By now our regular readers are aware that we think chemistry and economics define cool. But what could be cooler (figuratively and literally) than liquid nitrogen ice cream? You may have seen liquid nitrogen featured on cooking shows that highlight molecular gastronomy, and have wondered what it is. We are most familiar with nitrogen (N2) as a gas comprising 78% of earth’s atmosphere. Liquid nitrogen is made by fractional distillation of liquified air. Liquid nitrogen boils at -321 degrees on the Fahrenheit temperature scale (that’s 77 K or -196 degrees Celcius). This very cold temperature is what makes liquid nitrogen ice cream the smoothest and creamiest frozen treat we have ever tasted. It is also dramatic and fun – so much fun that the UCR Chemistry Department has an annual liquid nitrogen ice cream contest in which graduate students from the different groups compete to make the most delicious and creative flavors. This year’s contribution from the graduate students in the Larive group (Daryl, Greg, Derek, Consuelo, Meredith and Ngoc), Black Forest Ice Cream with Candied Cherries, was an especially creamy dark chocolate ice cream with dark chocolate chips, sweet candied cherries and a cherry sauce drizzled over the top. Yum!

Any standard ice cream base can be used for liquid nitrogen ice cream, which also means that those of you who do not have access to liquid nitrogen can use our recipe with standard ice cream freezers. To keep liquid nitrogen cold, it is transported in a special container called a dewar, which is basically a large thermos bottle.  The liquid nitrogen is added directly to the ice cream base while stirring. (Caution – liquid nitrogen can cause severe burns – see the safety precautions below.) Since it is so cold, liquid nitrogen freezes the ice cream very quickly, so quickly that the ice crystals formed are much smaller than in regular ice cream, giving  it an unbelievably smooth and creamy texture. The liquid nitrogen quickly evaporates into a colorless and odorless gas.  Although it appears to “smoke” it is really just condensing water vapor present in the air to form a fog.

Recipe (adapted from http://kitchensimplicity.com/black-forest-ice-cream/)

Chocolate Ice Cream

2 cups heavy cream
3 tablespoons dark cocoa powder
5 oz. dark or semisweet chocolate chips, chopped
1 cup whole milk
3/4 cup sugar
1/2 teaspoon vanilla extract

Candied Cherries

Candied cherries: Place cherries, water, sugar and lemon juice into a medium-sized sauce pan.  Bring to a boil and lower heat boiling gently for 25 minutes with frequent stirring until the liquid reaches a syrupy consistency. Remove from heat and add almond extract. Allow cherries to cool in the syrup then transfer to sealed container and store in the refrigerator (for up to 2 weeks) until ready to use. Drain in a strainer before adding to ice cream. Reserve syrup to drizzle over the top.

Chocolate ice cream: In a large bowl (if making liquid nitrogen ice cream  you must use a large metal bowl, glass or plastic can shatter from the liquid nitrogen), mix together the liquid ingredients. Add sugar and cocoa powder, stir until dissolved. Slowly and carefully add liquid nitrogen. Stir vigorously until the ice cream is smooth and set. Alternatively, add the mixture to a conventional ice cream machine. Once the ice cream has set, stir in finely chopped dark chocolate chips and candied cherries. Drizzle each serving with reserved cherry syrup and garnish with chopped toasted almonds.

Safety precautions for handling liquid nitrogen and making liquid nitrogen ice cream: Liquid nitrogen should only be handled carefully. Safety glasses should be worn to protect the eyes. It can cause severe burns, avoid direct contact with skin. Do not pour liquid nitrogen into any glass or plastic container as these can shatter. While a stainless steel bowl, like the one we use, will not shatter when the liquid nitrogen is added it will become very cold so handle with care to avoid frostbite. Stir the ice cream with a study plastic spoon or a metal spoon with a handle made of rubber or plastic that will not conduct cold.

Some flavor pairings are naturals; apples and cinnamon, garlic and tomatoes, and of course lemon with fish.

One reason is that lemon works so well with fish is that it reduces the unpleasant ”fishy” taste and smell. Did you ever wonder how this happens?

Lemons are very acidic. On the pH scale where 7 is neutral, lemon and lime juice are around pH 2.  The acidity of lemons and limes comes from their high citric acid content. Oranges have less citric acid and a pH over 4. Since the pH scale is logarithmic, like the Richter scale for earthquakes, that means that lemons and limes are more than 100 times more acidic than oranges!

