Heston Blumenthal has investigated how sound affects chewing, but I didn’t know that sound was so important for how we perceive the taste of apples. Studying particularily crisp apples, named Jazz apples, researchers found the following:

Professor Povey said, “When you munch a Jazz apple you create pulses of sound containing large amounts of ultrasound which our brains interpret differently from ordinary sounds such as speech. The pulses are so intense that if they were sustained as a tone, they would destroy our hearing.”

“It appears that ordinary hearing is short-circuited somehow and the greater the number of pulses of sound, the crisper we think the food is. Ultrasound is sound that is beyond the range of normal human hearing but it helps shape the noise into pulses that sound quite different.

“Our group of subjects were culturally diverse but all were able to identify crispness similarly. So perhaps there is a genetic disposition to the appreciation of crispness which has evolved as a sign of freshness in food.”

In a comment to my post on making carbonated fruit the iSi way, JoJo at eat2love made me aware of a company, FizzyFruit, that actually sells carbonated fruit in pressurized containers. The fruits currently available are grapes, honeydew and cantaloupe. Turns out that their homepage features some recipes by – surprise, surprise – Homaru Cantu! Here are some of the recipes:

Proscuitto and melon
150 g carbonated melon
12 slices proscuitto ham
1 dL balsamic vinegar, frozen, shaved to snow
salt
olive oil

Wrap melon pieces with proscuitto, season with salt and drizzle with olive oil. Scatter balsamic “snow” over the top just before serving.

Champagne and Crab
150 g carbonated grapes
350 g picked crabmeat
1/4 bunch of chives, chopped
1 diced shallot
1 orange, juiced and zested
1/2 dL mayonnaise
1/2 dL fennel, shaved thinly
salt

Toss crab with shallot, fennel, mayonnaise and orange juice/zest. Season with salt and leave in refridgerator for 1 hour. Add carbonated grapes, toss with crab mixture and chives. Serve immediately.

Orange Sangria
2 L fresh squeezed orange juice
150 g carbonated fruit (grapes, melon)
8 sprigs of crushed mint
5 dL of crushed ice

Combine ice, orange juice and mint. Add carbonated fruit and serve immediately.

Fresh Fruit Trifle
150 g carbonated fruit (grapes, melon)
2.5 dL fresh whipped cream
1/2 vanilla bean scraped

Add vanilla bean scrapings to cream and whip until stiff peaks are formed. Layer carbonated fruit with whipped cream and serve immediately.

Ants on a Log
150 g carbonated grapes
2.5 dL of chunky peanut butter
4 long ribs of celery

Rinse and dry celery. Fill celery with peanut butter. Stud the celery with the carbonated grapes. Serve immediately.

(The recipes were made generic and converted to metric units)

Based on some googling of espuma and foam recipes (including Ferran Adria’s coffee espuma), I figured that the following should work:

2 dL coffee
2 sheets of gelatine
3 dL heavy cream
sugar/vanilla sugar

Soak gelatine in cold water. Strain. Dissolve gelatin sheets in the hot coffee and stir in sugar while heating. Cool. Add heavy cream. Filter through a fine meshed sift (just in case there should be any undissolved sugar, gelatin or particles) into a 0.5 L iSi gourmet whipper. Screw on top and charge with a cream charger. Shake 2-3 times and leave in fridge for a couple of hours. Hold whipper upside down, shake once to displace mixture towards the nozzle in case it is stuck and dispense. Texture is soft and silky. Tastes delicious!

Some more chemistry: The cream chargers contain dinitrogen oxide (N₂O) which is less polar than carbon dioxide (CO₂), and hence more soluble in fat (such as heavy cream for instance). Another reason why carbon dioxide is not used in this recipe is probably that when it dissolves, some carbonic acid is formed which could curdle milk based products if pH drops to much and also influence taste (but carbonated milk has actually been marketed!). The idea of using dinitrogen oxide for soda/beer has also been explored.

(Photo by vintage_patrisha at flickr.com)

4. Learn how to control the texture of food

Taste and flavour normally get more attention when food is discussed, but the texture of food is equally important and our tongue is very sensitive, not only to taste and temperature, but also to the texture of food. The texture of food determines it’s mouthfeel and it is related to many physical properties of the food. Wikipedia lists the following aspects of mouthfeel (click to see the full description of each aspect) which can be useful when analyzing food:

Adhesiveness, Bounce/Springiness, Chewiness, Coarseness, Cohesiveness, Denseness, Dryness, Fracturability, Graininess, Gumminess, Hardness, Heaviness, Moisture absorption, Moisture release, Mouthcoating, Roughness, Slipperiness, Smoothness, Uniformity, Uniformity of chew, Uniformity of bite, Viscosity, Wetness

I will barely scratch the surface of how texture can be controlled by highlighting a couple of topics and point you to further resources. Hopefully it will spark your interest and give some new ideas for you to play with in the kitchen. Those interested in a comprehensive review of food texture are referred to the CRC handbooks on food texture (volume 1: semi-solid foods, volume 2: solid foods).

