Holiday How-to: Chocolate Leaves

My mom was a chemistry and home-ec teacher, so I grew up in a home where ingredients were carefully measured and food items were attractively arranged. While I got to help out in the kitchen as much as I wanted, I always liked being in the kitchen around the holidays. There were always new tricks or special touches added to dishes and along with these came short science lessons on why we were doing things that particular way.

One of my favorite things to help with in the kitchen were chocolate leaves. When done correctly, these are perfect little molds of the living leaf, just like the perfect molds and casts in the Morian Hall of Paleontology.

A chocolate leaf is made by smearing melted chocolate onto a leaf and putting it into the fridge to harden. Sounds easy, right? It is pretty easy. Read on!


Activity: Chocolate Leaves


Leaves (*See note in step 1.)

Chocolate candy melts

Parchment or wax paper

A cookie sheet or plate for your leaves to rest on as they cool


1. Pick your leaves. I like to use slightly waxy leaves so you don’t have to worry about fuzzy bits in your chocolate. NOTE: Learn about the plant you are picking leaves from before you decide to use them. Many household plants are decorative but poisonous.  Oleander is a great example of a plant that is pretty but poisonous. If you hate botany or don’t know about the Internet, getting pre-packaged basil or mint from the grocery store is a safe way to go. These leaves will be a little less firm, so you will need to be more careful with them.

2. Don’t pick leaves from poisonous plants. Seriously.

3. Wash your leaves with soap and water, rinse them thoroughly and then dry them completely. The chocolate won’t stick to wet leaves, so don’t rush this step. You will only be frustrated.

4. Put wax or parchment paper on a cookie sheet or plate. You want this to be something that will fit in the fridge with no problems.

5. Get out your candy melts. The melts come in a hundred colors. We are using chocolate colored ones in this tutorial. There will be instructions on the package on how to melt the specific brand of melts you purchased. In general, you will put the melts in a microwave safe bowl and microwave them a few seconds at a time stirring as you go. Don’t overheat the melts. They get gross and there is no coming back from that.

6. When you have everything melted and creamy, hold the leaf by its stem. I like pinching it between my thumb and index finger and then using my middle and ring finger to support the leaf. Do what feels comfortable to you.

7. Dip your stirring spoon into the chocolate. Use the BACK of the spoon to spread the chocolate on the leaf. Make sure the chocolate is thick enough that it won’t break when you try to peel it. Place the leaves on the parchment as you work, and don’t let them touch.


8. The side of the leaf you use is up to you. If you are using mint and you put the chocolate on the back of the leaf, you will have some crazy patterns.  If you want something more subtle, use the front of the leaf. Coat the leaf almost to the edges. If you go too far, you will get ugly edges that are hard to peel. But don’t worry! Those leaves are the best to eat.

9. Put the tray of leaves in the fridge and wait a few minutes.


10. When the chocolate is set, peel the leave off the chocolate. You should have a perfect little mold of your original leaf. This may take a little practice. Work quickly as you have something designed to melt with heat in your hot little hands.

11. Done! You can store the leaves in the fridge until you are ready to use them. If the leaves got soft when you were working with them, put them back in the fridge to firm them up. Once they are firm, you can toss them in a plastic container.


Okay! So what’s the science here?

The word “chocolate” comes from the Nahuatl word Xocolatl for “bitter water,” referring to its original incarnation as a hot, spiced beverage in the Mayan and Aztec traditions. Traditionally, chocolate is a mixture of cacao powder, cocoa butter, and a sweetener. To make chocolate palatable and stable, we now mix milk solids, added flavors, modifiers, and preservatives.

Those candy melts? NOT CHOCOLATE! In this example, they are sort of chocolate colored, so they have that going for them, but they also come in a bunch of colors that are not known to nature so… not chocolate. They are mostly made of sugar and vegetable fats – not cocoa butter – and depending on the brand, they may throw in a little wax for better melting. Mmmmm… wax.

The advantage to the melts over the regular chocolate is that they do have the wax and the vegetable oil in them, which makes melting easier since the chocolate doesn’t need to be tempered. It hardens pretty quickly and sticks to whatever you dip in it, so it makes a great coating for cake pops or whatever crazy things show up on Pinterest this month.

Want to get super nerdy about your chocolate?  (I assume you do…) MIT has these tidbits available.

What’s in typical chocolate?