So what does the acidity of lemons have to do with making fish taste less “fishy”?

That fishy taste and smell comes from natural compounds called amines. Low molecular weight amines are volatile, so they contribute strongly to the fish’s smell and taste.

You may have noticed that fresh fish tastes less “fishy” than fish that is a day or two old. This is because bacteria start to break down the compound trimethylamine oxide (TMAO) that is abundant in fish muscle forming volatile amines like trimethylamine. This process can be slowed by storing the fish on ice.

These amines are volatile only in their basic form, for example (CH₃)₃CNH₂. In the presence of lemon juice, the amine group adds a proton to form (CH₃)₃CNH₃⁺ and the trimethylamine is no longer volatile – no more fish smell!

Magic, and delicious.

Pla Poa – Thai Grilled Fish

Ingredients 
1 whole White Fish (Sea Bass, Tilapia, etc…), dressed
Fresh Thai Basil, coarsely torn
Fresh Lemongrass
Lemons and Limes, sliced
Canola Oil
Salt

Warm up your grill, and brush oil on the grates. Wash your fish, and pat him dry. Pound the lemongrass stalks and and cut into short pieces. Stuff the body cavity with basil, lemongrass, and lemon and lime slices. Slice each side of the fish 3-4 times, and coat the outside in canola oil and a generous quantity of salt. Grill on each side for about 10 min until flesh is opaque and flaky. Do not flip more than once.  Serve hot with extra citrus wedges.

Antioxidants are often used to advertise the health-giving properties of dietary supplements,  juices, baby food, and even dog treats.

As the name suggests, this class of compounds helps to fight against oxidation caused by other molecules. Although we need oxygen to survive, our bodies have to cope with powerful reactive oxygen compounds like peroxide (H₂O₂) superoxide anion (O₃^-) and hydroxide radical (OH^.) that are produced as a consequence of normal metabolism.

Although our bodies naturally produce antioxidant compounds and enzymes that help to convert these free radicals to less toxic species, sometimes the levels of these reactive oxygen species can overwhelm our ability to neutralize them and damage to proteins, lipids and DNA can result. Oxidative stress is thought to contribute to a number of diseases including Alzheimer’s disease, heart disease and cancer.

Luckily our bodies can also acquire antioxidants from our diet. Some of which, like ascorbic acid (vitamin C), are water soluble, while others, like retinol (vitamin A), β-carotene and α-tocopherol (vitamin E), are fat soluble. The physiological role of these antioxidant compounds is complex; for example vitamin C can act both as an antioxidant and a pro-oxidant through Fenton reactions that reduce metal ions like iron and produce free radicals in the process, and scientific studies evaluating the benefit of taking large doses of vitamin supplements have generated mixed results.

Another potent class of antioxidants is the polyphenols, which include plant-derived flavonoids. Polyphenols include catechins, which are found in chocolate, and prominent components of tea (especially green tea), ellagitannin from pomegranate, raspberries and blueberries, resveratrol from grapes and red wine, and anthocyanins, important pigments that lend color to red cabbage and blueberries.

While these compounds have potent antioxidant activities in laboratory tests, there is some indication that their health benefits actually come from their involvement in other processes such as cell-cell signaling, inflammation, and gene regulation.  Whatever the mechanism, it is increasingly clear that due to phytochemicals like polyphenols, eating a diet rich in brightly colored fruits and vegetables is not only delicious, but may also contribute to long-term health.

Mixed Berry Tartlets

(makes approximately 20)

Ingredients

1 Pie Crust (recipe here)
1 cup Mixed Berries, fresh or frozen
1/2 cup dry White Wine
1/4 cup Granulated Sugar
1 Tbsp. Flour
Squeeze of Lemon Juice

Preheat oven to 400 degrees, and lightly oil small tart pans or mini muffin tins.  Roll out pie dough, and cut to fit into your tins. Place a few dry beans in the bottom of each tart shell on top of the pie dough. Bake for 10-15 min. until the shells begin to brown, then remove from oven and allow to cool completely before removing from tins. Discard the beans.  Combine the remaining ingredients in a saucepan. Bring to a simmer and cook for approximately 10 min. Allow to cool, then spoon into the tart shells.

