Callebaut chocolates, a famous Belgian chocolaterie, started selling in bulk to bakers and chefs and mainstream use of chocolates as a food item became commonplace.

Roasting is Key

The process of making chocolate from cocoa beans is saturated with chemical reactions. About 600 types of chemicals such as alcohols, carboxylic acids, aldehydes, ketones, esters, and pyrazines have been identified as flavor and smell components of chocolates. Depending on the type of bean selected, chocolates can have over two hundred flavor compounds. At the early stage of the processing, during fermentation, a class of volatile nitrogen containing chemicals known as pyrazines is formed which add a distinct peppery flavor to the beans.

Next, the beans get ready for roasting. The roasting process constitutes of a chemical reaction known as the Maillard reaction. Maillard reaction is a complex set of chemical reactions that food chemists and chefs use to bring out flavors of their ingredients during roasting. The reaction occurs between amino groups of proteins and the carbonyl groups of natural sugars and is famous in the food science industry. Applying dry heat starts the reaction. This technique can be controlled by time, temperature, and pH. The Maillard reaction conditions are often ardently guarded by famous chocolatiers. “Dutching” or alkalizing, and a final heat treatment to remove by-products seals in the flavor of chocolates.

Many Forms of Chocolate

So what makes eating chocolates a delicious and melt in your mouth experience? The taste of chocolate depends on the structure of the cocoa butter. It turns out that there are six different crystalline forms (I-VI) of cocoa butter that emerges during chocolate making as the butter solidifies into hard chocolate. The higher forms have more densely packed chains (it’s a lipid), are more stable, snaps when broken, looks glossier, and tastes creamy. Form V is the most superior in taste and structure and sought after by most specialty chocolatiers. When the chocolate melts in a hot car, for instance, it hardens into a different texture and taste. Chocolate V can slowly change into another form of chocolate if stored it at room temperature for a few months. Cocoa butter is pricey; many candy bars try to achieve the same feel by using emulsifiers such as lecithin to retain the melt in the mouth experience.

So the lesson here is to eat chocolates immediately upon receiving or buying them. No chewing necessary! By keeping the chocolates longer or getting it melted, or storing it in the fridge, you are taking the chance of converting the cocoa butter into a different form which will alter it into a more unappealing flavor.

Resources

1. Owen, Gregory. “How Chocolate Is Made.” www.princeton.edu, 5 Jan. 2013.

2. G Tannenbaum, “Chocolate: A marvelous natural product of chemistry”,.J. Chem. Educ, 2004 – ACS Publications

3. http://www.rsc.org

4. http://www.callebaut.com

5. http://www.pexels.com (photos)

Why Does Ice Cream Float on Root Beer? And Some Other Stuff!

It is all about density! Ice cream has a high fat content, and fat is less dense than water, so a scoop of ice cream floats on water solution or a glass of root beer. More expensive ice creams are higher in fat, which gives their velvety texture, and are more ‘dense’ than their lower priced counterparts. Premium ones have the highest fat content and least air bubbles. Ice cream has a lot of air bubbles trapped in a matrix of fat and sugar molecules which also lowers its density.

Do an experiment about density and have a root beer float party! Buy a few different brands of ice creams, some root beer, and see if the kids can ‘guesstimate’ the fat content and density of each ice cream in each root beer float.

You can change the temperature of the root beer( or coca cola) by a tiny bit and see what happens to the float! An excellent way to have the kids think about science without going near a textbook.

For customers wanting more from their ice cream eating experience, functional ice cream is coming soon to mainstream grocery stores. Adding a probiotic culture instead of a stabilizer is fashioning ice cream into an attractive delivery tool for probiotics. A stabilizer is added to make ice cream melt slower, and to make it taste more smooth and creamy. Examples of routinely used stabilizers are gelatin, egg whites, guar gum and the like. Due to an increasingly health-conscious consumer market, food research is driven toward functional foods, improving taste and texture, while taking away additives that are viewed as ‘processed’. For alternative or nondairy, probiotic ice creams, coconut milk, and soy milk shows the most promise.