  • 10-20% cacao
  • 8-16% milk solids
  • 32-60% sugar
  • 10-20% cocoa butter
  • 2% theobromine and polyphenols

Cocoa Butter Chemistry

Fats and oils are organic molecules made up of three fatty acids chemically linked by an ester bond to glycerol. Fats are solid at room temperature, while oils are liquid.

Cocoa butter fats are made up predominantly by three major fatty acid molecules: Palmitic Acid, Stearic acid, and Oleic acid.

Oleic acid is unsaturated (has a double bond on its carbon chain), making it kinked and unable to pack well with other molecules. Because of this, a greater portion of oleic acid in the fat results in a lower melting temperature for the cocoa butter.

Chocolate makers can adjust the amounts of each fatty acid to produce a chocolate that melts only in the mouth, giving it a superior quality.

Tempering chocolate

The cocoa butter in chocolate can have several different crystal structures (three-dimensional patterns in which the fat molecules pack). There are six known chocolate crystal forms, or polymorphs. You can obtain each form by varying the fatty acid ratios and the temperature at which the chocolate is tempered (cooled).

Only a few of the polymorphs are considered good for gourmet chocolate because they give the right blend of snap (when you bite into the chocolate) and melting (when it warms up in your mouth). Melting is especially important because it controls how well the chocolate disperses and releases flavor onto your tongue.

Whether you will be constructing culinary masterpieces this fall or sitting back and enjoying the kitchen creations of others, we hope you have a happy holiday with you and yours!  (And when you’ve had a little too much togetherness, we will be open on Friday…)

With Soil, Make Me Wine: The Dirt on Growing Great Grapes

I like wine. And I make my own. Not huge batches, mind you. Just about 30 bottles per month in the winter months. I learned the hard way the chemistry of wine. If you let the wine get too hot while it’s fermenting, it can radically alter the taste.  I let one of my batches get above 95 degrees a few times this summer. I was making a port and the flavor was ruined. The entire batch came out tasting like welches grape juice. Flat, tasteless, 20 percent alcohol-by-volume grape juice. I only inflicted a few bottles on my friends.


Good wine is a combination of science and art. There is the botany of the grapes. The meteorology of the climate. And the pedology. What’s pedology you ask? It’s the study of soil.  And since it is the International Year of Soils, we are going to get down and dirty with the effect of soil on one of my favorite drinks.

The ground beneath us is incredibly active. There are millions of different types of bacteria, fungi, and arthropods that give dirt everywhere its characteristics. If you’ve been taking the museum’s class on gardening and landscaping, you’ll understand the importance of the health of soil for plants. To briefly sum it up, good soil makes good crops. A shocking concept. But beyond that, what effects can the soil have on wine?


The effect of soil and climate on wine is called terroir. Wine tasters with a good palates say they can discern the flavor of the soil in the wine. Scientists have begun to examine a comparison of terroir to wines in an attempt to explain this phenomenon but so far have not been able to. That doesn’t mean that the flavor of the soil isn’t in the wine; it just means more scientists will have to drink more good wines. That’s a study I want to be a part of!

Good soils will encourage the vines to produce grapes instead of growing more vine. So the best soils need to provide lots of water at just the right time and then be able to drain it away. And the soil needs to keep the right nutrients such as nitrogen and potassium available to the vine, which can help intensify the flavors in the grape.


Tasting wine is about more than just “good” or “bad.” With an entire family of varietals out there in the world, it’s about what gives the wine its identity. Fans of wine, like me, like to get closer to the wine and the wine-making process through the quality of its flavor. And, oddly enough, tasting isn’t just about the taste. Wine Folly offers a five-step process to tasting wine, and explains a few things to be aware of. Here’s the basic process outlined in their blog.

  1. Look at the color. This goes deeper than just red and white. Ask yourself how it compares to other reds or whites in color. Gauge whether you can see through it. With practice, you can gauge whether the wine is bold, rich or viscous.
  2. Smell the wine, but swirl it around first to aerate it. Put the wine on the table and move the base in little circles, then shove your nose into the glass and take a big whiff. What do you smell?
  3. Taste the wine. Get enough of the wine to coat your entire tongue and roll it around in your mouth to maximize contact with all your taste buds. Don’t just think about flavor; think about texture and body, how it feels in your mouth. Does it have an alcoholic burn? Do the flavors match the smell?
  4. Decide whether to spit or swallow. You may have to drive later, or you may have 20 wines to taste and want to stay sober enough to think about all of them. If you hate the wine, spit it out. If you don’t want to waste it, swallow it. There’s no right or wrong choice.
  5. Think about the wine and formulate your own conclusions. Wine Folly states, “Wine tasting is a head game. Confidence and bold assertion can often make someone look like a pro.”