Cardamom Clove Whipped Cream

Ingredients
1/2 cup Heavy Whipping Cream
4 Fancy Green Cardamom Pods
4 Whole Cloves
1 Tbsp. Powdered Sugar

Pour the heavy cream into an airtight container with the cardamom pods and cloves, and smash the pods with a muddler. Close container, shake and leave in the fridge for approximately 2 hours to let the flavors combine. When the desired flavor is obtained, remove the cardamom pods and cloves. Mix cream and powdered sugar in a large bowl, and whip until stiff.

One of our favorite ways to add polyphenols to our diet is by eating a mix of fresh or frozen berries. Berries make a wonderful addition to cereal, yogurt, pancakes, muffins and salads.

Incorporating the flavors of both summer and fall, these mixed berry tartlets will wow your taste buds and give you a healthy dose of polyphenol antioxidents.

Salmon patties are a great dinner choice when you forget to defrost the fish you were planning to cook for dinner or didn’t remember to stop at the market on your way home from work.

Although we love fresh salmon, canned salmon has a long shelf-life and should be a staple in everyone’s pantry. We use wild caught canned Alaskan salmon, which is ranked as “Best Choice” by the Monterey Bay Aquarium Seafood Watch program. Plus since it is prepared from wild, not farm-raise salmon, it contains no colorants or antibiotics and tends to have lower levels of polychlorinated biphenyls (PCBs) than the fresh salmon you will find at the fish counter of your supermarket.

The bones are largely absorbed during the canning process, making canned salmon an excellent source of calcium. Whether wild-caught or farmed, salmon does contain mercury and the FDA has recommended that consumption be limited to 12 oz per week. Still the benefits of the heart-healthy omega-3 fatty acids found at high levels in wild salmon plus its great flavor, make salmon patties a healthy choice for your family.

You may have heard a lot about the health benefits omega-3 fatty acids. They have been reported to reduce the risk of heart attack and stroke, lower triglyceride levels and fight inflammation.

With a general formula of CH₃(CH₂)_nCOOH, fatty acids are composed of a long-chain hydrocarbon backbone (CH₂) with a carboxylic acid (COOH) group at one end and a methyl group (CH₃) at the other. Omega-3 fatty acids are polyunsaturated, which means that they have several double bonds. In all naturally derived fatty acids the double bonds are in the cis configuration, meaning that the two hydrogens are on the same side of the double bond.

In contrast, trans fatty acids, which are synthesized chemically, have hydrogens on both sides of the double bond. The methyl group (CH₃) is called the omega end of the fatty acid, and an omega-3 fatty acid has its first double bond 3 carbons down from the methyl carbon. Mammals cannot synthesize omega-3 fatty acids and so we must get them from our diet. Fish, algae and flax seeds are all excellent sources of omega-3 fatty acids.

Salmon Patties

Ingredients
1 can (14.75 oz) Salmon
6 Scallions
1 cup Panko Bread Crumbs
2 Eggs
1/8 tsp Pepper
1 tbsp fresh Dill, finely chopped (optional)
1 tsp Red Pepper Flakes (optional)

Drain salmon and remove remaining bones (optional).  Finely chop scallions, reserving a few small green ends for garnish. Add eggs to a medium-sized bowl and stir lightly to break up yolks. Add salmon, bread crumbs, scallions, dill and pepper. Mix well and form into patties. In a large skillet heat a 50:50 mixture of olive and vegetable oil on medium high heat. Add patties after oil is hot and cook each side to a golden brown. If desired, serve with aioli or sour cream. Garnish with lemon wedges, and finely chopped green scallion ends.

On the table in less than 20 min.

One of my favorite cocktails is the gin and tonic — simple, crisp and refreshing on a late summer afternoon. As you probably know, gin is an English alcoholic spirit flavored with juniper berries, but what exactly is tonic? Sounds like medicine doesn’t it?

Actually tonic water originated as a form of medicine to help prevent people from getting malaria. Originally tonic water contained only carbonated water and quinine, as an antimalarial agent. Quinine is very bitter and gin was added to make the drink more palatable. Today’s tonic water is usually sweetened with corn syrup or sugar, an addition surely devised over time to counter the bitter taste.

Cucumber Watermelon Gin and Tonic

Ingredients (Makes One Cocktail)
2 oz. Watermelon Juice
1 oz. Cucumber Juice
1 oz. Gin
2 oz. Tonic Water
Squeeze of Lime Juice

I juiced the watermelon and cucumber by putting big chunks into the food processor until smooth and then straining out the “pulp”. To make the cocktail, just combine ingredients over ice, stir, and enjoy with friends.