Here is a link to a probiotic, home-made ice cream recipe from www.homemademommy.net, which hints an utterly delicious result looking at the ingredient list. To a first-time ice cream maker (such as myself), I would suggest being conscious of the ‘beating continuously’ part of instruction in the recipe, as that is the process where air gets mixed in which determine the structure of the ice cream. Structure relates to taste because structure relates to how slowly or quickly flavor releases into the mouth. (Think of whipped cream vs. a spoon of liquid sweetened cream.) But this is a fitting summer project for perfecting in the kitchen!

P.S – If you are doing a density experiment with ice cream, and need more details about preparing a data and results table, contact me and I can provide one.

 

Reference: Aboulfazli, Fatemeh, Amal Bakr Shori, and Ahmad Salihin Baba. “Effects of the Replacement of Cow Milk with Vegetable Milk on Probiotics and Nutritional Profile of Fermented Ice Cream.” LWT – Food Science and Technology 70 (2016): 261-70. Web.

California Eases Fire Retardant Restrictions With TB 117-2013

Technical Bulletin 117 gets a revision by California Gov. Jerry Brown and will now bear the tag TB 117-2013. Furniture makers are no longer required to fill in couches with flame retardant additives.

Fire retardants, a class of brominated molecules, termed as PBDE, have come under intense scrutiny from firefighter associations as PBDE degrades into carcinogenic dioxins, under high temperatures caused by fires. It does not end there. The smaller analogs are shown to bind to fatty tissues and bioaccumulate in humans and animals, data which is proved by a myriad of research studies with peer-reviewed publications. Thyroid hormone disruptions, estrogenic and androgenic hormone disruptions, impaired childhood development, are some other major health concerns.

Since the retardants are not chemically bonded to the foam (as in plastics) but injected as an additive, they readily shed into common house dust. If it is essential to fire-proof your home and must have furniture with the fire retardant additives, using a vacuum with a HEPA filter regularly is an effective method for cleaning up these pesky, harmful compounds that sneak into the home. Analytical chemists are continually testing for lower thresholds that would meet fire safety requirements, and many of the brominated analogs have already been phased out.  

Those of you still not satisfied with the TB 117-2013 revision and are looking for a greener option without spending $5000 on a couch; your best bet is to get it reupholstered. You can purchase natural replacement foam from http://www.foamorder.com/.

If you are concerned that it is a terrible thing to dump the old couch to sit in a landfill and emit greenhouse gasses, research is already continuing toward better processing of brominated fire retardants into cleaner and sustainable uses.

Resources you might like:

  1. http://www.greenhomeguide.com/askapro/question/how-do-i-select-safe-natural-fiber-products-for-my-home (provides choices of natural fabrics)
  2.  ”Chemical Recycling of Brominated Flame Retarded Plastics from E-waste for Clean Fuels Production: A Review.” Renewable and Sustainable Energy Reviews 61 (2016): 433-50. Elsevier.

Tracking Chemical Exposure with Colorful Wristbands

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Professor Kim Anderson of Oregon State University went to a college football game and got a very creative idea.

She observed fans sporting colorful wristbands, and decided to develop look-alike bands using a specialized silicone polymer. But her wristbands will be doing an investigative task as well – collecting data and tracking chemical exposure. Her target participants were school kids and construction site workers. After wearing the bands from a week to a month, researchers collected the bands, extracted the compounds, and screened them using GC/MS – a gold standard identification method used from pharmaceutical industry to forensics. So far 57 compounds were found in the bands, out of a targeted 1400 chemicals.

 MyExposome, a start-up biotech company in Corvallis, OR, which specializes in passive sampling technologies, developed the bands. The company designed the specialty polymer for optimal absorption of a diverse set of daily chemicals ranging from fire-retardants, personal care products and various compounds from pesticides. The bands are currently unavailable for the individual buyer, but the Environmental Defense Fund (EDF), in a joint effort with Myexposome is making them available to the public for expanding the research project. So far 5000 volunteers have signed up.

Dr. Anderson hopes to get funding for a larger design of her project, “You don’t have to wait for a disaster like a Flint”..she comments referring to the drinking water fiasco in Flint, Michigan. “We have developed a technology that inspires people to think about science and their environment and hopefully even act about their environment.”

> View the article abstract: Using silicone wristbands to evaluate preschool children’s exposure to flame retardants. Environ. Res.; May 2016