Join us for a Periscope wine tasting with local experts, curators, and myself on Wednesday, November 18 at 3 p.m. You’ll see some live wine tasting where we’ll talk about terroir and suggest some wine pairings for Thanksgiving. And to celebrate the International Year of Soils, join us for a film screening of the Symphony of the Soil at the Wortham Giant Screen Theatre Dec. 1 at 6 p.m.

A spider in your fruit? Unlikely, and less likely to hurt you.

This year we’ve seen a rash of negative publicity about “deadly” spiders hitchhiking in fruit from Central and South America, causing arachnophobes everywhere to, well, be super paranoid! In fact, spiders have not fared well in the media at all this year. Just check out some of these headlines:

Woman jumps from car after seeing spider, causes crash

Loose tarantula prompts Delta to call off flight

Man sets fire to gas pump trying to kill spider

So what’s the deal? Are spiders rising up against us by invading our fruit, vehicles, and homes? No. People are overreacting and the media is having a field day! We wanted to shed some light on what’s really happening and what you should do if you’re ever faced with a similar situation.

red faced banana

The redfaced banana spider, Cupiennius chiapanensis, from Central America is a harmless spider often misidentified as a potentially deadly spider from the Amazon in South America. Photo by: Rick Vetter.

Spiders hitchhiking in fruit — should we be concerned? Absolutely not; this is nothing new. Spiders and other arthropods have been accidentally hitching a ride in produce since it started being imported into the United States. Bunched fruits such as grapes and bananas make excellent hiding places for small insects and arachnids. Banana plantations, orchards, and vineyards attract plenty of insect visitors, both beneficial pollinators and detrimental pests. All of which make an easy meal for hungry spiders, so these are wonderful places for them to call home.

This can be a great thing for us because the spiders help control the pests, which can greatly reduce the amount of pesticide used on our food. But, obviously, when these fruits are harvested, it can bring them into our supermarkets and even our homes. The good news is that in the unlikely event you find a spider hiding in your fruit basket, it’s probably not a harmful one, according to arachnologist, Rick Vetter, who has been studying and identifying spiders brought into the country this way since 2006.

Most of the spiders that appear in banana shipments from Central and South America are either the pantropical huntsman spider (Heteropoda venatoria) or the red-faced banana spider (Cupiennius chiapanensis). Both are large spiders that can be misidentified as Brazilian wandering spiders, and both are harmless.

There have been several reports this year, mostly from the United Kingdom, of “deadly Brazilian wandering spider” eggs being found in banana shipments. The articles detailing these accounts have so many problems, it’s just mind boggling to me that they’re published and taken as any sort of reliable or accurate information. One article states that a woman purchased a bag of Tesco bananas and found an egg sac. After searching through Google, she saw an image that looked similar to hers, so she determined herself that they must be Brazilian wandering spider eggs. Hmmmm, interesting, wow, Google really can tell you EVERYTHING!

Another article states that a family “fled their home” after finding an egg sac on bananas from Aldi and an “expert,” some guy who runs a wildlife sanctuary, told them that “on the balance of probabilities, it was probably eggs from a Brazilian Wandering Spider.” Wait… what? That sentence doesn’t even make sense, come on, people!


The pantropical huntsman spider, Heteropoda venatoria, is a harmless spider found in many tropical locations around the world including Florida and Hawaii. Photo by: Rick Vetter.

The main problem here is the lack of an actual expert to identify the suspected eggs. Many trained entomologists cannot even correctly identify the actual spider, let alone their egg sack. Anyone who is not an entomologist or arachnologist is definitely not going to get it right!

Another major problem is with the media automatically labeling something as a “deadly Brazilian wandering spider” or “the deadliest spider in the world,” which creates so much hysteria. It makes people think that if they find a spider or eggs in bananas, it must be this kind, it will bite you, and you will die. But let’s look at the facts.

Brazilian wandering spiders are actually a genus of spiders (Phonuetria) found all over Central and South America. Each species in this genus has a different geographical range, size, behavior, and venom toxicity. The species reported to have the most toxic venom, Phonuetria fera, is restricted to the Brazilian Amazon and two similar species, P. nigriventer and P. keyserlingi, are restricted to the Atlantic coast of Brazil. The two latter species are the ones usually involved in envenomations of humans in Brazil, as P. fera is usually far from banana plantations and not likely to come into contact with people or get into banana shipments. Furthermore, most banana shipments these days come from places like Ecuador and Costa Rica, not Brazil. This is not to say that other species in this genus found in Central America don’t occasionally get into shipments, because they can, and have. But these species are usually smaller and have less toxic venom.