If you live in or are traveling to the tropics, don’t rely on gin and tonic to stay malaria free. Most strains of malaria today are quinine resistant, and the amount present in the tonic water today is much lower than would be required to be effective. Still, after a long day, a gin and tonic with a slice of lime can be good “tonic” for unwinding before dinner.

What is the difference between rain and fog? Both are droplets of water, the difference is in their size. Raindrops are large and heavy enough that they fall from the sky; whereas, the tiny droplets of water in fog are so small that they remain suspended in the air.

Aioli, mayonnaise, and other emulsions are similar to fog. These emulsions are created by making droplets of oil so tiny that when mixed together with egg yolks, a new, smooth and creamy substance is formed. The egg yolk, an emulsifier, stabilizes these tiny droplets and keeps them from recombining.

You can think about the emulsifier as acting like dish detergent. Have a greasy skillet to wash? Warm water and your favorite dish detergent help the oil dissolve so you can wash it away. Emulsifiers work similarly helping disperse the tiny droplets of oil to form a smooth opaque homogenous phase. Traditionally aioli was made using only garlic as an emulsifier, but today nearly every recipe will include egg yolk as well as garlic to ease the process of emulsification.

Although stable, an emulsion is not a solution. In a solution the substances mix at the molecular level and the result is clear, meaning that light can pass through. In an emulsion, the droplets are so tiny that we cannot see them, but they are big enough to scatter light, and the result is a substance that is not transparent even if the parent liquids are clear.

Simple Homemade Aioli

Ingredients
2 large Egg Yolks
3-4 large cloves of Raw Garlic
1 cup Oil
1/4 tsp Salt
1 Tbsp Water

It is important to use high quality,fresh eggs. This will give you better flavor, and a smaller chance of salmonella poisoning. Separate the egg yolks from the whites, and let it sit out for about 30 min to warm up to room temperature.  Meanwhile mince the garlic with a large knife, combining with the salt to form a thick paste. Also measure out the oil you will be using – canola oil and olive oil work best. I usually use a combination of the two depending on how strong my olive oil is and the flavor that I’m going for.

Whisk together the garlic and egg yolk in a large bowl. While whisking continuously begin to add the oil as slowly as possible. The mixture should combine forming a thick opaque emulsion. If you notice that the oil is starting to separate (maybe  you added to much oil), continue to whisk until it comes together before continuing. Continue to add the oil slowly until you’ve used all the oil. If you want to use the aioli for dipping, you may want to whisk in some water to thin the mixture.

Store the aioli in a covered container in the fridge for up to one week. Enjoy on sandwiches, french fries, roasted vegetables, or anything else you have laying around. Note: You can also use a small food processor to ease the emulsification process, but the basic idea is the same.

Baked Sweet Potato Fries

Ingredients
1 medium Sweet Potato
1 Tbsp Olive Oil
1/4 tsp Season Salt

Cut the sweet potato into thin rectangles. Try to make the thickness relatively even, so that they all cook at the same rate. Toss the raw sweet potato fries in oil and salt until coated. Bake on aluminum foil at 400 degrees for about 20-25 min until crispy, stirring every 5-10 min. Makes about 2 servings.

Caramelization is an amazing process. Although the chemical process of caramelization is fairly complex, it is quite possibly the tastiest outcome of humankind’s enlightened use of fire.

Some confuse the process of carmelization with the Maillard reaction that leads to the wonderful brown crust that forms on the outside of a seared steak, but that is a topic for another day. As the onions are heated, the sugars they release decompose by a process that is called pyrolysis. The sugar contained in onions is sucrose (table sugar), which itself is a molecule comprised of two other sugars: glucose and fructose. One of the reasons that carmelized onions have such a rich and complex flavor is that the pyrolysis of sucrose produces many different products through different chemical reactions. Sucrose breaks apart to form glucose and fructose, the sugar molecules lose water and recombine to form larger molecules (polymers) that are unsaturated, giving caramel its brown color.

Caramelization is a gentle process that is difficult to hurry. Throughout the process volatile components are produced that give the caramelized onions their distinctive smell and taste. The rate of the reaction is sensitive to pH, being slowest at neutral pH, so adding vinegar to lower the pH of your onions can help to speed the reaction. Balsamic vinegar, which is both sweet and acidic, is often used to speed up the caramelization process while at the same time enhancing the sweet flavor of the onions.