What determines the texture of food?
Put very simple, it’s the relative amounts of air, liquid and solids that determines the texture of food. This is complicated by the fact that liquids have different viscosities. Furthermore the air, liquid and solid ratio is not necessarily constant. A liquid can solidify or evaporate, solids can melt or dissolve, and air bubbles can escape during cooking or storage. An elegant but quite abstract way of describing the complicated mixtures of air, liquids and solids found in food, is to use the CDS formalism (CDS = complex disperse systems), introduced by Hervé This.

(Photo by Subspace at flickr.com)

How can texture be controlled and changed?
Texture can be controlled by temperature, pH, air/liquid/solid ratio, osmosis, hydrocolloids and emulsifiers – to mention a few. Here’s some examples:

(Photo by Trinity at flickr.com)

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Check out my previous blogpost for an overview of the tips for practical molecular gastronomy. The collection of books (favorite, molecular gastronomy, aroma/taste, reference/technique, food chemistry) and links (webresources, people/chefs/blogs, institutions, articles, audio/video) at khymos.org might also be of interest.

In a recent survey 72% of chefs say they may want to experiment with molecular gastronomy in 2007. That’s an impressive number and considering the attention molecular gastronomy gets in media I bet many home cooks would want to experiment in the kitchen as well. Here’s a list of things to consider if you want to make a scientific approach towards cooking:

1. Use good and fresh raw materials of the best quality available.

2. Know what temperature you’re cooking at. A dip probe thermometer with a digital read out is a cheap way to bring science into your kitchen.

3. Get a basic understanding of heat transfer, heat capacity and heat conductance. “Heat” in this context des not imply high temperature since it also applies to the understanding of freezing/thawing.

4. Learn how to control the texture of food. Some key points: temperature induced changes (freezing, heating), emulsifiers, thickeners, gelling agents, moisture content, pressure/vacuum, osmosis.

5. Learn how to control taste and flavor. Some key points: flavor pairings, spice synergies/antagonies, influence of temperature (Maillard reaction, caramelization, temperature stability, volatility), taste enhancers, taste suppresants, solubility of flavour compounds in fat/water, extraction.

6. Remember that prolonged exposure to a flavor causes desenzitation, meaning that your brain thinks the food smells less even though it’s still present in the same amount. Therefore, let different flavours enhance each other. Similarly, variation in taste, texture, temperature and color can open up new dimensions in a dish. This is referred to as “increased sensing by contrast amplification”.

7. Be critial to recipes and question authority – they do not necessarily represent “the truth”. Nevertheless, you can certainly learn a lot from the experts.

8. Dare to experiment and try new ingredients and procedures. Do control experiments so you can compare results. When evaluating the outcome, be aware that your own opinions will be biased. Have a friend help you perform a blind test, or even better a triangle test to evaluate the outcome of your experiments.

9. Keep a written record of what you do! It would be a pity if you couldn’t recreate that perfect concoction you made last week, simply because you forgot how you did it.

10. Have fun!

Heat causes many changes in food, but few appreciate how important it is to know at what temperature they are cooking and at what temperature the desired change occurs.

These tips for molecular gastronomy relate to the technical and scientific aspects of food preparation and eating, and I plan to elaborate on each of the points in separate blog posts. However, according to Hervé This’ definition of molecular gastronomy, one should also investigate the social and artistic components of cooking. A good example of this is the “Five Aspects Meal Model” developed at Grythyttan in Sweden (Gustafsson, I.B. et al. Journal of Food Service, 2006, 84.). Although intended for a restaurant setting, the general idea can also be applied for home cooking.

The meal takes place in a room (room), where the consumer meets waiters and other consumers (meeting), and where dishes and drinks (products) are served. Backstage there are several rules, laws and economic and management resources (management control system) that are needed to make the meal possible and make the experience an entirety as a meal (entirety – expressing an atmosphere).

Or to put it differently: average food eaten together with good friends while you’re sitting on a terrace with the sun setting in the ocean will taste superior to excellent food served on plastic plates and eaten alone in a room with mess all over the place.

One last thing: once you’re finished in the kitchen with your culinary alchemy, your gastro physics, your cutting edge science cuisine, your molecular cooking, your hypermodern emotional cooking, your science food or whatever fancy name you attach to it – remember the social and artistic components when you serve the food. Just so people won’t refer to you as a techno chef, a mad scientist or a modern day Willy Wonka. After all, molecular gastronomy is about the science of deliciousness, not technical wizardry.

Questions and topics for future blog posts are welcome at webmaster [a] khymos.org (substitute @ for [a]) or as a comment below.