The toxicity of the venom is always exaggerated as well. In a study of 422 bites from Phoneutria spiders in Brazil, only 2.3 percent of them had to seek treatment with antivenin, and only one death occurred. Most people had minor symptoms that resolved on their own. This is true when it comes to any spider considered “dangerous” like the black widow, brown recluse, or Brazilian wandering spider. Most spiders only bite in response to a threat they cannot escape from, such as being trapped.


Brazilian wandering spider.

If you succeed in doing this to a spider, the bite is a defensive one, which may not even result in envenomation. Most types of spiders, especially from North and South America, are capable of saving their venom and delivering a “dry bite.” If venom does make it into your system, it is most likely a very small amount that will cause no reaction or a very minor reaction. People who are sensitive may experience unpleasant symptoms and may even need to be treated at a medical facility to control these symptoms, but death is highly unlikely. The groups of people most susceptible to venom are small children, the elderly, and those with compromised immune systems. Obviously those in any of these categories should be protected from spider bites, but knowledge and education are the best way, not overreaction and hysteria!

So if you do happen to bring home fruit and find a spider lurking there, don’t do what these people did. Don’t flee your house or try to sue the supermarket. (It’s not really their fault!) Don’t call the media or 911. First, try to contain the spider or eggs by placing the bananas in a sealed plastic bag or box of some kind. It’s important to keep it intact for proper identification, a smushed spider is very hard to identify! If the spider drops to the counter or the ground, try throwing a cup or glass over it and slipping a piece of paper underneath to trap it inside. From there you can preserve it in the freezer, which will kill it, or the refrigerator which will slow it down until you can get it to someone for a proper identification. It’s not a bad idea to give the store at which you purchased the fruit a call, just to let them know you found a spider in their produce and you’re trying to get it identified.

banana spider

Finding a spider in a food product can be jarring, but don’t freak out. It’s most likely harmless. Report the spider to grocery store personnel or call an entomologist to be sure of the species.

Next, find an actual expert to identify the spider. Stay away from pest control companies, they don’t always have an actual entomologist on staff, but they will be happy to give you a wrong answer and then tell you that your house needs to be sprayed for extra precaution. Call a university or museum and ask for an entomologist. If they don’t have one, they will know where to find one.

Deliver the spider and wait for an answer. Most likely the results will come back as a harmless spider of some kind. In some rare cases, it may be a type of Brazilian wandering spider or perhaps a black widow. (This has happened.) As long as you kept a cool head and caught and isolated the spider without picking it up with your hands, you were not bitten by it! Call the store and tell them what type of spider it was. Then, move on with your life.

And for goodness sake, if you see a spider on or near you, don’t jump from a moving car or try to set it on fire in the proximity of highly combustible chemicals. These other things will kill you, the spider will not!


Mark Your Calendars for these events happening at HMNS 10/5-10/11

Bust out your planners, calendars, and PDAs (if you are throwback like that), it’s time to mark your calendars for the HMNS events of this week! 


Lecture – American Intelligence, The History And Evolution By Vince Houghton
Tuesday, Oct. 6
6:30 p.m.
Dr. Vince Houghton, historian and curator of the International Spy Museum in Washington DC will trace US intelligence tactics used before the American Revolution to today’s scientific and technological intelligence. His talk will include traditional espionage (HUMINT – HUMan INTelligenceôhe “spies”), technical collection (SIGINT – SIGnals INTelligence, IMINT IMagery INTelligence-spy planes, satellites, drones, the NSA), covert action (paramilitary action, assassination, propaganda, etc.), and counterintelligence (catching the other guys’ “spies”)

Cultural Feast – Terroir Wine Tasting, The Earth Science Of Wine
Wednesday, Oct. 7
7:00 p.m.
Providing wines their unique flavor and aroma, the environmental conditions-especially soil and climate-will be analyzed in an unusual lesson in Earth science. Goût de terroir will be introduced by Bear Dalton, Spec’s veteran wine buyer. This evening we will taste nine wines that will illustrate terroir. This look into the science and culinary history of wine will be hosted at Alliance Française de Houston. Bread and cheese will also be served.