Caramelized Onion, Fig and Goat Cheese Crostini

Ingredients
Caramelized Onions (see below)
Chèvre
A fresh Baguette
Fig Spread (I used Trader Joe’s Fig Butter)

These are such easy, elegant appetizers! Slice baguette, and toast lightly. Smear on some fig spread, top with caramelized onions and cheese, and serve.

Caramelized Onions

Ingredients
2 large Onions (white or yellow)
2 Tbsp Olive Oil
1 Tbsp Balsamic Vinegar

Slice onions thinly. Sauté onions and olive oil in a stainless steel pan over medium heat. After about 10 min. add vinegar, and reduce heat to low. Stir every 5 min or so for an additional 45-50 min. They can be made ahead of time, and stored in the refrigerator in an airtight container for several days.

Well worth the wait!

Illa making Hungarian pancakes

A few months ago I was in Budapest and was treated to a home cooked Hungarian dinner and wonderful conversation in the home of my friend Bela and his daughter Illa. The first course (as is typical in their home) was soup; a hearty and delicious soup prepared by Bela and served with wonderful crusty bread to sop up every last drop from the bowl. The second course was to be Hungarian pancakes, prepared by Illa (age 10). I was really curious about these Hungarian pancakes, because I had never seen them, so I watched carefully as Illa prepared the batter: eggs, milk, oil, flour, sugar and just a pinch of salt. She needed no recipe, but carefully added portions to get the consistency just right. The batter was much thinner than my pancake batter. “No leavening agent?” I asked Bela? “None” came the reply. Only after Illa made the first pancake, did I realize that these were what you and I would call crepes. They were wonderfully thin and light and we ate them rolled around spoonfuls of homemade apricot or plum jam, or filled with cottage cheese lightly sweetened with honey and seasoned with grated lemon zest. Delicious, delectable, but in my book – not pancakes.

Compared with crepes, American style pancakes have a thicker batter (a larger flour to milk ratio). Even though they are thicker, they are also light and airy as a result of the bubbles that form while they cook. I watch these bubbles to know when to flip my pancakes so that they are not doughy in the middle. Did you ever wonder what causes these bubbles, which are so important to the pancake texture? The bubbles are carbon dioxide (CO₂). This is the same gas we exhale, plants use to make sugar through photosynthesis, and in frozen form makes dry ice.

The source of the bubbles is the leavening agent added to our batter in the form of baking powder. A leavening agent is just a fancy name for something you add to make a batter rise. Baking powder contains sodium bicarbonate (NaHCO₃), which is also in your cupboard as baking soda. The difference is that in addition to the sodium bicarbonate, baking powder also has an acidic component which as added as a salt. A chemical reaction between the sodium bicarbonate and this acid releases carbon dioxide gas in our pancake batter. This is the same chemical reaction as is used to make a baking soda volcano by adding vinegar, an acid, to baking soda (along with some red food coloring, of course, to make the lava).

I use double action baking powder. This type contains two acid salts: one, usually cream of tartar, that acts while cold, and a second one that acts when heated. This double action gives the product better reliability. One reason that buttermilk is a popular component of many pancake batters is that it is naturally acidic, containing lactic acid, giving it a tart, sour taste. This acid also helps the baking powder or baking soda release their CO₂ bubbles, making the pancakes light and fluffy.

Buttermilk Pancakes

Ingredients 
1½ cups Flour
3 Tbsp Sugar
¾ tsp Salt
3 tsp baking powder
½ tsp baking soda
1 egg
1 ¼ cup buttermilk

3 Tbsp melted butter (can substitute vegetable oil)

Sift together dry ingredients. In a separate bowl beat egg and stir in buttermilk and melted butter. While stirring slowly add dry ingredients. Mix together quickly but do not beat.  Cook on a hot griddle.

Mixed Berry Compote

Ingredients
1 cup fresh or frozen Mixed Berries
3 Tbsp. Sugar
Juice of 1/2 of a Lemon

Combine ingredients in a sauce pan, bring to a simmer for 1-2 min, cool, and serve.

Sweet Vanilla Butter

Ingredients
4 Tbsp Unsalted Butter
2 tsp of powdered sugar
1 tsp vanilla extract

Let butter soften. Combine butter, sugar, and vanilla in a bowl, and whip together. Store in the refrigerator.

Sweet Vanilla Butter is HEAVEN.